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I don't know if the peculiarity of Allison engines was already mentioned here (I'm just too lazy to look for it). Soviet aviation technicians noted that the engine sound changes little when the supercharging increases above the allowed limits - unlike other engines. Thus. the pilots did not hesitate to use it in flight. It is clear that the engine lifetime was reduced several times, and the maximum speed of many Kittyhawks after this ruthless exploitation was below 400 km/h.
I was trying to keep the individual lines short, and I got "lucky" in that the weight breakdowns kept saying 720lbs for fuel until the near end, Which is one reason that some of the service tests change. For some reason the US and Curtiss agreed that 120US gal was "standard" despite what the tanks actually held. The 52 gal drop tank was an attempt to make up for the reduction from 181 gallons in the P-40 to under 150 gallons in the P-40B.
Curtiss themselves say for the P-40D
15,000ft at military power, 359mph without tank and 330mph with tank
15,000ft at 1000hp(normal) power, 345mph without tank and 324mph with tank. which doesn't track well to be but.........
15,000ft at 600hp (60% normal), 285mph without tank and 266mph with tank.
The D was supposed to have 175lbs of armor and glass together, some times the weights are separate.
Most of the specifications list take-off speeds and most give take-off and landing distances, sometimes for both runway and over 50ft obstacle. The P-40 was not a Spitfire or Hurricane here although much better than a lot of other American fighters.
Speed obviously didn't change much but climb took a real hit due to the increase in weight.
Some of the British/Commonwealth climb tests are going to be quite different than the US climb tests depending on test procedures. Standard British procedure was to use the "normal" rating (2600rpm/1000hp) for the entire time so climb really suffered in the first 5 minutes compared to American testing.
They test their own planes the same so all the British pilots had some understanding of what was going on.
It may also depend on which engines they were using, Beating up on the Tomahawks was not going to end well. They for sure did not have the nitrided crankshafts nor the better crankcases (less flex) so better oil culture could only do so much. Some of the early British planes (Tomahawk Is) may not have had the shot peened crankshafts. Over revving/over boosting those could really shorten the life.Yeah they burned out the engines fast, I think it was mainly to do with the cleanliness of the oil in field conditions. Many Soviet pilots referred to this as 'oil culture'. They worked a lot of these problems out with the P-39 before putting into the field.
"Oil culture" was another factor. I don't know which one was more important.Yeah they burned out the engines fast, I think it was mainly to do with the cleanliness of the oil in field conditions. Many Soviet pilots referred to this as 'oil culture'. They worked a lot of these problems out with the P-39 before putting into the field.
It may also depend on which engines they were using, Beating up on the Tomahawks was not going to end well. They for sure did not have the nitrided crankshafts nor the better crankcases (less flex) so better oil culture could only do so much. Some of the early British planes (Tomahawk Is) may not have had the shot peened crankshafts. Over revving/over boosting those could really shorten the life.
The Better engines showed up part way through the P-40E/Kittihawk production so how many early ones did the Russians get?
Fancy going into a fight with just 8 rockets 4 x 20mm cannon and a shark mouth, no wonder ground troops laughed so much at the sight.I t looks like it's about to hurl.
Or belch.
"Oil culture" was another factor. I don't know which one was more important.
I do not see any contradiction. The young pilots did not realize that they were killing the engine by overboosting for too long - they did not feel much difference in the engine sound. For other engines, the difference was more noticeable, so they were operated under more gentle conditions. But the quality of oil (and maintenance generally) was undoubtedly poor - at least for the first three years of the war. Moreover, not only oil filtration was necessary to improve the situation - Allison required lubricates with other characteristics than the Soviet engines (e.g.., more viscose). The Soviets needed to optimize the composition of the lubricant.Well, considering that we know they overboosted up to 72" Hg (nearly twice the stated limits in the early manual) in Australia / the South Pacific and the Middle East already in 1942, I'd say it was some kind of maintenance issue.
As noted, the Soviets had far less problems with the later P-40K and M, which arrived less worn out, and with much more spare parts and 'consumables'.
