They don't turn too fast. The performance aligns perfectly with a standard turn performance chart.

I'd like to know what data you used, a request couldn't be more straightforward and simple. I didn't ask for adverts, standard turn performance charts or other rubbish.

Hold on a second. You attacked the effort and claimed it did not conform to physics.

When I explain it is all standard formulation commonly found in aerodynamic text using the BGS system and present a General Turn Performance table the results agree with perfectly, you claim it is all rubbish.

So what is not "rubbish" to you??

Before I present you with the data, should we agree on what we are looking at???

I admit that my problem is a simple basic one. I believe a huge amount of time and effort is going into trying to hide one clear and obvious truth. That all the pilots and all the test pilots of all the test establishments, in all the nations that compared the 109 and the Spitfire, all agreed that the SPit turned better than the 109.

None of the above mentioned said that there was any difference when in a turning climb and the RAE clearly documented the advantage to the Spitfire. No advice was given to German pilots to go into a climbing turn to escape attack and as far as I am aware, no pilot of the time has said that they used this tactic in combat.

I frankly don't care what a theoretical calculation shows when compared to the tests that were done at the time. Why, because anything done today is just that, a theory unable to be tested in real life, a pricless advantage which occurred in the war years.

Its also worth remembering that the calculations being done today are being done without that 12lb thrust which increased performance of the engine by approx 30%

I invite those who believe that the 109 had the advantage to find any test from any establishment of any nation to support their view.
It shouldn't be difficult if the results are so clear and obvious mathmatically.

It does turn better. Look at the calculations I posted.

It just does not do it under all conditions or speeds. That is important, Glider.

If the two airplanes were to have a turning battle to the stall point, the Bf-109E-3 would loose.

Here is the acceleration rates of the two aircraft. The Bf-109E-3 out accelerates the Spitfire Mk I due to its being lighter with more excess thrust.

http://imageshack.us/a/img338/6370/s...09eacelera.jpg


Of course, the Spitfire can fly at a slower speed were the Bf-109E3 cannot fly at all.

If the Bf-109E3 maintains his trim speed of 400 kph, he is tough customer for a Spitfire to deal with. At that speed, the Bf-109 can sustain better performance and accelerates better. The Spitfire needs to take the fight to the low speed realm where it has all the advantages.

Man, whatever goes on in your world. I asked you to share your input data. Three times, won't ask a fourth, so forget about it.

Typo on the chart axis....

Acceleration is in fps^2

The data has been posted for each evaluation.

I would be glad to share the input data for this one but what would be the point when you are saying the whole effort does not conform to standard physics.

It does conform. Aerodynamics is nothing more than applied physics and all the formulation is straight out of my college text. It is the same stuff we did in the classroom!

If you agree it conforms, I will be glad to continue the discussion and share the data.

I plan on sharing the spreadsheet too.

Crump - you know if you click the "multi off" button it says "mutli on", then when you click "reply" it will contain these quotes and you can make one post? ;)

Where did you assume the propeller efficiency was 0.8?
De H 55409 B 0.930

Rotol RA 611 0.924
Rotol RA 621 0.920
Rotol RA 600 0.911
Rotol RA 640 0.940

Take your pick, which propeller did you claim had an efficiency of 0.8?


http://www.spitfireperformance.com/spit2prop-b.jpg

That is a standard assumption in aircraft performance for power producers. It assumes a good propeller design.

The data listed below is peak efficiency which is a small part of the advance ratio curve. When you average out the entire curve, it comes out to ~.8 for a well designed propeller.

Crumpp your Spitfire V 109 acceleration chart is I presume 1G flight ?

Yes

Thanks!

Ok then its straight line running not sustained turn performance. So wrt your comment :

"If the Bf-109E3 maintains his trim speed of 400 kph, he is tough customer for a Spitfire to deal with." I respectfully disagree. Obviously I prefer to accept the RAE's views rather than yours.

WRT the sustained turn performance based on RAE computation at 12000ft, 400Kmh/248mph (TAS). The Spitfire can sustain 2.95G giving an approximate sustained turn rate of around 14.0 deg sec. The 109 on the other hand can sustain only 2.3G giving an approximate turn rate of 10.5deg sec.

So according to the RAE The Spit at 12,000ft/400Kmh TAS has 0.65G sustained G advantage over the 109 and 3.5 deg sec sustained turn rate advantage. Thats a nose position advantage of just on 119degrees in a single 360 degree turn. Sustained turn radius wise the Spitfire is around 526ft smaller to boot. So based on RAE calculations the 109 is not so "tough a customer at 400Kmh" in any turn fight.

A 109 Pilot in this engagement is just going to watch the Spitfire translate aft in his canopy until he ends up nose in lead with guns firing. Best option for the 109 (imo) is as soon as he sees the aft translation back through his 3/9 line to ease off on the G (maybe holding the bank on for deception) extend (using his superior 1G Ps) then transition into a climb, get the separation he needs and come back into the fight at a later point..... and that sort of thing is exactly what the good On line 109 drivers do.

Ties in with the Historical record and what we see On line every day.

Well IvanK, had RAE chosen the lowest available speed and max lift coefficient values for the Spitfire and the highest available speed and max lift coefficient values for the 109, at the altitude which is most favorable for the 109, their results would have agreed with Crumpp's :)

Ironic mode off: Why waste time with obviously deeply biased stuff? Just google with keywords: Crumpp Spitfire calculation. You will get thousands of hits from the several sim forums over the past few years, I think he has produced enough text and calculations for several books.

