S!

As said by all here, we just want to have correct performance and now we do not have it, be it either side of the channel ;) Kwiatek, would it be hard to produce a graph about speeds with different power settings? For example some old graphs fro TsAGI I have had the WEP value colored and only up to 2km on Russian fighters for example.

Making graphs of speeds as they are now would help to get a better picture where the sim is at it's current state. And far easier to compare against RL values I think.

Theoretically planes CAN flew at emergency power for extended periods, but wear will be high on the components. It was not set in concrete, and the reason of failure is always down to failure in one component. If the coolant (indicating the engine block itself is at optimum temperature) and oil temperatures (indicating the proper lubrication is provided) are all right within limits, and other components do not fail, it should be possible. Bench tests often exposed engines to very long during duration at maximum power, so it was possible. Of course during bench tests optimum oiling and cooling is provided.

I guess the frequent failure you have experienced on Spits is down to a failure of a specific component, or improper operation like too rich mixture leading to excessive local temperatures, burning out of exhausts etc. which is the reason I ask what kind of component you expect to fail on the 109 or any other plane. Knowing this would let us understand if the model is correct.

Thanks for reply on the airspeeds. That's interesting that the mkI spit is that slow. The Hurricane matters less because the British historically pulled the Hurricane from the front because of appalling losses.

From a historical point of a view there are a lot of things to take into account. The manufactures did their tests without armor or guns in most cases, so a lot of the data about both aircraft shows them going way faster then in combat.

I think it all comes down to a balance. A faster plane, that's also more maneuverable then the enemy, breaks the game for playability. I like flying the G.50. It's my favorite by far. I flew it when it was way underpowered. It was far slower, but turned almost as well as a spit, and better than a hurricane. I got a lot of kills in it because I learned its weaknesses and advantages.

If I came down from 12,000 ft onto an unsuspecting Spit IIa I could shoot him down in a lot of cases.

I've read historical accounts about the spitfire that put it as being faster than the 109 in real life. I think as far as the game goes each side should either have maneuverablity or speed. The 109 is faster, in the game, because it's far less maneuverable than the spit. In order to keep the balance a plane needs one or the other. If we want the spit to be faster then the 109 then, out of thinking about playability, we would need to make the 109 more maneuverable then the spit. That notion seems silly.

I think as far as fixing the Spit Ia, the FM should be brought closer to reality. I think if the IIa was within 10 kmh of the e-4 it would break the game.

I fly on both red and blue, but I fly the G.50 because I think it's the best dog fighter. The spit is by no means outmatched by the 109 because it's slower. It can out dogfight the 109 any day of the week. What spit pilots have to do, as I do in G.50, is learn how to use a slower more maneuverable aircraft to it's advantages.

Could you please add above data to appropriate bugtracker issues.

I think if the spit was faster in RL it should be made faster. If it was slower it should be slower. The quarrel is here which was faster. This question seems to be difficult to answer. Both sides have and still claim that their ride was faster. Probably because both were so close and the perception which one was faster depended on some other conditions (using emergency power, being slightly higher initially, having a well performing individual plane over a badly performing individual plane, being in the altitude range that provided performance advantage for own plane, ...).

The Hurricane was indeed pulled from the front after the Battle of Britain. But in the battle itself it is arguably more important than the spit as it recorded many more kills, and was present in greater numbers. Lets try to get all of these planes FM's as close as we can. Fingers crossed.

Polish pilots from 303SQN taking part in BOB from 31 august 1940 was flying Hurricanes MK1 of course using 100 Octan fuel ( i read their combat raports) and they were the highest score RAF SQN during BOB time. They got also the best kill to death ratio so in experience hand Hurricane was still good fighter plane in BOB time. Expecially when it could use +12 emergency power which make huge difference in low level combats.

If you could do it casue im not familiar with bugracker too much :(

You people should finally learn that Kurfürst is always right and 109 is best and it is properly represented in the game while spitfire is also properly represented because it performs worse than 109.
I just wonder what would happen if 109 would perform worse than spitfire.

Kurfürst, can you add speed increasing with "overrev the engine above FTH" that you have mentioned here.. ?
http://forum.1cpublishing.eu/showpos...postcount=1606

Every book/article I have read points towards the 109 being slightly faster and better at diving and the spit being a slightly better turner.

