If the opposite side has aircraft doing 400 mph, like the Luftwaffe had in 1942 in the field, the 360 mph fighter is a slow fighter. Granted, not as slow as 320-330 mph Hurricane II or F4F.
But the Luftwaffe didn't have any 400 mph aircraft flying in the Med in 1942. With Trop filters their 109F and early G (toward the end of the year) were doing about 370-380 mph at their highest operating altitude. MC 202 was about the same or a little less. They got one squadron of Fw 190s briefly in 1943 but they were in Theater only for a short time.
The -33 impeller was turning at 8.77 times the crankshaft speed, the -39 impeller was turning at 8.80 times. A power of 1040 HP at 13600 ft is always 1040 HP at 13600 ft, whether made by the -33 or the -39.
As indicated on the charts I linked, the Tomahawk types were showing a higher critical altitude at military power.
Note the altitude for the WER there - sea level. It will be making more high up, as can be seen at the
chart I've previously posted. The ram effect adds another 2500 ft for the rated altitude for WER power setting (57 in Hg at 3000 rpm). The Alison memo indeed warns for not over-boosting the new engines (the ones where impeller turns at 9.60 times the crankshaft rpm), and the power tables and chart show that, the new engines making ~100 HP less at low level vs. 'old' versions that could be run at 60 in Hg down low with blessing from Allison and USAAF. The 'old' S/C will also consume less power to drive, so more power is left to turn the prop.
Allison didn't give that blessing until Dec of 1942, the power issues with the Kittyhawks were already resolved by then (for several months) as acknowledged in the memo. But in early 1942 they did not know how far the engines could safely be pushed, and the improved bearings, crank shaft and crank cases were not delivered yet. Hence the problems with the early Kittyhawks starting in Dec
1941.
This is the way 11 victory P-40 Ace and Squadron Leader
Bobby GIbbes put it:
"Well it was basically the same aeroplane. We were a little disappointed when we first got the Kitty, we thought it'd be way ahead of the Tomahawk. In actual fact, it was a little bit better. One thing I personally didn't like about it was the Tomahawk had fairly high sides and you'd be sitting behind a thin sheet of metal but you felt safer. The Kittyhawk had perspex coming way down and you felt as if you were sitting up, very vulnerable, because you could see out so much. That was one feature I do remember. However, later when we got our Kittyhawks running properly - were getting better performance - they were a better aeroplane."
There was no such thing as "this is a F/B P-40N, so easy on the throttle, fellas".
I believe there was though I don't know if this was just a bureaucratic thing (i.e. orders / policy) or literally a throttle limitation. Some of them had a wire which had to be broken to exceed a certain boost pressure. As Shortround6 often points out, the crew chief would typically know if they had been overboosting the engines (or just using WEP) when the plane landed due to scorch marks, oil leaks etc.
As it should be, it had more power there. Trick was finding the answer how to gain performance, altitude and situational advantage over the enemy at all combat altitudes: the P-40 was lacking in that domain vs. the Luftwaffe, and could get at best the parity in Asia/Pacific.
With the P-40, in all Theaters, they had to figure out how to contend with being attacked from above and carrying the day anyway. That is a very tall order, and it's the reason why the P-40 was considered so flawed. They worked out very specific tactics for this in the MTO, starting with just flying in pairs / figure 4 flights (which for some reason lagged in that Theater until around mid-1942) then flying in squadron formation and turning into the initial attacks as a unit (on the word of the squadron leader). And of course, using their escape maneuvers when they got into trouble.
Tactics in the Pacific and China were actually somewhat similar, except that they could extend more easily at or near co-altitude without doing a dramatic split S escape manuever and zoom climb.
Easy pick - the higher, the better.
FWIW, I was trying to note that 2-speed S/C is not be-all end-all qualifier, when we talk about 1-stage supercharged engines.
Well, generally I agree, but not always. In an Allison P-40, the higher critical altitude is a tradeoff to the much higher power down low. There were definitely more Aces made flying P-40K than M. This also depended where the fighting was taking place, which is a reflection of what kind of bombers were active and what kind of targets they were going for. In the Pacific with dive and torpedo bombers the fighting was often lower, similar in the Med and Russian Front. There is a reason why they made those LF Spitfires.
