Spit/109 sea level speed comparisons in 1.08 beta patch

[camber]

Since there is a bit of current interest in FMs, I did some quick sea level tests for the current beta patch (1.08 ), and compared to generally accepted real life performance. As patches could change any time I didn't want to spend much time doing full speed vs alt tests.
These are the tests (with real life data):

http://i406.photobucket.com/albums/pp142/wjhawaii/Comp2.jpg

My Spit CoD data is using 2700rpm (full boost) instead of 3000rpm to postpone engine failure and allow speed testing. This is not so much of a problem as there does not seem any speed increase from 2700-3000 rpm anyway. Rads full open, canopy closed (although speed effects from these are negligible to nonexistant). The 109E4 uses auto prop pitch, oil and water rads open.

For real life data, the RAE Spit I data is pretty well accepted (although speeds are a little high due to lack of pilot armour and IFF equipment). The real life 109 is a bit difficult, I started a thread on 109 performance a while back and argued that actual 109 performance at sea level was likely to be approximately on the pass/fail mark on the Messerschmitt official specification (475kmh) based on what flight tests were available. Kurfust disagreed and maintained that the appropriate value is 500kmh at sea level (average of Me official spec), which is a defensible position.

http://forum.1cpublishing.eu/showthread.php?t=32259

I think for the sake of CoD using the 500kmh@SL for the 109 would be reasonable, might save a few arguments and work well in multiplayer if it was implemented.

For graphing purposes I plot both 475kmh@SL ("close pass") and 500kmh@SL ("average Me guaranteed") 109s.

http://i406.photobucket.com/albums/pp142/wjhawaii/Comp1.jpg

From the real life data, the 87 octane Spit I (or 100 octane but not using "WEP") was slower than both the 475kmh and 500kmh 109Es. Using the 100 octane +12psi boost, the Spit was faster than the 475kmh 109 but about the same speed as the 500kmh 109E. So taking the 500kmh 109E as a good fit for CoD, we are looking at approximate speed parity for 100 octane Spits and 109s going all out on the deck.

Besides the fact that all speeds are around 50kmh low, the current CoD data is a bit dire in this respect when looking at relative 109/Spit speeds.
It's not too bad just looking at the Spit Ia at +12psi versus the 109 at 1.35ata (5 min limit), with both aircraft at about the same speed (similar to real life Spit + 12psi and "official spec" 500kmh 109). However, there are two big catches.

* First, the CoD 109 has access to it's historical 1 min takeoff only boost (1.45ata), and can use it (unhistorically) practically continuously with no engine problems. This allows it to go 20kmh faster than the CoD Spit all out at +12psi.

* Second, the CoD Spit has extremely time limited access to +12psi without blowing the engine. So very quickly, the Spit will have to turn off the boost cutout and drop back to around 400kmh. The CoD 109 is now 70kmh faster at SL if it continues to keep activating 1.45ata. However it doesn't need to bother as without it is still 50kmh faster than the CoD Spit stuck back at +6psi.

Some quick tests on turning off temp effects are interesting, this increases the SpitIa 100octane speeds by about 10mph/15kmh but doesn't affect the 109. Clearly the temperatures that the Spits run at decrease engine output even when the engine does not fail, which does not occur in the 109.

With temp effects off the Spit can maintain +12psi continuously at around 460kmh, against the 470kmh of the 109 using 1.45ata. It would be rather hard on the 109 driver having to continuously press his 1.45ata while the Spit driver can select +12psi and leave it on though! It would be closest match to historical performance we could get without FM revision though (at least at sea level!)

camber

[NZtyphoon]

Since there is a bit of current interest in FMs, I did some quick sea level tests for the current beta patch (1.08 ), and compared to generally accepted real life performance. As patches could change any time I didn't want to spend much time doing full speed vs alt tests.
These are the tests (with real life data):

http://i406.photobucket.com/albums/pp142/wjhawaii/Comp2.jpg

My Spit CoD data is using 2700rpm (full boost) instead of 3000rpm to postpone engine failure and allow speed testing. This is not so much of a problem as there does not seem any speed increase from 2700-3000 rpm anyway. Rads full open, canopy closed (although speed effects from these are negligible to nonexistant). The 109E4 uses auto prop pitch, oil and water rads open.

For real life data, the RAE Spit I data is pretty well accepted (although speeds are a little high due to lack of pilot armour and IFF equipment). The real life 109 is a bit difficult, I started a thread on 109 performance a while back and argued that actual 109 performance at sea level was likely to be approximately on the pass/fail mark on the Messerschmitt official specification (475kmh) based on what flight tests were available. Kurfust disagreed and maintained that the appropriate value is 500kmh at sea level (average of Me official spec), which is a defensible position.

http://forum.1cpublishing.eu/showthread.php?t=32259

I think for the sake of CoD using the 500kmh@SL for the 109 would be reasonable, might save a few arguments and work well in multiplayer if it was implemented.

For graphing purposes I plot both 475kmh@SL ("close pass") and 500kmh@SL ("average Me guaranteed") 109s.

http://i406.photobucket.com/albums/pp142/wjhawaii/Comp1.jpg

From the real life data, the 87 octane Spit I (or 100 octane but not using "WEP") was slower than both the 475kmh and 500kmh 109Es. Using the 100 octane +12psi boost, the Spit was faster than the 475kmh 109 but about the same speed as the 500kmh 109E. So taking the 500kmh 109E as a good fit for CoD, we are looking at approximate speed parity for 100 octane Spits and 109s going all out on the deck.

Besides the fact that all speeds are around 50kmh low, the current CoD data is a bit dire in this respect when looking at relative 109/Spit speeds.
It's not too bad just looking at the Spit Ia at +12psi versus the 109 at 1.35ata (5 min limit), with both aircraft at about the same speed (similar to real life Spit + 12psi and "official spec" 500kmh 109). However, there are two big catches.

* First, the CoD 109 has access to it's historical 1 min takeoff only boost (1.45ata), and can use it (unhistorically) practically continuously with no engine problems. This allows it to go 20kmh faster than the CoD Spit all out at +12psi.

* Second, the CoD Spit has extremely time limited access to +12psi without blowing the engine. So very quickly, the Spit will have to turn off the boost cutout and drop back to around 400kmh. The CoD 109 is now 70kmh faster at SL if it continues to keep activating 1.45ata. However it doesn't need to bother as without it is still 50kmh faster than the CoD Spit stuck back at +6psi.

Some quick tests on turning off temp effects are interesting, this increases the SpitIa 100octane speeds by about 10mph/15kmh but doesn't affect the 109. Clearly the temperatures that the Spits run at decrease engine output even when the engine does not fail, which does not occur in the 109.

With temp effects off the Spit can maintain +12psi continuously at around 460kmh, against the 470kmh of the 109 using 1.45ata. It would be rather hard on the 109 driver having to continuously press his 1.45ata while the Spit driver can select +12psi and leave it on though! It would be closest match to historical performance we could get without FM revision though (at least at sea level!)

camber

Good work Camber - as you know we did have a thread dealing with the CLOD Spitfire I and II performance http://forum.1cpublishing.eu/showthread.php?t=33942 and another one has been started http://forum.1cpublishing.eu/showthread.php?t=34075.

1)As shown below, the Merlin was more than capable of running for extended periods at +12 lbs boost (paragraph 4 8 hrs at +12 lbs, terminated by a glycol leak, a problem which was solved by a redesign of the head): Merlin engines should not be overheating or failing almost as soon as the 5 minute limit is up, there needs to be far more leeway than has been given.

2)I have not yet tested the Defiant or Hurricane but, as shown by ACE-OF-Aces, and below, the CLOD Spitfire performance figures do not match real world performance.

http://i91.photobucket.com/albums/k304/Major_Sharpe/spit1-013a.jpg

[5./JG27.Farber]

* First, the CoD 109 has access to it's historical 1 min takeoff only boost (1.45ata), and can use it (unhistorically) practically continuously with no engine problems. This allows it to go 20kmh faster than the CoD Spit all out at +12psi.


Actually it can't just be used willy nilly. Activating it at the top of a "zoom" climb when pitch is at 12:00 and your hanging on the prop will blow the engine. I'd also like to add pressing wep at SL when already going all out throttle, pitch and speed at 460 (rarley 480) doesnt add any more speed. The wep seems to add more power at lower sppeds to me.


The graphs having different scales makes it very hard to compare, any chance of putting it all on one graph? - Or at least the same scaled graph?

FT = Full Throttle? I think nearly all the speed tests on the 109 were done at 1.3 or 1.35 Ata were they not? Not full throttle...

[Ze-Jamz]

Nice work OP... interesting

[Ze-Jamz]

Actually it can't just be used willy nilly. Activating it at the top of a "zoom" climb when pitch is at 12:00 and your hanging on the prop will blow the engine. I'd also like to add pressing wep at SL when already going all out throttle, pitch and speed at 460 (rarley 480) doesnt add any more speed. The wep seems to add more power at lower sppeds to me.

Your correct on WEP having no effect at higher ALT IMO..

Climbing yes but all out power no.

And I agree also about boost being used as often as you like in the 109...not true and I think this cones from pilots that don't fly it, do it high Altitude continuously and see what happens, so it continuously on max pitch and full throttle with low speed and your kill it too..

[Kurfürst]

Merlin engines should not be overheating or failing almost as soon as the 5 minute limit is up, there needs to be far more leeway than has been given.

That would be an opinion. We need to see a cooling trial to see wheter it's a valid opinion or not. Preferably in a different thread.

[bongodriver]

That would be an opinion. We need to see a cooling trial to see wheter it's a valid opinion or not. Preferably in a different thread.


the 5 minute limit 'has' to be a guaranteed absolute minimum in order to be an allowed limit, the likelyhood of failure 'at' 5 minutes is low and increases proportionally with time beyond the 5 minutes, I don't care if the failure rate is 100% at 6 minutes it's just highly unrealistic to have guaranteed failure at 5:01.

[klem]

That would be an opinion. We need to see a cooling trial to see wheter it's a valid opinion or not. Preferably in a different thread.

5 mins was the instruction in the pilots notes. It did not mean instant failure.

Given that combats usually last only a few minutes it should not be a problem too often. Its true though that information on the maximum time before failure needs to be found or, perhaps more correctly, information that will allow the devs to simulate properly the temperature effects of BCO and then, presumably, the temperature effects on the engine will already have been modelled....... ermmmm I say the latter with my tongue in my cheek.

[5./JG27.Farber]

Your correct on WEP having no effect at higher ALT IMO..

Climbing yes but all out power no.

And I agree also about boost being used as often as you like in the 109...not true and I think this cones from pilots that don't fly it, do it high Altitude continuously and see what happens, so it continuously on max pitch and full throttle with low speed and your kill it too..

Yep and long periods over 1.3 and deffinatley over 1.4 (usually cos of wep) will destroy the engine even though temps and RPM are normal.

[Kurfürst]

the 5 minute limit 'has' to be a guaranteed absolute minimum in order to be an allowed limit, the likelyhood of failure 'at' 5 minutes is low and increases proportionally with time beyond the 5 minutes, I don't care if the failure rate is 100% at 6 minutes it's just highly unrealistic to have guaranteed failure at 5:01.

I agree, I am pretty sure the Merlin could operate well beyond 5 minutes at maximum power, if the prescribed temperature limits are also observed at the same time. After all these engines usually went through 100 hour tests before service approval, tested for many many hours at full power, but with controlled oil and coolant temperatures.

As I understand the reason for Merlin engine failures in CLOD are probably related to:

a, Exceeding oil and/or coolant operating temperatures of the Merlin. Obviously engine failure is a very obvious conseqence of too high temperatures, so the real question is IMHO
aa, how long the Spit / Hurri could be run at + 6 1/4
ab) how long the Spit / Hurri could be run at + 12, which is about 30% more power/heat load.

b, Fall of oil pressure during negative-g manouvers, resulting that the engine is insufficiently lubricated, which can and will destroy an engine in very short order, any engine, and should be correct for the 1940 neg-g sensitve Spit/Hurri (which's manual specifically warns against negative-g and low oil pressure conditions), so I sense that Red pilots not knowing/ignoring this limitation may be at the culprit.

[camber]

Actually it can't just be used willy nilly. Activating it at the top of a "zoom" climb when pitch is at 12:00 and your hanging on the prop will blow the engine. I'd also like to add pressing wep at SL when already going all out throttle, pitch and speed at 460 (rarley 480) doesnt add any more speed. The wep seems to add more power at lower sppeds to me.


The graphs having different scales makes it very hard to compare, any chance of putting it all on one graph? - Or at least the same scaled graph?

FT = Full Throttle? I think nearly all the speed tests on the 109 were done at 1.3 or 1.35 Ata were they not? Not full throttle...

Hi Farber,

Sounds like I may be overstating the ease and safety of 1.45ata use in the 109. In my speed tests I tried restarting it a few times at SL and didn't see engine problems but didn't try many variations. I got 450kmh without and 470 kmh with it on, is that consistent with you?. The 1.45ata in combat makes it harder to work out how best to configure the 109 in CoD, if you gave the 109 500kmh at around 1.3ata and combat access to 1.45ata, you have a VERY fast bird indeed in CoD considering historical information.

For the 109 tests I left auto prop pitch on and had the throttle fully open, with the boost regulation giving 1.35ata or 1.45ata. FT is full throttle as you surmise.

I scaled the plots seperately because I wanted to talk about relative speeds in real life and game. Both plots have a 120kmh range on the y axis, the CoD one starts 50kmh lower because all speeds in CoD are roughly 50kmh low. These tests are really a bit basic..only sea level max speeds done singly offline.

[Kurfürst]

5 mins was the instruction in the pilots notes. It did not mean instant failure.

I was more reflecting to the (baseless) part of the claim, that "Merlin engines should not overheat within 5 minutes"

Actually they can, like any other engine, depending on conditions.

The manual says that if possible, the pilot should not operate the engine for more than five minutes at + 6.25 (+12) boost / 3000 rpm, AND that the maximum oil and coolant (iirc 125 degrees Celsius) temperatures during that period are NOT to be exceeded. The overstepping five minutes is less a problem, it will wear out the engine quicker for sure, but temperatures will kill it much quicker. If you run the engine coolant/oil at 160 degrees Celsius it will fail anyway, and I would say, likely well before 5 minutes.

Given that combats usually last only a few minutes it should not be a problem too often. Its true though that information on the maximum time before failure needs to be found or, perhaps more correctly, information that will allow the devs to simulate properly the temperature effects of BCO and then, presumably, the temperature effects on the engine will already have been modelled....... ermmmm I say the latter with my tongue in my cheek.

I agree.

[Robo.]

Sounds like I may be overstating the ease and safety of 1.45ata use in the 109.

I guess that is because this is a fairly new feature in recent beta patches (1.07 onwards afik). It used to be just as you described it...

I haven't got enough hours in 109 in 1.08 to comment on that to be honest. I managed to damage the engine when I forgot to open the water rad, but I never damaged it by using the WEP as long as my rpm weren't too high.

[Ze-Jamz]

I guess that is because this is a fairly new feature in recent beta patches (1.07 onwards afik). It used to be just as you described it...

I haven't got enough hours in 109 in 1.08 to comment on that to be honest. I managed to damage the engine when I forgot to open the water rad, but I never damaged it by using the WEP as long as my rpm weren't too high.

The effect you get from execissve use at certain instances of Boost is not the same as cooking your engine throuh heat, I'm not sure what damage is modeled in game but you suffer with lack of power and can't seem to get your rpm as high as normal..can't remember the exact figure as I try not to do it often

[ATAG_Snapper]

The Merlin engines in the Spitfire MK 1a 100 octane die at 97 C oil temp for all boost and rpms settings in beta 1.08.

[ATAG_Dutch]

Rads full open, canopy closed (although speed effects from these are negligible to nonexistant).

Are you sure about this Camber?

Edit: Test conducted with Spit Ia100oct, prop as near to feathered as possible.

http://www.youtube.com/watch?v=ksCmgBaTrtQ

[NZtyphoon]

The Merlin engines in the Spitfire MK 1a 100 octane die at 97 C oil temp for all boost and rpms settings in beta 1.08.

Merlin II & III Temperatures: Oil = 90-95°, coolant <90° and 120° emergency maximum for five minutes.

The effect you get from execissve use at certain instances of Boost is not the same as cooking your engine throuh heat, I'm not sure what damage is modeled in game but you suffer with lack of power and can't seem to get your rpm as high as normal..can't remember the exact figure as I try not to do it often

Using high boost at low rpm can lead to pre-ignition, although I haven't yet tried it to see what happens in CLOD: the Pilot's Notes General advise raising the rpm before increasing boost and reduce the boost before decreasing rpm to cruising level.

Just looking at ATAG-Dutch's demo the rpm doesn't seem to go above 1,600 in two tests 130-440 mph...hmmm.

[Osprey]

Regarding the comment on relative difficulty in operating the 109 WEP vs just leaving the 12lbs 'on' with the Spit, please note that when operating the BCO one has to piddle about with the mixture, which isn't always that easy, or rough running occurs.

Regarding the oil pressure drop causing damage. RR performed tests on this and one Hurricane was subjected to 100 continuous rolls before any signs of damage occurred.

[ATAG_Dutch]

Just looking at ATAG-Dutch's demo the rpm doesn't seem to go above 1,600 in two tests 130-440 mph...hmmm.

Hi Typhoon, the test was conducted with the csp brought back to as close to feathered as possible, plus throttle zero. This was to minimize the other drag effects other than the radiator. Trims were not altogether uniform in the three runs either. However, in a vertical dive, gravity assisted only, the radiator shutter caused a full 3 second discrepancy from minimum time at 50% rad and maximum time at 100%.

I'll happily upload the mission I did this with in FMB if anyone would like to carry out the test themselves. The times in 100ths of a second were from the counter in windows movie-maker. This meant i could measure the time from the frame first 'unpaused' to the ASI hitting 440mph. Well, the next line on the gauge after 420.

[ATAG_Snapper]

On a positive note, losing the rudder far below its rated 450 mph IAS helps reduce the Spitfire's roll rate in a dive. Usually the ailerons and elevator are quick to go as well. Losing the elevator ensures the pilot will not overstrain the airframe even if he hauls back on the control column excessively. The airframe should thus remain relatively intact until impact with the ground. It's all good.

[5./JG27.Farber]

Hi Farber,

Sounds like I may be overstating the ease and safety of 1.45ata use in the 109. In my speed tests I tried restarting it a few times at SL and didn't see engine problems but didn't try many variations. I got 450kmh without and 470 kmh with it on, is that consistent with you?. The 1.45ata in combat makes it harder to work out how best to configure the 109 in CoD, if you gave the 109 500kmh at around 1.3ata and combat access to 1.45ata, you have a VERY fast bird indeed in CoD considering historical information.

For the 109 tests I left auto prop pitch on and had the throttle fully open, with the boost regulation giving 1.35ata or 1.45ata. FT is full throttle as you surmise.

I scaled the plots seperately because I wanted to talk about relative speeds in real life and game. Both plots have a 120kmh range on the y axis, the CoD one starts 50kmh lower because all speeds in CoD are roughly 50kmh low. These tests are really a bit basic..only sea level max speeds done singly offline.

Thank you for you intelligent and polite reply. Hopefully it can be an example for this thread so it doesnt get locked.

My squad mates and I have been discussing the difference between the E4 auto pitch and the E1 and E3 manual pitch which is quite different. I would also go as far to say when your using autopitch your almost using the AI FM in some respects. The exact difference is hard to describe and establish exactly... The auto pitch also runs at a lower RPM than I would manually, although it gets more acceleration, better fuel economy and is overall superior except when you rapidly climb and dive continiously and it cannot keep up with you. 5./JG27Gruber could explain more on this than I think, I will see if he wants to contribute.

I can achieve 460kmh sea level with out any wep during the acceleration... Occasionally if I have my aircraft trimmed perfectly and the planets align I can get a steady 480 kmh... At 5km altitude its more like 420kmh.

Klem started a thread about speed and the 109 was discussed also. I made some quick tracks which I will attempt to attach here. (they are messed up, I will fraps it and upload to youtube...) Close to sea level tests and 5km level flight speed tests 1.3 Ata and 2350 U/pm if I recall. I think these runs were made in 1.07. As far as I am aware the only difference to the 109 FM is the rad drag... - Which is neglible to a degree.

-Ultimatley, I am only Human. I'm proberbly not the best at flying straight and level and maybe I am even doing it wrong? I will let others be the judge of it.


EDIT1: WOW was I wrong?! 100% Fuel gave some interesting results but I need to test 50% also for comparison. There have been changes to Bf109 FM in 1.08.

[41Sqn_Banks]

Interesting .... http://www.spitfireperformance.com/n3171-cooling.jpg

From: http://www.spitfireperformance.com/n3171.html

[TomcatViP]

I agree there is some drag effect with the rads.

However, do you realize guys that there was no 100oct fuel during BoB ?

Wonder what you are looking after here?!!

Regarding the speed achieved by the tester, isn't it the same one that wasn't able to achieve 270 in a hurri ? I mean teh kind of guy taking off with a cold engine, flying hood open, at 400kph cruise speed and complaining about overheating in combat ?

I think it says it all...

I am sory but when I read "real life MkI 100oct" it really push me out of my brain.

[camber]

Are you sure about this Camber?

Edit: Test conducted with Spit Ia100oct, prop as near to feathered as possible.

http://www.youtube.com/watch?v=ksCmgBaTrtQ

Nice test Dutch, I remembered how much like I liked CoD watching Spitfires plummeting toward the green leafy fields of England.

For the last couple of patches, I found that rad position had slight effects on level speeds but only a few mph at best. I was rounding to nearest 5mph, so often the rad effect rounded out. I didn't try canopy this patch but the previous one couldn't detect anything.

From your test it looks like that rad has much more of an effect on accelleration between speeds, which is an interesting finding.

[bongodriver]

However, do you realize guys that there was no 100oct fuel during BoB ?



Troll

[Kurfürst]

Interesting .... http://www.spitfireperformance.com/n3171-cooling.jpg

From: http://www.spitfireperformance.com/n3171.html

Excellent. It should be tested in the sim under the same conditions (though this test was done in the winter) to wheter the sim has similar cooling modelling.

A vague look though tells me that the temps are rising slowly but steadily even at 6 1/4 / 2600 rpm. Overall it just looks just suitable for climbing conditions at lower powers.

[SlipBall]

Excellent. It should be tested in the sim under the same conditions (though this test was done in the winter) to wheter the sim has similar cooling modelling.

A vague look though tells me that the temps are rising slowly but steadily even at 6 1/4 / 2600 rpm. Overall it just looks just suitable for climbing conditions at lower powers.


That's just it though, some seem to want a 30,000 high power climb with no cooling problems.