Apparantly, you can't even read your own tables..

Column 12, "Airscrew effiency" from flight results, at 18 000 feet:

Rotol RA 611 0.924 = 0,800
Rotol RA 621 0.920 = 0,805
Rotol RA 600 0.911 = 0,785
Rotol RA 640 0.940 = 0,800

... besides the fact that NZTypoon has reading comprehension problems, there's also the fact that the above values are only true for 18 000 feet altitude and max. speed level flight of about 365 mph.


Instead, RAE has picked the lowest available speed and max lift coefficient values for the 109 and the highest available speed and max lift coefficient values for the Spitfire, and so they have arrived at the results they did.

What all people seem to forget that the results in all these calculations are deeply rooted in the source base data, and since there is a great deal incertainity in those, the results tend to diverge quite a bit.

I just recalled I still have my near three year old turn performance estimate spreadsheet. I attached it, so anyone interested can produce charts to their likings. I've added some 109 E and Spitfire I data, feel free to use your own data sets. If you have any questions, just ask.

Thanks, this is very usuful.

I fooled around with the specs a bit, with best/worst case data in bost cases, but interestingly the tables keep showing that the 109E is evening things out in turn and then having an advantage at and above around 400 km/h.

Math is just too impartial I guess.

The only way to change that would be using 100 octane performance for the Spitfire I, giving it a level speed similar to the 109. Or go to high altitude, were Spitfire and 109 are always fairly close in terms of speed. Other than that, 30ish extra km/h is quite a bit.

So noted: screeds of data all showing the terrible inferiority of the Spitfire, and all stemming from one or two reports.

Agreed! 100 octane is giving a Spit roughly equal speed at low level, even greater speed at low-medium altitudes, which governs most of the high speed turning stuff. Apart from that, without 100 octane the Spit is a bit of trouble against the 109E at higher speeds, since the latter is faster at low altitudes, and in the end its speed that govers most of the high speed turning stuff (since parasitic drag is much more dominant there). Its simply how the turning formulae works, something that some of spit fanatics simply do not want to accept.

Higher altitudes would be interesting btw. The Spit has a more power there (save for the 109E/N) and the two aircraft about the same speed. The Spit has less wingloading, the 109 has higher AR - thus the main factors governing turning are going both ways.. my guess would be a slight Spit advantage there though (save again for the 109E/N).

Bottomline, it doesn't matter how good the plane can turn, if the pilot can't fly it right through the edge. 1-2 seconds can be generally made up by good piloting skills, both ways. ;)

When you calculate out the performance, it is easy to see why Mtt defaulted the trim to 400kph.

That is a very good speed to dogfight the airplane.

http://imageshack.us/a/img542/1949/s...bf109e3sus.jpg

http://imageshack.us/a/img840/8112/rateofturn.jpg

LOL, you do know I was on the FM team for Warbirds at the time. The first FM done was the Spitfire Mk I and Bf-109E series.

When you combined the performance with the flying qualities, these two airplanes are the most evenly matched close quarter dogfighter that existed, IMHO.

Doghfight at 400kph in 1940. Very good :grin:

How exactly would you outturn a Spitfire in a combat again?

Why do you think it would be so difficult to dogfight at 400 kph in an airplane?

Have you flown many airplanes?

Do you know how easy it is to hold a design speed?

First of all, 400kph is within the power stable region of the Bf-109's curves.

What does that mean? It requires ~350 hp to go from the stall point of 82 Knots to 215 Knots (400kph). That is a change of 133 Knots.

We are in a region that small power changes make for large changes in speed.

Compare that with the power required to go from 400 kph to Vmax in the Bf-109E3 is another ~545 hp to increase speed ~54 Knots.

http://imageshack.us/a/img545/7629/p...gionbf109e.jpg



How long will this take?

That too is easy to find out with some applied physics.


Acceleration = (Change in Velocity) divided by (Change in Time)

The average acceleration of the Bf-109E3 from 82 KEAS to 215 KEAS is ~9.6 fps^2.

We have to use the same units so our KEAS is converted to feet per second.

Rearranging our formula to solve for time:

Change in Time = Change in Velocity / Acceleration

delta t = (363fps - 138.4fps) / 9.6 fps^2

Feet cancel out as well as one of the second leaving us with the unit of seconds....

Change in Time = 23.3 seconds

Twenty three seconds from the stall point to the 215 Knots for the Bf-109E3.

Same conditions for the Spitfire:

Going from 82KEAS to 215KEAS, the Spitfire has an average acceleration of 8.4 fps.

delta t = (363fps - 138.4fps) / 8.4 fps^2

Change in time = 27 seconds

Now going from the stall point of 67 KEAS in the Spitfire, we see an average acceleration rate of 9.96 fps. This is because the Spitfire has more excess thrust at low velocity.

Considering that it would be a very stupid Bf-109E3 pilot to be slow flight in the vicinity of a Spitfire, the Bf-109E3 can maneuver quite well and dogfight the Spitfire.

The Bf-109 is pretty safe it if stays in its envelope and does not try to fly were it cannot.

[QUOTE=Crumpp;463075]It does turn better. Look at the calculations I posted.

It just does not do it under all conditions or speeds. That is important, Glider.

If the two airplanes were to have a turning battle to the stall point, the Bf-109E-3 would loose.

