P-40 vs. ME-109 (1 Viewer)

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Not to get off the subject, but does anyone know if any P-40's that the Russians used had the Allisons replaced with Klimov V-12's, at any time, and if so how was performance affected?

Just curious.




Elvis
 
Hello claidemore
Notice that the second half of full circle is faster, in G-2's case when the speed was allowed to drop, full circle took 10+8secs, so on G-6 at most 13+11=24secs and as Kurfürst wrote, the G-6 figure might well be uncomparable to the MT-215 figure. I'm not avare same level of testing of G-6 than G-2 by the FAF, that in itself doesn't mean much.

Secondly, I don't know the criteria of Soviet tests, was the times for turns during which the speed was allowed to decay or turns when speed was kept constant.

Finnish Bf-109G pilots tended to think that the new Soviet fighters (Yak-9s and La-5s) were better in horizontal fight than Bf 109G, at least at lower levels, even by very experienced like Capt. Puhakka, who was regarded as very skillful pilot and one of our top aces.

Juha
 
Kool Kitty89,

My apologies. I just realized my last post omitted comments on your response to my other post, so please allow me to indulge you, here...

Quite true.
It seems like many of the "lesser" countries that participated tended to arm their fighters lightly, and yet, a number made a pretty good showing of themselves..
Take the Italian fighters, most of which I believe were only armed with two 7.7mm machine guns. Yet, they did ok.
I believe the Romanian IAR 80 was also lightly armed, yet did quite a bit of damage (or protection, however you want to look at that) at Ploesti.

Its like, which do you take - 2x 7.7 + 1x 20mm (109) or 2x .50 cal (P-40) ?

...and here's another question for you to ponder...

Do you think the P-40 could''ve benefitted from a larger prop?



Elvis
 
Hi Juha,

>in it he wrote that the turning tests of MT-215 were flown at 1000m. On the 360 deg turn at 360kmh: the a/c was rolled to 70deg and the G-force was 3. Nothing on use of flaps.

Thanks! My results calculated result for a Me 109G-2 at 3023 kg (like MT-215) are in fact 2.97 G at 360 km/h, so that matches the test result quite well (assuming this was a sustained turn at 2600 rpm/1.32 ata).

However, it's possible to directly calculate the lift coefficient for that situation - and it comes out as just 0.98. As an optimum turn is flown at the maximum lift coefficient, which for the Me 109 is probably around 1.5, the Finnish test result actually doesn't represent the optimum combat turn.

By reducing speed and flying a tighter turn at the maximum coefficient of lift, the same MT-215 should have been able to achieve a time of 19.2 s for a 360 degree circle at 1000 m altitude (according to my calculation).

Excellent that the Finns have recorded the exact conditions of the turn - all too often, you find that test results and calculation yield a differenct figure, which in the absence of detailed data can be hard to explain!

Regards,

Henning (HoHun)
 
Hello HoHun
yes, to my understanding when the speed was kept constant and without any info on altitude lost it means sustained turn. Raunio mentioned "kaasu auki" which I interpret "full throttle" even if exact translation to full throttle is "kaasu täysin auki". And in FAF the max power used in 109G-2s was 2600rpm/1.32ata.

Yes we Finns are lucky that we have writters like Raunio, who had made his career in aviation industry and in same time have had intrest to went through massive amount of archival material and wrote books on technical aspects of those old planes.

Juha
 
LOL Juha. After I wrote that post about the G6 at 26 seconds, I also thought that we could knock two seconds off as in the case of MT-215, with a resultant time of 24 seconds. Great minds do think alike!

In the Finnish 109G6 manual they give a time of 14 seconds at 450kmh for 100 degrees. I wonder if that is a typo or misprint, and should read 180 degrees? Since these times are 6 to 8 seconds more than with a G2, would I be safe assuming they are for sustained turns?

Anybody got any inkling as to whether the Soviet turn tests were sustained turns or optimal turns?

Claidemore
 

Nearly all Italian fighters were carring at the least 2x 12.7 mm guns at the start of the war. (except some CR.42's that may not have been refitted) many were suplemented by wing guns as well (sometimes 7.7 mm) and most late war planes had either an engine mounted 20mm gun or 2x wing mounted cannons.

