On Soviet turning time tests. Comments Please

[claidemore]

Claidemore,

Considering that the 109s Clmax was higher than the Spitfire's by a factor of 0.34 at freeflow I believe it will stay at this. So if the Spitfire at full throttle reached a Clmax of 1.85 then the Bf-109 would reach one at around 2.15 to 2.20.

Also remember that the British Clmax figures are calculations based on the turn performance achieved in British tests, and we all know that these are highly unreliable as the pilots were vary about going beyond slat deployment. Hence why a 190 Jabo did much better in their tests.

Soren: You assume of a clmax value of 2.0to 2.1, then bump that up to 2.15-2.20 when your original assumed numbers don't sut you when compared to the Spitfire. That really takes away credibility.

There is no doubt whatsoever that the British clmax values for the 109 are with slats deployed. With the small wing area of the 109E (172sq ft) and no slats, the clmax values at full throttle would be in the order of 1.38-1.4 .

In any case, clmax is only one value used in calculating turn performance or stall speed, by itself it does not show superiority or inferiority. Wing area is also an important vlaue in the forumlas for those calculations, and those numbers are not 'assumed', they are measured historical fact. 172 sq feet for the 109, 242 sq feet for the Spitfire and 235 sq feet for the P40.

 

[Soren]

Claidemore,

The first assumption was based on the Clmax of the Spitfire, so no it doesn't yake away any credibility. If the difference was at a factor of 0.36 at freeflow then it would remain the same at the same amount of thrust added. So the Clmax of the Bf-109 would've been around 2.15 to 2.20 if the Clmax of the Spitfire was 1.85. That's all. How that takes away credibility I can't really see. It has nothing to do with what suits me.

Soren - If you wish to prove your thesis, get the weights of the Me 109s under test, the horsepoer and velocity at stall for a specific altitude and the turn times and you will have your specific Clmax for that condition.. and BTW is will be a valid one independent of whether the 109 tested was perfect or whether the test pilot was the best - it will be close enough within a couple of percent.

The weights are listed in the documents, 2,890 kg. No need to keep asking for it Bill.

The Soviet and Brit tests will be good enough to establish the range of Clmax for the 109 tested.

I disagree, as the a/c in question weren't put to the limit. And there is plenty of proof to support this Bill and we've been over it again again before. If a heavy and draggy Fw-190G Jabo manages to turn with a Mustang Mk.III in several trials but a Bf109 doesn't then something is terribly wrong, and the most likely issue was that the pilot didn't want to go past slat deployment. This has also been explained by several LW aces as an issue which many pilots new to the Bf-109 had.

Fact is that the Bf-109 was a far better turn fighter than any version of the Fw-190, as proven in ALL LW tests made. And I've presented several here before by request as-well, you know that as well as I.

They are a collection of data. So far I have seen US and Brit and VVS and Finn test results but nobody seems to be able to present the Rechlin Test resluts (and data) demonstrating the German POV..

Just because you have a collection of data doesn't mean it's right. And as a serious researcher you know better than to judge a book by its' cover.

As for the German tests, there is only one comparison between the Spitfire 109 available at this point, and it's from 1940, a period in which not many pilots trusted the slats as they tended to jam in the Emil series.

There is another one however which lists a turn time of 18.92 seconds, and from all I can see it is a flight testsed figure and not a calculated one as VG-33 claims. (And I'd like to see his proof that they are calculated values!)

 

[claidemore]

Soren: Your assertation that the RAE test pilots did not operate the 109 beyond the opening of the slots is completely wrong.
They measured the speed at which the slots opened during the stall tests, getting a true airspeed of 120.5 mph for slat deployment and 95.5 mph for the stall (flaps and gear up).
They recorded that the slots opened about 1/2 g before the stall during the dogfight trials with Spitfires, (see clip below).
The plane was flown with slats deployed in performance measurement tests, and in mock dogfights. This is recorded in the original RAE documents and cannot be refuted.

 

[Soren]

I know about that one claidemore, but as can be seen on the document aileron snatching is mentioned, which means something was terribly wrong. Normally there would be no disturbance to any axis at the deployment of the slats, yet in the British tests snatching was observed which was so violent that it rocked the whole a/c and disturbed the aim.

So that document only strenghtens what I've been saying all along.

Here's what Dave Southwood had to say after reading the report:

Dave Southwood, a modern 109 pilot:
"One interesting feature is the leading edge slats. When these deploy at low speeds or in a turn, a 'clunk' can be heard and felt, but there is no disturbance to the aircraft about any axis. I understand that the Bf109E rolled violently as the slats deployed, and I am curious to know the difference to the Gustav that caused this."