[camber]

Regarding the speed achieved by the tester, isn't it the same one that wasn't able to achieve 270 in a hurri ? I mean teh kind of guy taking off with a cold engine, flying hood open, at 400kph cruise speed and complaining about overheating in combat ?

I think it says it all...

I am sory but when I read "real life MkI 100oct" it really push me out of my brain.

Hi Tomcat

Er, not sure if it is an English issue, but that reads like a hilarious insult so I will reply as such.

Maybe I (it) WAS the kind of tester that wasn't able to achieve 270 (mph?) in a Hurri while complaining. But what would you say if it got back to the airfield, abducted Spitgirl from the officer's mess, and took her to the nightspots of Picadilly in an open top Lagonda?

Looking back the only flight test of a Hurri I remember was 240-245mph on the deck in the first beta patch with FM revision (slowing Hurris down). I think it was a fair bit faster in the previous retail patch 1.05.

Will not comment on the fuel with high round number
in case the padlock gods are roused from fitful slumber.

Cheers M8

[Glider]

However, do you realize guys that there was no 100oct fuel during BoB ?


Priceless

[NZtyphoon]

Will not comment on the fuel with high round number
in case the padlock gods are roused from fitful slumber.

Cheers M8

:grin::grin::grin: I see ATAG_Dutch has been doing some tests, with interesting results, http://forum.1cpublishing.eu/showthread.php?p=457624#post457624

[5./JG27.Farber]

I have done the tests using the values in the table for the DB 601 A and B manual. I believe the new compressor is modeled, so in the box "Flying Altitude" I used the left hand column, as there is significant drop off in Ata at 4.5 to 5km rather than 4 to 4.5km... I also performed the test on a multiplayer server in case FM's are different in single player.


Using ATAG_Keller's IAS TAS converter the results are:

Test 1 Sea level 1.3Ata 2400U/pm IAS 440 TAS 440 or 273 mph
Test 2 Sea level 1.23Ata 2300U/pm IAS 430 TAS 430 or 267 mph
Test 3 Sea level 1.15Ata 2200U/pm IAS 420 TAS 420 or 261 mph

Test 4 4500metres 1.3Ata 2400U/pm IAS 400 TAS 518 or 322 mph
Test 5 5000metres 1.23Ata 2400U/pm IAS 390 TAS 518 or 322 mph
Test 6 4900metres 1.15Ata 2200U/pm IAS 370 TAS 489 or 304 mph

http://youtu.be/O4jHSMyYdkg <---- Video of tests.

Now we need to dig out the real life tests and compare.


The effect of WEP also seems to have changed. I tried making it break the engine in the usual ways but could not manage it... It also seems to have effect at all altitudes now.

[TomcatViP]

As I remember it I use to fly with a much higher pitch setting to get speed. You need to increase the blade angle. At alt, it's much around 2k or 2.1k.

Otherwise you can't convert the power of the engine into speed. Maybe there is a need to tweak the game engine.

[VO101_Tom]

As I remember it I use to fly with a much higher pitch setting to get speed. You need to increase the blade angle. At alt, it's much around 2k or 2.1k.

Otherwise you can't convert the power of the engine into speed. Maybe there is a need to tweak the game engine.

Hi. The purpose of these test to see the ingame performances, when you keep the original engine operation limits (DB 601 A-B Btriebs und Wartungsvorschrift Ausgabe C (Okt 1940) 60AE 601-XXII C10 1940). You can see this table on the first seconds of the video.

[bugmenot]

I have done the tests using the values in the table for the DB 601 A and B manual. I believe the new compressor is modeled, so in the box "Flying Altitude" I used the left hand column, as there is significant drop off in Ata at 4.5 to 5km rather than 4 to 4.5km... I also performed the test on a multiplayer server in case FM's are different in single player.


Using ATAG_Keller's IAS TAS converter the results are:

Test 1 Sea level 1.3Ata 2400U/pm IAS 440 TAS 440 or 273 mph
Test 2 Sea level 1.23Ata 2300U/pm IAS 430 TAS 430 or 267 mph
Test 3 Sea level 1.15Ata 2200U/pm IAS 420 TAS 420 or 261 mph

Test 4 4500metres 1.3Ata 2400U/pm IAS 400 TAS 518 or 322 mph
Test 5 5000metres 1.23Ata 2400U/pm IAS 390 TAS 518 or 322 mph
Test 6 4900metres 1.15Ata 2200U/pm IAS 370 TAS 489 or 304 mph

http://youtu.be/O4jHSMyYdkg <---- Video of tests.

Now we need to dig out the real life tests and compare.


The effect of WEP also seems to have changed. I tried making it break the engine in the usual ways but could not manage it... It also seems to have effect at all altitudes now.



http://www.rolfwolf.de/daten/E4/Emil.html


Auszüge aus Flugzeugdatenblatt Bf 109 E-1, E-3 nach L.Dv.556/3


Motor DB601A mit Alter Lader "Old Supercharger"


Höchstgeschwindigkeiten in Steig/Kampfleistung (Diagram)

2300 U/min 1.23 ata

http://www.rolfwolf.de/daten/E4/Emil_html_4785a2b8.gif

Höchstgeschwindigkeiten in Steig/Kampfleistung (Tabelle)

2300 U/min 1.23 ata

0km 460km/h

1km 480km/h

2km 500km/h

3km 520km/h

4km 540km/h

5km 555km/h

6km 555km/h

7km 550km/h

[5./JG27.Farber]

bugmenot,

So it would appear at sea level the 109 is too slow by at least 30kmh. However I felt that IL2:clod used the new supercharger as the Ata does not drop off untill higher altitudes which seems to match the new one. So essentially its even SLOWER than it actually should be! The new compressor gave the 109 a higher effective cieling before the Ata dropped off and therefore made it faster at a slightly higher altitude.

Are your speeds in TAS?


I also found this which was of worth:

http://www.ww2aircraft.net/forum/flight-test-data/fighter-combat-comparison-no-2-bf109e-3-vs-spitfire-mki-26994.html

So we know all the aircraft are too slow and roughly by how much although I have not seen a through test (video) which shows values for RL and clod but I believe they have been done by some trust worthy people... Having this info here in this thread would be nice.


However:

What about climb, dive, turn and roll? Speeds are one thing and need addressing but are not these more fundamental? Especially from the perspective of a Hurricane pilot who are being overshadowed by the spits?

[ACE-OF-ACES]

However:

What about climb, dive, turn and roll? Speeds are one thing and need addressing but are not these more fundamental?
Sadly the dive, turn and roll parameters where not typically parameters they tested for in WWII..

This is not to say that you can not find any WWII testing of drive, turn and roll, only that they were not typically part of 'performance' testing in WWII.

Thus most if not all flight sims have to 'calculate' these values.. That is to say you will be hard pressed to find real world data on these values, so they have to calcualte them.

The two important performance values of WWII and thus the two you can typically find are climb (ROC) and speed (TSPA).

There is a third, which is really just part of the ROC and that is the time to climb (TTC).

[5./JG27.Farber]

Which from the minute amount of this information I followed before - I thought as much...

Shame.

However hopefully we can come to some kind of accord and present the data to 1c:MG...


This is the part where we must choose what I would call "Folklore" (eye witness accounts) and "facts" actual graphs... I dont see how you can truely have purley one or the other and I think this is where the real nitty gritty arguments break out... So with an open mind I am finding myself more in the "feeling" group than the facts but with a balance of both.

We can have all the facts nailed on the head like ROC and TAS but as you say we are still guessing the rest which is where "folklore" fills the gap... However then we are down to the spit always out turns the 109 and vice versa... - from pilot accounts...

So, its a mine field...

Should we try to get 1c:MG nail the "fact" figures as close as possible and then the "pilot account" things like turn and roll?


This is my first forray into a FM debate... So forgive the open mindedness and lack of direction.

S!

[ACE-OF-ACES]

Which from the minute amount of this information I followed before - I thought as much...

Shame.
Agreed

However hopefully we can come to some kind of accord and present the data to 1c:MG...
When it comes to calculating data.. I am sure 1C can do it as well if not better than any member of this forum.. The math is the math! The only time the math comes into question is when it does not match reality.. And in this case, where we have no reality to compare to, no one can say one way or the other how good the math is doing in simulating the aircraft.

This is the part where we must choose what I would call "Folklore" (eye witness accounts) and "facts" actual graphs... I don't see how you can truly have purely one or the other and I think this is where the real nitty gritty arguments break out...
Considering the fact that people can find a way to argue about the hard data (graphs) it is no wonder they can argue about the folklore.

So with an open mind I am finding myself more in the "feeling" group than the facts but with a balance of both.
The difference is the hard data (graphs) can be reviewed such as to minimize the errors..

Which is not the case with folklore!

There are just too many unknowns associated with the folklore to make it useful. Some people think they can do some statistically analysis of all the folklore and come up with some sort of consensus.. But it is just not the case.. Or should I say that in the past 20 years of flight simming, I have seen many make that claim, but no one has yet do pull it off.

Which is not surprising, in that we are NOT talking about gathering up folklore statements that somewhat agree..

For example, assume 3 WWII pilots said they could climb to 20kft in 9.2min, 10.2min, 9.8min.. And we say, hey that is great, we will just take the average of those three staments and call it good. NOPE! What we have is folklore that is many cases is 180 out! Fore example, there are WWII Spitfire pilots that said they could easily out turn or turn with a Bf109.. At the same time we have WWII Bf109 pilots who say they could easily out turn or turn with the Spitfire.

What do we do in that case?

Flip a coin?

I think not!

That is why most if not all folklore (pilot accounts, pilot action reports, etc) are so useless! In that they typically never provide enough information to even recreate the scenario in the game.

For example, a P51 pilot reports says he got behind a Bf109, closed in on it, and shot it down.

Ok..

Did he dive down from above to get on the 109s six? Or did he climb up to the Bf109? Or was he at co-alt and got in behind the 109? Did the 109 even know the P51 was behind him? Was the 109 pilot wounded and just trying to make it home, was the 109 engine damaged from a previous dog fight that just ended..

The list of un-knows is ENDLESS!

Which is why most if not all folklore is useless when it comes to tweaking the FM! IMHO your better off relying on the math and leaving it at that!

Long story short, typicall folkloare (pilot accounts and reports) tell us alot about the 'men' and thier 'tatics' but they tell us very little about the 'performance' of the planes.

We can have all the facts nailed on the head like ROC and TAS
Most but not all.. In that as I noted above, even with hard data like graphs, there are some unknowns associated with it that can cast doubt on the data..

The funny ones are the folks with double standards that will cast doubt on a test of a plane they don't like but at the same time accept lesser data for the planes they love as proof positive! It would be funny if it was not so sad!

but as you say we are still guessing the rest which is where "folklore" fills the gap...
Disagree

There may be a handful of folklore accounts that are 'useful'

But as noted above, most if not all folklore is useless!

Just to many unknowns!

Not to mention the fact that most if not all pilot reports are ONE SIDED STORIES!

That and they typicall dont include enough info to re-produce the scenario in the game to see if the plane the pilot was flying can do what he said, let alone the fact that we have absolutely no idea of what the state of the other plane and pilot was!

However then we are down to the spit always out turns the 109 and vice versa... - from pilot accounts...
Bingo!

So, its a mine field...

Should we try to get 1c:MG nail the "fact" figures as close as possible and then the "pilot account" things like turn and roll?
No not in my honest opinion, best to rely on the math when there is no real world data to compare to

This is my first forray into a FM debate... So forgive the open mindedness and lack of direction.
No worries!

[swift]

The results of a calculation (what you call maths) is only as good as its data. Also there are equations and equations. Some are highly approxamtive and only thump rules for quick estimates, others may be closer to reality but also very complicated and requiring a lot of divers input data.

I would agree to use mathematical relationships to deduce aircraft behaviour if we had enough reliable data or data at all for input into the equation and some reliable data to verify the results.

My guess is the data we would need to calculate it is not available. I mean what would be great if we had all the aerodynamic coefficients as a function of Mach number and angle of attack and the corresponding reference area for each plane.

"Equations" deducing turn performance from the wing loading, sorry, this is far from anything near accurate. I would not like to have the fm built on this kind of thump rules. Then I'd rather prefer anecdotical evidence.

[5./JG27.Farber]

AoA, you seem to agree with what I thought before... Folklore is fairly useless except from that particular pilots expericence... and the maths and graphs is what counts...

I am interested in what swift has to say... He makes good points.

In these days, is there surely not computer models that could aid us? - as for 1c:MG doing the maths... they are surley not doing quite a good job? ;)


I state somethings in argument... Like do we use the folklore, maths or combination? I agree with your statement on folklore... Adrenaline, fear and rapid actions can distort the memory... Unless it can be proved just by maths what else can you do?!

[ACE-OF-ACES]

The results of a calculation (what you call maths) is only as good as its data.
Correction..

The 6DOF math (what you call thumb rules) is more than adequate to simulate flight!

And the 'data' that the 6DOF math uses has nothing to do with any of the real world performance data (ROC, TSPA, etc). The 'data' the 6DOF math uses is coefficients only. That is to say the 6DOF math for a P51 is the same as that for a Bf109, what makes a P51 a P51 is the coefficients loaded into the 6DOF equation. That is to say, no where do you 'load' say the ROC or TSPA values from a WWII performance test.

The only time you make use of the WWII performance data is in the validation of the 'outputs' of the 6DOF math and the corsponding coefficients selected.

That is to say the math never changes, only the coefficients.

Basically they can get a good set of coefficients to use based off the geometry of the plane (CL, CD, mass, wing loading, etc). Than they 'tweak' the coefficients until the outputs of the equations match the real world data. As part of all this the power plant (engine) is also simulated and is one of the inputs to the 6DOF (thrust) equation.

Also there are equations and equations. Some are highly approxamtive and only thump rules for quick estimates, others may be closer to reality but also very complicated and requiring a lot of divers input data.
The more complicated versions were an issue back in the early 90s.. Where games like AOTP made use of fixed point math, in that the floating point processors were just not fast enough to do the complex calculations in real time. Mater of fact back then they were even limited to a 3DOF flight model, but than around 1995 a flight sim called Pacific Air War 1942 came out, that was one of if not the first PC flight sim to implement a 6DOF flight model, it still used fixed point math. These days there is no need for fixed point math and thus no need to use the simplified versions of the 6DOF flight model equations.

I would agree to use mathematical relationships to deduce aircraft behaviour if we had enough reliable data or data at all for input into the equation and some reliable data to verify the results.
Who wouldn't?

My guess is the data we would need to calculate it is not available.
Depends on which data your referring too.. As noted above, a good estimate of the 6DOF coefficients can be derived from the planes geometry. Actually the hard part to simulate is the engine! In that many of those records do not exist and no good way to derive them from looking at the dementions of the engine.

I mean what would be great if we had all the aerodynamic coefficients as a function of Mach number and angle of attack and the corresponding reference area for each plane.
As noted above, if they have enough info to draw the plane in 3D, then they have enough info to derive many if not all the coefficients for the 6DOF FM.. What is lacking in the power plant info (thrust)

"Equations" deducing turn performance from the wing loading, sorry, this is far from anything near accurate.
Disagree 100%

I would not like to have the fm built on this kind of thump rules. Then I'd rather prefer anecdotical evidence.
To each his own than

[ACE-OF-ACES]

Unless it can be proved just by maths what else can you do?!
In many cases all we have is math to fill in the blanks.. Sad but true! ;)

[5./JG27.Farber]

In many cases all we have is math to fill in the blanks.. Sad but true! ;)

Well this is a proactive thread so get cracking and then show us some results! :-P

[swift]

Correction..

The 6DOF math (what you call thumb rules) is more than adequate to simulate flight!

And the 'data' that the 6DOF math uses has nothing to do with any of the real world performance data (ROC, TSPA, etc). The 'data' the 6DOF math uses is coefficients only. That is to say the 6DOF math for a P51 is the same as that for a Bf109, what makes a P51 a P51 is the coefficients loaded into the 6DOF equation. That is to say, no where do you 'load' say the ROC or TSPA values from a WWII performance test.

The only time you make use of the WWII performance data is in the validation of the 'outputs' of the 6DOF math and the corsponding coefficients selected.

That is to say the math never changes, only the coefficients.

Basically they can get a good set of coefficients to use based off the geometry of the plane (CL, CD, mass, wing loading, etc). Than they 'tweak' the coefficients until the outputs of the equations match the real world data. As part of all this the power plant (engine) is also simulated and is one of the inputs to the 6DOF (thrust) equation.


The more complicated versions were an issue back in the early 90s.. Where games like AOTP made use of fixed point math, in that the floating point processors were just not fast enough to do the complex calculations in real time. Mater of fact back then they were even limited to a 3DOF flight model, but than around 1995 a flight sim called Pacific Air War 1942 came out, that was one of if not the first PC flight sim to implement a 6DOF flight model, it still used fixed point math. These days there is no need for fixed point math and thus no need to use the simplified versions of the 6DOF flight model equations.


Who wouldn't?


Depends on which data your referring too.. As noted above, a good estimate of the 6DOF coefficients can be derived from the planes geometry. Actually the hard part to simulate is the engine! In that many of those records do not exist and no good way to derive them from looking at the dementions of the engine.


As noted above, if they have enough info to draw the plane in 3D, then they have enough info to derive many if not all the coefficients for the 6DOF FM.. What is lacking in the power plant info (thrust)


Disagree 100%


To each his own than

My point is that you will have difficulties to derive reliable coefficients and you seem to agree on this. I do know a little about flight mechanics and trajectory computation (where the 6dof equations intervene) and about coefficient determinations (it is my daily business).

At work we frequently use a simplified tool to calculate the aerodynamic coefficients for subsonic and transsonic flight conditions and I can tell you I would not trust them for applications such as CoD. We use them for different applications where the impact is minor so we can live with it. But CoD would rely heavily on these coefficients and I'd say to obtain something that is halfway close to reality such a tool is not sufficient. And from experts working for years in the aerospace business using modern and highly sophisticated cfd tools I know that using these methods for subsonic regions is far from trivial. And it would take hours to days to calculate just one flight point for one configuration and probably would take longer if one would take into account the viscious terms instead of relying on simplified Euler calculations.

But what we need in CoD does not stop at the determination of lift, drag and lateral force coefficients and the moment coefficients about the three axis. We also need the derivate coefficients to obtain a believable flight model. Up to now the means with which these are "determined" is more than crude and very little reliable.

This gets even more complicated when one considers that each flap, rudder and aileron movement will have an impact on the aerodynamic coefficients (the 6 static coefficients and the derivates). You'd need a database set for several flap, rudder and aileron deflection combination. Then we have the trimmed and untrimmed flight conditions and other aerodynamic control surfaces such as flaps and airbrakes. Now let's talk about canopy open or closed and radiator and oil cooler openings ...

And these are just the coefficients for the airframe. We'd also need reliable data for the propulsion set.

I really do not believe in being able to obtain a full AEDB that will result in a flight performance that will be close to the real thing anyway, provided we even know where the real thing was. I think it is smarter to take the bottom up approach by tweaking the used coefficients in such a way that they fit to the experienced behaviour including test results and, where values are missing, to anecdotical evidence as long as there is a bunch of anecdotes saying the same.

BTW: CoD is definitely using 6dof. What we are disputing is how they come up with the forces and moments they inject into the 6dof equations.

[camber]

I had a sad 109 experience yesterday. Flying in overcast it is easy to get confused between the top and bottom of the aircraft, leading to the following:

http://i406.photobucket.com/albums/pp142/wjhawaii/IMG_06451.jpg



Test 4 4500metres 1.3Ata 2400U/pm IAS 400 TAS 518 or 322 mph
Test 5 5000metres 1.23Ata 2400U/pm IAS 390 TAS 518 or 322 mph
Test 6 4900metres 1.15Ata 2200U/pm IAS 370 TAS 489 or 304 mph

http://youtu.be/O4jHSMyYdkg <---- Video of tests.

Now we need to dig out the real life tests and compare.engine in the usual way
.

Seeing as you are doing some altitude 109 tests I did the same on patch 1.08. It seems not to have changed the last two patches though.

At 5000m 1.23ata 2400rpm I get IAS 400kmh which seems consistent with your Test 5 above.

The 109 does not change max speed between 2100 and 2400rpm which simplifies things.

Messerschmitt "guaranteed" top speed: (backed up by the flight test record)

570kmh TAS @ 5000m, 2400rpm, 1.3 ata (5 min limit).

CloD 109E4 (manual prop pitch) top speeds:

425kmh IAS = 561kmh TAS @5000m, 2400rpm, 1.32 ata

Full throttle boost has dropped below 1.35ata at 5000m. However the 109 1 minute takeoff boost is still working and oddly enough will still increment boost at 5000m (to 1.42ata).

440kmh IAS = 581kmh TAS @5000m, 2400rpm, 1.42ata.

So the CloD 109E4 at 5000m is 10kmh slow at the 1.3ata combat setting (will assume boosts in the 1.3-1.35ata range can be considered effectively the same). However it has access to the takeoff boost at altitude, which enables it to be 10kmh faster than the real life version.

Cheers, camber

Offline tests, cockpit off, speeds rounded to 5kmh, 4950-5050m, oil/water rads fully open, OAT 25/1000ft rule for IAS/TAS conversion.

[SlipBall]

Well this is a proactive thread so get cracking and then show us some results! :-P

AoA will need some direction and study material...first link Spitfire study 1941

http://ntrs.nasa.gov/search.jsp?R=19930092582&hterms=spitfire+lateral+715+Gilruth+Turner&qs=Ntx%3Dmode%2520matchall%7Cmode%2520matchall%7Cm ode%2520matchall%26Ntk%3DAll%7CAll%7CAll%26N%3D0%2 6Ntt%3D715%7CGilruth%2C%2520R.%2520R.%2C%2520and%2 520Turner%7Cspitfire%2520lateral

http://ntrs.nasa.gov/search.jsp?R=19800073772&hterms=supermarine+spitfire+715+Gilruth+Turner+spi tfire+lateral&qs=Ntx%3Dmode%2520matchall%7Cmode%2520matchall%7Cm ode%2520matchall%7Cmode%2520matchall%26Ntk%3DAll%7 CAll%7CAll%7CAll%26N%3D0%26Ntt%3D715%7CGilruth%2C% 2520R.%2520R.%2C%2520and%2520Turner%7Cspitfire%252 0lateral%7Csupermarine%2520spitfire

http://www.bing.com/search?q=+NATIONAL+ADVISORY+COMMITTEE+FOR+AERONAUT ICS%0D%0AREPORT+No.+868%0D%0ASUMMARY+OF+LATERAL-CONTROL+RESEARCH&src=IE-SearchBox&FORM=IE8SRC

[David198502]

My point is that you will have difficulties to derive reliable coefficients and you seem to agree on this. I do know a little about flight mechanics and trajectory computation (where the 6dof equations intervene) and about coefficient determinations (it is my daily business).