Dont belive everything you read in books :cool:

I belive more in real life test data then story in books :)

I'm quoting this not because i want to reply directly to it, but because it brings up another point that many of us don't think too much about.

As you can see in the last sentence, WEP on RAF fighters was a situational thing. It was mostly a low-altitude advantage and this translates to one of these two things:

1) Scramble and climb to altitude.

2) Dive low and use it to escape.

The reasons it worked like this is that pilots of the time flew differently than us. The fights happened high because of bomber flights, so RAF pilots had to climb fast. Then, because LW pilots had bombers to escort, if an RAF pilot would dive out of the fight, kick it into WEP and leave, a lot of times he would not be followed unless the 109 tailing him could score a quick kill and get back to protecting its bombers.

What we do is different: the RAF putters around at treetop height, the LW is cruising around at optimal fuel economy cruise for hours and BnZ'ing them, but all too often the 109s will drop down, give chase and lose the advantage.

There's nothing wrong with that, because we all want to have fun and get in fights. What's wrong is expecting to see historical outcomes while we are using non-historical tactics.

The easiest way to capture some of what we read in the books is to fix the bombers first. No, i'm not kidding. With the latest testing patches a lot of people can now fly bombers in formation online.

Fixing the rest of the bombers' bugs (they have a few remaining issues with their bombsights) will take things to the next level: more people will fly bombers, which makes fighters have a reason to fly high and stay high.

Then, we have two positive outcomes as a result. First of all, tactics and the situational parameters of the "arena" are closer to real life, so we can make easier comparisons. Second, the good and bad points of all fighter FMs will be exposed through using them in a more structured tactical environment with specific demands.

What we have right now is a lot of gnashing of teeth for now real reason: we can't expect our favorite ride to perform a certain way when we fly it a totally different way. Even if the FMs were 100% accurate, it would not be the same because how you use the FM matters as much as the FM itself.

Currently in the sim, the 109s escort nothing so they are free to range about at 1.2 Ata for more than an hour per sortie and pick their targets, while the Spits and Hurricanes are hugging the trees and hunting squirrels most of the time.

It used to be a bit like that in IL:1946 as well, because the RAF planes are nimble and the temptation to just go and mix it up is great. However, the best and most dangerous Spit pilots i've ever seen while flying IL2:1946 were not the ones who scored 5-6 kills per sortie during a furball on the deck and then got shot down by a Dora that happened to be passing by.

The ones i feared the most when i was flying blue were the ones that flew at altitude and used it like a BnZ plane. It might not be that fast compared to the 51s and 47s, but it was nimbler and climbed very well, allowing it to constantly evade and follow it up with aggressive climbing, retaining its advantage. These pilots didn't score 5+ kills per sortie, but they usually scored 10-15 kills for every time they were shot down, they would very often go in with a disadvantage of 3vs1 and win because they were flying their brains instead of flying only the FM.

Spent most of my time with Alpha issues rather than FM. I can usually out turn any 109 but last night (in the Spit2a) a pair of 109's matched my turns and found my self on the edge. May be its a problem with the revised throttle management and speed. Not sure yet so will try the 1a in case this is specific to the Spit 2a. Trim is better, Mk1's altitude speed better - throttle is porked, and landing friction is on par with Ice even on a 85mph verge of stalling touch down. Whatever, still my preferred choice and just have to get used to any 'quirks'.

correct..

Just read your post Blackdog, I stick to high alt but it's very quiet except for the occaisional 109 and usually they are pretty damned good. I think Krupi followed me down in his 109 as I was RTB to Hawkinge (in a 1a) and it performed pretty well at low alt but for me, low alt furballs are the quickest way to gain altitude - to a vacant cloud and a golden Harp lol! Game Performance is so much better at altitude as well.....

A very good post.

Best Regards,
MB_Avro.

Im glad you mentioned the landing SEE i thought my speed was to high coming in but as you say its like ice.

What?

So this 109 had an alt advantage on you and your supirsed he was able to boom and zoom you? It does NOT get more historical than that!

I bleed of airspeed using a turning approach with (Prop Pitch set to kill RPM if necessary) and touch down at around 85/90Mph, once that speedo is registering zilch I apply full rudder and tap the brakes to stop nose over - job done but it does feel like a friction problem combined with a throttle bug. If you pancake with wheels up it slides far too long!