I do not see any contradiction. The young pilots did not realize that they were killing the engine by overboosting for too long - they did not feel much difference in the engine sound. For other engines, the difference was more noticeable, so they were operated under more gentle conditions. But the quality of oil (and maintenance generally) was undoubtedly poor - at least for the first three years of the war. Moreover, not only oil filtration was necessary to improve the situation - Allison required lubricates with other characteristics than the Soviet engines (e.g.., more viscose). The Soviets needed to optimize the composition of the lubricant.
A Mustang was about 40-50mph faster than a P-40 at sea level and could generate a bit more RAM (higher pressure going into the supercharger).A US colonel noted in a letter to the War Dept that British pilots flying Allison engined Mustangs were flying at 72" Hg for up to 40 minutes at a time. "War Emergency" five minute rating was 57-60" depending on specific variant. This is with the same engine (V-1710-73) used in the later model Kittyhawks.
Western supplies of lubricating oils were insufficient (at least until 1943), so it was necessary to use the available ones. Many P-40s fought on the northern sector of the front, where the dust was not so important factor, but the problems remained the same. Moreover, many of P-40 (or even the most of them) were moved to the second line in 1943.I believe they were using Anglo-American supplied lubricants, filters, spark plugs, and fuel.
I was not there, but your theory that the pilots did not know they were overboosting the engines does not hold water for me, because Soviet pilots noted that they overboosted the engines (and, according to some, increased RPM) and they knew that this potentially shortened the engine life.
A US colonel noted in a letter to the War Dept that British pilots flying Allison engined Mustangs were flying at 72" Hg for up to 40 minutes at a time. "War Emergency" five minute rating was 57-60" depending on specific variant. This is with the same engine (V-1710-73) used in the later model Kittyhawks.
So based on that, IMO, and given that the Soviet fighter bases were typically very close to the front and most missions probably wouldn't exceed 40 minutes, even if they were unusually oblivious, I doubt very much that they would have burned out their engines from overboosting if there were not also serious maintenance problems.
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Also, boosting above 50" Hg would leave a big scorch mark down the side of the aircraft, which mechanics were trained to look for.
A Mustang was about 40-50mph faster than a P-40 at sea level and could generate a bit more RAM (higher pressure going into the supercharger).
Depending on temperature the air pressure and density of the air could both be higher in Europe than in Africa or the tropics. This is sort of triangle, A higher intake air temperature can increase the risk of detonation but the lower air density may reduce (by a few percent ) the amount of power.
Trying to get 72" Hg out a P-40 may very well require 3200rpm or higher while the Mustang may only require 3000rpm.
The use of the Mustang information helps justify the increased boost to 60" or perhaps even 66". 70-72" in a P-40 may be cutting things too thin.
the -73 engines had all the good parts.
That is another thing, the book 5 minute limit was subject to the temperature (both oil and coolant) staying within limits. If the temperature went over limit sooner the pilot was supposed to reduce boost. Sometimes the performance tests say an engine wouldn't be in limits at military power, although they sometimes gave an extra 5-10 degrees at WEP power levels. Running at high boost may have been easier in cold weather.During long engagements US pilots described in detail (in excerpts I have posted to this forum in the past) overboosting up to 60" and then going back down to military power for a few minutes to cool the engine off, then back to overboosting, over and over through the course of long running fights lasting up to an hour.
Running military power for an hour, you'd better be defending your home base or you'll run out of gas on the way home.During long engagements US pilots described in detail (in excerpts I have posted to this forum in the past) overboosting up to 60" and then going back down to military power for a few minutes to cool the engine off, then back to overboosting, over and over through the course of long running fights lasting up to an hour.
For a long time I thought that they never overboosted the Tomahawks, but it turned out that at least the AVG did.
If the lining deteriorated, than the free material also most likely clogged the fuel filters.The linings of the fuel tanks on P-40Es and some P-40Ns delivered to the RAAF broke down when using high octane fuel. So, lots of RAAF Kittyhawks were plauged with leaky fuel tanks after a certain amount of time.