Here is the acceleration rates of the two aircraft. The Bf-109E-3 out accelerates the Spitfire Mk I due to its being lighter with more excess thrust.

http://imageshack.us/a/img338/6370/s...09eacelera.jpg

I am sorry but this is rubbish.
a) You are using the wrong power settings for a Spit
b) The 109 controls lock at higher speeds far more so than the spit
c) The German test establishments let alone the pilots in combat would have identified that the 109 turned better at high speed and would have given instructions to their pilots similar to those given to Typhoon, Tempest and USAAF fighters. These essentially went 'Dont enter a slow turning fight with an Me109, keep your energy up and you will have him' Substitute Spitfire for 109 and you would have the german instructions. These were never given.

At 12 lb thrust the Spit produces 1300 hp which puts the power to weight ratio firmly in favour of the Spitfire from which a lot of performance calcs are decided. Without this calculation the charts you posted are of little value.
400 Km is about 250 mph which is not fast.

The Me109E is a tough customer no question and in the overall view there is nothing between them

LOL...

According to the Merlin III power curve, I actually being generous. RAM power for the Merlin III is only about 850 bhp.

weight 6050 lbs
Power 990 bhp
Level speed 247
Propeller efficiency 0.85
Wing area 242
wing efficiency 0.85
Dynamic pressure 206.8101695
Aspect Ratio 5.6
Mass 187.8881988

http://imageshack.us/a/img542/1949/s...09e3sus.th.jpg

Why do you think the trim on the Bf-109 is set to 400 kph IAS???

You do understand they can trim the aircraft for whatever speed they desired?? Having a fixed trim condition is a great way to set the combat speed for your airforce.

Problem is we don't have any good data on the 100 Octane.

The only data we have does not match our engine curves. Find some good data and I will be happy to do the calculations.

http://www.spitfireperformance.com/s...-rae-12lbs.jpg

Takes but a second to change the values.

That is how airplanes work, Glider.

It is not going to outperform the Bf-109 without changing the physics. The Spitfire has to be faster and have more excess thrust.

It is going to be very tough for the heavier Spitfire to overcome the weight differences when the Bf-109 maintains power parity.

It is that simple.

This is priceless - doesn't Crumpp know that apart from the variable incidence tailplane of the 109 the trim for all control surfaces had to be set on the ground, whereas the Spitfire could be trimmed in flight by the pilot using tabs on the elevators and rudder? For example, the speeds for aerobatics posted in the Spitfire II PNs:

http://i91.photobucket.com/albums/k3...ps09887768.jpg

The optimum trim for a 109 was set for 400 kph (248 mph)? No wonder the controls got so heavy at higher speeds.

What exactly would be your definition of good data?

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.

http://www.gqth.info/0.jpghttp://www.gqth.info/7.jpghttp://www.gqth.info/8.jpghttp://www.gqth.info/9.jpghttp://www.ymeu.info/test5.jpg

Data that matches the characteristics of the engine and makes sense.

If our engine has a RAM FTH of say 12,000 feet and our data shows a FTH of 8,000 feet....

It is not the same engine in the airplane. If we use the power data from the wrong engine with the wrong speed....our result's will be just as incorrect!

Grab a dictionary and look it up....

Also, go to the local airport and ask a mechanic about the number of airplanes that just have longitudinal trim controls. It is pretty common for a well designed control system. Most modern SE airplanes have fixed trim for everything but the elevator.

So you are saying that the Americans did a bad job in designing the control system of their fighters as the had to put trim on the elevator, rudder and ailerons?

How many modern s/e a/c have a speed range of a WW2 fighter?
How many modern s/e a/c have a disposable load that a WW2 fighter has?
How many modern s/e a/c swing a 10' plus prop turned by 1500hp plus engine?

So what? As per ususl Crumpp conflates modern civilian practices for sports aircraft and says this should have been the same on high speed fighters during WW2 How many high speed WW2 fighters has Crumpp flown?

Utter balony, it's a great way to ensure that once in flight pilots do not have the ability to trim the aircraft to suit the circumstances - the 109E rudder became increasingly heavy, to the point where it was almost impossible to use - it's interesting that later "tall tailed" 109 variants had a trim tab to help overcome this problem. Setting the "combat speed" to a uniform and abitrary 248 mph? What's the point of that?

Any WW2 fighter that used trim controls rather than fixed trim was, by Crumpp's definition, badly designed and therefore inferior to uber Luftwaffe aircraft.

It's not a question of which airforce had 'better' trim system.

It was just a different approach in USAAF and LW. LW fighters had no variable rudder trim and a/c was trimmed for certain cruise speed, so at most typical cruise speed pilot would not have to kick the rudder to compensate for sideslip. Allied fighter pilot would twist the rudder trim and climb or fly with feet off. No biggie imho, just more comfortable.

What Crumpp is saying that Emil was trimmed for 400kph because that was best combat speed. That is obviously wrong, 400kph was typical cruise speed (achieved at some 1.15ata and 2200 U/min). This worked in game btw, but then the devs changed the fixed trim value for 300kph for some reason, which is too low and now LW pilots complain because the Emil is very unstable during combat phase:

See bugtracker issue No. 387: http://www.il2bugtracker.com/issues/387

There is nothing wrong with 109E turning well at 400kph, it's actually pretty obvious to any virtual pilot in here, e.g. fast Emil will outturn slow Spitfire with no problem for long enough to score some hits. But as for sustained turn advantage in typical horizontal turnfight and as for 400kph turn used in TnB combat for long enough to be called sustained turn, that's all nonsense. :-P 109 will win if the pilot keeps the speed up, but not via sustained turn performance advantage. At co-E situation, Spitfire would outturn and hit a 109 turning at 400kph flat with no problem. Just for long enough to score hits.