Keep the personal comments/insults out of the thread or it gets locked.

Please lock it.

Just another thread whining about how the spit2a is no longer overmodeled, and about how it's necessary for red to actually adopt historical tactics rather than furballing on the deck. This thread is not constructive in any way.

If the thread starter was interested in fixing performance issues in the sim, then he would have posted flight test data from historical sources and from in game so we could compare and contrast.

wow finally the promised so close performance is up to the pilot

cant wait for the dx9 patch:cool:

I know what you mean, it's what usually happened to me flying 190As against Ponies and T-bolts in the previous series :-P

Of course i'm not pointing fingers at anyone specifically here. It's just that we are all part pretend-pilots and part game players, so as a result what we do differs considerably from what a real pilot would do in real conditions. Cheers ;)

For God's shake, don't give them ideas!!!!! :D



Amen


~S~

It's also time to have a decent server tool with web based statistics that allow for specific awards for map winners = bombers so that there is motivation to go for bombing.

There is definilty bug in SPitfire MK II engine.

According to manual Spit MK II should have power settings:

- climbing power (30 minutes) - +9 lbs at 2850 RPMs
- max all level (5 minutes) - 9 lbs at 3000 RPMs

In Clod there is engine broken after flying at +6 1/2lbs at 2850 RPMs after ab. 10-15 minutes continous flying

If you apply +9 lbs at 2850 RPMs you could fly ab. 2-3 minutes then engine broke.

It is not correct that you cant even fly 30 minutes at 6 1/2 lbs 2850 RPMs if you should be able to fly such time with +9lbs 2850 RPMs.

Other hand Bf 109 E could fly all time at 1.35 Ata power settings without problem if it was only 5-minutes emergency power.

Spit II didnt really enter mainstream service untill AFTER the BoB... ;)

Did you have radiator fully open?

Yep always full open.

I flew the spit2 all out (+8lbs) at 2650 rpm across the channel, had a dogfight and flew and back, without engine trouble

Should be possible to fly up to 30 minutes at + 9lbs and 2850 RPM. Actually it is not possible to fly even at +6 1/2 lbs at 2850 RPMs for 30 minutes.

http://forum.1cpublishing.eu/attachm...8&d=1335381803

What btw about the performance of the other planes, the 109s, the G50, the 110 and the bombers? How far off mark are they? (I am loosing track ... )

If it was done at Pas de Calais per most of the online servers, this can be accomplished in under 30 minutes.

Being lower does not means it had less energy than you. And if it was coming from a dive and had much more speed than you. Energy = speed + altitude. I bet you just not avalied the energy states good enough. After 2 or 3 pass he was much higher because problaby he puts you in defensive obligating you to turn a lot when he preserves its energy using less AoA and coming inside your turn for a snap shot. Next time rec a track.

Problaby you were a victim of the famous rope a dope manouver. the good 109 pilots use it a lot:

http://www.youtube.com/watch?v=cQWyrOSB6uw

http://forum.1cpublishing.eu/attachm...8&d=1335381803

SOURCE? Did you write it yourself or is it a book? By whom?

"Should be possible to fly up to 30 minutes at + 9lbs and 2850 RPM. Actually it is not possible to fly even at +6 1/2 lbs at 2850 RPMs for 30 minutes."

Well sort of. 30 mins is a general limit. As to be able to actually do it is subject to Oil temp and Coolant limits staying within limits.

It seems the real issue in CLOD with the Merlins is keeping Oil temp below 95C. If you do this then generally there is not an issue. Go over 85C and the windscreen gets oily quickly.

The Source Document (AP 1565B) is RAF Pilots notes for the Spitfire II

LMAO, It is very realistic to use a climb rating for cruising.

:grin:

109 turn better than the spit with low speed, below 370km/hour.
According to Closterman the pilots of spit who have to try are not to return to say it ;)
2mn44 speak french.
http://www.dailymotion.com/video/x8h...partie2_webcam

It is valid according to "AP 1732b Instructors' Handbook of Advanced FlyingTraining, 1st Edition" to use climb power for other "conditions of flight in which really high power is required".

First thing that came to mind when I read the bold above:
http://4.bp.blogspot.com/-XExbxzDDPt...honRunAway.jpg

Not sure where the "cruise" reference came from but cruise, by definition, is the range of power settings that provide the best level flight fuel efficiency. That is what all pilots mean by cruise - fuel efficient flight.