 

[Soren]

And here a friend of Skip Holm and himself, probably the most experienced pilot in the world today and a great guy:

View: https://www.youtube.com/watch?v=TFl8X4y9-94

 

[VG-33]

Here's some info that backs up the Soviet turn time tests on the Spitfire. The following clip is from R&M2381, June 1940.
Note the turn time, 18.5 seconds (at normal power). Also note Clmax of 1.75.

Hello Claidmore,

I don't know where is that Clmax 1.75 is taking from...maybe in dynamic way with unconstant speed, maybe with flaps.

From R&M2361-me109 handling test you have for :

695ft 20s (spitfire) Cl = 1.13

885ft 25s (109E) Cl = 1.24

So don't be lazy, don't listen for soren's bullshits and make your own calculations on the Cl value, with full data that you have previously send in your tread.
Thank you for the turn ability drawing.

Regards

VG-33

 

[Soren]

The only one posting bullshit here is you VG-33. Now please crawl back into that hole of yours and stay there until you actually know anything.

 

[claidemore]

Soren: none of this takes away from the fact that British test pilots flew their captured 109s well past slat deployment.

 

[drgondog]

Just because you have a collection of data doesn't mean it's right. And as a serious researcher you know better than to judge a book by its' cover.

Soren - I agree the analogy but the 'book' so far has three serious documented chapters with data that you can assess and think upon - the chapters read "RAF', Finn and VVS' regarding documented and reported comparative flight tests surrounding the 109 and 109 vs Fw 190 vs Spit vs Mustang - but the chapter on Luftwaffe test results is still missing.

As for the German tests, there is only one comparison between the Spitfire 109 available at this point, and it's from 1940, a period in which not many pilots trusted the slats as they tended to jam in the Emil series.

I agree that just one documented report with the framework you describe above is not above reproach, nor is it the last word - but even that, if introduced into this dialogue, provides a reference for 'serious research'.

Absent even this report you are thrust into making your agruments based on anecdotal references from LW pilots which have equal and opposite points of view from anecdotal recollections from Soviet, US and RAF pilots

There is another one however which lists a turn time of 18.92 seconds, and from all I can see it is a flight testsed figure and not a calculated one as VG-33 claims. (And I'd like to see his proof that they are calculated values!)

I am also waiting for the analytical approach because of my oft stated predjudices regarding 'models with many assumptions not provable for the aerodynamics of of a complex wing-body in curvilinear, non-symmetrical, non linear motion".

I have thought a lot about this subject and realize that for me to do a serious analysis (say for a research project) which I could point to and state - here are the data, here is the free body diagram for all the positions in the flight path, here are the assumptions I had to make' - then I would want:

Drag Polar for each airframe - with that I could pull Cd0 and CdI for each velocity point in the Polar and state as an Assumption - that they approximate the same values at the same speed in a banked turn as they do in level flight. The Drag Polar has a 'built in' compensation for Reynolds number that only needs to be varied by density for different altitudes.

Absent a drag polar everyone is simply guessing about total drag in a sustained turn in the middle velocity ranges - unless and until one has UNIMPEACHABLE and repeated valuse for Turn performance for the aircraft in question - If you have this then you can reverse engineer the drag values - given velocity, Hp/Thrust/prop efficiency, AR, weight, wing Area, etc

If the assumption is nearly correct then I have the 'near correct' total drag values at all stages of the turn as a function of velocity and have the force balance at equilibrium during 'best rate' or 'best radius'.

Still need Hp as function of boost and altitude as well as gear ratios and rpm. Have to ponder more regarding activity factor, meredith effect, exhaust thrust.

I would further 'assume' that I should compensate for Trim Drag of deflected ailerons, rudder and elevators by adding to the base parasite drag factors summed and calculated for level flight parasite drag at top speed in which flight surfaces were at minimum deflection (and value).

I don't have an approach for evaluating the leading edge slat contribution to drag absent 2-D wing section data - so the 109 will always be 'iffy' for me on true wing contribution in steeply banked flight.

I would initially discount the effect to thrust for high angle of attack effects to prop efficiency as well as drag caused by asymmetric flow separation of fuselage and initially assume all aircraft compared separate at nearly the same point..The differences in parasite drag increase might be proportional to 1/2 the fuselage area but still small relative to total drag.

Then I would compare the model against multiple reports to see whether it was BS.

I would need a lot more time than I currently have to screw with the research.

 

[DerAdlerIstGelandet]

Soren, VG-33, one more bullshit comment from both you, and you are both history! Permanently! I am tired of both you and your childishness. Consider this your warning!

I am sick and tired of thread being derailed by Flame Wars!