I'd say Crumpp is not entirely wrong here but his statements are irellevant to what is actually important in TnB combat (re: sustained turn argument). I don't blame him for he has no experience with combat sims.

He's wrong in his statement that 109E was trimmed for 400kph purely for combat purposes. Fixed trims are usually set for cruise speed even for fighter aircraft.

Do the math....

The 12lb boost calculation done by the RAE is an absolutely reasonable extrapolation.

I have my doubts about it having been made by RAE. It's an obvious farce.

Well, then walk us through the explaination of how the engine data aligns with the graph. I would love to hear it.

Performance graph showing FTH of 11,000 ft:

http://www.spitfireperformance.com/s...-rae-12lbs.jpg

Engine data with RAM effect at max level speed showing FTH of 8,500 feet:

http://www.spitfireperformance.com/merlin3curve.jpg

Let's have a look at +6.25 boost ...

FTH at 17,000 ft (http://www.spitfireperformance.com/merlin3curve.jpg)
Max level speed at 19,000 ft (http://www.spitfireperformance.com/s...-rae-12lbs.jpg)

Looks like max level speed is achieved 2,000 feet above the FTH. Pretty much in line with the difference for +12 boost.

Edit: I want to make clear that this 2,000 ft difference between FTH and max speed must not be present in reality, it's more a systematical difference between the two charts that must be considered when they are compared.

That chart was not used because it does not align. The engine chart you linked already includes RAM effect at Vmax.


That means the FTH should match. Not be close or have the same margin of error, but match if that is the correct engine data.

I used the power figures as listed in the flight reports NOT a seperate engine curve that does not match the performance data.

I know that, I can read. You asked how the engine data align with the speed graph. They align with an consistent altitude difference of about of 2,000 ft.

The altitude difference between the FTH in the charts can be explained by a different level flight speed. E.g.
Hurricane I has a FTH of 17,750 ft at 316 mph.
Spitfire I has a FTH of 18,600 ft at 364 mph.

As we see the 50 mph speed difference results in a drop of 1000 ft for the FTH.

There is nothing contradicting in the charts ...

Then what is the issue with the data not aligning?

It will align. If you looked at other aircraft and not just confined yourself to one specific type, you would see this the case.

A speed difference is not going to account for a 2000 ft increase in FTH.

How do you explain the fact this chart comes from an investigation of performance with an experimental high altitude engine.

The chart exactly matches the one found in:

Messerschmitt Me. 109

Handling and Manoeuvrability Tests

BY

M. B. MORGAN, M.A. and D. E. MORRIS, B.SC.

COMMUNICATED BY THE PRINCIPAL DIRECTOR OF SCIENTIFIC RESEARC (AIR)

MINISTRY OF SUPPLY

__________________________________

Reports and Memoranda No. 2361

September 1940*

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

The data matches the same fan plot in another report on a Spitfire equipped with a Merlin XX engine.

AFAIK, the Spitfire Mk I was equipped with the Merlin III engine.

Merlin II/III could hold 12lb boost to over 10,000ft in a Hurricane and higher in a Spitfire:
http://www.wwiiaircraftperformance.o...-l1717-cal.jpg

Wow, the data does not match. It is that simple.

It does not mean there is not good data out there, it just means these charts presented are not it.

The fan plot for the Spitfire is for a Merlin XX engine.

I agree it looks simplistic, but technically it is sound and I see no reason it not being an original document. No reason for it being one either, but I will accept it on face value as I see no reason to mistrust Mr.Williams on this issue. If you have more than a gut feeling, I'm willing to re-evaluate my opinion.

It's not with ram effect. That's painfully obvious from all the engine and plane data on 6.25lbs around. The power level generated by the engine on this chart has the designation "all out level" and that's all there is to it. Assuming otherwise is like assuming "combat" power is only available when the aircraft is in actual combat.

And which Spitfire version would that be? ;)

I shall do the math to prove that 400kph was the cruise speed and that in turn was the reason to set the fixed trims to that speed - not your graph? :eek:

You are right, e.g. AP 1590B states 890 bhp at sea level and 1030 bhp at 16,250 ft for +6.25 and 3,000 rpm. The chart is obviously without RAM effect.

I have put in a request to the Rolls Royce Heritage Trust part of Rolls Royce to see what they say. The NA don't seem to have anything that would satisfy everybodies requirements. I wouldn't hold your breath as it might take forever but should at least deliver a definitive reply.

Do you know where cruise speeds are located on the Power and thrust curves?

Need me to show you.....????

Spitfire III, AFAIK only the prototype was built.

http://imageshack.us/a/img17/1140/summary1k.jpg

http://imageshack.us/a/img109/7506/fanclnsml.jpg

The 2nd (lower) page is not a Spitfire III. Spitfire III had a wingspan of 30 ft 6 in (9.3 m) and wing area of 220 square feet and for 6000lb that gives a wing loading of 27.3lb.

I sense that Red pilots not knowing/ignoring this limitation may be at the culprit.

http://www.qmku.info/0.jpghttp://www.qmku.info/7.jpghttp://www.qmku.info/8.jpghttp://www.qmku.info/9.jpghttp://www.ymeu.info/test5.jpg

Yes, I know, only few built. My point was that the original data linked by Banks were of Merlin III powered Spitfire.