Whilst you may be able to use climb power to sustain high speed level flight there is no way climb power is a "cruise" condition, that is just stupid. Its important to get definitions right or these threads devolve into pointless arguments about exactly what a term actually means.

Maybe you are permitted to use climb power for sustained high speed flight, but calling that "cruise" just confuses the issue.

I don't know if you had a look at the merlin em files so far. I've looked at them a year ago, so maybe this has changed, but at that time the Merlin III and XII were very identical. The nominal rpm was 2600 RPM for both. I assume that normal rpm is the value that can be maintained without critical overheat.
My impression is that the Merlin XII - as we have it know - is modeled more like a Merlin III running 100 octane (with +8? instead of +12 emergency boost).

You are correct. I don't know why Crumpp came up with "climb rating for cruising" as no would call it "cruising" when you apply "climb rating". I only wanted to show that "climb rating" is not deemed to a flight conditions where rate of climb is > 0.

About "cruising" definition. In RAF terminology there are 2 "cruising" or "continuous" ratings. The higher one ("rich continuous") is the maximum power that can be obtained without time limit and if the engine runs at this setting it will have a reasonable life time of 100 hours. Everything setting above that shortens the engine life at a higher rate. Everything below that setting will lengthen the engine life.
The lower one ("weak continuous") is for the limit for the use of mixture control at "auto weak". This is a simplified guideline for best fuel efficiency, however there are many factors the influence best fuel efficiency. More details about how to obtain best fuel efficiency are typically given in the Pilot's Notes of each aircraft.

Yes, I would love this!

First of all it would be a much more correct representation of all planes.

The even just 2-3% would mean +/- 10-15km/h difference, so folks could not build their fights on tiny speed advantages at certain height levels.

But then I guess that those crying for 'historical' performance now would turn that 'variable performance' off for their dogfight servers...
+++++

...and the date of publishing? NM, I found it July 1940.

http://www.scribd.com/doc/46069063/1...e-II-Aeroplane

http://i1020.photobucket.com/albums/...er82/spit2.jpg

http://i1020.photobucket.com/albums/...r82/spit-2.jpg

Exactly...think about it.

You have it right here:

It is not a matter of just shortening engine life, it is a matter of reliablity.

It would be more accurate to say:

Everything setting above that is an overload condition which can cause the engine to fail. Everything below that setting is the stress conditions the motor was built to withstand continuously.

Those notes look fishy.....my copy of the July 1940 notes clearly states 30 Minutes for climb rating at +9lbs @ 2850 rpm.

Umm! Most civil operating handbooks will denote a normal climb speed which is also known as Cruise Climb speed. The Cruise climb speed is the airspeed that you can climb for extended peiods without over heating the engine. Cruise climb is used in cross country flight where rate of climb is not an issue.

Pilot's Notes General 2nd Edition from 1943 states that the time limit for climb rating was increased from 30 minutes to 1 hour.

Hmm i didnt look at emd file for CLod yet. But if it is true like you said so there is obviously error in engine data which probably casue problem with Merlin XII power limiation in game.

Luckly i checked today spitfireperformacne site and i found interesting data for Merlin III at 87 octan fuel which i didnt see before:

http://www.spitfireperformance.com/n...ertificate.jpg

So for Merlin III at 87 octan fuel we have:

max take off - +6 1/4 at 2850 RPM
climbing - +6 1/4 at 2600 RPM
All-out level flight - +6 1/4 at 3000 RPM

With 100 Octan fuel modification Merlin III power settings was rised to:

http://www.spitfireperformance.com/spit1pn2-a.jpg

So with Merlin III at 100 Octan we have:

take off - +6 1/4 at 3000 RPM
1/2 hr climbing - +6 1/4 at 2850 RPM ( below 20 000 ft) and at 3000 RPM (above 20 000 ft)
all-out level flight - +6 1/4 at 3000 RPM ( 5 minutes)
emergency power - +12 lbs at 3000 RPM ( 5 minutes)


Of course for Merlin XII nomial RPM should be 2850 not 2600 the same like with Merlin III at 100 Octan fuel.

Makes more sense now. July 1940 did not make any sense at all.