At work we frequently use a simplified tool to calculate the aerodynamic coefficients for subsonic and transsonic flight conditions and I can tell you I would not trust them for applications such as CoD. We use them for different applications where the impact is minor so we can live with it. But CoD would rely heavily on these coefficients and I'd say to obtain something that is halfway close to reality such a tool is not sufficient. And from experts working for years in the aerospace business using modern and highly sophisticated cfd tools I know that using these methods for subsonic regions is far from trivial. And it would take hours to days to calculate just one flight point for one configuration and probably would take longer if one would take into account the viscious terms instead of relying on simplified Euler calculations.

But what we need in CoD does not stop at the determination of lift, drag and lateral force coefficients and the moment coefficients about the three axis. We also need the derivate coefficients to obtain a believable flight model. Up to now the means with which these are "determined" is more than crude and very little reliable.

This gets even more complicated when one considers that each flap, rudder and aileron movement will have an impact on the aerodynamic coefficients (the 6 static coefficients and the derivates). You'd need a database set for several flap, rudder and aileron deflection combination. Then we have the trimmed and untrimmed flight conditions and other aerodynamic control surfaces such as flaps and airbrakes. Now let's talk about canopy open or closed and radiator and oil cooler openings ...

And these are just the coefficients for the airframe. We'd also need reliable data for the propulsion set.

I really do not believe in being able to obtain a full AEDB that will result in a flight performance that will be close to the real thing anyway, provided we even know where the real thing was. I think it is smarter to take the bottom up approach by tweaking the used coefficients in such a way that they fit to the experienced behaviour including test results and, where values are missing, to anecdotical evidence as long as there is a bunch of anecdotes saying the same.

BTW: CoD is definitely using 6dof. What we are disputing is how they come up with the forces and moments they inject into the 6dof equations.

really good thread so far, and very good and interesting post!

[ACE-OF-ACES]

My point is that you will have difficulties to derive reliable coefficients and you seem to agree on this.
Key word being reliable..

Now ask yourself..

How do you prove to yourself they are reliable?

Answer is you compare the results (outputs, such as tas, roc, roll-rates, turn rates, etc) of the 6DOF using these coefficients to the real world data..

Which is pretty easy to do when you have the real world data!

But what do you do when you don't have any real world data?

You guess it.. You rely on, aka trust, the math!

That is my point

That being we do NOT have real world data on each aspect of the WWII plane.. So unless we come up with a time machine, we are going to have to rely on calculated results (the math) for not only simulation but validation.

I do know a little about flight mechanics and trajectory computation (where the 6dof equations intervene) and about coefficient determinations (it is my daily business).
You too? Here as WSMR we use a lot of trajectory math to calculate the launch to impact site of the missiles we test here. We also have our own flight simulation software that we call RAGE

http://www.csc.com/public_sector/success_stories/9225-3_d_visualization_tool_lets_engineers_observe_how_ missiles_fly_over_actual_landscape

I work with the guy who wrote that software on a daily bases.. I also write plug-ins for RAGE but he is the true gu-roo of the software. All in all a great job, on my way to work I may see anything from a F22 to a UAV fly by at tree top level (landing or taking off from holloman).. It can be dangerous sometimes.. In that I am always looking up in the blue instead of looking forward at the road! ;)

At work we frequently use a simplified tool to calculate the aerodynamic coefficients for subsonic and transsonic flight conditions and I can tell you I would not trust them for applications such as CoD. We use them for different applications where the impact is minor so we can live with it. But CoD would rely heavily on these coefficients and I'd say to obtain something that is halfway close to reality such a tool is not sufficient.
Well than I guess we will have to agree to disagree on that point

And from experts working for years in the aerospace business using modern and highly sophisticated cfd tools I know that using these methods for subsonic regions is far from trivial. And it would take hours to days to calculate just one flight point for one configuration
Note I never said it was easy or trivial.. My only point is it is doable! Many have for many years now.

and probably would take longer if one would take into account the viscious terms instead of relying on simplified Euler calculations.
I know of only one PC flight sim that implemented a real-time computational fluid dynamics flight model (what you call 'viscious') and that was FLIGHT Unlimited

http://en.wikipedia.org/wiki/Flight_Unlimited

It was done back in 1995.. And was not only overkill IMHO but too much for the PCs of that time. Maybe even today, I don't know in that not many make use of it in that the 6DOF (what you call simple euler) has proven itself to be more than adequate for military applications, thus more than adequate for PC games IMHO.

But what we need in CoD does not stop at the determination of lift, drag and lateral force coefficients and the moment coefficients about the three axis. We also need the derivate coefficients to obtain a believable flight model.
Key word being believable..

Now ask yourself..

How do you prove to yourself they are believable?

Answer is you compare the results (outputs, such as tas, roc, roll-rates, turn rates, etc) of the 6DOF using these coefficients to the real world data..

Which is pretty easy to do when you have the real world data!

But what do you do when you don't have any real world data?

You guess it.. You rely on, aka trust, the math!

That is my point

That being we do NOT have real world data on each aspect of the WWII plane.. So unless we come up with a time machine, we are going to have to rely on calculated results (the math) for not only simulation but validation.

Up to now the means with which these are "determined" is more than crude and very little reliable.
Well than I guess we will have to agree to disagree on that point

This gets even more complicated when one considers that each flap, rudder and aileron movement will have an impact on the aerodynamic coefficients (the 6 static coefficients and the derivates). You'd need a database set for several flap, rudder and aileron deflection combination. Then we have the trimmed and untrimmed flight conditions and other aerodynamic control surfaces such as flaps and airbrakes.
Which has all been done before and done for years!

Now let's talk about canopy open or closed and radiator and oil cooler openings ...
Better yet..

To drive my point home..

Let talk about you going out and finding the real world test data for each plane in the game of the 'effects' of the canopy open vs. the canopy closed on each aspect of the plane (tas, roc, roll-rate, turn-rate, etc)

Allow me to spare you that effort!

In that you wont find such data! ;)

Thus, back to square one of my point

You will have to trust the math and how it says the canopy open vs. closed will 'affect' the flight

Oh sure you may find some anecdotical evidence for some of the planes.. For example we have all read the stories.. Like the Me262 that was stuck in a high speed dive, until the pilot popped the canopy and started to bail out, at which point he noticed that popping the canopy 'changed something' such that he was able to regain control, and thus didn't bail out. What is not 'clear' about such stories is the parameters to re-create that scenario in the game to see (validate) the flight model. For example..

What was his altitude when he popped the canopy?
What was his speed when he popped the canopy?
What was his dive angel when he popped the canopy?
What was his flap setting when he popped the canopy?
What was his trim setting when he popped the canopy?

The list goes on and that is only for the point in time of when he popped the canopy..

So all we know from that story is that 'something' changed.. For all we know his plane was slowing down and the popping of the canopy had NOTHING to do with it.. It could have just been a coincidence that he popped the canopy at the same time the plane had slowed down enough that he was able to regain control

And these are just the coefficients for the airframe. We'd also need reliable data for the propulsion set.
Ah, glad to see you agree with what I said in my last post!

So not all is lost, in that we can agree on some things! ;)

I really do not believe in being able to obtain a full AEDB that will result in a flight performance that will be close to the real thing anyway, provided we even know where the real thing was.
Bingo!

So do we give up?

Or do we trust the math and move on?

I think it is smarter to take the bottom up approach by tweaking the used coefficients in such a way that they fit to the experienced behaviour including test results and, where values are missing, to anecdotical evidence as long as there is a bunch of anecdotes saying the same.
Which is exactly what I was saying minus the anecdotical evidence (aka pilot combat reports)

Just too many variables involved to make most if not all anecdotical evidence useful

As I noted early on

Many 'feel' the can derive some sort of statistical average of the anecdotical evidence.. Many have tried, all have failed! Which is not surprising when you consider the fact that the anecdotical evidence is not something that varies a 'little' As in one reports says the top speed is 305, another say 307, and another says 302, and another say 310. If that was the case it would be a simple mater of taking the average and calling it good! But that is not the case for anecdotical evidence, what we have there is Spitfire pilots saying they could out turn 109s and 109 pilots saying they could out turn Spitfires. So based on that it is not surprising that those who have tried have failed.

BTW: CoD is definitely using 6dof.
Ah, glad to see you agree with what I said in my last post!

So not all is lost, in that we can agree on some things! ;)

What we are disputing is how they come up with the forces and moments they inject into the 6dof equations.
No, we know how they come up with them.. What we are disputing IMHO is how they validate the flight model.. For the aspects of which we have no real world test data to use in the validation. In such situations I am saying we have to trust the math to fill in the blanks, where as your saying we should use anecdotical evidence to fill in the blanks..

In summary

I put more faith in the 6DOF math than you do
You put more faith in anecdotical evidence than I do

Other than that I think we agree

[swift]

You do not need to do this surgical argument deplugging (what I always feel to be a bit rude although I understand that you do not mean it this way). I understood perfectly where you want to go.

My point is that with the maths what you have in mind you will be likely as far off the reality as with what we have right now in the game if you cannot check it against reality.

So you apply maths but the chances are great that you will be far off the mark as with the current methods (which might by the way be based on some simplified maths I guess). You will never know if you will be below or above the mark. So I could as well trust in what we have now. I could as well trust in anecdotical evidence provided the sample is large enough to allow a statistically sound picture about the real thing. If 1000 pilots say the spit could outturn the 109 I'd tend to believe that 1000 pilots cannot be wrong even if I do not know the 1000 initial conditions. The number of pilot accounts however may suggest that the variety of initial conditions in which these guys made their observation was large enough to provide for a good hint about a qualitative not measurable behaviour.

It will be simply an impossible task to have fully viscious cfd simulations for each aircraft for a game that is basically just a niche product. It had perhaps been tried once. It has never been done again. This talks books. And cfd is again basically useless anyway if it cannot be checked against wind tunnel tests. Now this won't ever happen anyway.

And don't mix up the effort you and your company can put into a product for which your company will be payed a fortune with the possibilities of a small game developer company.

[5./JG27.Farber]

I suppose there could be a way to settle this. If AoA used his method on a spitIa and Swift used his method on a SpitIa and we had some results?

Aside from having different approches to the same problem, what about some results?

[Crumpp]

So it would appear at sea level the 109 is too slow by at least 30kmh.

There was another monster silly thread over this issue.

It appears all of the aircraft are slow by a similar margin of error.

So while actual performance is not correct, relative performance is not effected.

[Robo.]

So while actual performance is not correct, relative performance is not effected.

Oh yes it is, unfortunately. ;)

[ATAG_Snapper]

There was another monster silly thread over this issue.

It appears all of the aircraft are slow by a similar margin of error.

So while actual performance is not correct, relative performance is not effected.

Right. :rolleyes:

[ACE-OF-ACES]

You do not need to do this surgical argument deplugging (what I always feel to be a bit rude although I understand that you do not mean it this way).
Not a need as much as a style that I find useful and actually respectful in that I take the time to address each of your comments.

PS wrt my style, I have spoken with several mods and it does not break any forum rules!!

I understood perfectly where you want to go.
Really? Because I did not get that impression

My point is that with the maths what you have in mind you will be likely as far off the reality
Yes we have already established that you do not trust the math..

Got it!

So if not math.. Than what should we trust?

as with what we have right now in the game
And how far off is it?

Only way to tell is to apply some math and derive a percent error

if you cannot check it against reality.
Agreed 100%

The part we don't agree on is the definition of reality..

I for one am all for checking against reality when reality exists.. Like real world test data

But when real world test data does not exist, than my point is you have to trust the math to fill in the blanks

Where as you want to fill in the blanks with anecdotical evidence..

And I have already given several examples of why that is a bad idea

So you apply maths but the chances are great that you will be far off the mark as with the current methods (which might by the way be based on some simplified maths I guess). You will never know if you will be below or above the mark. So I could as well trust in what we have now. I could as well trust in anecdotical evidence provided the sample is large enough to allow a statistically sound picture about the real thing. If 1000 pilots say the spit could outturn the 109 I'd tend to believe that 1000 pilots cannot be wrong even if I do not know the 1000 initial conditions.
If large enough?

Again, as I noted, EASY to say, but until you try you don't know just how hard it is to try and do that..

Many have made that claim over the my past 20 years of simming

All have failed!

All in all I would still take my chances with 6DOF math over some sort of statistical conclusion drawn from anecdotical evidence..

Why?

Because there is something you are forgetting about anecdotical evidence

We only hear from (read the reports of) the pilots that made it home to write about it..

Thus a filtered set of data!

In short, we don't know how many Spitfire pilots were SHOT DOWN trying to turn with a 109 and thus never got a chance to write about it!

The number of pilot accounts however may suggest that the variety of initial conditions in which these guys made their observation was large enough to provide for a good hint about a qualitative not measurable behavior.
Chances are it will not..

Again, not trying to bum you out

All I am saying is that many like yourself have made such claims over my past 20 years of simming

All have failed

But who knows, maybe your different?

Maybe you are the one to do it?

On that note, don't take this wrong, but talk is cheap!

Do it and than lets talk about it!

It will be simply an impossible task to have fully viscious cfd simulations for each aircraft for a game that is basically just a niche product.
My guess is the main reason it has not been done is that it is over kill from the get go..

That is to say the benefits of it are so small that most would not even notice the difference..

At the human level that is!

It had perhaps been tried once. It has never been done again. This talks books. And cfd is again basically useless anyway if it cannot be checked against wind tunnel tests. Now this won't ever happen anyway.

Yes as I pointed out, FLIGHT Unlimited tried it back in 1995, and as I noted in my last post, I don't know of anyone else that has tried it since.

And don't mix up the effort you and your company can put into a product for which your company will be payed a fortune with the possibilities of a small game developer company.

LOL

Trust me, we are as small if not smaller than 1C when it comes to budgets

[swift]

Sh, I tell you a secret: CloD is already based on 6dof ... but don't tell anybody ;)

[ACE-OF-ACES]

Sh, I tell you a secret: CloD is already based on 6dof ... but don't tell anybody ;)
Huh?

It is no secret..

You will be hard pressed to find a PC flight sim made in the past 10 years that is NOT using a 6DOF FM..

Except maybe for some of the x-box quake types of flight sims..

So...

No comment on the FACT that we only hear from (read the reports of) the pilots that made it home to write about it..

So maybe now you can see my point of view as to why anecdotical evidence is 'flittered data' and thus not useful in any sort of statistical summary!

It would be like going to San Francisco or New York city and asking people on the street how good of a job they think the president is doing and using those results to place a bet on the next election! ;)

And that is just one problem with anecdotical evidence!

Let's not forget that anecdotical evidence is typically, if not allways, a 'one sided' story!

That is to say you will be hard pressed to find a WWII after action reports that consist of both comments from the Spitfire pilot and the Bf109 pilot in that report talking about the same encounter..

Thus math ftw! ;)

[5./JG27.Farber]

So aside from this intellectual joust - what about some results?

[Kurfürst]

So aside from this intellectual joust - what about some results?

We do know exactly how the 109 turned, the math was done in the 1940s, so whats the fuss about? And the last time I check the turn times, its about right in CLOD.

[5./JG27.Farber]

We do know exactly how the 109 turned, the math was done in the 1940s, so whats the fuss about? And the last time I check the turn times, its about right in CLOD.

But what about roll rate, climb and level speed? Swift and AoA are jousting but not getting anywhere. The devs only acknowledge the bug tracker so the information will have to collected and agreed upon and submitted there...

[ACE-OF-ACES]

So aside from this intellectual joust - what about some results?
Before you can move forward..

And obtain results..

You first have to agree upon some basics and some pass fail criteria..

I have tried to open up the conversation of how to validate a flight model..

And the first thing that comes up is what I have seen come up time and time again over the past 20 years of flight simming..

That anecdotical evidence should be used to validate the flight model..

I have pointed out some of the short comings and pit falls of anecdotical evidence..

And why I feel it should not and can not be used in the validation of a flight model..

But all I get in return is more of the same and/or restating things I already knew to be true (CoD is 6DOF)

I have an open mind on this, if swift or anyone else can 'do' what they say can be 'done' than great! But as I noted, many in the past have made the same claims that swift is making, and nothing ever comes from it!

So, I don't see any 'results' coming from this conversation..

In that it is not a conversation..

It is just me expressing my concerns about anecdotical evidence, looking for a reply back that will provide some information that will elevate my concerns

But as noted above all I get in return is more of the same and/or restating things I already knew to be true (CoD is 6DOF)

I can not say I am surprised, in that this is not the first time this has come up in the past 20 years of PC flight sims

And I suspect it will not be the last

I keep hoping someone will prove me wrong about anecdotical evidence, in that the more data the better!

But it has not happened yet

[swift]

Your problem, AoA, is that you only accept results that are in accordance with your philosophy. I'd say IL2 1947 came up with results that used anecdotical evidence where hard data was not available and the job was not bad. You refuse this on a categoric basis and that is why we won't get anywhere in this discussion.

I do not convince you obviously.

You don't convince me either because I do think that anecdotical evidence can be used as a support (also because I do not believe your claim that those spit pilots if outturned by a 109 would inevitably have been killed. I am convinced that there would have been sufficient cases of lucky blokes who would have escaped nonetheless to report about them being outturned by a 109. Now even if their number would have been small we have to see that there is just zero accounts on this).

We might continue jousting but this won't lead to anything. So let's agree that we disagree.

[ACE-OF-ACES]

Your problem, AoA, is that you only accept results that are in accordance with your philosophy.
Not true

I am willing to accept anything, as I noted, I have an open mind on this..

As a mater of fact, 20 years ago I was making the same argument your making now!

But over the past 20 years I have come to the conclusion that it can not be done (read I and others tried it)!

As noted, I wish someone could prove me wrong on this!

So, who knows, maybe you are the one who can do it?

But up to now you have not provided anything to elevate the concerns I have brought up!

To re-cap, I have brought up two concerns (two of many, but the two I find to be the most important)

1) anecdotical evidence is typically, if not always a one sided story
2) anecdotical evidence is written by those who lived to write about it

For Examples..

WRT item 1) You will be hard pressed to find an after actions report that has input from both the axis and allied pilot with regards to the encounter (say dog fight).
WRT item 2) Using your example of 1,000 Spitfires saying they could out turn a 109, you don't know how many Spitfire pilots were shot down trying to turn with a 109.

Explain to me how you account for these two items in your statistical analysis and than maybe I can start to see it from your point of view..

Because you just saying 'this method worked' wrt IL-2 explains nothing..

And has that used car salesman "trust me" feel to it..

Better yet, give us an example of how you applied this method in IL-2!!

Just one!

Than maybe I can see it from your point of view?

[winny]

Interesting debate, I thought I'd throw my 2 pence worth in..

You're both right, you need the maths, but you also need the combat reports.

You do the maths, then check to see if what's happening relates to what actually happened.

As far as I know combat reports and pilot's recollections are the only record of the use of these aircraft in the role they were designed for, combat.

I've read literally hundreds of combat reports from the Battle of Britain, both sides. Most of these guys were professionals, and eventually if you read enough, you can build a picture of what happened. OK, there's no numbers, but it's foolish to disregard them.

As Geoffry Wellum P/O 19 squadron BoB said "People ask me how can I remember it all, I just say, how could I forget?"

Read Brian Lanes account of a turning battle with a 109 where he sees the aileron snatch on the 109 , read Gallands stories of diving down onto Spits and being able to engage and disengage at will. Both from men who knew what they were doing.

The truth is a blend, where the math's ends the history helps.

Don't be partisan about it, there's enough people on here from both sides with enough knowledge to make CLoD/BoM the definitive sim.... If everyone would just stop arguing....

There you go, I think they call this "sitting on the fence".. oh well.

[NZtyphoon]

As far as I know combat reports and pilot's recollections are the only record of the use of these aircraft in the role they were designed for, combat.

I've read literally hundreds of combat reports from the Battle of Britain, both sides. Most of these guys were professionals, and eventually if you read enough, you can build a picture of what happened. OK, there's no numbers, but it's foolish to disregard them.

As Geoffry Wellum P/O 19 squadron BoB said "People ask me how can I remember it all, I just say, how could I forget?"

Read Brian Lanes account of a turning battle with a 109 where he sees the aileron snatch on the 109 , read Gallands stories of diving down onto Spits and being able to engage and disengage at will. Both from men who knew what they were doing.

The truth is a blend, where the math's ends the history helps.

Don't be partisan about it, there's enough people on here from both sides with enough knowledge to make CLoD/BoM the definitive sim.... If everyone would just stop arguing....

There you go, I think they call this "sitting on the fence".. oh well.

+1


(Nothing wrong with fence sitting...or is there? ;) ) (http://www.youtube.com/watch?v=fudOagMeVKk)

[5./JG27.Farber]

Well if we are using anecdotal and pilot accounts lets throw these into the fire:

http://www.virtualpilots.fi/feature/articles/109myths/

I stongley urge the red fliers especially to read this. Its a shed load of pilot accounts with sources, all about the 109 and what an Uber plane she really is! :-P



I have done the tests using the values in the table for the DB 601 A and B manual. I believe the new compressor is modeled, so in the box "Flying Altitude" I used the left hand column, as there is significant drop off in Ata at 4.5 to 5km rather than 4 to 4.5km... I also performed the test on a multiplayer server in case FM's are different in single player.


Using ATAG_Keller's IAS TAS converter the results are:

Test 1 Sea level 1.3Ata 2400U/pm IAS 440 TAS 440 or 273 mph
Test 2 Sea level 1.23Ata 2300U/pm IAS 430 TAS 430 or 267 mph
Test 3 Sea level 1.15Ata 2200U/pm IAS 420 TAS 420 or 261 mph

Test 4 4500metres 1.3Ata 2400U/pm IAS 400 TAS 518 or 322 mph
Test 5 5000metres 1.23Ata 2400U/pm IAS 390 TAS 518 or 322 mph
Test 6 4900metres 1.15Ata 2200U/pm IAS 370 TAS 489 or 304 mph

http://youtu.be/O4jHSMyYdkg <---- Video of tests.

Now we need to dig out the real life tests and compare.


The effect of WEP also seems to have changed. I tried making it break the engine in the usual ways but could not manage it... It also seems to have effect at all altitudes now.

I found this:

http://www.rolfwolf.de/daten/E4/Emil.html


http://www.rolfwolf.de/daten/E4/Emil_html_4785a2b8.gif
I assume these are full throttle speeds.