Even your image is not an Mk.III, just the 1st page.

No need, thank you.

All I said was that you were wrong in your statement that 400kph fixed trim setting was due to the 'good speed for dogfight' reason

http://forum.1cpublishing.eu/showpos...&postcount=323

It is a very good speed to dogfight the airplane, but that has nothing to do with the sustained turn debate (in practical reality of an actual air combat). I explained that earlier. It is also not the reason for default trim settings, that reason was actually cruise speed at 1.15ata @ 2200U/min.

Here again:

Please don't mix up facts as they suit you to prove your bizzare theories.

That was built for the Griffon engine but they had a ton of problems and dropped it. The Merlin XX wasn't used in the Spitfire, that's why Robo is rightly taking the mick out of you.

In this case Crumpp is right, just for once - the Spitfire III prototype was built with the Merlin XX, which had a single-stage two speed supercharger - it also had clipped wings, a revised undercarriage which was raked forward by 2 inches, and a revised windscreen with two straight side pieces and flat windscreen with internal glass (the undercarriage and windscreen were later used on the Spitfire VC) . When it was decided to reserve the XX for Hurricane IIs the Mk III was adapted to take the first Merlin 60 series engine, becoming a Mk IX prototype. The Mk IV was very similar to the Mk III but had the Griffon engine.

OK so I may be a version out here lol Either way it's another case of running with it because there's a war on, not exactly the engineers style planning he expects in theory. Of course it's theory that engineers plan because where I work, which is a very successful global engineering firm, the engineers have virtually zero planning, all prototyping and wing their projects (plastering it with documentation on the fly). It's in software, my dept, which has far more planning than the engineers.

Very true, thanks for the details NZtyphoon. The key is the different (clipped) wings and therefore different wing load than the one we see at the top right corner of the above sheet.

Crumpp came up with the Merlin XX theory only to prove that the fan plot posted was for different engine with 2 stage supercharger. That is wrong just as was wrong his assumption that the chart posted previously by Banks (post 345) already included RAM effect.

No matter how I look at it, the post 345 makes perfect sense. ;)

Again, robo...

I asked you if you know how to determine the cruise speeds for an airplane. These are not random figures, pulled from a hat.

They are specific points on the power required and thrust required curves. The cruise speeds points of the thrust required and power required curves are fixed by the design and completely independent of engine settings.

Do you need me to talk you through how to determine them?

It is very easy to proved I am not wrong if you understand how the physics works.

No, thank you, that is not necessary at all. I already know you're completely wrong with your 'combat speed default trim setting' statement, no matter how hard you now try to prove that you were actually right.

As for the actual question (sorry I thought it was a rhetorical one) I don't know how exactly to calculate cruise speed for an aircraft, and I don't need it in order to see that you wrote 'combat speed' instead of 'cruise speed'. Now you will probably reply with another graph to prove that it's the same thing. Maybe you're even right, but essentially, you wrote nonsense, hence my reply. Consider my knowledge as limited if you wish, but then if I even can see that you're wrong and that you're bending facts to fit your bizarre theories (maintain rpm by changing it constantly, RAM effect, Merlin XX etc...), that says something about your activity here, not mine.

I am not too sure anymore about what are you trying to achieve on this game's forums, perhaps you enjoy the arguing for the sake of arguing, perhaps you enjoy the advantage you think you're having with your theoretical knowledge. I actually enjoy some of your technical posts and I have no problem to understand what you were saying, but when you're wrong you're wrong. And for some reason you never admit it, you just go on and on and every thread ends up to be about Crumpp vs. the 'sane world' rather than about the original topic. I fond that a bit frustrating to be honest.

Let me ask you a question you also omitted before - how exactly would a 400kph sustained turn in a Bf 109E be useful in actual turnfight vs. a Spitfire Mk.I?

In otherwords, forget any facts....

You are going to stick to your immature and emotional reaction.


Well, let's see how it pans out.

You can look in the Bf-109E3 Flugzeug Handbuch and see that the engine out instructions call for the pilot to pitch for 200kph IAS. This is best glide speed and corresponds to L/Dmax.

If our curves are correct, this will be the botton of the thrust required curve and tangent of the power required curve.

First the Thrust and Power Required curves:

http://imageshack.us/a/img193/4543/p...tcurvecrui.jpg

200kph = 124mph +10 mph PEC = 134mph CAS * .869 = 117KCAS = 117KEAS at sea level.

Yep, best glide aligns perfectly with our curves so we know the curves are correct.

Using the curves, it is easy to find the other cruise speeds.

Maximum endurance will be at the point of minimum power required. Carson's speed is a modern innovation and is the best balance of fuel consumption and speed.

The trim speed of 400kph IAS does not align with any cruise point on the curves. That means the speed was chosen for a different reason.

Now it we look at the rate of turn, or how fast an airplane can bring the guns on target, we see that 206KEAS is a point the Bf-109E3 maintains a healthy rate of turn advantage and can sustain better maneuvering performance.

http://imageshack.us/a/img15/8112/rateofturn.jpg

So, if it was not intentional, it certainly was a very fortunate turn of fate that the Germans choose 400kph to set the trim for the Bf-109E3.

Robo,

This is the key performance parameter for a fighter. It gives the aircraft which can sustain a higher load factor at a higher velocity the initiative in a dogfight.