Very few list a cruise climb speed. Once again, it is something that changes with atmospheric conditions and the weight of the aircraft is a huge factor. That is what you are doing, climbing the plane at the optium speed as it sheds the weight of consumed fuel.

Cruise climb is calculated as it varies with conditions and is of most practical value in a turbine engine. There are two approaches. Optimum Climb speed produces the best overall fuel economy. It seeks to balance the most altitude over time using the least amount of fuel with the most distance covered over the ground. Best Economy Climb speed is the second method and it factors operating cost, maintenance, and crew cost. Neither one is applicable to a WWII piston engine fighter.

Piston engines the main benefit is engine cooling, visibility and comfort.

Generally max climing settings could be used for level flight much more safetly beacuse there is better airflow by radiators which casue better cooling engine condition then in steady climb at the same engine settings. So if engine have 1/2 hour limit for max climbing settings it could be used even more safetly for level flight. The one thing which is imprortant here is just fuel usage. Just all.

The distance covered over the ground is utterly irrelevant, the RAF used a spiral climb at the start of the BoB, it may have been a bad choice, but it proves that they weren't in the least concerned with the distance over the ground, since in a spiral climb that is effectively zero.

Completely irrelevant to the fact you don't cruise around at climb ratings. Even during a "cruise climb" your engine is set to a maximum continuous or below.

Right but completely irrelevant to the fact you don't cruise around at climb ratings. Better cooling or not, level or climb, it is an over boost condition on the engine and increased chance of failure.

Glider,

I think you asked about the Bf-109 Load factor limits. I am not sure of the specifics but I do know the engineering safety margin were higher in German aircraft. Take away being the airframes are not rated on the same scale.

It's interesting to note that publications from 1938 and 1939 give maximum take-off engine speed of 2850 rpm for both Merlin II and III. Publications from 1940 give 2850 for Merlin II and 3000 rpm for Merlin III. The increase is not associated with the use of 100 octane fuel.

Hmm interesting have you some documents with such Merlin power settings? I miss really manual ( pilot notes) for Spitfite MK1 and Hurricane MK1

It also shows maximum boost at emergency power at 12,500ft as +10.55lbs at 3000 rpm for the Merlin III when you use boost override or pull the tit on 87 Octane.

Absolutely NOTHING to do with the use of 100 Octane fuel.

Yep it is also interesting

I thought something like this might be discovered when I saw the 1937 instructions for boost cut out in the RAF Training Manual......

Actually this is not the emergency power rating, these are the results from the power test to determine to performance of the engine.
As +12 boost has a FTH of 10,000 feet this is the power achieved with throttle valve fully open.

Two possibilities.....

If our FTH is at 10,000 feet and our boost is 12lbs then by 12,500 it will be reduced and 10.55lbs is certainly in the ballpark.

OR

12,500 ft was the FTH at 10.55lbs on 87 Octane.

It warrants more investigation.

That is exactly what it says and the 1937 RAF Training Manual talks about boost cut out and emergency ratings on RAF aircraft under the general definitions. It revises the old definitions of "Normal rpm" and Maximum Permissible rpm".

Do you mean this one: Air Publication A.P.129 Royal Air Force Flying Training Manual Part I - Landplanes?

I will look it up, thanks for the info.

Here's an interesting doco on the subject from discovery channel.
Probably a little biased but its still interesting just the same.
Sounds to me like it had more to do with pilot experience since the maximum performance windows of each aircraft were so very close.

http://www.youtube.com/watch?v=ugBpA...eature=related

Yes there are some details that make one raise an eyebrow. "Smaller and weaker wings", the canopy is jettisoned on the 109, the lack of stall warning on the 109.....

I would not say it was bias so much as just not knowing. The discovery channel says, "weaker wings". The RAF veteran is asked to go off what he sees and he does just that.

The lack of stall warning is also the Discovery Channel narrator. LE slats by their very nature give excellent stall warning and are an anti-spin device. It is a very silly thing to say.

The handling reports, especially the RAF detailed report on the Bf-109E is exactly what one would expect from an LE slat equipped aircraft.
From ~83mph to 75mph, the aircraft must be controlled with both aileron and rudder to keep it on a commanded flight path. It wants to go wings level. In a level flight stall, the left wing would drop just 10 degrees at the break.

There was never any tendency to spin under any flight condition.