Höchstgeschwindigkeiten in Steig/Kampfleistung (Tabelle)
I assume this is TAS

0km 460km/h

1km 480km/h

2km 500km/h

3km 520km/h

4km 540km/h

5km 555km/h

6km 555km/h

7km 550km/h

[macro]

Yes farber the 109 is slower than it should be, i remember seeing this on aonther thread somewhere. I think if they can get the speed, climb rate, turn rate and acceleration of the planes sorted that would go along way to the realistic settings, then add plane specifics after, such as stalling in the spits in hard turns or aerliron snatching in the 109 with the slats etc. We'd be getting there.

Is the basic info available as fact? If so then the basics shouldnt be a problem for the devs to sort out, and in my opinion should have done already.

[5./JG27.Farber]

Yes macro, I think which ever way you look at it people would be happy either way if the figures added up for all aircraft - mathmatically or by accounts.

Thing is the devs dont come here. Only B6. If you want somethign doing you have to do the hard work then submit a bug report. We all know the phantom (ghost) formations were here from the start, people spoke of them on this forum but the devs did nothing because they didnt know, only after I got off my backside and submitted a bug report and evidence (ntrk) did they even know about it. The next patch is supposedly the steam official and after which no more changes specific to clod will be added - as I have read. So its vitally important we get it done now!

POST 19:

http://forum.1cpublishing.eu/showthread.php?t=32600&page=2

Posted by TNT
Take for instance the implementation of the view (I mean for owners TrackIR). Was she in the sequel gets like this? Where Igromir property shown on the Su-26? Then if Su-26 tucked back in CloD, then so much interesting start in virtual reality.

Posted by steam_
From what or whom depends the fate official CloD?
If CloD "will throw" the developers (no matter for what reasons) whether SDK to give modelers? Or the position of the publisher (as they say in Ukraine) "did not clutter and do not give the other"?
Again, mostly known facts:

Blacksix
1) All requests on views and TrackIR were collected and passed up, in the sequel, the case should move.
2) Su-26 and SDK are not canceled, but the priority they have is minimal. Deal with these issues now, no one. This is not the position of the publisher, it is a forced alignment tasks by priority because of the banal deficiency of resources.
3) At the moment, the main goal for CloD - to bring the current series of beta patches to the final status and publication on Steam. After that, the leadership will have take a decision on the future of the game.
4) We have a very tight schedule for a sequel. We are now focused with full strength on it, as of the success and timely appearance of a new game depends all of our future.

Now, regarding the further communication, if all of the CloD after the patch on the Steam will be phased out, we have a pause there, because on the sequel I have no right to tell absolutely nothing until its announcement. How is it to fill my mind right now.

[notafinger!]

I think the devs and the community would be best served by focusing on modeling the comparative differences between the fighters. Using historical documents, pilot testimonials, and any other sources available to create a flight model that feels historical. Let's ask ourselves some basic questions about the 3 major single seat fighters of BoB. In order how do the aircraft rank in _____ performance:

High Alt Speed:
Low Alt Speed:
Acceleration:
Climb:
Dive:
Roll:
Turn:

Maybe this should be a different thread as we, as a community, might come to some kind of agreement of what we would expect to see without focusing on absolute numbers.

[macro]

From what iv read in reports and such

High alt speed spit slightly faster
Low alt 109 slightly faster
Roll: spit rolls slower at high speeds but about same at slow speeds. The 109 more stable at slow speed roll due to slats.
Spit could catch 109 accell in dive with+12 boost. 109 Elevator very heavy and hard to pull out of dive at high speeds.
Iv read the common tactic of steep but rarher slow climb of 109 was actually used by 109 pilots to get away from spits. Sounds like this is realistic in game.

Turn rate in spit was better that 109 when pushed to the limit, would need some sort of stall characteristic in spit for game balance.

Am i right or well off the mark? Not read enough about hurri to comment my opinion

[Matt255]

High alt speed spit slightly faster
Low alt 109 slightly faster
Roll: spit rolls slower at high speeds but about same at slow speeds. The 109 more stable at slow speed roll due to slats.
I read exactly the opposite.

Spit faster at low level, 109 faster at very high altitude.
Spit rolling slower at very low speed, both Spit and 109 ailerons becoming very hard to move at speeds above ~ 600 km/h / 400 mph.

Spits controls overall slightly less heavy at high speed.

I also don't see what the 109 slats have to do with rolling or why the plane would be more stable because of them.

[SlipBall]

From what iv read in reports and such

High alt speed spit slightly faster
Low alt 109 slightly faster
Roll: spit rolls slower at high speeds but about same at slow speeds. The 109 more stable at slow speed roll due to slats.
Spit could catch 109 accell in dive with+12 boost. 109 Elevator very heavy and hard to pull out of dive at high speeds.
Iv read the common tactic of steep but rarher slow climb of 109 was actually used by 109 pilots to get away from spits. Sounds like this is realistic in game.

Turn rate in spit was better that 109 when pushed to the limit, would need some sort of stall characteristic in spit for game balance.

Am i right or well off the mark? Not read enough about hurri to comment my opinion

I read exactly the opposite.

Spit faster at low level, 109 faster at very high altitude.
Spit rolling slower at very low speed, both Spit and 109 ailerons becoming very hard to move at speeds above ~ 600 km/h / 400 mph.

Spits controls overall slightly less heavy at high speed.

I also don't see what the 109 slats have to do with rolling or why the plane would be more stable because of them.


Just make them the same then pilot skill will be the wild card:-P

[ATAG_Snapper]

Just make them the same then pilot skill will be the wild card:-P

We did that briefly in ATAG's Server #2 a couple of weeks ago. The Engine Temperature Management was temporarily switched off so we could evaluate the effects of radiator drag without overheating the engines. (Radiators are closed by default and cannot be opened). The 109 E4 and the Spitfire MK 1a 100 octane had the exact same speed at sea level at full WEP (109) and 11 lbs boost (Spitfire). Both aircraft would travel literally wingtip to wingtip for miles above the waves going full out - neither aircraft gaining an inch on the other. On cue (using Teamspeak) both aircraft were then pulled hard up into a vertical climb, engines remaining at full throttle WEP/11 lbs boost. Both aircraft climbed to the same height wingtip to wingtip, stalling out at precisely the same instant.

We did this online so we could easily do plane vs plane comparos, but you can test this easily offline with your favourite aircraft simply by unchecking Engine Temperature Management in your Realism Options. The flight models tested to be the same offline and online.

This was a very brief test on Server 2, it was soon put back to Full Switch. But for a brief time it was exhilarating to fly a Spit in equal terms with a 109. Makes for some very long -- and exciting -- dogfights between equal pilots. Once Engine Temperature Management is turned back on, the Spits are saddled with huge, no......make that HUGE.....radiator drag penalties in terms of square area, drag coefficients, and no apparent modelling of the Meredith Effect.

[ACE-OF-ACES]

but you also need the combat reports.
Don't get me wrong..

I think combat reports are great for many things..

Just not great for validating a flight model!

Combat reports say more about the men and their mind set and their tactics..

But very little about the planes performance!

I will say this, you can gleam flying qualities from combat reports.. Stuff like

'I felt a slight buzz in the stick just before the stall while turning with the 109'..

But that description tells you nothing about the stall speed at which this occurred..

As I already pointed out..

Most combat reports don't include enough info to recreate the scenario in the game to see if you get the same results in-game..

Unlike real world data (test reports) that are performed using strict and repeatable methods..

For example..

I can recreate an ROC test in-game using the same real world methods to see if the real world results match the in-game results..

But how do I recreate a scenario to test from a combat report that says..

'In my Spitfire, I dove down on a 109, who spotted me at the last second and tried to evade me before I shot him down'

You cant!

There is not enough information there to recreate the scenario to see if the in-game results match the real world results..

That and the results depend more on the relative pilot experience..

That is to say assume you did try to re-create this scenario in the game..

Put a good pilot in the 109 and a Cherry in the Spitfire and there is a chance the 109 will NOT get shot down..

Does this test prove the 109 flight model is uber and the Spitfire flight model is broken?

NOT AT ALL!

All this proves is the relative experience of the sim pilots involved in the scenario affect the outcome more than the performance of the plane!

Same can be said wrt the orginal combat reports (anecdotical evidence), you don't know how much of 'it' was due to the relative experience of the pilots!

As in was the Spitfire pilot able to turn with the 109 because he was a better pilot?

All in all do we really want our flight models tweaked based on the results of some sim pilot's atempt re-create of a poorly documented WWII event?

I THINK NOT!

But I digress!

Combat reports are also useful to gain in site as to what was actually going in the trenches vs. what the generals thought was going on..

A good case in point is the whole 100 oct usage

As far as I know combat reports and pilot's recollections are the only record of the use of these aircraft in the role they were designed for, combat.
As noted

Combat reports are great for determining how the pilots used these aircraft and the tactics they used..

Just not good for validating a flight model

Like in the stick buzz example above..

We know it stalled (the event)
We know the pilot felt something in the stick before the stall (the useful flying quality info)
We DON'T know what the stall speed was (what is needed to validate the flight model)
We DON'T know what the throttle setting was (what is needed to validate the flight model)
We DON'T know what the flap setting was (what is needed to validate the flight model)
We DON'T know what the e state was (what is needed to validate the flight model)
We DON'T know what the altitude was (what is needed to validate the flight model)

This list goes on but you should be starting to see my point

TOO MANY UNKNOWNS!

and eventually if you read enough, you can build a picture of what happened. OK, there's no numbers, but it's foolish to disregard them.
Problem with that method is you can have two people read the same reports and draw two very different pictures of what happened

That is the problem with human nature

Where as with math

1 + 1 = 2

And nobody but raaaid could disagree with that! ;)

read Gallands stories of diving down onto Spits and being able to engage and disengage at will.
A good example of tactics

But not a good example of how to validate a flight model

All that statement really proves is the plane with a better 'e' state will control the fight, until that pilot does something stupid to give up his 'e' advantage! ;)

[ACE-OF-ACES]

I read exactly the opposite.
And here is a perfect example of what I was refering to, that being how two people can read the same 'accounts' and get different results

Where as 1 + 1 = 2 in real world test data and you would be hard pressed to find anyone to disagree with that! ;)

[JtD]

1+1=10 ;)

[ACE-OF-ACES]

1+1=10 ;)
I stand corrected.. raaaid and JtD! ;)

[macro]

ok maybe i got it completly wrong lol! :confused:

i thought the slats were the to give stability at low speeds? but maybe wrong about that also :confused:

And i think AoA is correct, math is math. it it adds up it cant be denied.

best get your calculator out mate and get to work cos that sort of math well beyond me lol :(

1+1=11 :P

[Matt255]

And here is a perfect example of what I was refering to, that being how two people can read the same 'accounts' and get different results
I wasn't writing that i read the same accounts (no idea what accounts he read anyway, definately never read that the Spit rolls worse than the 109 E at high speed though) or that what i read is (more) correct.

I think these planes are quite well documented, as opposed to WW1 planes for instance. I also wouldn't say that those two planes "feel" totally unrealistic regarding rollrate, turnrate or whatever in CloD, except for the too low speed of these planes, unlikely engine reliability (impossibility to run the Merlin using historical limits) etc.

I don't think we would have many FM discussions, if the speed would be close to the avaliable data.

[ACE-OF-ACES]

I wasn't writing that i read the same accounts (no idea what accounts he read anyway, definately never read that the Spit rolls worse than the 109 E at high speed though) or that what i read is (more) correct.
Ok, Ill reword it and remove the word 'the same' to read as follow..

And here is a perfect example of what I was refering to, that being how two people can read 'pilot accounts' and get different results

[SlipBall]

http://i51.photobucket.com/albums/f394/SlipBall/Spit2.jpg
http://i51.photobucket.com/albums/f394/SlipBall/Spit3.jpg
http://i51.photobucket.com/albums/f394/SlipBall/Spit1.jpg

From the 1941 study, it sounds to me that hi-speed rolling was not a strong point

[JtD]

This is a Spitfire V with metal covered ailerons, tested up to 300 mph. The Spitfire I/II with fabric covered ailerons are a lot worse, and at 400 mph IAS pretty much hopeless - ineffective ailerons combined with a rather flexible wing. British tests indicate a roll rate of about 12°/s at 400 mph with 50 lbs stick force for early Spitfires - in other words half a minute for a 360° roll.

Also sorry for the cheap joke above, but I would say that while people may not disagree on the math, they may very well have different opinions regarding the input and different interpretations regarding the output. I'd also say that anecdotal evidence is valuable in getting input and interpretation right. For example, popular numbers regarding sea level top speed show the F4F to be faster than the A6M-2, however, anecdotal evidence from both sides agrees that the A6M-2 could and would outrun an F4F. A good enough indication that the numbers are not plausible and some research is warranted...but data for the A6M-2 just isn't around in quality and quantity as it is for say Spitfires and 109's.

[NZtyphoon]

http://i51.photobucket.com/albums/f394/SlipBall/Spit2.jpg
http://i51.photobucket.com/albums/f394/SlipBall/Spit3.jpg
http://i51.photobucket.com/albums/f394/SlipBall/Spit1.jpg

From the 1941 study, it sounds to me that hi-speed rolling was not a strong point

Rolling was never really a Spitfire strength, partly because of the large area of wing tip outside of the aileron; the clipped-wing Spitfires had a better roll-rate at all speeds than those with conventional wing tips while those with pointed, high altitude tips were worse. Another part of the problem was the fabric covered ailerons, still fitted to the NACA Spitfire Va, which tended to "balloon" at high speeds, further reducing their effectiveness.

[Kurfürst]

Another part of the problem was the fabric covered ailerons, still fitted to the NACA Spitfire Va

Which is why the NACA report specifically notes that metal ailerons were fitted to the Spitfire Mark VA tested, right?

[Igo kyu]

1+1=10 ;)
As you may know, he's counting, correctly, in binary.

[Kurfürst]

I also don't see what the 109 slats have to do with rolling or why the plane would be more stable because of them.

Because leading edge slats were fitted for exactly to this reason. Its no coincidence that slats cover the wing area ahead of ailerons, and maintain steady airflow without stalling at that part of the wing. Slats allow for higher Angle of attack without stalling - meaning the airplane is still controllable is rolling plane. The brief aileron snatching noted on the 109E while the slats deployed, until fully open is also due to this reason. It was fixed on later models of the 109 though, either through the redesign of the wing or through the redesign of the slat actuating mechanism.

Designers always aimed to maintain aileron control near the stall, ie. that the wing root would stall sooner than the part before the ailerons, so that ailerons remain effective. Slatless airplanes typically aimed for this by using washout, a sort of twist in the wing that gave the outer wing less AoA in any flight condition, and a result delayed the stalling point and made the ailerons effective longer. This of course decreased the lift generated by the wing in all conditions, since lift is more or less equal to wing area x AoA. Though slats do the same, their plus side is that they only deploy when needed, and otherwise the aircrafts wings develop their full lift potential. Therefore, they combine the best features for high speed flight, TO/Landing and turn fight.

[SlipBall]

Which is why the NACA report specifically notes that metal ailerons were fitted to the Spitfire Mark VA tested, right?


I did see that in the report...back then, from the graph, would it be safe to watch for/anticipate that a pilot would favor/maybe even trained, to favor doing a roll to the right.

Also, I'm always amazed at your sig, taxiing must have been hell with that line of sight he has, I wish it was modeled in this sim as-well (our pilot seems to sit just a little higher). Do you have any history of the plane and pilot.

[NZtyphoon]

This is a Spitfire V with metal covered ailerons, tested up to 300 mph. The Spitfire I/II with fabric covered ailerons are a lot worse, and at 400 mph IAS pretty much hopeless - ineffective ailerons combined with a rather flexible wing. British tests indicate a roll rate of about 12°/s at 400 mph with 50 lbs stick force for early Spitfires - in other words half a minute for a 360° roll.

My bad -the NACA Spitfire had metal covered ailerons, I should have absorbed the first sentence before reading the report ;) - still, that does not invalidate anything I said about the damping effect of the wingtips on the Spitfire's roll-rate. A report on a clipped wing Spitfire V vs standard bears this out:

http://i91.photobucket.com/albums/k304/Major_Sharpe/SpitfireVclippedwings-page-005a.jpg
http://i91.photobucket.com/albums/k304/Major_Sharpe/SpitfireVclippedwings-page-006.jpg

It is interesting to see how small aerodynamic alterations can alter flight characteristics - the total area of the wingtips removed was 12sq ft but, because this was all outboard of the ailerons, removing the wingtips increased the aileron's effectiveness up to 25,000 feet. It probably increased the torsional stiffness of the wings as well. (http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930091876_1993091876.pdf)

Just for interest the P-47N also showed the benefits of "clipped" wings:
http://i91.photobucket.com/albums/k304/Major_Sharpe/P-47Nrollrate-page-003.jpg

[Matt255]

And here is a perfect example of what I was refering to, that being how two people can read 'pilot accounts' and get different results
I think in that case, the pilots got different results.

Unless you really try very hard to make one plane appear better or worse than the other, ie abusing historical pilot reports to support your point of view. But who cares. :-P

I generally base my idea of how these planes compared (maneuverability wise), on reports of pilots, who flew both (or more) types. And most of those reports fit each other exceptionally well. Which might not be the "correct" approach, but atleast it rules out some bias.

Because leading edge slats were fitted for exactly to this reason. Its no coincidence that slats cover the wing area ahead of ailerons, and maintain steady airflow without stalling at that part of the wing.
(sorry for cutting your post)

I'm totally aware of that and how slats work, but i don't think that's what macro meant when he compared slow speed rolling. But i probably misunderstood his post or interpreted it wrongly.

Anyway, yes, in the case you describe, slats definately help rolling and are in case of the 109 (lacking washout) a requirement for controllability at critically low speeds / high AoA.

So yes, the slats help, when they come out. Wether or not they are an advantage compared to washout or similar design features of a plane, regarding roll "performance", is a different thing though.

[bugmenot]

Well if we are using anecdotal and pilot accounts lets throw these into the fire:

http://www.virtualpilots.fi/feature/articles/109myths/

I stongley urge the red fliers especially to read this. Its a shed load of pilot accounts with sources, all about the 109 and what an Uber plane she really is! :-P





I found this:

http://www.rolfwolf.de/daten/E4/Emil.html


http://www.rolfwolf.de/daten/E4/Emil_html_4785a2b8.gif
I assume these are full throttle speeds.

Höchstgeschwindigkeiten in Steig/Kampfleistung (Tabelle)
I assume this is TAS

0km 460km/h

1km 480km/h

2km 500km/h

3km 520km/h

4km 540km/h

5km 555km/h

6km 555km/h

7km 550km/h


http://www.rolfwolf.de/daten/E4/Emil.html


Leistungen

Motorleistungen DB601A

Kurzleistung (1 min) 1100PS bei 2400 U/min 1.4 ata

Startleistung 990PS bei 2400 U/min 1.30 ata

Steig/Kampflleistung 910PS bei 2300 U/min 1.23 ata

Volldruckhöhe 4000m


http://www.rolfwolf.de/daten/E4/Emil_html_4785a2b8.gif


Farber, Bf109E-3 data, shown in Kennblatt has been obtained on 30 min Steig/Kampflleistung bei 2300 U/min 1.23 ata of aircraft with DB601A-1 'bei altem Lader'

Yes, this is TAS -Wirklich Geschwindigkeit

http://www.wwiiaircraftperformance.org/me109/me109e-handbookcurve.jpg

[5./JG27.Farber]

http://www.rolfwolf.de/daten/E4/Emil.html


Leistungen

Motorleistungen DB601A

Kurzleistung (1 min) 1100PS bei 2400 U/min 1.4 ata

Startleistung 990PS bei 2400 U/min 1.30 ata

Steig/Kampflleistung 910PS bei 2300 U/min 1.23 ata

Volldruckhöhe 4000m


http://www.rolfwolf.de/daten/E4/Emil_html_4785a2b8.gif


Farber, Bf109E-3 data, shown in Kennblatt has been obtained on 30 min Steig/Kampflleistung bei 2300 U/min 1.23 ata of aircraft with DB601A-1 'bei altem Lader'

Yes, this is TAS -Wirklich Geschwindigkeit

http://www.wwiiaircraftperformance.org/me109/me109e-handbookcurve.jpg

I cant tell what your trying to say? - Just to add a graph? Mein Deutsch ist Scheiße

[ATAG_Dutch]

I cant tell what your trying to say? - Just to add a graph? Mein Deutsch ist Scheiße

Vielleicht kannst du im schule zuruck gehen? Never mind, so's mine. :D

[5./JG27.Farber]

services

Engine performance DB601A

Intermittent (1 min) 1100PS at 2400 r / min 1.4 ata

Start power 990PS at 2400 r / min 1.30 ata

Climb / combat power 910PS at 2300 r / min 1.23 ata

Full pressure altitude 4000m


Farber, Bf109E-3 data, shown in Kennblatt has been obtained on 30 min Steig/Kampflleistung bei 2300 U/min 1.23 ata of aircraft with DB601A-1 'bei altem Lader'

Yes, this is TAS -Wirklich Geschwindigkeit

ok I got it. That graph is not full throttle but the limited combat setting and it also uses the old compressor which begins to loose Ata at 4500metres not 5000metres. Therefore the results are lesser than they should be in clod which seems to use the new compressor.

I wonder when the new compressor was rolled out into the field and at what rate?

[ACE-OF-ACES]

I think in that case, the pilots got different results.
Maybe.. maybe not

The point being..

Two people can read a combat report and draw two different conclusions..

Due to their background and biases

Where as..

Two people can add 1 + 1 and draw the same conclusion.. i.e. 2

Independent of their background and biases

In summary..

The problem with anecdotical evidence (aka after action pilot reports) is as follows

1) anecdotical evidence is a one sided story.
2) anecdotical evidence is written by those who lived to write about it.
3) anecdotical evidence does not contain enough info to recreate the scenario in-game.
4) anecdotical evidence is subject to interpretation.

For example of each..

WRT 1) As most of us know there are two sides to every story, and you will not find anecdotical evidence that has input from both side (axis and allied pilot) with regards to the encounter being described.

WRT 2) As most of us know a statistical result depends on the input data. The fact that anecdotical evidence was written by the pilots who lived to write about it excludes the pilots who did not live to write about it. Which makes the statistical result based on the anecdotical evidence biased/filtered towards pilots who lived to write about it. For example, assume there are 100 after actions reports describing how the pilot in his 109 out turned a Spitfire.. We don't know how many 109 pilots died while trying to turn with a Spitfire a thus un-able to write about it, was it 10, 100, 1000? We don't know.