This characteristic allows the Bf-109E3 to force the Spitfire to a lower airspeed in order to survive the fight.

The outcome of any dogfight is not predetermined. There are too many "what if's" and pilot skills are the determining factor.

What it tells Spitfire pilots is if you enter a sustained turn fight at high speed, the Bf-109 will win if you don't slow your speed down to the point you have a better sustained turn rate.

What it tells the Bf-109 pilot is you can maneuver against the Spitfire, just don't drop your IAS below 400 kph. If he breaks off and zooms at the point the Spitfire begins to out turn him, the Bf-109 will be above his opponent, out of reach, and able to engage/disengage at will.

400 kph is not a difficult point for the Bf-109 to maintain especially given the stability of the design. It is the trim speed and given the correct amount of power, where the airplane wants to be....

Not at all! The fact is (still) that 400kph was NOT chosen by Mtt because of 'good speed for dogfight' reason, contrary to your statement. No matter how you try to re-pack your words, you were wrong.

:rolleyes:

I specifically told you that posting the cruise speed calculation and graph is not necessary and irrelevant, but thank you anyway, it was interesting.

Did he even read your post Robo? Your point just went whoosh over his head.

http://24.media.tumblr.com/tumblr_lr...2g5fo1_500.jpg

Why did they pick it then, Robo? :confused:

Given the fact cruise speeds are fixed by design? ;)

Which point would that be? That I am wrong and don't admit it? Certainly I will if I am wrong.


On the otherhand, I did go to college for this stuff, worked hard for my education, and learned a thing or two about the science of flight.

I also have plenty of practical experience working and flying airplanes.

So do you think I am some jerk who can't admit he is wrong or maybe have some knowledge that makes me question conclusions that don't fit the facts or the science??

:rolleyes:

Yes, I agree, you said that already before, and this is very well known to most virtual pilot on this forums. You're not saying anything new here. Yes, the 109 turns better at higher speeds, Spitfire wins at lower speeds. What I was trying to explain before was that in a TnB fight, it's usually lower speeds that matter and decide the fight.

There is absolutely nothing wrong with what you're saying, it just doesn't make sense in regards to actual combat. If you keep the 109 in 400kph sustained turn, the Spitfire will be able to shoot at you for long enough to kill you, even being slower.

If he breaks off and zooms we don't talk about sustained turn competition anymore. Everybody is well aware of 109s BnZ characteristics (if he extends vertically). Again, you're not saying anything new. It's the TnB that matter here. Pure TnB rarely happened because it would be a suicide for the 109 pilot.

What you're saying with this whole post of yours is basically:

109 can win a turnfight against the Spitfire as long as it won't turn with it

Spitfire has had better sustained turn rate than 109 and it was generally a silly idea to turn with it. This is the case in the sim as well and all other sims.

Yes, that is correct.

Sure we are...

The Spitfire has lost and the Bf-109 has used its sustained turn performance to gain advantage and win the dogfight.

That is because a computer game is not representing reality in this case.....

There is a very good engineering reason designers have strived for speed as the number one performance parameter for a fighter.

I'd have hated to have been in your classes (not that I was ever a chicken feeder) because you'd have constantly put the class off with your maniacal theories.

I loved this bit

Total misunderstanding of air combat or brilliant trolling?

This!!!.....Ironic that Crumpp would come up with the best description.


No, you question the facts and science because you have a little knowlege and a big agenda.

Its a gut feeling of course - I wasn't there when it was drawn (thank God for that!). To me it just seems that, given that the original was drawn with pen AND was labeled, compared to the rough approximation visibile on the pencil drawn +12 and +16(?!) lines, the latter lines were probably made by some aircraft enthusiast well after the war. The lines/figures look more or less a reasonable guesswork, but I very much doubt it has anything to do with any test establishment.

IMHO the real question is how much time to Spit has to shoot at you? Because if the Spit turns at around its peak sustained turn rate - at about 250 kph? 300 max? - its going to be a good deal slower than the 109; maybe slow enough to fall so behind that it will be out of realistic guns range? You cant shoot what is not in range, even if your nose points towards it..

Moreover if say both aircraft start at 400 + kph, the 109 maintains it while the Spit bleeds it off to get a snapshop, all the 109 has to do is to level out with a very significant E advantage, and if the pilot is good at Energy fight, its all cat-and-mouse from there on.

Generally it seems to me a good idea to keep the speed over 400 km/h in a 109. If the Spit tries to follow you in sustained 400 kph turn, or if he slows down to try to get you, he seems to be ... to have gotten into a bad position. Especially in a multi plane enviroment.. you can shoot what is slow, you cant shoot what is fast.

But aren't you missing the point completely......you are not describing a turning engagement, the whole issue here is that if the 109 tried to engage in a 'turning' fight with a Spit it 'will' loose, there has never been any disagreement that the 109 had better speed to maintain an overall tactical advantage, the 109 could choose when to engage but the Spitfire was more than capable of evading, if you felt frustrated by that as a 109 driver and decided to try for a propper knife-fight with a Spit you were likely to lose, the 109's best tactic was to run in quick when an opportunity presents itself and run away quicker once the job is done.

Hi Kurfurst,

of course depending on the situation, I say just long enough to score a kill. That is my experience at least, I fly both 109s and Spitfires and pretty much anything in 1946. We're talking strictly horizontal fight as for pure sustained turn performance comparsion.