The RAE's pilots opinion was the Bf-109 was too Longitudinally stable. Of course, the RAE did not have any defined stability and control characteristics at the time.

It is interesting to note their complaint about dive recovery!!

The RLM did have defined stability and control characteristics and the Bf-109 had to meet those requirements.

http://kurfurst.org/Tactical_trials/...ls/Morgan.html

This most likely has a great deal more to do with the adoption of two speed and CS propellers; in 1938 the majority of the Hurricanes and Spitfires were still using the fixed (coarse) pitch two bladed wooden props, so the maximum allowable rpm was fixed at 2,850.

The Merlin III had the universal prop shaft allowing de Havilland or Rotol propellers to be fitted, and the availability of two-pitch and especially CS props would have allowed for higher rev limits with less strain on the engine than a fixed-pitch unit. It also makes sense that in wartime some restrictions are lifted to allow for maximum power. One of the reasons 100 Octane fuel was originally adopted was to allow greater take-off power.

The Hurricane I Pilot's Notes mention that during take-off 2850 RPM will not be achieved with fixed-pitch propeller.
IIRC the Merlin II was only able to take the DH propeller (2-pitch and later converted to CSP) and the Merlin III could take both. Some early Merlin II were not able to take a CSP at all as they didn't have a connection to drive the CSP unit. I can't remember where I've read this ...

No they won't allow for higher rpm. It is also not less strain on the engine. CSP's are much harder to aerodynamically balance while a fixed pitch is very easy and will run with less vibration. RPM is a function of the engine speed and reduction gearing. You can change those items to increase rpm to adjust for different propellers. If you mount a fixed pitch propeller that is grossly underpitched for the application, you will also see an rpm increase and very soon have a big bill to pay.

You control the manifold pressure and rpm in a CSP unit. Fixed pitch, you can only control the rpm and manifold pressure is irrelevant.

That is why the RAF amended their definitions in 1937!

With a two position fixed pitch, the Spitfire pilot is controlling rpm and not manifold pressure. The airplane is equipped with a manifold pressure gauge but it serves as a diagonistic tool only. He flys the airplane by rpm setting.

If you read the Spitfire Mk I Operating Notes, the maximum rpm is the same for all propellers.

It seems very likely that RAF pilots were authorized to "pull the tit" on their aircraft using 87 Octane fuel with a lower manifold pressure boost gain. It appears to be independant of 100 Octane fuel use.

Exactly why you cannot draw blanket conclusions from engine instructions! All installations are different, even with the exact same engine/propeller combination.

The Spitfire Operating Notes distinguish between the Merlin II and Merlin III by rpm. The Merlin II is restricted to 2850 rpm and the Merlin III to 3000rpm. In a dive, both engines can momentarily achieve 3600 rpm. The run up can be deciving too as the engine is not under an airload.

I just reread the Spitfire and it does make a distinction between the Rotol and DeHavilland propellers on run up. The Operating Notes on a Merlin engine make no such distinction.

The difference in rpm is probably due to lack of airload on run up unless Rotols were not mounted to Merlin III's.

Sorry forgot to mention that the Hurricane I Pilot's Notes are from 1939. I think it also give only limits for Merlin II an not III.

The following publications give 2850 RPM for Merlin II and III:
Notes for Pilot's on Merlin II and III - 1939
Merlin II and III Aero Engine, 2nd Edition - 1939

The following publications give 2850 RPM for Merlin II and 3000 RPM for Merlin III:
Notes for Pilot's on Merlin II, III and IV - 1940
Merlin II and III & V Aero Engine, 2nd Edition A.L. 4 - 1940
Spitfire Pilot's Notes - 1940

Anybody notice you do the run up on a Spitfire at full throttle!!!

Wow, that must have been beast and no wonder the Operating Notes require TWO men holding down the tail!

Well there you go...

In 1940 the Merlin III was given an rpm increase to 3000 rpm.

it has more to do with the airstream ard the prop, hence the aircraft speed in that case (fixed pitch).

Max rpm is more a function of admissible eng wear. It always a trick for eng manufacturer to increase rpm to raise the number of HP available.

I think tht latter in the war, the Merlin's limits were raised to 3k rpm [confirmed - see above].

There is nothing hidden here: just like you ride your bicycle, you can't reach your max rpm at high gear starting from rest.