WRT 3) As most of us know anecdotical evidence does not contain enough information about the scenario to recreate scenario in game to preform a test to see if the results are the same. That and the results in both case (real and recreated simulation) depend more on the relative pilot experience than the relative plane performance. That is to say change the pilots and you can change the outcome of the scenario. In essence you would be making changes to the flight modeled based on the relative experience of the pilots not the relative performance of the planes. This is why they did testing under formal and controlled conditions. (see sig)

WRT 4) As most of us know people are different, and therefore peoples take on events will be based on their life experiences. That is to say two people can read the same anecdotical evidence and draw to very different conclusions. Ask any cop who has interviewed several people who have witnessed a crime and they will tell you how peoples perceptions of events can vary. Where as 1 + 1 = 2 is not open to interpretation. (math ftw)

PS in each statement above, there are no absolutes! To improve the readability, in this post I removed my previous qualifying text where I said things like 'typically this' or 'typically that' or 'you will be hard pressed to find'. That is to say, you may be able to find a couple of cases where both an axis and allied pilot had input to an after actions report, but this exception to the rule does NOT change the rule. Also note, I am not saying math is without error, only that math is your best hope of being on the same sheet of music, in that it removes most if not all human bias and interpretation errors. In short, given time, you can track down the source of math errors, where as even with all the time in the world you would still be hard pressed to track down the source of human bias and interpretation errors! ;)

[notafinger!]

Comparative performance between the major single seat fighters from "The Most Dangerous Enemy" by Stephen Bungay.

http://i153.photobucket.com/albums/s207/atp9697/IMAG0145.jpg

[ACE-OF-ACES]

Turning circles are as calculated by John Ackroyd of the Manchester Schoold of Engineering
That is a strange looking turning circles graph..

Altitude vs. Radius?

Where alt units state ('000 ft)

Something is strange here.. as in some info is missing (calc at a fixxed speed?)

I mean based on that graph the Spit is not able to go above 700ft in alt?

At a glance one might conclude that the Spit and Hurry have better turn radius..

But it is allmost as if that was done on purpose..

Does the book say more about that graph and how Mr. Ackroyd calculated it?

[NZtyphoon]

That is a strange looking turning circles graph..

Altitude vs. Radius?

Where alt units state ('000 ft)

Something is strange here.. as in some info is missing (calc at a fixxed speed?)

I mean based on that graph the Spit is not able to go above 700ft in alt?

At a glance one might conclude that the Spit and Hurry have better turn radius..

But it is allmost as if that was done on purpose..

Does the book say more about that graph and how Mr. Ackroyd calculated it?

At first glance I though the altitudes were reading as 600,000 to 900,000 ft -

shades of the Dr Who Spitfires! (http://www.youtube.com/watch?v=HirwnpeugNM&feature=related)

[ATAG_Snapper]

It appears the Turning Circle chart is poorly presented. It's not an X-axis/Y-axis graph at all that I can see. It's simply drawing the turning circle arcs showing the relative diameters; all at "000 ft" which I take to be sea level.

Secondly, have a look at the relative speed charts between the Hurricane I, 109 E3, and the Spitfire I. The speed curve for the Spitfire I looks remarkably like the one for the much-decried "Über Sissyfire IIa" in the current retail version 1.05, as does the curve for the E3 to the CoD v. 1.05 E3, and, by gosh.....there's JTDawg's old Rotol!!!!!

Obviously that chart is wrong and the author sadly misinformed. :rolleyes:

[Crumpp]

Obviously that chart is wrong

Typical....

Most of these history are written by amateurs who know very little about the science of aircraft.


I think the author is a Management consultant.

[ATAG_Snapper]

Typical....

Most of these history are written by amateurs who know very little about the science of aircraft.


I think the author is a Management consultant.

No doubt. Barely able to tie his shoelaces, I should think!

[Crumpp]

I did not say the guy was stupid, Snapper. He is very intelligent and well respected. He has also written some good books.

He is not an aircraft performance engineer or an aerodynamicist.

[Al Schlageter]

Bungay didn't do the graphs as anyone who can read can easily see.

"Turning circles are calculated by John Ackroyd of Manchester School of Engineering."

[Crumpp]

John Ackroyd of Manchester School of Engineering

Care to explain them.......

:-P

[ATAG_Snapper]

I did not say the guy was stupid, Snapper. He is very intelligent and well respected. He has also written some good books.

He is not an aircraft performance engineer or an aerodynamicist.

Sooooo, he's very intelligent and well respected....but since he is not an aircraft performance engineer or an aerodynamicist he therefore publishes incorrect information? Please clarify.

[Al Schlageter]

Care to explain them.......

:-P
:rolleyes:

The altitude for the graph is at 0.0ft. The sources for them is stated at the bottom of the page.

[NZtyphoon]

Sooooo, he's very intelligent and well respected....but since he is not an aircraft performance engineer or an aerodynamicist he therefore publishes incorrect information? Please clarify.

Unfortunately there are very few aviation or aviation related books that meet Crumpp's extremely high standards, because they are not written by engineers. Until true professionals like Crumpp descend from their elevated heights and start researching, writing and publishing books on aircraft, our bookshelves will continue to be cluttered with books written by intelligent, well respected amateurs who know nothing and write abysmal nonsense.

[Crumpp]

The altitude for the graph is at 0.0ft

So the entire left column showing altitude does not exist or is a typo or are you saying the turn performance is in EAS??

Maybe some experts will be along to tell us how wrong it is to use EAS??

LMAO!!!!!

:grin::grin::grin:

Thanks Milo, you are so predictable in your zeal to prove me wrong!

;)

[bongodriver]

My interpretation of the graph is that that bot the left and bottom figures are radius (note how the lines intersect exactly the same figures on both) and the note on the left just means 'sea level', no EAS or IAS involved, admittedly it is a very badly designed illustration.......what's the big deal?

[ATAG_Dutch]

I just googled EAS. So are you referring to the sports nutrition product, Energy Action Scotland, Employment Agency Standards, the European Athletes Society, European Astronomical Society, or are you just throwing in an acronym for the sake of it? :)

The graph in the book is a simple demonstration of relative turning circles. It's not scientific. It's very 'layperson', but not necessarily 'wrong' per se.

I'd say the altitude is a typo. The x and y axes obviously show the same parameter, i.e. radius of turning circle in feet. But I have the book, so I'll check if it's clarified in the text.

[bongodriver]

EAS is equivalent air speed, Crumpp will be along in a minute to teach you all about it....

[ATAG_Dutch]

EAS is equivalent air speed, Crumpp will be along in a minute to teach you all about it....

Ah, thanks Bongo. I did guess that really. Bit of facetiousness I'm afraid. :)

However, I checked the text and there is no clarification as to the methods of calculation re the turning circle. It's a simple example for the readers of a book who don't have PhDs in aerodynamics. Or even a GCSE come to that.

But this doesn't make it 'wrong' per se.

[Crumpp]

the note on the left just means 'sea level',

:?


It does just mean sea level.

You would have to understand that True Airspeed at Sea level equals EAS.....

:rolleyes:

[Al Schlageter]

So the entire left column showing altitude does not exist or is a typo or are you saying the turn performance is in EAS??

Maybe some experts will be along to tell us how wrong it is to use EAS??

LMAO!!!!!

:grin::grin::grin:

Thanks Milo, you are so predictable in your zeal to prove me wrong!

;)

I see your comprehension is as good as it ever was.:rolleyes:

And you were wrong as Bungay didn't do the graphs.:) I don't have to prove you wrong as you do that very well all by yourself.

But do continue making a Olympus Mons out of a mole hill if it helps your ego.

[bongodriver]

It does just mean sea level.



I know...


You would have to understand that True Airspeed at Sea level equals EAS.....


Why do you assume I don't know that? I am merely trying to clear up some confusion on what the figures on the left side of the graph mean...some people seemed confused by it's meaning....:rolleyes:


So the entire left column showing altitude does not exist or is a typo or are you saying the turn performance is in EAS??

Maybe some experts will be along to tell us how wrong it is to use EAS??

LMAO!!!!!

:grin::grin::grin:

Thanks Milo, you are so predictable in your zeal to prove me wrong!

;)


your zeal is eqally as predictable.

[Crumpp]

It's not scientific.

It is scientific and all my calculations agree with the results. Unfortunately, radius of turn is not the best indicator of actual turn performance.

[Crumpp]

Why do you assume I don't know that?

Because your statement is contrary and wrong.

Bongodriver says:
My interpretation of the graph is that that bot the left and bottom figures are radius (note how the lines intersect exactly the same figures on both) and the note on the left just means 'sea level', no EAS or IAS involved, admittedly it is a very badly designed illustration.......what's the big deal?

http://forum.1cpublishing.eu/showpost.php?p=460443&postcount=107

It is cut and dry and requires no interpretation. You are just plain wrong.

That is why anyone would assume you don't know that True Airspeed equals Equivilent Airspeed at sea level. If you did know, then you are just lying about it in your above reply.

The performance is radius of turn in EAS.

[Crumpp]

I will let you guys mull over it and post some calculations with graphs. Not to define any specific performance but to see how the relative performance of these airplanes makes them very equal dogfighters.

We can look at the whole picture and examine various performance improvements in each design along with their effect on the combat performance.

We can see how the relative performance in the game stands up.

[bongodriver]

Because your statement is contrary and wrong.



http://forum.1cpublishing.eu/showpost.php?p=460443&postcount=107

It is cut and dry and requires no interpretation. You are just plain wrong.

That is why anyone would assume you don't know that True Airspeed equals Equivilent Airspeed at sea level. If you did know, then you are just lying about it in your above reply.

The performance is radius of turn in EAS.


No my statement is 100% correct, the graph is turn radius at sea level, would you care to show me exactly where any reference to speeds are made on that graph.

Now kindly remove claims of me being a liar and other accusations....thanks :rolleyes:

[ACE-OF-ACES]

He is not an aircraft performance engineer or an aerodynamicist.
Actually the graphs were done by an engineer..

Which is something I pointed out in the first response to this graph where I took the time to read and than quoted the graph's source, i.e.

Turning circles are as calculated by John Ackroyd of the Manchester School of Engineering

Thus proving that humans (pilots, engineers, etc) can make mistakes..

As for the graph, as I initially noted, I questioned it's purpose..

Initially it seemed like it was done to give the impression that the 109 turn circles are far worse than the Spit and Hurri..

Which they well may be!

But, if that is the case this graph does not do a very good job of showing it!

It actually raises more questions and cast doubt for those who are use to looking at performance graphs (like myself)

If the purpose was to convey the turn radius (circle) at sea level than there is no need to provide an X (radius) vs. Y (alt) graph in that there is no X (radius) vs. Y (alt) taking place..

It is just X (radius) @ Y (alt)

IF that is the case, than placing 'Altitude (000ft) along the Y axis was wrong!

A better way to 'graph' this 'data' would have been to draw circles inside of circle with the radius associated with each circle and title the plot turn radius (circle) at sea level

[bongodriver]

like this one...

http://www.wwiiaircraftperformance.org/wade-turning.jpg

[ACE-OF-ACES]

like this one...
Bingo!

Now looking at this graph..

We can see that the P51 and Spitfire both have a tighter turning circle (smaller radius) because their circles are inside the outer circle that

Also note, the outer circle (bigger radius) contains the the Bf109 along with the Tempest, Fw190, P47

The only info left off here is what is the speed and altitude?

Because these relationships can change with altitude

Also we can safely assume that this are the best turn circles at the best turn rates, but what is the rate?

Which is important, because what you really care about is the time it takes to do a say a 180 (reverse direction).

[Kurfürst]

There is no doubt that there is some sort of demonstrating our superiority ooze about these turn radii graphs... but regardless the figures seem to be about right.

It is entirely another question why this so called superiority is given so much importance. Even the graph shows that the turn radii difference between the Hurri and the 109 was about 200 feet, or about 60 meters. Even the span of these aircraft was 11-12 meters, and actually that's about the distance a 109 wingman kept from his leader... or even less. So what's all the fuss about it?

BTW the figures are rather similiar to what Morgan and Morris came up with in 1940 (for 12k feet - both figures are more of an educated estimate, not trials): http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan.html

http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan_files/image019.jpg

[Crumpp]

No my statement is 100% correct, the graph is turn radius at sea level

Your statement the graph is at sea level is correct and not the issue.

The issue is you imply that speed is not part of the equation and therefore it is wrong to say it is Equivilent Airspeed.

You do know we cannot have rotational motion without velocity, right?

An airplane that is not in motion has no turn radius.

It is not the fact the performance is graphed at sea level.

In fact, that is WHY it is Equivilent Airspeed!

Bongodriver says:
My interpretation of the graph is that that bot the left and bottom figures are radius (note how the lines intersect exactly the same figures on both) and the note on the left just means 'sea level', no EAS or IAS involved, admittedly it is a very badly designed illustration.......what's the big deal?

It is the claim that you knew what EAS is used for and do not recognize that is questionable.

Does that mean EAS is just a term that you heard someplace or do you know its uses? It is ok to admit you don't know everything. I certainly don't, just ask my wife! :-P

I did not call you a liar at all either. I said either you did not know or you are lying. You claimed to know about Equivilent Airspeed in your second reply but you made the statement EAS or IAS is not a part of the math used to derive the graph published in the book. It is probably NOT done in IAS. While it is valid to do a turn performance analysis in IAS, it is not valid for performance comparision because of the PEC. It is also valid to do it in Calibrated Airspeed but CAS = EAS = TAS at sea level.

The fact is your only point is get the conversation shut down at this point so that we do not get to see any analysis that might not fit a small and very vocal agenda. Don't do that. What will follow is unbiased math that anyone can reproduce given the knowledge of aerodynamics. I will even keep it to the college algebra level so it is easy to see.

I am hoping it will quiet down the critism of developers on their FM's. I think they are close in the big picture and the Spitfire's issue is the heat effects. We can prove that.

Bottom line, I did not call you a liar. I said you made the claim to know something and either you did not fully understand it or not forthcoming about the level of understanding you posses. I have no idea what you do or do not know outside of what you write on these forums. The impetus is on you.

[bongodriver]

The issue is you imply that speed is not part of the equation and therefore it is wrong to say it is Equivilent Airspeed.


merely a case of you making the wrong assumption, I made no reference to equations or any such thing, you were obviously a little over eager to jump all over a grammatical error, I should really have said 'no EAS or IAS refered to'......there.....does that help your blood pressure any?


I have no idea what you do or do not know outside of what you write on these forums. The impetus is on you.


Not really, I provided all the evidence of my qualification...what do you need? a picture of me holding a 'hello Crumpp' sign while actually flying an aircraft?....:rolleyes:

[ACE-OF-ACES]

what do you need? a picture of me holding a 'hello Crumpp' sign while actually flying an aircraft?....:rolleyes:
lol

[bongodriver]

There is no doubt that there is some sort of demonstrating our superiority ooze about these turn radii graphs... but regardless the figures seem to be about right.



Really?....the graphs were sourced from litterature as far as I can see, nobody on this forum produced them in any attempt to ooze superiority, and you can still say that despite providing your own source which verifies the accuracy?.......


It is entirely another question why this so called superiority is given so much importance


only because it is further evidence to the argument the Spitfire was a more agile aircraft with better turn performance.....whats all the fuss about?

[bongodriver]

lol


;)

[ACE-OF-ACES]

and you can still say that despite providing your own source which verifies the accuracy?.......
That is a good point

Initially I got the impression that is what the graph was trying to do..

But based on the table that Kurfurst just posted, I see now the graph is right, just it's presentation was not all that it could be.

Put another way

As the graph implied.. (at sea level)

And Kurfurst table confirmed.. (at 12kft)

The Spit does turn a lot better than the Bf109

At more than one altitude!

[JtD]

Turn radius is for turns at sea level. Estimated best sustained turn. Corresponding turn times from same calculation:
Hurricane I: 17.6s
Spitfire I: 18.2s
Bf 109E-3: 20.5s
Bf 110C-4: 20.5s (was also calculated, with radius of 840ft)

[Crumpp]

Turn radius is for turns at sea level. Estimated best sustained turn. Corresponding turn times from same calculation:
Hurricane I: 17.6s
Spitfire I: 18.2s
Bf 109E-3: 20.5s
Bf 110C-4: 20.5s (was also calculated, with radius of 840ft)


While absolutely correct for relative performance, just examining a single point of best performance does not give one the best picture of the relative dogfighting capability.

Looking at one single point in the envelope tells us the Bf-109E3 is hopelessly outclassed IF it tries to match the Spitfire at the Spitfires best performance velocity.

Fortunately, all airplanes have their own unique best performance speeds and the Bf-109E3 is no different.

Here we can see the entire sustainable load factor envelope for both aircraft.

http://imageshack.us/a/img802/1949/spitfiremkivsbf109e3sus.jpg (http://imageshack.us/photo/my-images/802/spitfiremkivsbf109e3sus.jpg/)

What is shows us is that in order for the Spitfire to realize it's turn performance advantage, it must go slower than the Bf-109E3 by some 30Kph or 18 mph.

That means the Bf-109E3 gains the initiative in the fight if the Spitfire tries to use its sustained turn advantage.

Once more, the Bf-109E3 pilot can take his aircraft all the way to its best sustained turn performance point without fear of losing the initiative.

Factor in the stability characteristics and these airplanes are very evenly matched in close quarters dogfighting.

[pstyle]

That means the Bf-109E3 gains the initiative in the fight if the Spitfire tries to use its sustained turn advantage.

Can you reword this so it does not come accross as a bizarre contradiction?

[Crumpp]

Can you reword this so it does not come accross as a bizarre contradiction?

It is not a bizarre contradiction in aerodynamics. ;)

It is a general trend in aircraft performance. You have stumbled across the reason why designers concentrated on high speed instead of low speed performance.

[Robo.]

That means the Bf-109E3 gains the initiative in the fight if the Spitfire tries to use its sustained turn advantage.

Can you reword this so it does not come accross as a bizarre contradiction?

Ah yes, he seems to be slightly confusing again. What I think he's trying to say is that a 109 turns better than a Spitfire at higher speeds - which is no news and pretty obvious, but it also has nothing to do with sustained turn times comparsions.

I'd like to see a Hurricane in the game that has better sustained turn than a Spitfire AND a 109. What we have got now is:

1 Spitfire
2 109
3 Hurricane

[Osprey]

Let me add in game speed, climb and dive to that Robo :D

1. 109
2. Spitfire
3. Hurricane

1. 109
2. Spitfire
3. Hurricane

1. 109
2. Spitfire
3. Hurricane

.....still willing to take the Hun on :)

[pstyle]

Allow me to ask again, what I'm reading in that odd sentance is;
The spitfire has an advantage, unless it tries to use it.

[bongodriver]

Allow me to ask again, what I'm reading in that odd sentance is;
The spitfire has an advantage, unless it tries to use it.

it roughly translates in Crumpp parlance to:

The Spitfire has an advantage until it is matched against anything German and I produce the graph to prove it'

takes a little time to learn Crumpp but it becomes reasonably predictable.

[JtD]

Looking at one single point in the envelope tells us the Bf-109E3 is hopelessly outclassed IF it tries to match the Spitfire at the Spitfires best performance velocity.No, it says the Spitfire at its best turn performance velocity beats the 109 at its best turn performance velocity. According to these figures, the 109 cannot outturn a Spitfire in a sustained turning fight at sea level unless the Spitfire lets it happen, however, the Spitfire can outturn the 109 in said scenario no matter what the 109 does.

[JtD]

The spitfire has an advantage, unless it tries to use it.Great summary. :) I guess that's the way he put it, but it boils down to the statement that the faster plane generally holds the advantage. This remains true in turnfights. The 109 has the choice to maintain the higher airspeed at a lower corner velocity, the Spitfire has the choice to maintain a higher corner velocity at a lower airspeed, so the 109 can maintain the initiative.

It should be noted that on Crumpps chart the 109 has a level speed advantage of ~18 knots, however representative that is for a BoB scenario.

[Crumpp]

Feel free to calculate it yourselves!!

which is no news and pretty obvious, but it also has nothing to do with sustained turn times comparsions.

The performance is the sustained envelope. It is just over the entire envelope both aircraft can sustain instead of just choosing one single point.


So it is everything to do with sustained turn time comparisions as it IS A SUSTAINED TURN TIME COMPARISION under the same condition of flight. At the same altitude and airspeed, that is how the relative performance will play out.


You do understand the Spitfire and BF-109 do not achieve their best turn performance under the same conditions of flight?

[Crumpp]

It should be noted that on Crumpps chart the 109 has a level speed advantage of ~18 knots, however representative that is for a BoB scenario.


It was manufacturer's data for each type.

There is a wide range of data available on both types. Choose what you want.....

[Crumpp]

The Spitfire has an advantage until it is matched against anything German and I produce the graph to prove it'


Do the math...it does not lie.

[Crumpp]

Spitfire data used

http://www.spitfireperformance.com/n3171.html

Bf-109E3 data used:

http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan.html

[Glider]

An obvious statement but the Spit trials you quote above seems to be without the extra boost that 100 octane allows.

A second observation, can someone explain how the Me109 is supposed to have a better manoverability at higher speeds than the SPitfire when all the tests point out how difficult the 109 is to manoever at high speeds due to the way the controls stiffen up at high speed compared to the Spitfire?

Last I don't see how the chart on posting 129 page 13 proves what it says it proves. I would appreciate it if it could be explained to me in simple terms or explain the maths behind the criteria thanks

[Robo.]

No, it says the Spitfire at its best turn performance velocity beats the 109 at its best turn performance velocity. According to these figures, the 109 cannot outturn a Spitfire in a sustained turning fight at sea level unless the Spitfire lets it happen, however, the Spitfire can outturn the 109 in said scenario no matter what the 109 does.

Yes that pretty much nails it.

The speed advantage is still speed advantage as JtD said it 100% ly - ''This remains true in turnfights. The 109 has the choice to maintain the higher airspeed at a lower corner velocity, the Spitfire has the choice to maintain a higher corner velocity at a lower airspeed, so the 109 can maintain the initiative.''

[Robo.]

You do understand the Spitfire and BF-109 do not achieve their best turn performance under the same conditions of flight?

Yes that's what I was saying before. ;) But when it comes to sustained turn that does not really matter.

Do you know what would happen if you entered a pure turn and burn (TnB) fight against a Spitfire (you in a 109)? :-P

[Crumpp]

An obvious statement but the Spit trials you quote above seems to be without the extra boost that 100 octane allows.


It does not change the outcome or outlook. Despite the higher wingloading, the Bf-109 has more excess thrust because it is lighter.

JtD says:

No, it says the Spitfire at its best turn performance velocity beats the 109 at its best turn performance velocity.

How is your statement ANY different from mine???? :confused:

Crumpp says:
Looking at one single point in the envelope tells us the Bf-109E3 is hopelessly outclassed IF it tries to match the Spitfire at the Spitfires best performance velocity.

Performance in the context of the conversation is TURN performance.

The Spitfire has to reduce speed significantly below the Bf-109's to reach that best turn velocity.

That is a fact.

According to these figures, the 109 cannot outturn a Spitfire in a sustained turning fight at sea level unless the Spitfire lets it happen, however, the Spitfire can outturn the 109 in said scenario no matter what the 109 does.