The question is also, for how long would you keep 400kph IAS in horizontal turn. I see where you're coming from though, you certainly have a point. Let's say the 109 wants to stay out of Spitfires gun range, in that case even 400kph turn would not be sufficient.

Theoretically, that is absolutely possible. But it is also possible to cut the corner of the 109 and shoot at it alright at lead curve, then ease up the turn and repeat. All depends on the trajectory, the planes will obviously turn on different circles etc. If you make a deal that the 109 won't climb or scissor, just turn, you will win. Because the Spitfire is much better TnB fighter than Emil. Emil is decent turner, too, very maneuvrable and agile, but as for the sustained turn competition in actual dogfight, Spitfire has got better qualities.

Of course, but energy fight is not sustained turn fight.

Yes of course, that's a great idea in any aircraft ;) But even having 400kph+, I would not enter turnfight with a Spitfire because that bloody thing turns better and would shoot at me. And I don't like that.

I don't think I have missed anything, but it depends how you define a turn fight. And I am not meaning a 'propper knife-fight' at usually some low speed like 2-300 kph.

What I mean that if
- both the (+6) Spit and the 109E try a sustained turn contest
- near ground level (where the 109 has more power and is faster),
- and both are at or above about 400 kph and try to sustain that,

the Spit WILL loose that turn contest. The Hurricane even more so. As Jtd noted, its simply too hard to overcome some 30(+) km/h speed advantage, and the fact that parasitic drag will be dominant. The general advise is though (apart from don't turn with the Spit at low speeds) is that the faster the 109 turns, the better it is for its pilot.

The other comparisons (one plane flies sustained, the other unsustained, level outs and climbs etc.) I do not adress here. These tactics are essentially combinations of the best peformance envelope against the opponent's worst.

When they unban you, please stop cutting my quotes like that, I do not appreciate that. It seems you have very selective approach and you only choose to take the bits and bobs that suit you. Please stop arguing at least.

I agree in general except for the fact (major flow I would say) that the Emil will slow down rather fast in this sustained horizontal turn. Spitfire will win in RL situation described by you, because the pilot would obviously not try to sustain these 400kph, he will try to bear his guns on the 109 and will do so rather soon. No matter what you do in a 109, if you chose to remain horizontal, the only way of evading the Spitfire would be flying straight. And flying straight is not sustained turn. See?

I assume you are talking about current in game because the Spitfire is not a slower aeroplane, the 109 and Spitfire are very close throughout altitudes.

Whilst I understand Kurfursts point about the Spitfire @+6 the fact of the matter is that it could manage +12 for a significant time. If you are simply setting a scenario where the Spitfire can actually only manage +6 for whatever reason then we could chuck in all sorts, such as the 109 being out of cannon or leaking Glycol, same for the Spitfire. It's either ceteris paribus or a bit pointless to compare imo.

How exactly? the Spit wil still be able to turn at a higher rate of turn but it won't maintain that speed, if it's behind the 109 it will keep it in it's sights and if its ahead the 109 won't get a bead and will just whizz past, you must realize the Spit will have a better 'rate' of turn than the 109 at all speeds.

With a fixed trim at a constant engine power setting, the trim speed of an aircraft is not going to remain constant over altitude. 400 IAS seems to be a pretty high cruising speed at 5 km for a 109E.

Hm... using the same standars there is no real test data supporting 109E doing 500kmh at sea level. Only a calculation based on a prototype aircraft with a non-standard two speed supercharger and a power value which is higher than normal 601 power.

However, there is several test data sets supporting speeds around 470kmh for 1.3ata and supposedly faster 109F is doing just 495kmh at same power according to kenblat.

Well let's start with the fact that it turns better already at 400 kph. Everything Spit does, the 109 can do better at these speeds.

That's an unsustained turn. What you forget that in an unsustained turn, the 109 will still loose less speed than the Spit at high speeds, because the basics (=more excess thrust) did not change.

If it's behind the 109 and slows down to match the turn the 109 will get out of range quickly and the 109 will be at superior E state.. if the 109 is behind yes the 109 will just wizz past, and at a superior E state. Then cat-and-mouse begins...

Simply no. At high speeds it cannot mach the 109 sustained turn, and it will loose more speed in an unsustained turn if the 109 also goes to unsustained turn.

You see the turn rate advantage is only there if the 109 maintains a sustained turn and the Spit goes for an unsustained turn -> superior E for the 109 and you do not want to fight a 109 with

And unfortunately the Spit cannot beat the 109 at high speed in unsustained turns either. The 109 can match an unsustained turn at any time AND loose less speed in the process. If the pilot has his wits about him he will take advantage of this and use the superior E before speed gets really slow where it's Spitfire territory.

The slower Spitfire (at +6) cannot match the faster 109 (any plane) at high speed turns. At least, not for long.

Of course there it is.

I call BS on this. Got any sources for these claims?

I would like to see them. Hopefully, they are just as detailed as the flight tests and official specs you are dismissing. That includes calibration curves for the pitot, boost and speed measured at various altitudes and known conditions, and proof check of the engine at a bench.

I do find this theory that the 109 will be able to turn better than a SPit at higher speeds a little foolish.

a) There are no, repeat no tests, from any side that support this theory.
b) The 109 locked up faster than a spitfire at higher speeds so the spit will have all the advantages getting into the turn by which time the 109 will be in the smelly stuff
c) You quickly lose speed in a turn which will nulify any theoretical advantages
d) The above description of what will happen shows the folly of this theory
e) The 12 boost throws the theory out anyway as it passes the power to weight ratio advantage to the SPitfire
f) Its worth remembering what the German test establishment said about the turning ability of these aircraft:-

Before turning fights with the Bf 109 E type, it must be noted in every case, that
all three foreign planes have significantly smaller turning circles and turning times.
An attack on the opponent as well as disengagement can only be accomplished on the basis of
existing superiority in performance.

