varsity07840
Airman 1st Class
- 176
- Jun 25, 2013
Has anybody ever read a convincing explanation for why the P-40N, with it's weight reduction measures was slower than the P-40K which was heavier?
P-40N (1 Viewer)
- Thread starter varsity07840
- Start date
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The really lightweight P-40N - the one with just 4 MGs, less fuel and some other weight-saving measures - was supposed to do 378 mph on WER.
link
What he said. There were light and heavy configurations of the P-40N. Lightweight variants included not just the first "interceptor" version, but some later versions with the same types of modifications. The same changes could be and were done in the field, and they could be configured for a more or less pure fighter role (or for a higher altitude role like when flying over the "Hump" in Burma) for an almost pure bomber role, as the British mostly used them and as they were used at some points and in some places in the Pacific. Most often for an "in between" role. Also for shorter or longer range.
Speed was not just a factor of the weight but also how many protrusions like bomb shackles they carried, and other things like direction finder loops which were added to some planes, and if there were holes or gaps between plates and so forth. Even the quality of the paint job seemed to make a difference of 5-10 mph.
Finally the power setting mattered, some were used at higher power settings. At WEP it was obviously much faster for a given altitude, and different power settings were used in different areas and at different times.
Some P-40N's also had some things added back in like the internal starter, as not having it caused some problems.
How fast a given aircraft, or the aircraft in a given squadron were flying was in large part a reflection of A) what kind of missions they were flying, B) how dangerous were the missions (how many casualties were they suffering), C) how old or battle weary the aircraft were and D) how good the commander and maintenance crews were. Good maintenance crews could tighten the plane up a lot, especially when sufficiently motivated. This was apparently the case for example with both the 23rd FG in China and the 49th FG in the Pacific. Aircraft operating in bad conditions could be conversely running rough and flying a lot slower.
Speed was not just a factor of the weight but also how many protrusions like bomb shackles they carried, and other things like direction finder loops which were added to some planes, and if there were holes or gaps between plates and so forth. Even the quality of the paint job seemed to make a difference of 5-10 mph.
Finally the power setting mattered, some were used at higher power settings. At WEP it was obviously much faster for a given altitude, and different power settings were used in different areas and at different times.
Some P-40N's also had some things added back in like the internal starter, as not having it caused some problems.
How fast a given aircraft, or the aircraft in a given squadron were flying was in large part a reflection of A) what kind of missions they were flying, B) how dangerous were the missions (how many casualties were they suffering), C) how old or battle weary the aircraft were and D) how good the commander and maintenance crews were. Good maintenance crews could tighten the plane up a lot, especially when sufficiently motivated. This was apparently the case for example with both the 23rd FG in China and the 49th FG in the Pacific. Aircraft operating in bad conditions could be conversely running rough and flying a lot slower.
TheMadPenguin
Senior Airman
Kindly post your source's boasted speed for P-40N and P-40K?
Tomo already linked the test for the P-40N (although actually it was a P-40K modified with the engine and other new equipment of a P-40N). The P-40N, the lightweight version(s), was actually a good bit faster than a P-40K.
The lightweight P-40N achieved a top speed of 378 mph in tests, whereas the best reported speed for a P-40K was 362 mph
However, this was largely due to the critical altitude of their respective engines. You can go faster for the same horsepower at higher altitude because the air is thinner. The V-1710-81 (and later models) on the P-40N had a critical altitude of about 17,000 ft, whereas the V-1710-73 on the P-40K had a critical altitude of about 12,000 ft. Meaning it peaked in power at a much lower altitude. But whereas the P-40N had a maximum power (at WEP boost settings) of roughly 1400 hp, the P-40K had a max power at high boost of about 1550 hp. So at lower altitudes the P-40K was almost certainly much faster.
The difference between the two types of engines was the gear ratio of the single speed supercharger.
When it came to air to air combat, in China and the Pacific, and in the hands of the Russians, the P-40K was the one which did the most damage to the enemy and was flown by the most Aces etc. By the time the P-40N arrived on scene combat for P-40s was tapering off.
In the MTO and Italy the versions which really mattered for air to air combat were the Merlin powered P-40F and P-40L, which had critical altitudes up around 19,000 ft and could still fly and fight pretty well up to around 25,000. That was more important against the German and (German engined) Italian fighters. At one point there were 5 American fighter groups and 2 British Squadrons flying P-40F and L on the front line against the Germans in Tunisia, Sicily and Italy, and they did quite well with them.
The lightweight P-40N achieved a top speed of 378 mph in tests, whereas the best reported speed for a P-40K was 362 mph
However, this was largely due to the critical altitude of their respective engines. You can go faster for the same horsepower at higher altitude because the air is thinner. The V-1710-81 (and later models) on the P-40N had a critical altitude of about 17,000 ft, whereas the V-1710-73 on the P-40K had a critical altitude of about 12,000 ft. Meaning it peaked in power at a much lower altitude. But whereas the P-40N had a maximum power (at WEP boost settings) of roughly 1400 hp, the P-40K had a max power at high boost of about 1550 hp. So at lower altitudes the P-40K was almost certainly much faster.
The difference between the two types of engines was the gear ratio of the single speed supercharger.
When it came to air to air combat, in China and the Pacific, and in the hands of the Russians, the P-40K was the one which did the most damage to the enemy and was flown by the most Aces etc. By the time the P-40N arrived on scene combat for P-40s was tapering off.
In the MTO and Italy the versions which really mattered for air to air combat were the Merlin powered P-40F and P-40L, which had critical altitudes up around 19,000 ft and could still fly and fight pretty well up to around 25,000. That was more important against the German and (German engined) Italian fighters. At one point there were 5 American fighter groups and 2 British Squadrons flying P-40F and L on the front line against the Germans in Tunisia, Sicily and Italy, and they did quite well with them.