The IAR 80 first had only 4x 7.92mm guns the 80A had 6x, the 81 had 4x + 2x 20mm guns.

The P-40E's were sometimes refitted with Kilimov engines, with some modifications. (new spinner, and maybe different prop) Performance would have been similar due to similar power, but I think the V-1710s of the P-40E had better altitude performance though. (the Kilimove was best below 10,000 ft, but the Allison was decent up to ~15,000 ft iirc)

The P-40E had a larger 3-bleded prop than the P-40B/C/Tomahawk, and this was fine up to the P-40K (and moreso with the M/N), but with the K's more powerful engine a larger (4-bladed) prop should have been fitted. Same goes for the P-40M/N which had the same V-1710-81 as the P-51A which had a better prop. (earlier Mustangs had 3-blade props) THe P-39N/Q could have used better props too, but it wasn't 'till very late model P-39Q's that they got 'em.
 
Hi Juha,

>And in FAF the max power used in 109G-2s was 2600rpm/1.32ata.

Roger that, that's what I used for the 19.2 s @ 1000 m sustained turn result, too.

>Yes we Finns are lucky that we have writters like Raunio, who had made his career in aviation industry and in same time have had intrest to went through massive amount of archival material and wrote books on technical aspects of those old planes.

Absolutely! Without the data on speed and G rate, a detailed analysis of the Finnish tests would not be possible

Looking at my calculation again, I noticed that the 360 km/h turn is actual an "optimum" turn in a way too, as it's the turn that yields the highest sustained G rate. So it appears that the speed of 360 km/h might not have been chosen randomly, but in fact was carefully selected to produce a specific result.

The question of the "quickest sustained turn" would yield a different answer - according to my calculation, the Messerschmitt would have to fly at just 285 km/h at a slightly lower G rate to achieve minimum turn time, the aforementioned 19.2 s for 360 degrees.

Regards,

Henning (HoHun)
 
Hello HoHun
" Looking at my calculation again, I noticed that the 360 km/h turn is actual an "optimum" turn in a way too, as it's the turn that yields the highest sustained G rate."

Thanks for the info. I don't understand much on aerodynamics but I have always being a little amiss on the 360kmh speed, I have felt that it was too high, feeling that appr. 300-310kmh would have been more likely "optimum" speed.

Juha
 
Hi Juha,

>I don't understand much on aerodynamics but I have always being a little amiss on the 360kmh speed, I have felt that it was too high, feeling that appr. 300-310kmh would have been more likely "optimum" speed.

Your intuition was very good in that regard!

I'll have to think on the issue for a while, but my spontaneous impression is that it's a good idea to test for best sustained G rate if you have a G meter available because it will give excellent control of the conditions of the turn.

It's more difficult to try and actually fly the aircraft at the maximum lift coefficient - it could either enter the stall region with shuddering and abrupt loss of lift, making the current turn sub-optimum, of if the aircraft has a "soft" stall transition (like for example the Spitfire), you might fly at sub-optimum coefficient of lift without even noticing.

If you keep airspeed and G rate constant (and G rate at the maximum), you still have a good margin before you stall, and while you don't get the optimum turn rate, I believe the difference to the optimum turn rate will be almost identical for most WW2 propeller fighters. (That's the bit I'll still have to think about.)

In other words, flying for best G rate seems like a good test flight technique that will give accurate results that can be compared well with results from other aircraft that have been measured using the same technique.

This almost makes me suspect that the Finns routinely tested fighter aircraft for turn rate, as the technique seems to be designed with comparability in mind. Do you perhaps know if there are similar figures for the other fighter types flown (or perhaps even captured) by the Finnish Air Force?

Thanks again for the Finnish test results, I feel I'm learning something new about WW2 era flight testing at the moment!

Regards,

Henning (HoHun)
 
Hey Kool Kitty89,

Looks like I need to research my Italian fighters a little more.
I've always been under the impression they were pretty lightly armed and only with 7.7's (or 7.9's?) in the nose.
...and I found that IAR article later on. Sorry about that, my bad.

Thanks for answering my question about the Klimov re-engine.