That is one way of looking at it.

Another way is the Spitfire must give up 30 kph of speed in order to realize any advantage at all.

It is the same exact scenario. One that leaves the Spitfire with no choice but hope it sticks around in the turn fight.

If the Bf-109 does not, the Spitfire has lost the initiative.

[Crumpp]

Do you know what would happen if you entered a pure turn and burn (TnB) fight against a Spitfire (you in a 109)?

Sure, you would use the Bf-109's sustainable load factor advantage to put the Spitfire turning defensive circles beneath you until you killed him.

[Crumpp]

A second observation, can someone explain how the Me109 is supposed to have a better manoverability at higher speeds than the SPitfire when all the tests point out how difficult the 109 is to manoever at high speeds due to the way the controls stiffen up at high speed compared to the Spitfire?



Don't confuse high load factors found in instantaneous performance with low load factors achievable in sustained performance.

[Robo.]

Sure, you would use the Bf-109's sustainable load factor advantage to put the Spitfire turning defensive circles beneath you until you killed him.

That's not the TnB mate. ;)

[macro]

yea i thought that was ZnB?

[JtD]

How is your statement ANY different from mine???? :confused:You're saying the 109 is flying at the Spitfires best turn performance speed, I am saying the 109 is flying at its own best turn performance speed. Quite a difference.

[Crumpp]

You're saying the 109 is flying at the Spitfires best turn performance speed, I am saying the 109 is flying at its own best turn performance speed. Quite a difference.


No I am not. I am saying both aircraft are flying best turn performance.

Best turn performance is a specific speed.

In the single point analysis of best turn performance, the airplanes are at different speeds.

When we look at the entire envelope, the Spitfire must be at a slower speed in order to outturn the Bf-109.

http://imageshack.us/a/img228/1949/spitfiremkivsbf109e3sus.jpg (http://imageshack.us/photo/my-images/228/spitfiremkivsbf109e3sus.jpg/)

[Igo kyu]

That graph must be rubbish.

I don't pretend to understand what it's supposed to mean, but the aircraft leave the graph in opposite directions. That just doesn't happen in graphs of real world effects.

[Glider]

First thanks for the replies

My first observation was that the Spit test you used didn't include the extra power from the 100 octane fuel

It does not change the outcome or outlook. Despite the higher wingloading, the Bf-109 has more excess thrust because it is lighter.

I say it does make a difference as the extra boost came with a significant increase in power which significantly improves the power weight ratio. Also lighter is a factor but a bigger one is drag which is where the 109 loses out.

Re your second reply

Don't confuse high load factors found in instantaneous performance with low load factors achievable in sustained performance
You have a point but nowhere have I seen anything that says that the 109 had a better sustained performance. Also what is sustained? Everyone seems to agree that the SPit turned tighter and faster so what is sustained. Are you trying to say that after X turns the 109 would start catching up because it has a better sustained performance?
My understanding is that a sustained turn rate is one that can be maintained for long periods of time without losing altitude, maximising the turn rate and radius of turn.
On both these counts the Spit will beat the Me109 as proven in the Rae tests which were sustained turns without losing height

Re the Graph,s I still don't understand what you are trying to prove. Lift limit is a new term to me but I assume it has something to do with the max lift the wing will generate given a certain angle of bank, but how load factor impacts this I don't have a clue, as the load doesn't impact lift. Load factor increases with bank which will increase the amount of lift required but lift available in the wing is a constant
Thrust Limit is also a new term to me I assume its a power to weight thing, but again don't understand how load would impact it as thrust is a given depending on height etc but not as far as I am aware load factor. The thrust required is increased as the bank increases but in a given aircraft it is a fixed amount.

[Crumpp]

I say it does make a difference as the extra boost came with a significant increase in power which significantly improves the power weight ratio

What power and speed? I will recalculate and repost.

You have a point

If you understand stability and control engineering, Mtt did a good job on the Bf-109.

Also what is sustained?

It is the performance the engine can perform until it runs out of gas.

My understanding is that a sustained turn rate is one that can be maintained for long periods of time without losing altitude, maximising the turn rate and radius of turn.


Yes

On both these counts the Spit will beat the Me109 as proven in the Rae tests which were sustained turns without losing height


The RAE test's were of turning ability. If you look at the test the RAE flew the airplanes at ~115KEAS in their evaluation.

[Crumpp]

Lift limit is a new term to me

Lift limit is the aerodynamic limits of the wing. Propeller aircraft are called power producers and are aerodynamically limited at the stall point.

The lift line is the stall line.

load doesn't impact lift

Load does impact lift.....

Thrust Limit is also a new term to me

It is the thrust limited portion of our envelope. Here the aerodynamics of the wing are not the limiting factor but rather how much excess thrust the aircraft can produce.

[Kurfürst]

Also lighter is a factor but a bigger one is drag which is where the 109 loses out.

Actually drag is the factor where the 109 may win out at high speeds. Parasitic drag is much lower on the 109 than on the Spitfire, and parasitic drag is what dominates total drag at higher speeds. The Spitfire turns better at low speeds because it has lower induced drag, and induced drag is what dominates total drag at low speeds.

Sustained turn is just the maximum g-load at which drag = thrust. Maximum sustained turn (i.e. the number usually quoted for turn times) is always achieved at lower speeds, but that doesn't mean the trends continue to high speeds and may be reversed. I am not sure if there is much to it - it can be well true that both aircraft can only turn so slowly in a sustained fashion that there is no tactical point in it.

Bottom line, a faster aircraft will always outturn a slower aircraft at high speeds, the question is not really wheter this happens or not, but: by how much?

[ACE-OF-ACES]

No, it says the Spitfire at its best turn performance velocity beats the 109 at its best turn performance velocity. According to these figures, the 109 cannot outturn a Spitfire in a sustained turning fight at sea level unless the Spitfire lets it happen, however, the Spitfire can outturn the 109 in said scenario no matter what the 109 does.
Bingo!

[Crumpp]

I still don't understand what you are trying to prove.

Not sure you understand much of the science at all. I certainly don't like the attitude or implication I have something to prove or a vested interest in the outcome.

The math is what it is.....

[Glider]

What power and speed? I will recalculate and repost.



If you understand stability and control engineering, Mtt did a good job on the Bf-109.



It is the performance the engine can perform until it runs out of gas.



Yes



The RAE test's were of turning ability. If you look at the test the RAE flew the airplanes at ~115KEAS in their evaluation.

So to sum up you do not disagree that the Spit had a better sustained turning ability, your position is that the 109 had a better sustained straight line performance because the engine had a better sustained performance.

Just trying to get things straight in my mind before going any further

[Glider]

Load does impact lift.

I think you will find that load increases the lift required in a certain situation and if I remember correctly roughly doubles at 60 degree bank

[Glider]

Actually drag is the factor where the 109 may win out at high speeds. Parasitic drag is much lower on the 109 than on the Spitfire, and parasitic drag is what dominates total drag at higher speeds. The Spitfire turns better at low speeds because it has lower induced drag, and induced drag is what dominates total drag at low speeds.

Sustained turn is just the maximum g-load at which drag = thrust. Maximum sustained turn (i.e. the number usually quoted for turn times) is always achieved at lower speeds, but that doesn't mean the trends continue to high speeds and may be reversed. I am not sure if there is much to it - it can be well true that both aircraft can only turn so slowly in a sustained fashion that there is no tactical point in it.

Bottom line, a faster aircraft will always outturn a slower aircraft at high speeds, the question is not really wheter this happens or not, but: by how much?

I don't know the numbers for the parasitic drag for these aircraft but would expect the difference to be marginal. The Spitfire is a larger aircraft and this would count against it but the 109E has less curves and is less aerodynamic which would balance it out. Indeed the 109F was more streamlined and this contributed to its improved performance. Which has the advantage I don't know but I would expect it to be close.

I believe your bottom line re a faster aircraft always outturning a slower one to be wrong. If it were right the 262 would out turn everything

[Glider]

Not sure you understand much of the science at all. I certainly don't like the attitude or implication I have something to prove or a vested interest in the outcome.

The math is what it is.....

I don't know if your trying to prove that the 109 had a better sustained turn or straight line speed and don't see how the diagram helps either case.

In short I don't see how it proves anything.

[MusseMus]

Inspired by another post here about possible speed gauge error I made a little test.

I created a mission in FMB, where I let 2 AI planes fly next to each other for some miles. One was a 109E-4 and the other a Spit 1 and they were programmed to go at 300 kph at 500 meters.
I measured the time it took for them to travel 20 km and I checked their speed gaugets (AI on).

Observation 1: The 109E-4 outran the Spit on every try No idea why they did not match speed since I used exactly the same settings on them. :grin:

Observation 2:
The airspeed gauge on the 109 red 310 kph, but the calculation gave me 325 kph=a difference of about 5%

The spits gauge showd 170 mph=273 kph, but the calculations gave me 316 kph=a difference of about 15%

I'm aware that I'm comparing IAS and ground speed here, but the difference at 500 meters should not be this big, right?

Compare theese results with Cambers table :grin:
Coincidence? :confused:

/m

http://i406.photobucket.com/albums/pp142/wjhawaii/Comp2.jpg

[Crumpp]

In short I don't see how it proves anything.


Well, that is because you don't understand aircraft performance.

That is ok and you are not alone.

It proves exactly what I said and the math does not lie nor is it bias.

I will see if I can help you. If I can't, oh well, it does not change the physics or the math.

Angle of bank and load factor have a fixed relationship in a steady state turn.

For example, 60 degree of bank will always produce a 2g load factor no matter what the aircraft under consideration.

Turn rate and radius is a function of angle of bank and velocity.

All aircraft at the same angle of bank and velocity will make exactly the same turn. So if a Cessna Corvalis and a Boeing 747 are going 200 knots and banks 60 degrees, they will both make the same rate and radius of turn.

Radius is very velocity dependant.

From an FAA question when getting your commercial certificate.....

An aircraft holds a constant angle of bank and velocity increases. What is the effect on radius?

The correct answer is load factor remains constant and radius increases.

At the same velocity, the aircraft which can sustain the highest angle of bank is achieving the higher load factor and will make a smaller radius as well as higher rate of turn.


So that diagram shows the Spitfire cannot realize a sustained turn performance advantage until it reaches the portion of the envelope the Bf-109 cannot fly in anyway. Then the Bf-109 must reduce its angle of bank in order to match speed and the Spitfire can sustain a higher angle of bank in that portion of the envelope.

If a Spitfire enters a turn fight with a Bf-109, the Bf-109 can force the Spitfire into this low speed realm. The Bf-109 will simply outturn or match any Spitfire that tries to remain at the same speed or maintain velocity.

So both pilots have to make a choice. The Spitfire pilot can choose to hold onto his airspeed and be shot down. The Bf-109 pilot can choose to follow the Spitfire into the low speed realm and be shot down.

Factor in stability and control, these aircraft are even more equal dogfighters. The Bf-109 pilot can precisely attain and hold a target load factor to achive maximum performance.

The Spitfire requires a skilled pilot to precisely achieve and maintain a target load factor in order to achieve maximum performance.

Understand?

[ACE-OF-ACES]

Coincidence? :confused:
There is some debate on this issue.. But one thing that I am sure of (99%) is the guage values are.. well.. not great! ;) I have seen that they lag other values (see below), I think to simulate guage reaction times.. Also they have some strange offsets associated with them.. For example, the ROC reads around 65+ fpm while sitting still on the runway! ;) So for those reason and more I have been leaning towards using the 3D world relative values (Z) over the cockpit guage aka indicated (I) values. They are not without issues either.. I say issue but it just maybe something we are not told about them yet, maybe the soon to be released read me will clear some of that up? Anyway the Z values seem to be the way to go for now IMHO.

[Crumpp]

I believe your bottom line re a faster aircraft always outturning a slower one to be wrong.

An aircraft at Vmax has zero excess power.

So, the slower airplane has zeo excess power at its top level speed while the faster still has excess power to maneuver.

Understand?

[Crumpp]

For example, the ROC reads around 65+ fpm while sitting still on the runway!

Have you sat in the cockpit of many real airplanes?

;)

[IvanK]

Emm we have this chart from RAE

http://i40.photobucket.com/albums/e215/zulu64/spiv109susturn.jpg

It clearly shows that the Spitfire MK I has better sustained turn performance throughout the speed range than the Bf109E3. It also shows Max sustained G of the Spit as 3G whilst the max sustained G of the BF109E3 is about 2.3G. With the Spit I weighing 6000lbs and the 109E3 weighing 5600lb.

We then have this chart

http://imageshack.us/a/img228/1949/spitfiremkivsbf109e3sus.jpg

Which shows the BF109E3 having a better sustained turn performance than the Spifire MKI throughout the speed range. This chart shows (at Take off weight nonetheless) the Spitfire max sustained G of 3.2 g and the BF109E3 max sustained G of 3.25g

Whose chart do you believe RAE or this other thing ?

[Al Schlageter]

Well Ivan I would believe the chart made by a practicing aeronautical engineer over a theoretical aeronautical engineer.

[camber]

Not sure you understand much of the science at all. I certainly don't like the attitude or implication I have something to prove or a vested interest in the outcome.

The math is what it is.....

math is math, and physics is physics.

But coding useful models is a different animal. Part of my job is coding physical process simulations. Providing you have implemented the correct maths, your output depends on the physical constants you choose as appropriate.

Perhaps if you listed the constant values you used for the Spit and 109 we could evaluate your graph a little better. The math equations would be good too.

camber

[Robo.]

Sustained turn is just the maximum g-load at which drag = thrust. Maximum sustained turn (i.e. the number usually quoted for turn times) is always achieved at lower speeds, but that doesn't mean the trends continue to high speeds and may be reversed.

Very true, but this has nothing to do with a sustained turn time. Say you're attacking a Spitfire in a Fw 190. You're much faster, he breaks and at that speed difference (him slowish, you very fast), you can turn inside him for long enough to place a burst in front of him. You lose some speed, he loses a wing if you hit, but that's not a sustained turn competitiion. You would never ever even at this theoretical advantage at this particular speeds enter a turn and burn fight and remain in that turn because you would lose the fight.

Not to mention G-load and blackout. Or if you're in a 109 the elevator stiffness at high speed would be (and is) a massive issue, too. In a sustained turn entered from higher speed, you happen to slow down anyway and the best you can do as a pilot is keep your speed at optimum (not to slow down too much) and watch the G load because if you can't see you can't shoot. We're talking pure TnB fight where the sustained turn rate plays a huge role (and pilot's skill is another 50% because). Obviously, this rarely happens in RL (or virtual skies) because you don't want to burn all your Es in a sustained turn, especially so in a 109.

I am not sure if there is much to it - it can be well true that both aircraft can only turn so slowly in a sustained fashion that there is no tactical point in it.

You would be surprised how many 109 pilots still enter TnB fight vs. Spitfires. And they will almost always lose because (surprise surprise) the Spit has got much better sustained turn.

Bottom line, a faster aircraft will always outturn a slower aircraft at high speeds, the question is not really wheter this happens or not, but: by how much?

In theory. I would really like to see how a Me 262 outturns a P-51 in a sustained turn even at very high speeds. :o

[Robo.]

All aircraft at the same angle of bank and velocity will make exactly the same turn. So if a Cessna Corvalis and a Boeing 747 are going 200 knots and banks 60 degrees, they will both make the same rate and radius of turn.

Yes this is true. For a graph of a hypothetical situation, but if it was actual dogfight, the Cessna would outturn the 747. I understand what you're saying though.

So that diagram shows the Spitfire cannot realize a sustained turn performance advantage until it reaches the portion of the envelope the Bf-109 cannot fly in anyway.

Diagram shows something that did not exist in real life and luckily it does not exist in the sim either. Spitfire can realize the turn performance advantage at almost any moment unless the speed difference is largely in favour of the 109 - at which point the 109 pilot won't try to enter a pure turning competition (and that's what we're talking here about) anyway.

Then the Bf-109 must reduce its angle of bank in order to match speed and the Spitfire can sustain a higher angle of bank in that portion of the envelope.

First pilot to reduce the angle of bank is very likely to lose the (turn)fight. If the 109 pilot gains speed and climbs we haven't got pure turnfight anymore and we can't speak of sustained turn either. Of course, in real virtual dogfights this is exactly what happens and both pilots usually fly yo-yos and the turn is egg-shaped rather than a circle etc. There is much more to it in actual combat. Sustained horizontal turn rate is still very important when it comes to TnB and this is where Spitfire beats the 109. (still depending on the pilots of course).

If a Spitfire enters a turn fight with a Bf-109, the Bf-109 can force the Spitfire into this low speed realm. The Bf-109 will simply outturn or match any Spitfire that tries to remain at the same speed or maintain velocity.

I suggest you start flying these combat flight sims, while you're hangin around on the forums you might as well want to actually try what you're typing in here. It won't work I am telling you now :-P

So both pilots have to make a choice. The Spitfire pilot can choose to hold onto his airspeed and be shot down. The Bf-109 pilot can choose to follow the Spitfire into the low speed realm and be shot down.

This is as wrong as it can get mate :grin:

The Bf-109 pilot can precisely attain and hold a target load factor to achive maximum performance.

Any pilot can do that. Of course pilot skill plays a huge role in here, too. There are more tricks in how to outturn your opponent and win the edge. This is where the human factor comes in. But speaking strictly of the machines and the sustained turn potential, Spitfire would be the winner at typical TnB speeds. That's why any sane 109 pilot avoids TnB with a Spitfire.

The Spitfire requires a skilled pilot to precisely achieve and maintain a target load factor in order to achieve maximum performance.

Actually it's the other way around. Average Spitfire pilot will outturn any average 109 pilot hands down when it comes to sustained turn. It requires exceptional 109 pilot (esp. engine management and stall control, very clean rudder) to outturn a decent Spitfire pilot in a proper turnfight.

Understand?

I understand that you have no experience with virtual dogfight. Your theoretical knoweledge is useful but you would die in combat if you tried to apply it. ;)

[MusseMus]

There is some debate on this issue.. But one thing that I am sure of (99%) is the guage values are.. well.. not great! ;) I have seen that they lag other values (see below), I think to simulate guage reaction times.. Also they have some strange offsets associated with them.. For example, the ROC reads around 65+ fpm while sitting still on the runway! ;) So for those reason and more I have been leaning towards using the 3D world relative values (Z) over the cockpit guage aka indicated (I) values. They are not without issues either.. I say issue but it just maybe something we are not told about them yet, maybe the soon to be released read me will clear some of that up? Anyway the Z values seem to be the way to go for now IMHO.

:grin: Yes it seems the Z value is the only reliable "gaguge" för speed. My point was that it seems like there is quite a big difference between the speed gauge in the spit and 109. Countless posts on this forum complain about the spit is going too slow in level flight and most of them draw this conclution from the speed gauge alone. I'm not saying they are wrong, but reading the speed gauge gives the impression that a 109 is travelling much faster than a spit, even if they are flying side by side.

[IvanK]

Don't forget the inherent display bug on all RAF ASI's .... that is the needle drops rapidly in response to G. You can drive the RAF ASI any way you want with minor applications of G. So any time you are pulling G the RAF ASI bug will result in a grossly low IAS that bears no resemblance to your real IAS. The German ASI's are not "afflicted" by this bug.

The current bug renders the RAF ASI totally useless as a manoeuvre/energy cue. its only useful in 1G flight.

[winny]

Here's a quote from the Spitfire, Hurricane, Curtis and 109E trial carried out by the Germans at E-Stelle Rechlin.

"Before tuning fights with the ME109E, it must be noted that in every case, that all 3 foreign planes have significantly smaller turning circles and turning times"


Just thought I'd throw that in..

[camber]

Inspired by another post here about possible speed gauge error I made a little test.

I created a mission in FMB, where I let 2 AI planes fly next to each other for some miles. One was a 109E-4 and the other a Spit 1 and they were programmed to go at 300 kph at 500 meters.
I measured the time it took for them to travel 20 km and I checked their speed gaugets (AI on).


Thank you MusseMus, that is very interesting!

In previous speed tests I put in the phrase that these comparisons were only valid if a 109 and Spit flying side by side showed the same speeds on their gauges. From your tests it looks like the answer is no! From flying in ATAG it is clear that 109s show a large speed advantage at all alts but perhaps not as much as the gayges suggest :(

camber

[MusseMus]

Thank you MusseMus, that is very interesting!

In previous speed tests I put in the phrase that these comparisons were only valid if a 109 and Spit flying side by side showed the same speeds on their gauges. From your tests it looks like the answer is no! From flying in ATAG it is clear that 109s show a large speed advantage at all alts but perhaps not as much as the gayges suggest :(

camber

Thank you Camber!

My test was not very scientific because I only ran it 3 times and maybe the distance was a little short :) I would like to see if others get similar results.
It would also be interesting if 2 pilots could run side by side online and compare their speed gauget readings.
It would be good news if the speed difference between the COD spit & 109 is smaller than we thought :grin:

[klem]

:grin: Yes it seems the Z value is the only reliable "gaguge" för speed. My point was that it seems like there is quite a big difference between the speed gauge in the spit and 109. Countless posts on this forum complain about the spit is going too slow in level flight and most of them draw this conclution from the speed gauge alone. I'm not saying they are wrong, but reading the speed gauge gives the impression that a 109 is travelling much faster than a spit, even if they are flying side by side.

You may like to know that (deep breath):

Z values for IAS, TAS are given in 'world co-ordinates' units, e.g. 130.5 means 130.5 world co-ordinate units. I did some tests of distances on the CoD map versus Google Earth and to cut a long story short 'world co-ordinates' are effectively in meters, e.g. if you subtract one from another (using pythagoras unless you travelled perfectly east or west) the distance is in metres.

In one set of Spitfire tests I did I registered 249.83mph (402.06kph) on the IAS gauge at 10,000 feet (thats a scripted-out value that is fed to the gauge graphic, the needle can't be read that accurately and the tooltip rounds to whole numbers). Using rough conversion 2% per 000 feet that's 299.79mph TAS or 482.47kph TAS. More accurately using Density altitude that calculates as 290.72mph TAS or 467.87kph TAS.

The Z values were 132.09 IAS and 134.92 TAS. Assuming these to be metres per second (nothing else fits) that's 475.52kph Z_IAS, 485.71kph Z_TAS.