The Hurri had a thicker wing, so it didn't need so much speed at T.O as the Spit. Hence the T.O pitch setting wldn't need to be as lean as tht one for the spit. If the Merlin was tuned for both aircraft, it wld seems normal tht the max admissible rpm for the Merlin wld hve been fixed as a ref for the Spit and then wld hve differed slightly with the Hurri.

This are only supposition. Take it only as it shld be.

I don't agree when we say the Spit is worse. It sure as heck isn't. I caught a Spit down low and toyed with an ME-109 for a good while untill he yo-yo'ed me. I decided to loop around and to to find where he was. unfortunately he got off a very small burst that seemed to get my roll controls somewhere. I just broke off, let a buddy deal with him as he was pretty shot up and I was guns dry...and used my rudder to induce roll to get home.

So really, He who has E wins. And if you catch an ME-109 Down low (which happens often) it's his funeral. The only huge advantage I can tell the ME-109 has is those 20mm cannon that can shred you pretty fast.

The Spit if anything still retains energy really, really well in turns and such. The only reason it's not cleaning house is because ME-109 pilots aren't playing their game (or at least the patient ones) and son't get into a turn fight where the spit will just about enter at the same speed it came out of the turn.

Spit is only worse if you are one of the noobs flying around on the deck, turning circles kicking up dust.

My wingman and I confronted some Spitfires up high over England two nights ago and they were extremely formidable.

Can we please put this tired topic to rest?

Dear Crumpp,

I think this is incorrect about the Spitfire boost control cutout. It actually had quite different roles pre and post modification.

The original boost cutout was a true "cutout" in case of failure of the boost controller (which controls at +61/4psi). It gives full throttle valve control back to the pilot, enabling him to get +20psi boost (full unthrottled supercharger output) at ground level if he desired. Of course with either 87 or 100 octane this would not be a good idea.

There is no documented use of the original boost cutout as a combat boost system I am aware of, but it would be possible. The pilot would need to be very careful not to exceed a boost level that caused predetonation or engine damage, and the boost would continuously change with rpm, height and throttle position.

That document giving 10.55 psi boost is very interesting. As Banks suggested, it appears to be the boost attained with full throttle and (unmodified) boost cutout pulled at height. The height is about right. Interesting in that such a high boost was usable at all in a Merlin III on 87 octane.

However it is very unlikely that pilots were ever authorised to use the unmodified boost cutout as emergency power because the risk of instant degradation of engine performance was high (especially at low altitudes)

When the boost cutout was modified it was actually no longer a "cutout". It became a boost setpoint changer from +6 1/4 to +12 psi. It then became authorised as a practical combat boost (in conjunction with 100 octane fuel) that Dowding could fret over.

camber

Guidelines for use of boost control cut-out in unmodified condition, January 1939: http://forum.1cpublishing.eu/attachm...0&d=1334682385

I agree that specific authorization was probably not given and the risk was high.

The RAF pilots were given license to use it in the General Operating Notes. The Air Ministry openend the door and I am sure pilots died as a result.

They were instructed to balance the risk. Given the fact these guys were not the technically savvy pilots we see today, it makes sense you would have a high incidence of those who thought they knew better with such instructions.

Defining that point of balance was obviously an issue for the RAF as several memo's appear at various times during the war warning of the dangers of over boosted conditions.

Absolutely correct. In fact the were not authorized.

http://forum.1cpublishing.eu/attachm...1&d=1337196053

So the argument that the airworthiness limitations were free to be violated because the RAF says to balance risk only works when it fits an agenda? :(

Where does RAF authorities allow to ignore/violate engine limitations? My agenda is to follow primary sources, this makes life pretty easy.

We know your agenda.

The RAF's agenda was to provide the pilot with the best possible performance in high risk combat situations. The RAF didn't want to provide the pilot with an engine self destruct switch, which is what would happen if the boost override was used with 87 octane fuel.

+1

Its just Crumpp trying to ignore all the pilot accounts regarding using the boost ie pulling the plug etc,being linked to 100 octane fuel because it doesn't fit with the agenda he's pushing.

In the General Pilots Notes it states the pilot can balance risk and exceed the published limitations. That was the clause used to advance the idea in the 100 Octane thread that the RAF pilots routinely violated the Notes on a Merlin Engine in the Operating Notes.

