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[edit] P-39 performance
Answering to the 2 previous guys - indeed Spitfire could exceed 450mph, however its wing structure was not able to substain more speed than that with safety.This meant that some high-g would break the wing apast.Instead the P-39 could dive that fast with safety. In recent years what changed people's perconception's about P-39 is the Ubisoft flight simulator IL-2 FB, which as people who flew the P-39 (and several other warbirds) claim that is very close to the real thing as a flight sim can go. I would describe my impressions from the sim, and indeed war vets confirm these impressions.(by the way, I have a pilot lisence, even I have logged hours only in Cessnas 152/182, if that matters). You had to be very able with this plane.For example,with the Spitfire there was not much you could do:Just press 110% power, and try to go to the enemy.Spitfire didn't have even combat flaps.If you were going to make a stupidity, Spit would stall and then just give it a bit of opposite rudder and it would gain some speed and come back to your control. With P-39 you had to play with the throttle, combat flaps to try to get the best of it.P-39 was like a mid-engined car in some ways.It was oversensitive in pitch and this could make difficult for a novice pilot to aim and shoot a target.At least in the flight sim, it felt almost like sliding in the air like a car that slides in its four tires! Roll was fast, even not as fast as P-40 or Fw-190. A P-39 pilot had to be very careful with the rudder too.This was something that was greatly improved in P-63.P-39 didn't like sudden turns of the stick in various directions, something that a novice pilot would often do in his panic to avoid an enemy in its 6 o' clock.This was a certain way to stall.P-39 had a very unusual 30km/h flat spin which was impossible to escape!This was the worst characteristic in this plane. In various maneuvres it was necessary to obtain a certain speed.On the other hand, it could fly in the vertical until almost 30km/h, however this was extremely dangerous for a un-experienced pilot.Only the fantastic Bf-109 was better in this. A Spitfire would just point its nose down, as Yaks would do and other well-mannered planes, however in much higher speed... The P-39 was extremely aerodynamic, actually possibly even better than the P-51 and P-38, two planes that were excellent in this area.Pushing the throttle down, it wouldn't mean an instantaneous fall in speed as it would mean for various aircooled figthers...This would make more difficult to calculate its speed and then been in danger to fly ahead a target. For these reasons the P-39 was from fast to very fast in low altitudes and NOT as bad in medium altitudes, depending on the version and the year-period we are talking about.Don't think that a Spit LF IX was faster in low altitudes...just a bit better in climb speed, due to its more powerful engine. In dive was very fast (again only Bf-109 and the P-38/P-51 were as good). It was, probably to its engine arrangement, more difficult to shoot down than every-other liquid-engined fighter.Its 37mm cannon was really devastating ( I cut in 2 pieces a Ju-88 with just one shell in a mission...), however you needed to approach very close, due to its low muzzle velocity.This again needed an experienced pilot.Instead a novice P-47 pilot could almost spray the sky with bullets of high-velocity muzzles and have a chance to shoot down an enemy plane when the P-39's 2 0.50's were inadequate. Ah, and the car-like canopy was horrible, restricting vision. Conclusion: The P-39 was unpopular because it need an experienced pilot to get the best out of it (something not good at all when thousends of young americans were thrown in battle with absolutely no combat experience).Its canopy would make escape difficult and it didn't fit well to the specific operational needs of the USAAF. In a few words...what a plane! (the flight sim has the versions P-400, P-39D-1, P-39D-2, P-39N, P-39Q-1, P-39Q-10)
One paragraph states P-39 was too heavy compared to its contemporaries which made it inferior to other fighters, then the following parapgraph states it was an air superiority fighter in the hands of VVS. The truth is that while P-39 was somewhat heavier than some of its contemporaries, it was held by many to be one of the best low-altitude fighters of the war in terms of both speed and agility. Soviets liked it so much they worked with Bell on P-63 (least favorite lend-lease aircraft? Hurricane hands down). A remarkable feature of the P-39 was its very clean aerodynamics - I've read pilot accounts of difficulty bleeding off speed. The P-39Q-1 pilot's manual authorizes dives to 523 mph (825 km/h)! Spitfire IX manual says 450 mph (725 km/h) is the limit. - Emt147 Burninate! 17:23, 4 December 2005 (UTC)
- I suspect the 450 mph figure for the Spitifre IX is given for a height an Airacobra coudn't even reach. The 450 mph figure you've quoted itself seems strange, as it's not that much faster than a Spitifre IX's top speed in level flight, and the Spitfire had one of the highest Critical Mach numbers ever measured. There should be higher IAS figures given for lower heights, the indicated speed increasing as the air becomes thicker at the lower altitudes. I suspect the highest figure should be around 550 mph for a Sptifire IX, but I don't have the Pilot's Notes myself.
- According to Jeffery Quill's Spitfire - A Test Pilot's Story, the Mark IX's Pilot's Notes gives a table of Vne figures at various heights, one of which works out at M 0.85. Quill's department themselves were diving Spitfire IXs to speeds slightly in excess of Mach 0.86
- As mentioned in the article, the Airacobra/P-39s measured performance was considerably down on the figures given to the British Purchasing Commission and on which the 1940 British order was based. The results of an enquiry into this led to the setting up of an evaluation centre, similar to the A&AEE at Martlesham Heath (later Boscombe Down), at Muroc Field in the US. Ian Dunster 12:17, 26 July 2006 (UTC)