More confusion because I understood the rough conversion to TAS is 2% per thousand feet which should put the Z_TAS at 475.52 * 1.2 = 570.62kph not 485.71. OR... Z_TAS should put Z_IAS at 485.71 / 1.2 = 404.76. If we trust Z_TAS the IAS begins to look right and Z_IAS wrong. If we trust Z_IAS the IAS gauge and Z_TAS are wrong. Conclusion? Who knows but Z_TAS and IAS gauge have more going for it, after all the IAS value has to come from somewhere.

so at 10,000ft
IAS mph....IAS kph.....Z_IAS kph......IAS kph (from Z_TAS) ...Z_TAS(kph).....TAS@D.A.(kph from IAS)
249.83......402.06........475.52.........404.76... ...................485.71.....................467. 86 (remember TS@D.A. will be different because its calculated for a standard day)

Now you could argue that according to the Z_IAS value the Spitfire is travelling 18% faster than the IAS gauge says. Alternatively..... Z_TAS converted to IAS says the IAS gauge is near enough correct. If that's right then the small difference between IAS gauge and IAS from Z_TAS could be caused by atmosphere factors (standard day to CoD day).

We have to be sure we're testing these aircraft properly. With respect, "I tested it at 10,000 feet and it isn't as fast as it should be" is very subjective because:
1. It was being tested using the IAS gauge which now falls under suspicion (for ALL aircraft). Or does it?
2. It "isn't the same top speed as the historical" data because it isn't being tested at or converted to a 'standard day' which is how historical data is published. How many of you know that the default SL pressure for CoD on line is 995mb, not 1013.25 as on a standard day? And that doesn't take account of CoD's SL temperature which is never the standard day 15C.
3. We don't really know if/which IAS, Z_data or whatever is truly accurate but I'm more inclined to trust the Z data and particularly Z_TAS.

I have never tested the 109 but I will after the patch although it would be nice to have some other guys help.

[Crumpp]

Diagram shows something that did not exist in real life and luckily it does not exist in the sim either. Spitfire can realize the turn performance advantage at almost any moment unless the speed difference is largely in favour of the 109 - at which point the 109 pilot won't try to enter a pure turning competition (and that's what we're talking here about) anyway.

The diagram is accurate and uses industry norms for determining aircraft performance. Its does not fit any aerodynamic science that the Spitfire shoudl realize a turn performance advantage under all conditions.

[Crumpp]

Yes this is true. For a graph of a hypothetical situation, but if it was actual dogfight, the Cessna would outturn the 747. I understand what you're saying though.

In actual dogfight, physics does not change.

Diagram shows something that did not exist in real life and luckily it does not exist in the sim either. Spitfire can realize the turn performance advantage at almost any moment unless the speed difference is largely in favour of the 109 - at which point the 109 pilot won't try to enter a pure turning competition (and that's what we're talking here about) anyway.

See Above, the math is the math.

First pilot to reduce the angle of bank is very likely to lose the (turn)fight. If the 109 pilot gains speed and climbs we haven't got pure turnfight anymore and we can't speak of sustained turn either. Of course, in real virtual dogfights this is exactly what happens and both pilots usually fly yo-yos and the turn is egg-shaped rather than a circle etc. There is much more to it in actual combat. Sustained horizontal turn rate is still very important when it comes to TnB and this is where Spitfire beats the 109. (still depending on the pilots of course).

Right, and the Spitfire is outturned at higher velocity because it cannot sustain as high a turn rate at higher speeds.

I suggest you start flying these combat flight sims, while you're hangin around on the forums you might as well want to actually try what you're typing in here. It won't work I am telling you now :-P

This is as wrong as it can get mate :grin:

Not an issue and has not effect with what happens in reality. It is hard to overcome the physics of the Bf-109 being lighter with the same power. This is an advantage where performance is thrust limited.


Any pilot can do that. Of course pilot skill plays a huge role in here, too. There are more tricks in how to outturn your opponent and win the edge. This is where the human factor comes in. But speaking strictly of the machines and the sustained turn potential, Spitfire would be the winner at typical TnB speeds. That's why any sane 109 pilot avoids TnB with a Spitfire.

Sure, it depends on the speed though.

Actually it's the other way around. Average Spitfire pilot will outturn any average 109 pilot hands down when it comes to sustained turn. It requires exceptional 109 pilot (esp. engine management and stall control, very clean rudder) to outturn a decent Spitfire pilot in a proper turnfight.

Maybe if they fix the stability and control it will be more realistic. Of course that will not change the speeds performance occurs....

I understand that you have no experience with virtual dogfight. Your theoretical knoweledge is useful but you would die in combat if you tried to apply it. ;)

I admit I have limited knowledge about virtual airplanes. My expertise lies with the real ones.

[bongodriver]

I admit I have limited knowledge about airplanes. My expertise is lies.


fixed that for ya.

[ACE-OF-ACES]

More confusion because I understood the rough conversion to TAS is 2% per thousand feet
The key word being 'rough'

A few years back, while testing IL-2, I did a comparison between the gauge IAS to TAS values using the 'rough' conversion to the 'full' conversion using the IL-2 'internal' values obtained via SJacks ZINFOMOD.. I than graphed the two values side by side, at which point the word 'rough' came to light! In short this rule-of-thumb pilot real time in your head calculation is very 'rough', there are points (altitudes) where it is spot on, but there are other points (alts) where is is way off.

but I'm more inclined to trust the Z data and particularly Z_TAS.
Hopefully the soon to be released 'readme' will shed some light on the subject, but like you, I am leaning towards using some of the Z data values.. at least when it comes to speed measurements. They do seem to agree with the real world data better, at least for the few planes I have tested.

For now my plan is to provide both the Z and I values and let the user decide which to use with my CoD analysis tools that I provide online at www.flightsimtesting.com

[ATAG_Snapper]

Thank you MusseMus, that is very interesting!

In previous speed tests I put in the phrase that these comparisons were only valid if a 109 and Spit flying side by side showed the same speeds on their gauges. From your tests it looks like the answer is no! From flying in ATAG it is clear that 109s show a large speed advantage at all alts but perhaps not as much as the gayges suggest :(

camber


Definitely worth looking at -- good work. I see this question of airspeed gauge accuracy has been posed in the Questions thread, as it should be. Anything like this should be examined, IMHO, and I hope Ilya does. RAF aircraft need accurate instruments for navigation as well -- especially if cloud cover is someday introduced. Hopefully you will post a Bugtracker Report using your data as its basis.

Having said that, I must admit I'm not convinced that perceived major FM inequities lie just with simple instrument error. As the old saying goes, "Just because you're paranoid doesn't mean they're not out to get you.". The hundreds of hours (literally) most of us have virtually flown on type (for both sides) to believe this notwithstanding, the RAF models alone are hobbled with huge radiator drag, with radiator surface area assigned three times the surface area of the 109's TWO radiators combined, with the double whammy of the RAF rads being assigned a drag coefficient 40% greater than their 109 counterparts. This alone has the Spits and Hurries flying with a huge drogue chute behind them when the pilot tries to cool his glycol and oil even under normal operating conditions, let alone in a fast interception climb or actual combat.

Only when Engine Temperature Management is deactivated in the Realism Options do the Spits and 109's actually achieve parity in engine performance. By default, with ETM off, all radiators are closed (huge benefit for Spits, Hurries, small benefit for 109's), and all temps are now AI - regulated (again, huge benefit for RAF, smaller benefit for LW). This is wrong and must be corrected, instrument error or no instrument error.

The devs are aware of this, and they should be made aware of all instrument error -- including the dodgy Rate of Climb indicator in the RAF aircraft as well.

None of this is rocket science, it just remains if Ilya sees fit to order the corrections or not.

Plus, I want to emphasize how much I respect and support your hands on initiative and the work you've done, and sincerely wish for any and all instrument inaccuracies be fixed -- at least to authentic specs. I tend to agree with my colleague, Dutch, that if the radiator drag issue is remedied in the RAF aircraft that the FM's for both RAF and LW will be closer aligned in relative performance. And I certainly want accurate gauges!

[Kurfürst]

The hundreds of hours (literally) most of us have virtually flown on type (for both sides) to believe this notwithstanding, the RAF models alone are hobbled with huge radiator drag, with radiator surface area assigned three times the surface area of the 109's TWO radiators combined, with the double whammy of the RAF rads being assigned a drag coefficient 40% greater than their 109 counterparts.

Is this a fact or a feeling? I have the relevant radiator areas, so what are the figures and from where?

The devs are aware of this, and they should be made aware of all instrument error -- including the dodgy Rate of Climb indicator in the RAF aircraft as well.

As I understand the indicators have "electric" and "mechanical" types in the sim. Could it be that real world RAF and LW preferred different type of instruments, and this is modelled (perhaps wrongly) in the sim?

[bongodriver]

As I understand the indicators have "electric" and "mechanical" types in the sim


only the RPM gauges.

[pstyle]

Is this a fact or a feeling? I have the relevant radiator areas, so what are the figures and from where?

Hey kufürst, Dutch put a wee post someplace about how thwy had measured this.. I don't have a link right now tho.

[ATAG_Snapper]

Is this a fact or a feeling? I have the relevant radiator areas, so what are the figures and from where?

Fact.

As I understand the indicators have "electric" and "mechanical" types in the sim. Could it be that real world RAF and LW preferred different type of instruments, and this is modelled (perhaps wrongly) in the sim?

That could well be, I'm only reporting what others have measured in sim.

[ATAG_Dutch]

Hey kufürst, Dutch put a wee post someplace about how thwy had measured this.. I don't have a link right now tho.

Hiya pstyle. I posted a video of the effect of radiator drag in the Spit alone. It's post #16 in this thread. This didn't actually measure the relative surface areas Snapper mentions.

Just thought I'd better clarify that. ;)

[pstyle]

Hiya pstyle. I posted a video of the effect of radiator drag in the Spit alone. This didn't actually measure the relative surface areas Snapper mentions.

Just thought I'd better clarify that. ;)

Roger, cheers for the correction.

[JtD]

No I am not. I am saying both aircraft are flying best turn performance.I can't really know what you were trying to say, or what you are going to say, but you were exactly saying what I stated:the Bf-109E3 is hopelessly outclassed IF it tries to match the Spitfire at the Spitfires best performance velocityI'm happy to see that you now are saying something much more meaningful.

[JtD]

The general error of the interpretation of a speed advantage is the assumption that the slower plane has to match the faster plane at all costs. That assumption is totally unrealistic.

The general trend is in fact that the faster plane has the biggest advantage while flying straight, true against both better climbers in a sustained climb or better turners in a sustained turn. Entering a climb or turn that will be matched by the opponent, will in return reduce the speed advantage. That's how it works in combat.

[Robo.]

I admit I have limited knowledge about virtual airplanes. My expertise lies with the real ones.

Do you dogfight in the real ones? :grin: Do you dogfight at least in the virtual ones? Apparently not - that's all I am saying. I appreciate your theoretical knowledge of a/c engineering but you're simply wrong here. Not with the physics, there is nothing to argue about - but everything else you're saying makes no sense from the fighter pilot's point of view.

In actual dogfight, physics does not change.

Of course not but what you're saying has nothing to do with the ability of the aircraft to turn in a combat situation. You got it right with the best performance velocities - and that's all the turnfight is. The fact that the 109 at say 400km/h can turn better than a Spitfire at say 250km/h is irrelevant. Useful in combat, but not for turnfight. It's called 'turn and burn' where the opponents get the best use of turn rate advantage. In this particular case, Spitfire has got the advantage.

Not an issue and has not effect with what happens in reality. It is hard to overcome the physics of the Bf-109 being lighter with the same power. This is an advantage where performance is thrust limited.

Lighter with the same power = better climbrate but not necessarily better turnrate in typical combat situations. The Spitfire though could still outturn the 109

If you could perhaps describe how exactly would you outturn a Spitfire Mk.I in a Bf 109E, I am very interested. Everything you are saying is true but you would be dead in a turnfight because you're wrong about what is important in actual combat.

[pstyle]

Crumpp, can you advise the source of your graph data? Cheers.

[Kurfürst]

I don't know the numbers for the parasitic drag for these aircraft but would expect the difference to be marginal. The Spitfire is a larger aircraft and this would count against it but the 109E has less curves and is less aerodynamic which would balance it out. Indeed the 109F was more streamlined and this contributed to its improved performance. Which has the advantage I don't know but I would expect it to be close.

Parasitic drag is easy to approximate. The 109E needs less power at all altitudes to achieve the same or higher speeds (check for example the power available / speed reached at FTH. The Merlin III has a bit more power, yet both aircraft reach the same speed, 570 kph, which clearly points to less parasitic drag on the 109E.) This is true for the Emil/Mark I., and even more so to later variants. The 109G for example is about 30 kph faster on the same power, the 109K is about 40 kph faster on the same power.

I believe your bottom line re a faster aircraft always outturning a slower one to be wrong. If it were right the 262 would out turn everything

You seem to have missed the "at high speed" part. ;)

And yes, the 262 does outclimb and outturn every prop job at high speed. It is simply to understand, say a Mustang has a top speed of about 600-630 kph even at +25 lbs boost. At this speed it is pulling 1G, drag is about minimal (almost entirely parasitic drag), and thrust equals total drag. It has no excess thrust. If it starts to turn, induced drag and so total will increase, and since the aircraft has no thrust reserves, it will start to decelerate, and loose speed. Its incapable of pulling any sort of sustained turn.

The 262 at about 600 kph still has a LOT of excess thrust - enough for another 230 kph. If it starts to turn, induced drag and so total drag will increase the same, BUT since the aircraft has no thrust reserves, it can use this excess thrust to overcome excess thrust in say, a 2 g turn. The turn is not very fast but its still a steady turn and the aircraft maintains speed.

See attachment for Spit IX. The Spit IX was an excellent turner and runs circles around the 262 at lower speeds. Come 500 kph, and the Spit is simply running out of thrust, can hardly turn at all, while the 262 can still pull a fairly decent turn. The Spits only hope is to go for an instantanous turn and hope for snapshot a few seconds before it blows all speed and becomes hapless. Its an extreme example, but demonstrates very well how things can get very different at high speed where one aircraft has a speed advantage.

Very true, but this has nothing to do with a sustained turn time. Say you're attacking a Spitfire in a Fw 190. You're much faster, he breaks and at that speed difference (him slowish, you very fast), you can turn inside him for long enough to place a burst in front of him. You lose some speed, he loses a wing if you hit, but that's not a sustained turn competitiion. You would never ever even at this theoretical advantage at this particular speeds enter a turn and burn fight and remain in that turn because you would lose the fight.

Hi Robo!

I guess there is some kind of misunderstand, what I meant is when two aircraft turn at (the same) high speed, and one of them is faster. In these circumstances the curves change to the favour of the aircraft with more excess thrust (generally speaking, the faster aircraft). See the Mark Vc vs. 190A-5 turn curve. Again the Mark V runs circles around the 190A-5 at lower speeds. Come 450 kph, and the Spit is simply running out of thrust, can hardly turn at all, while the 190A-5 can still pull a fairly decent turn. The Spits only hope is to go for an instantanous turn and hope for snapshot a few seconds before it blows all speed and becomes hapless.

Not to mention G-load and blackout. Or if you're in a 109 the elevator stiffness at high speed would be (and is) a massive issue, too. In a sustained turn entered from higher speed, you happen to slow down anyway and the best you can do as a pilot is keep your speed at optimum (not to slow down too much) and watch the G load because if you can't see you can't shoot. We're talking pure TnB fight where the sustained turn rate plays a huge role (and pilot's skill is another 50% because).

In sustained turns - no. Few if any aircraft could pull more than 2.5 g, some of the best like the Mark IX at +25 could hope to pull around 3 g and sustain airspeed. 3 g is very easy to pull even in a 109 with one hand, and blackout doesnt start until about 5 g. This the best turn possible at about 270 kph, at higher speeds the aircraft can pull even less, so g load is not a factor - unless you are going for an unsustained turn (lead pursuit) at which you blow speed to get a snapshot.

Obviously, this rarely happens in RL (or virtual skies) because you don't want to burn all your Es in a sustained turn, especially so in a 109.



You would be surprised how many 109 pilots still enter TnB fight vs. Spitfires. And they will almost always lose because (surprise surprise) the Spit has got much better sustained turn.

Bad tactics. ;) Spitfires are tougher nut to crack, because they are about as fast as 109s - but for example against Hurricanes, which are much slower, a slow turn above 350 km/h might bring surprising results. The Hurri may try to blow speed, but that's usually a death sentence against a good pilot who knows how to exploit superior E-state.

In theory. I would really like to see how a Me 262 outturns a P-51 in a sustained turn even at very high speeds. :o

It simply has much more excess thurst at high speed - hence it can maintain a sustained turn while the P-51 cannot at all - provided both aircraft are at high speed.

[bongodriver]

See attachment for Spit IX. The Spit IX was an excellent turner and runs circles around the 262 at lower speeds. Come 500 kph, and the Spit is simply running out of thrust, can hardly turn at all


So are you suggesting aircraft can't turn without thrust?......so every glider I have seen change direction is purely my imagination?

surely you really mean to say the Spitfire will simply loose some ground, but it will without doubt still be able to turn.........some of these theories are getting bizarre.

[Crumpp]

Crumpp, can you advise the source of your graph data? Cheers.

It is a spreadsheet that calculates turn performance I made.

It is a sophisticated analytical tool that determines relative turn performance using standard incompressible flow theory. That was the predominate theory in use during WWII and is the same one used by the RAE.

By using EAS, all you have to adjust power production and you are in the ballpark for the Indicated Airspeed you should see performance.

I did it that way so it would be useful for the game. If you know the PEC, it is not hard to have the spreadsheet convert EAS to IAS directly.

It takes a little time but it can reworked for any aircraft.

[Crumpp]

So are you suggesting aircraft can't turn without thrust?......so every glider I have seen change direction is purely my imagination?


Now we have to teach people the basics.

Aircraft cannot sustain performance without excess thrust and the forces in balance.

Any airplane without excess thrust can use gravity and momentum to achieve instantenous performance.

A glider uses gravity to propel itself which is why we don't use them on transatlantic flights. They exist in a purely instantenous performance condition. They cannot sustain performance under the power of gravity alone and must constantly trade altitude for airspeed without an alternate form of energy.

Gliders seek an alternate form of energy in the form of rising air currents to stay aloft.

Flying a sailplane is probably the closest thing any human will come to feeling like a bird. Powered only by gravity and air currents, these gliders move silently through the sky, often for hours at a time.

http://www.mansfieldct.org/Schools/MMS/staff/hand/flightglider.htm

Bongodriver, try to make a turn from maximum level speed in an airplane maintaining both airspeed and altitude.

[macro]

So are you suggesting aircraft can't turn without thrust?......so every glider I have seen change direction is purely my imagination?

surely you really mean to say the Spitfire will simply loose some ground, but it will without doubt still be able to turn.........some of these theories are getting bizarre.

no mate he means (i think if i got it right) turning without loosing speed. any spit pilot can turn and loose a EA on his tale in clod but will loose speed instantly. he is talkign about going into a turn and keeping the turn without loosing speed. which isnt that bigger deal imo

this isnt all bad for the spit tho as this can be used so the plane behind overshoots and misses, i.e turning inside his turn so he cant get guns on you. puts you out of the fight but also keeps you alive, at least a while.
a 109 couldnt do this to a spit, this is why you go into a fight with a 109 always with higher energy or dont bother at all, so you can afford to loose that speed.

[Crumpp]

better climbrate but not necessarily better turnrate in typical combat situations.

The readers understand that a better climb rate is indicative of more excess thrust?

Once again, the Spitfire shines in lift limited performance while the Bf-109 shines in thrust limited performance.

[Crumpp]

this isnt all bad for the spit tho as this can be used so the plane behind overshoots and misses, i.e turning inside his turn so he cant get guns on you. puts you out of the fight but also keeps you alive, at least a while.
a 109 couldnt do this to a spit, this is why you go into a fight with a 109 always with higher energy or dont bother at all, so you can afford to loose that speed.

Any airplane can do this to another airplane.

[macro]

how was that patronising drivel?

that was just plain rude.

also on the ignore list, im ouita this conversation. leave to your 2 oversized ego's

I wish we were having this conversation in the pub, I woulda bashed you both out by now.

[bongodriver]

how was that patronising drivel?

that was just plain rude.

also on the ignore list, im ouita this conversation. leave to your 2 oversized ego's

I wish we were having this conversation in the pub, I woulda bashed you both out by now.

Oh crap, sorry......I somehow saw Crumpps avatar and your post, I honestly had no idea I replied to someone else, my most sincere appologies.....I think it's because it was quoting the same post by me.

[bongodriver]

Now we have to teach people the basics.

Aircraft cannot sustain performance without excess thrust and the forces in balance.

Any airplane without excess thrust can use gravity and momentum to achieve instantenous performance.

A glider uses gravity to propel itself which is why we don't use them on transatlantic flights. They exist in a purely instantenous performance condition. They cannot sustain performance under the power of gravity alone and must constantly trade altitude for airspeed without an alternate form of energy.

Gliders seek an alternate form of energy in the form of rising air currents to stay aloft.



http://www.mansfieldct.org/Schools/MMS/staff/hand/flightglider.htm

Bongodriver, try to make a turn from maximum level speed in an airplane maintaining both airspeed and altitude.

Read macros reply to my post and learn how to actually process information.

[Crumpp]

:confused:

[bongodriver]

:confused:

Youre confused?....ok I'll take you through it carefully

Kurfurst said of the Spit in his scenario 'can hardly turn at all'......but why would the aircraft suddenly not be able to turn any more?......it in fact will continue to turn quite happily, what it won't do is sustain speed.

[Crumpp]

As my 6 year old would say, I am confused on who is whose friend, LOL.

:wink:

:-P

[bongodriver]

As my 6 year old would say, I am confused on who is whose friend, LOL.

:wink:

:-P

:confused:

[IvanK]

It is a spreadsheet that calculates turn performance I made.

It is a sophisticated analytical tool that determines relative turn performance using standard incompressible flow theory. That was the predominate theory in use during WWII and is the same one used by the RAE.

By using EAS, all you have to adjust power production and you are in the ballpark for the Indicated Airspeed you should see performance.

I did it that way so it would be useful for the game. If you know the PEC, it is not hard to have the spreadsheet convert EAS to IAS directly.

It takes a little time but it can reworked for any aircraft.

But your graph Crumpp bears little resemblance to the RAE chart. Your chart gives the 109 a better sustained capability whilst the RAE chart gives the Spitfire a better sustained turn performance ?

RAE Chart from AVIA 6/2394

http://i40.photobucket.com/albums/e215/zulu64/spiv109susturn.jpg

Crumpp chart:
http://imageshack.us/a/img228/1949/spitfiremkivsbf109e3sus.jpg

Dont see any parameters/conditions/assumptions used on your chart either Crumpp

Who is right RAE or Crumpp ?

[Crumpp]

But your graph Crumpp bears little resemblance to the RAE chart.

Do some math....

The RAE chart is at 12,000 feet and was taken off one data point. It did puzzle me as our radius and other data aligns. It puzzled me until I stated getting into the details of the chart.