You say that the Prop got larger starting with the P-40E.
Do you happen to know what those diameters were?
I remember a book that was in the school library of the elementary school I attended. I believe it was written in '46 and was a catalogue of a whole bunch of aircraft used up through WWII.
Of the specs, I remember many listed prop diameters, and I remember the P-51's being listed as around 10.5', but the P-40's was less than 10'.
Variations were not listed and that was presented as "this is the diameter of the prop for this airplane" with no mention of whether they were referring to the "A" or "B" or "whatever" version.




Elvis
 
I was wrong about the P-51A, it had a 3-blade prop, but it should have had a 4-blade one and so should the P-40M/N (and probably K) as the V-1710-81 was producing similar power as the P-51B's Merlin. (the prop change would explain the gain in climb of the P-51B as it was heavier and had no significant power advantage below 13,000 ft)

The Diameter didn't change much on the P-40E (I think the D got it too, but there weren't too many P-40D's anyway). The main change was a broader chord iirc.

 
HoHun
Thanks a lot for Your enlightening explanation.
I only have copies on 2 short flight test reports, on LaGG-3 (3pages) and on Pe-2 (2pages). They are more like summaries and didn't have numerical representations on turning abilities.

From Raunio's book there are some, but not as exact than on 109G-2.

Brewster Model 239
Sustained 180deg at 350kmh (IAS) at 2000m 7sec, no wonder that Finns liked the plane.

Morane-Saulnier M.S. 406
instantaneous/temporary (meaning unsustained) 360deg, speed at the beginning 320kmh (IAS), under 16sec, G-force at the beginning 4G, radius 265m.

Gloster Gladiator Mk. II
at low level 360sec sustained 10-11sec, radius 90m

Polikarpov I-153
at low level 360sec sustained 12 sec and radius 110m

There was a more detailed report on LaGG-3, a copy of which was given also to Swedes, who passed it to British and it was published in Flight(?) during the war and reprinted in Aeroplane maybe early 2000s. I have a copy of the Aeroplane, I cannot recall that in it there was exact info on turning times, but cannot be sure. IIRC it was more on structures and systems.

Juha
 
This may be of interest. Its the 'official' record for the 325 Gp which was equipped with the P40 for a time and breaks down the losses/claims by the type of aircraft it was equipped with at the time.

Can I make it clear that I am not saying that I believe these figures, its just something I found that people may want to look at.

Ops Summary
 

I bet if you did the math you would probably find a 3 bladed prop was used for a reason.
 

The 51H was another example where weight reduction was foremost. The expereimental XP-51G and J were by far the best performers of the series, but the H was very close in production versions.

By AF standards of the time it should have had another designation than P-51because only about 11 parts were truly common (allegedly) between D and H.. It was 'cleaner', had more internal fuel in wings, less in fuse tank, smaller tires, designed to 11 G versus 12G for 'Utimate' and was about 900 pounds lighter with a more powerful engine.

A lot of 8th AF pilots that flew the B's in combat removed the two out board 50's and ammo to lighten the D by some 300 pounds. That should have improved roll, turn, acceleration, climb, range and top speed to a small degree
 
FLYBOYJ said:
I bet if you did the math you would probably find a 3 bladed prop was used for a reason.
Click to expand...

Maybe, but they still had the same HP. (with normal boost limitations of the Merlin) Top speed probably wouldn't change, but climb probably would. (like with the P-47's paddle prop, no change at high speed, but climb and initial acceleration did)


7 seconds?! it was a good turner, but that's just unrealistic, especially when you compare the biplane figures. Are you sure it wasn't 17 sec?
 
Hello
as it stands, 7sec for 180deg, especially mentioned that it went to turn clearly faster than Hawk 75A (P-36), so 360deg probably appr 13 sec.

Juha
 
Hi Juha,

>From Raunio's book there are some, but not as exact than on 109G-2.

Thanks a lot, at least it shows that the Finns did indeed consider turning capabilities to be important, and that they routinely tested at least some of the aspects of turning. I think that these figures are not directly comparable probably means that we have only some bits of the reports, not that the Finns didn't test systematically.

>There was a more detailed report on LaGG-3, a copy of which was given also to Swedes, who passed it to British and it was published in Flight(?) during the war and reprinted in Aeroplane maybe early 2000s.

Ah, that's a good lead - maybe Micdrow in his extensive research on the Flight site has seen something on the LaGG?

Regards,

Henning (HoHun)
 
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