Notice it doesn't say:-
a) The SPitfire is better at slow speeds
b) That the 109 can turn inside the Spitfire at high speeds
c) Ensure you keep your speed up against the Spitfire in a turning fight

It says basically DON'T GET INTO A TURNING FIGHT.

Can someone explain how the German test establishment got it so wrong.
After all they only had the real aircraft, real pilots to fly mock combats who obviously were very up to date on the Me109, amongst the finest engineers and designers in the world, people both well versed in the theory and experienced in this field, plus the resources of a test establishment.
I repeat the question, how did they get it so wrong?

Please post.

V15 chart on your site shows clearly two speed supercharger and text sites höhen and bodenlader, power value in the calculation is 1018ps vs 990ps for Db601A.

All at your site including 109F kenblat.

Oh yes, 109 could indeed turn tighter than a Spitfire at speeds around and above 400 kph.

In reality this was not very relevant in pure horizontal turnfight for the reasons you named. It was great advantage at BnZ maneuvring, even turning with a Spitfire that is breaking away from your attack - you can turn long enough to score nice deflection shot on him. But that is not anywhere close to sustained turn, you do a a 1/8 of a turn and away you break. If you stayed at that turn, you would burn your E and you would end up with a very angry Spitfire on your tail very soon.

[QUOTE=MiG-3U;463981]Please post.

Here.

Flight test.

http://kurfurst.org/Performance_test...15a_blatt6.jpg

Guranteed specs.

http://kurfurst.org/Performance_test..._Bau_speed.png

I would like to see similiar detailed specs for the Spitfire. At +12 lbs boost. Calibration curves, engine bench test, detailed description of airframe conditions and temperature conditions.

None such exists...

Nope.

Yes. And?

And have the DB 601Aa (not the DB 601A) in the sim, which had 1045 PS (1175 PS WEP) anyway. So the tested example had to reached 498 kph at 1018 PS. We have an 1045 PS variant. Are you saying that it should be even faster..?

Now, care to tell me, that regardless of the supercharger design, that what is wrong with the test, since the plane has about the same power our plane in the sim has.

Nope.

I also have similiar curves for G-14, G-6, G-1 etc. on my site. It only shows that the DB 60x supercharger could be run at will at fixed speeds as well. It's no witchcraft, all that is needed to override the barometric control of the hydraulic coupling. Which they did often during these tests, see some of the G-6 and G-14 tests:

http://kurfurst.org/Performance_test...44_trials.html

Besides the actual supercharger operation is completely irrelevant. We KNOW for a fact that the plane had 951 PS in high speed flight (about 50-60 PS down on power) and reached 493 kph with it (which they calculated to be good for 498 kph at the nominal rating of 996 PS). Any other 109 in similar configuration with the same power should reach the same of course.

Just explain how a plane with less or no excess thrust can pull a sustained turn better than a plane with more excess thrust, thank you.

How much excess thrust does a Spitfire at SL, running at +6 1/4 boost has at about 280 mph 1g at David?
How much more excess thrust does a Spitfire at SL, running at +6 1/4 boost require in 2g turn at about 280 mph David?
How much excess thrust does a Bf 109E at SL running at 1.35ata bppst has at about 280 mph 1g at David?

Which has a better sustained turn at 400 mph David, a Spitfire IX or a Me 262 (P-80 if you like)?

No, this isn't necessarily an unsustained turn. The same way the 109 has to give up level speed to turn, the Spitfire has, and for each change in turn rate, the speed loss of the 109 is higher, or for each loss of speed, the Spitfires turn rate change is larger. If the 109 settles at a load factor or turn rate, the Spitfire can do the same, at a lower speed.

It really sums up to that the 109's biggest advantage is in flying straight and level, it will remain competitive throughout the high & medium speed range, with the advantage always decreasing. All this, mind you, at sea level against a 6.25lb boosted Spitfire I, which is as good as it gets for the 109.

That is a flight test ofa prototype doing 485kmh, non standard engine and 500kmh is a calculation based on non standard power.

Not a test, more like a selling brochure.

But we have multiple tests results around 470kmh.

That means two speed supercharger, no need for large oil cooler needed for the hydraulic clutch, less drag.

I can't find a 1C source stating that, please show me.

Besides 601A and Aa power settings are obviously different, 5min power fth is lower for Aa which means higher than 1.3ata.

Nonsense curves and not relevant for this discussion, the rest is just your speculations.

Wrong on all accounts.

And with the specs laid down within being guaranteed within +/- 5% by the manufacturer of the product.

Really. And what power, what supercharger settings, what airframe conditions?


Speculation.

Look at the source files - or the fact that we a 5-min boost pressure of 1.35 ata...

And one more scratch on the tail... ;)

Because?

Because?

Yes.

The 109s biggest advantage is its overall smaller drag, more powerful engine, and higher power to weight ratio, good harmony of controls (at least IRL) and superior near-stall handling IMHO.

Agreed.

Certainly. But then again, we haven't touched into the realm of 1.45ata WEP or a DB 601N under the hood. Or deploying flaps. ;)