AviationDiscuss P-40 vs. ME-109 in the World War II - Aviation forums; Originally Posted by Elvis
You know, one thing no one's mentioned yet, is how the Russians thought outside of the ...
You know, one thing no one's mentioned yet, is how the Russians thought outside of the box, concerning performance improvements to the the P-40's they used.
While everyone else was increasing the power of their drivetrains (i.e., engines/props), the Russians decided to work with what they had, concerning the P-40's, and instead, lighten the load a little, to better match the power/thrust they had at hand.
The only other aircraft I can think of, off hand, that goes with that train of thought would be F8F, which used the same engine as the F6F, and (possibly) the P-63.
Kudos to the Russians, for seeing another way of upgrade the performance of an airplane.
Elvis
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
I bet if you did the math you would probably find a 3 bladed prop was used for a reason.
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)
Originally Posted by Juha
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
Juha
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?
>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?
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)
If you change a prop (pitch, blade count, etc.) you gain and loose. What you make up in climb, you're gonna loose in speed, what you make up in speed, you loose in fuel consumption and so on. Matching props to the airframe/ engine combo is an exact science and sometimes compromise is the end result.
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
Sorry missed the 180 degrees, but why 13 sec and not 14 for 360*?
The B-239 was certainly agile though, and could certainly out "dogfight" the Hurricane I. (though the Hurri had much better performance above 10,000 ft, the Finn's Brewsters' engines being rated for low altitude)
If you change a prop (pitch, blade count, etc.) you gain and loose. What you make up in climb, you're gonna loose in speed, what you make up in speed, you loose in fuel consumption and so on. Matching props to the airframe/ engine combo is an exact science and sometimes compromise is the end result.
Hello Claidemore
because 1st half of full turn takes more time that the 2nd half, but because Finns reported that 239 went into turn clearly quicker than Curtiss Hawk 75 which was a good turner. maybe 13½ sec is nearer to truth.
HoHun
"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."
Probably Finnish test got more scientific as time passed. In 1942 it became clear that the new fighter, Myrsky, would be too slow to be used as first line fighter and Finns began to design a faster fighter, Pyörremyrsky, with DB605A engine. My guess is that Bf 109G-2 was seen as very interesting a/c for thorough testing to get basic data for modern high speed fighter. Finns went to roomier, bigger wing solution.
Finns were very pleased with Brewster Model 239 and planned to built 90 "copies" of it, called Humu (new, wooden wing, different fuel tank system, war booty M-63 engine etc), so they probably tested 239 thorougly.
MS 406 was also much tested, because Finns modified it for war booty M-105P engine, so called Mörkö-Morane. Main reason for this project was that MS 406 was underpowered and clearly too slow and too poor climber. So maybe the turning ability of MS 406 was not test as thorougly that 239 and 109G.
Yeah, (on the prop issue) plus there's the fact that the Merlin P-51 would be operating with much higher powers at altitude as well.
THe Humu turned out to be a bust though, too heavy and much slower than the B-239. It also came even later than the Mirsky, which was considerably faster than the B-239.
Yeah, (on the prop issue) plus there's the fact that the Merlin P-51 would be operating with much higher powers at altitude as well.
THe Humu turned out to be a bust though, too heavy and much slower than the B-239. It also came even later than the Mirsky, which was considerably faster than the B-239.
KK- As Joe said - it's more complicated...
Prop design is all about rotating 'wings'.. more props in the disk (usually) mean more thrust and more drag, ditto increasing pitch to take a bigger bite (higher local angle attack) but getting more drag and requiring more torgue, keeping the diameter to point below tip speed>high transonic, keeping the prop at smaller diameter but greater RPM so my airplane can take off and land w/o stubbing a prop, resonance issues based on natural frequency of the blades, etc, etc..
As you speculated "where do I want my best performances at (pick one - long range cruise?, high thrust at altitude where the density/drag is lower?, etc, etc)
"Ivan the Terrible or Russian Achilles" Ivan Kozhedub - Hero of the USSR (x3), Order of Lenin (x2), Order of Red Banner (x7), Order of Alexander Nevsky, Order of the Great Patriotic War (x2), Order of the Red Star (x2), 62 kills during 1943-1945
Prop design is all about rotating 'wings'.. more props in the disk (usually) mean more thrust and more drag, ditto increasing pitch to take a bigger bite (higher local angle attack) but getting more drag and requiring more torgue, keeping the diameter to point below tip speed>high transonic, keeping the prop at smaller diameter but greater RPM so my airplane can take off and land w/o stubbing a prop, resonance issues based on natural frequency of the blades, etc, etc..
As you speculated "where do I want my best performances at (pick one - long range cruise?, high thrust at altitude where the density/drag is lower?, etc, etc)
Just for the discussion - I had to choose a prop for our Supercubs - one that would pull at a high altitude (the academy is 6000' MSL) and at the same time limit noise and be efficient enough so we could fly our cubs cross country. After 3 weeks of research I had a headache for a week and didn't even want to see a propeller!
Sorry, by yeah, I was agreeing with Joe that it's more compicated than I was initially thinking. I was just pointing out that, despite similar power up to ~10,000-12,000 ft there would also be more consideration of power at high altitude with the Merlin. (at 18,000 ft the V-1710-81 dropped to ~1,100 hp)
Also it may not have been the prop that resulted in the P-51B's better climb at low alt (obviously at high alt as well), but that it seems that it used the full 1,485 hp at 10,000 ft while the P-51A tests were limited to 1,320 hp at a similar altitude. (in the speed tests full hp was used) If pushed to full WEP the P-51A would probably climb at least as well as the P-51B from 3,000 ft to 11,000 ft. (below 3,000 ft power would limited by overboost)
Just for the discussion - I had to choose a prop for our Supercubs - one that would pull at a high altitude (the academy is 6000' MSL) and at the same time limit noise and be efficient enough so we could fly our cubs cross country. After 3 weeks of research I had a headache for a week and didn't even want to see a propeller!
ROFLMAO - just go fast forward and try to figure out what kind of rotor you need to put on a completely divergent system from your entire design experience - one in which you go from two blade semi articulate to four (or more) blade, rigid rotor for a new attack helicopter RFP - and we lost to the Apache.
There is art, and science. The good news is you can try a lot of differnt designs after you make your decision - to fine tune the analytics. A major benefit to test versus 'analyze' when involved in the Arcane.
I have never done any analysis on a conventional prop other than class work.
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Originally Posted by Elvis
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Sorry missed the 180 degrees, but why 13 sec and not 14 for 360*?
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