 

[claidemore]

Here's an excerpt from this page:
Translation result for http://www.airpages.ru/uk/p63_2.shtml

According to the estimations of our enemy, German General Walter [Shvabedissen] in his book "Stalin falcons" the number of commanders [Lyuftvaffe] they mention, that at the end 1941 g. on the scene appeared the English and American fighters (Curtiss R -40 and "Hurricane"), which were being supplied within the framework of agreement about the lend-lease. This created some difficulties German fighters, but Soviet pilots could not attain from these machines of the best indices, than from their. Evaluating American fighter R -40, in the report JG 54 it is indicated that on the horizontal maneuverability it was equal German Bf to 109F, but it was inferior to it in the speed and the rate of climb. According to the Russian captured pilot, the aircraft did not enjoy popularity in Soviet pilots.

I'd say JG54's opinion is pretty much the same as mine! lol

 

[Soren]

Yes claidemore, that they are equal makes more sense, I could agree with that conclusion. Although I am sure that if flown to the limit the Bf-109 would show a clear superiority, and not just remain equal.

Anyway lets leave it at that.

Bill,

I hope you get the time to do an analysis, would be great.

 

[Juha]

Hello
Maybe Soren believes Dave Southwood, at least he often quotes him. In FlyPast Special 1997 LW Eagles Southwood notes (talking Black 6 109G-2):" In a turn with 2300rpm/1.15 ata set, stall warning is given by light buffet at around 3g and the stall occurs at about 3.5g with inside wing dropping…"

Juha

 

[Soren]

Juha,

Yes I believe Dave Southwood. As for the quote, no issues with it, but you do realize that G force figures with no listed speed figure is useless to us right ?

 

[Juha]

Hello Soren
dave didn't give the speed the only clue is that he said that " For singleton display, I run in trimmed at about 450km/h with 1.15 ata/2300rpm set." He used t/o with 1.1 ata. Usual problem with modern pilot comments, they flew lighter planes with less power than used in wartime. Rightly so, nowadays the warbirds are very rare so it would not be clever to push them to their limits.

Juha

 

[Juha]

Hello
because I came across info that the LaGG-3s used by 9.IAP, VVS KBF were LaGG-3-37s not LaGG-3 Series 66 a/c as I had remembered I modified the LaGG-3 Series 66 comment and added LaGG-3-37 info into my table in my message #99 .

Juha

 

[claidemore]

Interesting tidbit:
In WARPLANES TO ALASKA, by Blake W. Smith, on pg.198 there are two photographs of a P39Q-5 undergoing stall tests in the wind-tunnel at the Soviet Air Force Research Institute (NII-VVS).
I would hazard a guess they also tested other foreign planes in that wind-tunnel, both American, and German.

 

[bada]

I would like to take advantage of this discussion to ask something in parallel to the "109 vertical heaviness"...

i read several times in polish and french books that the SPIT's ailerons authority and force needed to move them increased dramasticaly with the speed, something like you needed 2hands to roll the spit above 500mk/h, some pilots pushing with their elbow on the cockpit's sides to put the plane in the turn at high speed.
Are ther some "real numbers" on the stick forces needed Vs Speed for the spit?

Thanks.

Ps: My english still sucks, so pardon me.

 

[Juha]

Hello Bada
British noted the increased heavines of Spitfire's and Hurricane's aileron control forces when speed increased at least in 39 when they tested a French AF Hawk 75A-1 and made special aileron forces comparasion test with Spit, Hurri, Hawk75 and Gloster G.5, which showed that Hawk rolled much better at high speeds than Spit and Hurri. They at least partly resolved the problem by introducing metal covered ailerons, IIRC in summer 1941. The Hawk etc test report had some info on stick forces needed.

Juha

 

[claidemore]

I would like to take advantage of this discussion to ask something in parallel to the "109 vertical heaviness"...

i read several times in polish and french books that the SPIT's ailerons authority and force needed to move them increased dramasticaly with the speed, something like you needed 2hands to roll the spit above 500mk/h, some pilots pushing with their elbow on the cockpit's sides to put the plane in the turn at high speed.
Are ther some "real numbers" on the stick forces needed Vs Speed for the spit?

Thanks.

Ps: My english still sucks, so pardon me.

Your English is fine bada.

From R&M2379, the comparison of aileron forces on Curtis 75, Spitfire and Gloster F5/34.

Estimated by pilots, the stick forces for 1/4 aileron on Spitfire were under 10 lbs at 200 mph, close to 20 lbs at 300 mph and greater than 50 lbs at 400 mph.
Below is a comparison of the Spit and 109 from R&M2361. Note that both planes had heavy ailerons at high speeds, the spit requiring more lbs of force, but having more room and stick travel to achieve it.