According to that chart, the Spitfire Mk 1 is capable of reaching 340mph (+) at 12,000 feet on 1050 bhp.

The RAE graph found in AVIA 6/2394 is a performance estimate from September 1940.


A flight report from March 1940 gives the power at 12,000 feet:

Normal B.H.P 950/990 at Rated Altitude 12,250 ft

And lists the Vmax for the type as 326 mph TAS.

http://www.spitfireperformance.com/n3171.html

The AVIA 6/2394 does not fit the only +12lbs estimate we have for level speeds.

http://www.spitfireperformance.com/spitfire-I-rae-12lbs.jpg

This estimate shows 359mph TAS at 12,000 feet.

That is over a 5% error from the speed found in AVIA 6/2394. It would be unusual for such a large estimate error in an established design.

I don't know what Spitfire data they used but I suspect it was for an improved high altitude version as we saw before in a similar report previously posted on these forums in which you were involved in the discussion.

All that can be said is we don't know the details and the ones we do know, do not fit any existing service model at the time.

When we plug in the data from the Spitfire Mk I serving in the RAF during the BoB, we get a different result.

Another anomaly is the CLmax. In order to get a CLmax of 1.87 on the Spitfire, you have to drop the stall speed far below what the Spitfire POH list's to a scant 62 knots.

At the 76mph Vs (69mph IAS Vs + 7mph PEC) found in the POH, we get a CLmax of 1.69 which is far below the 1.87 Gates uses in the report.

I am pretty sure Gates was not using a standard Spitfire Mk I for his base data in the estimate. It does not align with one.


Calculate Sea level CL max:

CL = Lift/(dynamic pressure * Reference Area)
Dynamic Pressure = density ratio * Velocity^2 / 295

Dynamic pressure = (1 * 66^2)/295 = 14.76610169psf

CL = 6050lbs / (14.76610169psf * 242sqft) = 1.693067034

Lift = CLqS

Lift = 1.87 * 14.76610169psf * 242sqft = 6682 lbs of Lift generated.

[IvanK]

"I don't know what Spitfire data they used but I suspect it was for an improved high altitude version as we saw before in a similar report previously posted on these forums in which you were involved in the discussion.

All that can be said is we don't know the details and the ones we do know, do not fit any existing service model at the time."

"Normal B.H.P 950/990 at Rated Altitude 12,250 ft '

Garbage ! you are confusing rated power at 2600RPM with maximum power at 3000RPM. Here are 2 inspection test certificates for 2 different Spitfire MKI's one with a Merlin II the other with Merkin III. As you can see Max power is 1030hp at 16,250ft. at 6.25lbs boost 3000RPM.

The RAE chart references 1050hp at 6.25lbs Boost 3000RPM at 12,000ft.

http://i40.photobucket.com/albums/e215/zulu64/Spiti%20rated%20power_zps5d31181a.jpg

http://i40.photobucket.com/albums/e215/zulu64/Spitpower2_zps805b515b.jpg

You are again trying to change history. You cover up your case by a smokescreen of Mathematical verbiage. RAE calculated that the Spitfire MKI had better sustained turn performance than the BF109E3. Pretty much every other report technical and general from either side of the conflict say the same. You on the other hand construct a graph that clearly shows the opposite.

Find another single independent reference that proves the BF109E3/4 had better sustained turn performance than a Spitfire MKI.

Whilst you are at it show us what this Mythical improved high altitude version that I supposedly referred to in another report and how this is supposedly used in the RAE turn chart

[NZtyphoon]

Do some math....

The RAE chart is at 12,000 feet and was taken off one data point. It did puzzle me as our radius and other data aligns. It puzzled me until I stated getting into the details of the chart.

According to that chart, the Spitfire Mk 1 is capable of reaching 340mph (+) at 12,000 feet on 1050 bhp.

The RAE graph found in AVIA 6/2394 is a performance estimate from September 1940.


A flight report from March 1940 gives the power at 12,000 feet:



And lists the Vmax for the type as 326 mph TAS.

http://www.spitfireperformance.com/n3171.html

The AVIA 6/2394 does not fit the only +12lbs estimate we have for level speeds.

http://www.spitfireperformance.com/spitfire-I-rae-12lbs.jpg

This estimate shows 359mph TAS at 12,000 feet.


And what do we see on the 109 data? Estimate on chart = 1,200 Bhp at 2,400 rpm 15,000 feet, TAS 340 mph + at 12,000 which Crumpp, conveniently has ignored, whereas the true output was about 960 ps 2,300 rpm at about 3,500 metres

http://www.wwiiaircraftperformance.org/me109/DB601A-B-oct40-pg22.jpg

So Gates was also using an unusually powerful 109 for the chart as well. I suspect it was probably an experimental high-altitude 109E.

Question is what data did Crumpp use to compile his chart? There's no engine rating shown, no take of weights, nor anything else to indicate on what basis Crumpp's "calculations" were made. For any proper analysis Crumpp's chart is totally useless.

[Crumpp]

There's no engine rating shown

The data is listed in the thread.

Here it is too, right off the spreadsheet:

Spitfire Mk I

Aircraft Data
weight 6050lbs
Power 990bhp
Level speed 247KEAS
Propeller efficiency 0.8
Wing area 242 sqft
wing efficiency 0.85
Dynamic pressure 206.8101695psf
Aspect Ratio 5.6
Mass 187.8881988 ft/s^2


Bf-109E-3

Aircraft Data
weight 5580lbs
Power 990bhp
Level speed 269KEAS
Propeller efficiency 0.85
Wing area 174.9 sqft
wing efficiency 0.85
Dynamic pressure 245.2915254
Aspect Ratio 5.77
Mass 173.2919255 ft/s^2

[Crumpp]

And what do we see on the 109 data?

Again, it just calls into question the validity of the RAE estimate. I just figured it was a given the RAE would not have the best data on the German aircraft.

They did a lot of estimating off very few data points. The CLmax for both aircraft closely matches the full flaps CLmax and not clean configuration.

[IvanK]

Again, it just calls into question the validity of the RAE estimate. I just figured it was a given the RAE would not have the best data on the German aircraft.

They did a lot of estimating off very few data points. The CLmax for both aircraft closely matches the full flaps CLmax and not clean configuration.


Well clearly you haven't read AVIA 6/2934 They had reasonable data on the aircraft in question. AVIA 6/2934 is based on actual flight test of a BF109E3 in RAF hands.

Here is AVIA 6/2934 summary of turn performance based on Flight tests and calculation :

http://i40.photobucket.com/albums/e215/zulu64/avia62934turnsummary_zps5a547e44.jpg

So the RAE determined the opposite to you based on flight test and calculation.

[Kurfürst]

So the RAE determined the opposite to you based on flight test and calculation.

To me it seems RAE determined something entirely different than Crumpp's calculation... (turns at and only at minimum turn radius vs. Crumpps calculations over the speed range)

[IvanK]

The RAE chart on its own shows sustained G over the complete speed range at 12,000ft altitude.
Its the a similar but more detailed chart to Crumpps.

[Kurfürst]

The RAE chart on its own shows sustained G over the complete speed range at 12,000ft altitude.
Its the a similar but more detailed chart to Crumpps.

RAE's calculation also using estimated/guessworked stall speeds, Clmax and rather questionable power values for both the Spit and 109 (the latter probably understood with the effect of engine thrust). That's the problem with these charts in general - there's such a margin of error with the base values, that the results are all over the place. (estimated) Propeller effiency can vary results by 5-10% alone, drag values are unknown, the wing's oswald effiency factor is unknown (directly shifts the results, since its a multiplier in the equation), Cl max is unknown.

Just to make it clear I don't doubt the Spit had a sustained turn advantage at lower speeds, but OTOH I am pretty sure the situation reverses at higher speeds (for the 6 1/2 lbs version) at lower altitudes, since the 109E has both less drag and more power.

I am also curious about the effect of the two speed prop on turn capacity. Having 990 HP at the prop shaft is nice, but its all for naught if the two pitch prop can't properly convert it into thrust at turning speeds.

[IvanK]

The RAE chart shows a Spitfire sustained turn advantage across the entire speed range from the Lift limit through to the max 1G sustained speed of around 340mph.

i.e. if the "Angle of straight climb" (Ps=0) for both the Spitfire and BF109 were overlayed on the same chart the Spitfire angle of straight climb would be above the 109 line from the Lift limit through to 1G Vmax. So at any speed in this range the Spit can sustain a higher G according to the RAE .... but not according to the Crumpp plot ... at any speed.

Both aircraft in this chart having similar values of 1g Vmax at the charted altitude.

There is no mention of prop type in the AVIA report for either the Spitfire or the 109. I take your point on propeller efficiency though ... that is touched on in another AVIA report (AVIA 6/13805) in which the RAE believe the 109 and Spit prop efficiency was essentially the same at 10,000ft with the 109 around 3% better at 15,000ft.... though with caveats.

http://i40.photobucket.com/albums/e215/zulu64/Propeffec_zpsdc0a9590.jpg

[Glider]

Just one observation. Janes gives the Merlin III with 100 octane as 1,310 hp at 9,000 ft, not 990 hp, which would make a difference

[NZtyphoon]

The data is listed in the thread.

Here it is too, right off the spreadsheet:
Bf-109E-3

Aircraft Data
weight 5580lbs
Power 990bhp
Level speed 269KEAS
Propeller efficiency 0.85
Wing area 174.9 sqft
wing efficiency 0.85
Dynamic pressure 245.2915254
Aspect Ratio 5.77
Mass 173.2919255 ft/s^2

Interesting how the Bf 109E-3 loading chart http://www.wwiiaircraftperformance.org/me109/Me109e3-ladeplanes.jpg shows the weights as 2,608 kg (5,749 lbs) fully loaded for combat while, without ammunition for training flights, the weight is 2,532kg (5,582 lbs)...

[Osprey]

All that extra power from 12 fewer litres. According to some of the logic here I conclude, mathematically, that the DB601 was rubbish.

[Kurfürst]

All that extra power from 12 fewer litres. According to some of the logic here I conclude, mathematically, that the DB601 was rubbish.

Well good for you, now would you kindly push that thing you call a flight stick forward. :p

[Crumpp]

Interesting how the Bf 109E-3 loading chart http://www.wwiiaircraftperformance.o...ladeplanes.jpg shows the weights as 2,608 kg (5,749 lbs) fully loaded for combat while, without ammunition for training flights, the weight is 2,532kg (5,582 lbs)...


I got the weights from several flight test but did not have a ladeplan. The weight I used leaves out the pilot.

I fixed it and it narrows the gap but does not eliminate it.

The RAE chart shows a Spitfire sustained turn advantage across the entire speed range

The RAE chart uses CLmax neither airplane can attain in clean configuration by any calculation or measurement, including the RAE's. Read the report you claim I have not!

In fact, the CLmax comes very close to matching full flaps for both aircraft.

[Glider]

All that extra power from 12 fewer litres. According to some of the logic here I conclude, mathematically, that the DB601 was rubbish.

I don't know about rubbish, that is a bit strong, but its worth remembering that it was soon changed for the DB 605 and the Germans wouldn't have done that without a reason. I can only assume that it lacked development potential

[Glider]

I got the weights from several flight test but did not have a ladeplan. The weight I used leaves out the pilot..
Why on earth would you leave out the pilot?

Seriously are you going to redo the numbers with the extra Merlin power, 30% will make a huge difference.

[bongodriver]

Why on earth would you leave out the pilot?

Seriously are you going to redo the numbers with the extra Merlin power, 30% will make a huge difference.

Crumpp has to be carefull...if he starts using realistic figures the results won't come out as he intends.

[IvanK]

I guess RAE were clueless ... and you have superior knowledge Crumpp... trouble is your graph reflects the opposite of pretty much every known record,chart,computation or actual flight test or pilots account of the facts !

http://i40.photobucket.com/albums/e215/zulu64/susturn2934_zps42dd3e5b.jpg

One more from the RAE clearly showing better turn performance of the Spitfire in all regimes.

[Crumpp]

Ivank says:
Its the a similar but more detailed chart

It is not a more detailed chart. It is the same thing.

Only difference is the CLmax estimates. The RAE used a trailing rake to measure speed.

Those are very accurate when properly operated but are complex to operate. They measured the CLmax in flight. I see a problem with operating such a system at the edge of the envelope trying to stall a high performance fighter.

As for the weight of the Bf-109, my original estimate just used the one the RAE used for the test. Using the ladeplan does not change the relative performance significantly.

The all-up weight was 5,580 lb. with the C.G. 24.8 in. aft of the leading edge at the root (h = 0.302). This loading agrees well with the value of 5,600 lb. quoted for the all-up weight by the Germans.


http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan.html

My calculated CLmax agrees with the RAE measurements for the Bf-109.

Speeds Dynamic pressure CL
82 22.79322034 1.433906325


http://imageshack.us/a/img705/576/109estallandslats.jpg (http://imageshack.us/photo/my-images/705/109estallandslats.jpg/)

My Spitfire CLmax agrees with the NACA findings and the calculations were made using standard data on the type with the weights and stall speed listed in the Operating Notes.

Kurfust says:
RAE's calculation also using estimated/guessworked stall speeds, Clmax and rather questionable power values for both the Spit and 109 (the latter probably understood with the effect of engine thrust). That's the problem with these charts in general - there's such a margin of error with the base values, that the results are all over the place. (estimated) Propeller effiency can vary results by 5-10% alone, drag values are unknown, the wing's oswald effiency factor is unknown (directly shifts the results, since its a multiplier in the equation), Cl max is unknown.


That was my first thought. Gates was using high angle of attack theory to determine turn performance. High angle of attack theory is good for estimation but has to be based on measured data otherwise it is a complete crapshoot and guesswork.

The stumbling block to the assumption that Gates used high angle of attack theory is the fact he clearly list's the 1G stall CLmax for both aircraft.

That listed CLmax is clearly labeled on the chart as "assumed values of CLmax":

Spitfire 1G CLmax = 1.87

Bf-109E-3 1G CLmax = 1.95

The only way either aircraft can achieve such a CLmax at 1G is in landing configuration with full flaps and gear down.

The CLmax Gates used matches both aircraft in landing configuration.

It is definate proof Gates used the landing configuration CLmax for his estimate.

[Glider]

Crumpp has to be carefull...if he starts using realistic figures the results won't come out as he intends.

Give the guy a chance, he said he would

[Crumpp]

IvanK says:
--------------------------------------------------------------------------------

I guess RAE were clueless ... and you have superior knowledge Crumpp... trouble is your graph reflects the opposite of pretty much every known record,chart,computation or actual flight test or pilots account of the facts !

Explain the "assumed values for CLmax at 1G" listed on the chart, Ivan??

I am listening....

Here is the mathmatical proof it is not correct for a clean configuration fighter:

Calculate Sea level CL max:

CL = Lift/(dynamic pressure * Reference Area)
Dynamic Pressure = density ratio * Velocity^2 / 295

Dynamic pressure = (1 * 66^2)/295 = 14.76610169psf

CL = 6050lbs / (14.76610169psf * 242sqft) = 1.693067034

Lift = CLqS

Lift = 1.87 * 14.76610169psf * 242sqft = 6682 lbs of Lift generated.

[pstyle]

Hi crumpp, I've no issue with the math. Frankly I'm not scooled up in the formulae to critique it anyways. My interest is more as a historian, rather than engineer.

Can you advise why the Merlin power assumption is around 990bhp? And, when you use, say the Merlin 3, the auto prop and/or the 100 octanes, how do the graphs look?

Sorry if this creates loads of work....

[Crumpp]

IvanK says:
One more from the RAE clearly showing better turn performance of the Spitfire in all regimes.


With landing gear and flaps down......

[ATAG_Dutch]

With landing gear and flaps down......

Crummp, when quoting other people in the thread, please could you leave in the name of the person you're quoting as above? Quoting people without reference to who it is makes following the conversation very difficult.

Many thanks. :)

[bongodriver]

With landing gear and flaps down......

At 300MPH?

[Crumpp]

Psyle says:
Sorry if this creates loads of work....


No problem at all. In fact I am going to clean up the sheet and post it so others can use it. It just runs the math for the conditions given.

I wish I was more computer savvy to make it more user friendly. Perhaps some in the community can improve upon it.

The 990 hp comes directly from the RAE.

SUMMARY OF TRIALS

AEROPLANE Spitfire I No. N.3171
SPEC. NO. 16/36
CONTRACTOR Vickers-Armstrong (Supermarine)Ltd.


TYPE Landplane DUTY Single Seater Fighter.

ENGINES. Merlin III Normal B.H.P 950/990 at Rated Altitude 12,250 ft

http://www.spitfireperformance.com/n3171.html



Once I get good engine data on 100 Octane, I will do the estimate.

On these charts the data does not line up. The FTH do not even come close to assume RAM effect.

Level speed - FTH MS Gear = 11,000 ft

http://www.spitfireperformance.com/spitfire-I-rae-12lbs.jpg

Engine power estimate at Vmax (RAM effect) shows a FTH MS Gear = 8,000 ft

http://www.spitfireperformance.com/merlin3curve.jpg

Not saying the data is bad, just that this engine does not match this airplane. We need to find the same engine in the same airplane to get good data points.

[Crumpp]

bongodriver says:
At 300MPH?

Exactly....

Once again, explain the assumed values of CLmax on the RAE chart. I am listening.

[Crumpp]

ATAG DUTCH says:
Crummp, when quoting other people in the thread, please could you leave in the name of the person you're quoting as above? Quoting people without reference to who it is makes following the conversation very difficult.


Sure thing.

[pstyle]

No problem at all. In fact I am going to clean up the sheet and post it so others can use it. It just runs the math for the conditions given.

I wish I was more computer savvy to make it more user friendly. Perhaps some in the community can improve upon it.

Thanks. I think this would be a good idea.
At least then we are all able to work to the same assumptions and review each others work. It's be good to see how the manipulation of one or more of the variables influences tge overall outputs.

[pstyle]

Crummp, when the RAE refer to "normal bhp", do you know what the term "normal" refers to. Are there other bhp values which might be arrived at which are outside of that description?

[Kurfürst]

I don't know about rubbish, that is a bit strong, but its worth remembering that it was soon changed for the DB 605 and the Germans wouldn't have done that without a reason. I can only assume that it lacked development potential

Uhmm... the DB 605 is the same thing as the 601, but with "bored-up" cylinders... which had a larger diameter by a mighty [i]4 milimeter (0,154 inch for you guys).

[Crumpp]

I guess RAE were clueless ... and you have superior knowledge Crumpp... trouble is your graph reflects the opposite of pretty much every known record,chart,computation or actual flight test or pilots account of the facts !

http://i40.photobucket.com/albums/e215/zulu64/susturn2934_zps42dd3e5b.jpg

One more from the RAE clearly showing better turn performance of the Spitfire in all regimes.

The RAE shows better turn radius in this chart. The Spitfire always has a better turn radius than the Bf-109.

Radius being just one parameter of turn performance and not the most important either.

Pstyle says:
Crummp, when the RAE refer to "normal bhp", do you know what the term "normal" refers to.

Not specifically. It appears to be RAM power because the chart list's power in flight.

Pstyle says:
At least then we are all able to work to the same assumptions and review each others work. It's be good to see how the manipulation of one or more of the variables influences tge overall outputs.

Exactly, once the parameters are input, the math does it's magic.

[Kwiatek]

Spitfire 1G CLmax = 1.87

Bf-109E-3 1G CLmax = 1.95

The only way either aircraft can achieve such a CLmax at 1G is in landing configuration with full flaps and gear down.

The CLmax Gates used matches both aircraft in landing configuration.

It is definate proof Gates used the landing configuration CLmax for his estimate.

Clmax is also depend of engine power. Prop wash adds considerable lift due to the higher speed of airflow.

Looking RAE turn charts for 109 and Spitfire there is discribtion:
" Assumed values for Clmax at full throttle ".

So Clmax in RAE charts is not for landing configuration or stall speed ( engine idle) but assumed for full engine power which of course is needed in sustained turn rate.

[JtD]

Explain the "assumed values for CLmax at 1G" listed on the chart, Ivan??I'm not Ivan but they are obviously power on clmax.

Edit: Kwiatek is right, it is stated on the chart in plain text.

[Kurfürst]

The RAE shows better turn radius in this chart. The Spitfire always has a better turn radius than the Bf-109.

Flaps... ;)

[pstyle]

The RAE shows better turn radius in this chart. The Spitfire always has a better turn radius than the Bf-109.

Radius being just one parameter of turn performance and not the most important either.

True, if the aircraft are BOTH at the same speed (according to that chart) , the spitfire will have less distance to travel, and thus will turn faster, in every case.

I think I can convert the figures to turn rate fairly easily... Then we can see, using that very ddata, the combinations of speeds at which the two have varying turn speeds right?
See here, http://s13.postimage.org/4fo4e806f/turns_comparison.jpg

According to that, Provided the sptfire remains between 200kph and 370kph TAS, the 109 can never out turn it.

[bongodriver]

Wow....maths really is magic........it made Crumpp dissapear.

[TomcatViP]

"Normal" shld stand for standard atmospheric value. The HP being a function of the air density, the Power have to be converted to the reference to be absolutely rigorous.

Note that standards varies (and still does) from one country to another.

ISO being 0°C and 1013mbar - CFM around 15°C etc..

Note also that if this is the case, there might be some error in the the conversion.

[Crumpp]

True, if the aircraft are BOTH at the same speed (according to that chart) , the spitfire will have less distance to travel, and thus will turn faster, in every case.


They are not at the same speed or angle of bank!

I'm not Ivan but they are obviously power on clmax.


They don't match CLmax power on for either type. In otherwords, a bad assumption.

Only one flight was made, as operating a suspended static head from a single-seater aircraft with a rather cramped cockpit is difficult.

http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan.html

[Crumpp]

"Normal" shld stand for standard atmospheric value. The HP being a function of the air density, the Power have to be converted to the reference to be absolutely rigorous.


I think you are right.

[bongodriver]

They are not at the same speed or angle of bank!

Doesn't matter if they are not at the same angle of bank, it's almost entirely the point that the spitfire was able to maintain level and sustained turns at a higher angle of bank than the 109.....kinda the key to a tighter turn don't you think? and in any case the Spit is achieving the tighter turn at higher speed than the 109 too.


They don't match CLmax power on for either type. In otherwords, a bad assumption.

I'd still rather accept the professionals theory on it opposed to yours....no offence.




Quote: Only one flight was made, as operating a suspended static head from a single-seater aircraft with a rather cramped cockpit is difficult.
Only one flight was made, as operating a suspended static head from a single-seater aircraft with a rather cramped cockpit is difficult.

http://kurfurst.org/Tactical_trials/109E_UKtrials/Morgan.html

Not sure why you quoted a snippet from a 'stalling' Cl max trial.