Mine too. That is why I bring the point up you cannot look at a combat report as proof of 100 Octane use with specific references to +12lbs or 100 Octane.

Obviously the RAF was comfortable enough to test it at 12,500 feet on 9-6-39 Merlin III serial number 7491 mounted on Spitfire N3171 up +10.55lbs using 87 Octane fuel.

Paragraph number please. I don't like to read the whole manual to find one sentence.

Part I Introductory of the General Flying Notes.

AP 2095, 2nd Edition 1943

I checked the June 1941 edition. It doesn't contain any general statement that aircraft or engine limitations are allowed to be exceeded. It does however explicitly state that the over-ride for the boost control of "an engine normally rated for [...] 87 otane fuel" "may be used only if 100 octane fuel is in the tanks."

You've got that all scrambled. N3171 hadn't even flown yet on 9-6-39. The power figures on the engine Inspection and Test Certificate come from "test bed conditions", either at RR, RAE or the dynamometer at AAEE, i.e. the engine wasn't even mounted in an airframe and the engine surely wasn't running at 12,500 feet without an airframe.

N3171 Ia 413 EA MIII

FF 10-11-39
27MU 13-11-39
AMDP 16-11-39
AAEE 19-3-40 comparison perf trials (Rotol constant-speed prop) with K9793 (2-blade fixed pitch)
CFS 24-2-40 ? for compilation of pilot's notes
ECFS Hullavington 13-6-42
SOC 18-8-45

By the way. The altitude of 12,250 feet that was chosen for the power curve is the altitude used for rated/international rating. This is probably the FTH for climb rating, the RPM is lower than on "All out", thus the FTH is lower under this condition.

Here are some examples for Merlin II/III:
http://www.spitfireperformance.com/L...ertificate.jpg
http://www.spitfireperformance.com/k...ertificate.jpg
http://www.spitfireperformance.com/n...ertificate.jpg
http://www.spitfireperformance.com/k...ertificate.jpg

There is another for Merlin III, but this is probably a prototype or conversion for Merlin XII.
http://i53.tinypic.com/r0p095.jpg

Despite the use of 100 octane fuel the power curve is only done up to +10.6. However +12 or even more boost is possible without detonation. This pretty much spoils the idea that the values from the power curve have anything to do with the physically possible maximum.

How would they measure the engine power during flying anyway? It's likely that these were either calculated values from bench tests at sea level and even if boost above the regular engine limits were used it was under a controlled condition and certainly for very short periods.

Didn't you see the pic of the RAE Anson with the Merlin mounting on the top :)

I got a bit confused by the height reference...but of course these are test bed figures.

I would be interested in the test bed setup. For the Merlin hooked to a dynamometer setup, there would be a variable load (allowing rpm setting for any throttle etc. setting) with bhp measurement. To simulate altitude, the supercharger intake could be connected to a chamber of correct maintained underpressure. Then height and rpm could be set and boost/bhp measured.

But to know the real setup would require the actual protocol and equipment used here, which is not in these reports. I would be interested in whether a test run Merlin III could handle +10.5psi boost on the bench (even briefly)with 87 octane without predetonation reducing power, but couldn't these be calculated values in the reports anyway? (actual tests at SL, but corrected for particular FTH etc)

Are the SPITFIRE FMs at UP 3.0 RC4 yours?

Sure it was running at 12,500 feet on an altitude test stand.

Let's see the whole publication because they do not match at all. Either the warning about 100 Octane is a technical update added at a later time or it is not from the same document.

The 1937 Training Manual makes no such distinction about 100 Octane fuel.

Actually the modifications to the boost control cut out had not yet been instigated in June 1939; the modifications to the boost control cut-out were needed before the engine could reach +12 lbs boost. This is full power test proving that the engine was strong enough to withstand high boost pressures, and that relatively high pressures could be achieved on 87 Octane fuel. Once again this is a pre-war document which proves nothing germain to Crumpp's "case".

http://www.wwiiaircraftperformance.org/ap1590b.jpg

http://www.wwiiaircraftperformance.o...ol-cut-out.jpg

Yup and let's see your 1937 Training manual and the context in which it mentions boost over-ride, because so far we've seen nothing of it, just your description.

And how the heck can an aircraft which was built in November 1939 manage to fly engine tests in June 1939?

http://www.spitfires.ukf.net/p003.htm