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Ivan and a few others on this site are way more versed in the politics of the USSR during WW2 than I am.
I will attempt a simple answer...?
Arkadi Shvetsov.s
M-82 (A): 1,330 PS normal power & high S/C (1,510 PS combat power & low S/C)
M-82F: 1,350 (1,700) Take-off: 1,700 PS @ 1,140 mm Hg.
M-82FN: 1,470 (1,850) Take-off: 1,850 PS @ 1,200 mm Hg.
ASh-82FN: 1,470 (1,850) Take-off: 1,850 PS @ 1,200 mm Hg.
It wouldn't make sense cuz La-5, La-5F and La-5FN have same drag coefficientYour thread reminded me that I had a copy of an official flight test report for the La-5 in which the maximum SL speed at nominal power (1400HP) was 509 hm/h and 535 km/h at takeoff power (1700HP).
The maximum speed depended drastically on the manufacturing quality and could vary even for airplanes of the same batch. The La-5 suffered from A LARGE NUMBER of defects - especially at the beginning of serial production. It was a long, long story of the La-5 improvement. It became more or less appropriate rather by the end of 1943.It wouldn't make sense cuz La-5, La-5F and La-5FN have same drag coefficient
How can La-5F do 561 with 1700hp
But La-5 only do 535 with 1700hp
That's trueThe maximum speed depended drastically on the manufacturing quality and could vary even for airplanes of the same batch. The La-5 suffered from A LARGE NUMBER of defects - especially at the beginning of serial production. It was a long, long story of the La-5 improvement. It became more or less appropriate rather by the end of 1943.
YeahThe real engine power was frequently lower than specified.
The aerodynamic perfection of the early versions was much worse than of the later ones.
Usually prototypes were manufactured much more carefully, etc.
The report's figures only indicate poor manufacturing quality and numerous problems with both the airplane and the engine.
Just letting you know I sent you request to get access to view itThis might be of use: test results
Translation by yours truly, so you know whom to blame.
The real engine power was frequently lower than specified.
The aerodynamic perfection of the early versions was much worse than of the later ones.
Usually prototypes were manufactured much more carefully, etc.
The report's figures only indicate poor manufacturing quality and numerous problems with both the airplane and the engine.
Not only La suffered from cockpit overheating - e.g., this problem was observed for Yak-9U and Il-10 as well. For the Il-10 the problem was solved only in the post-war time. Quality of the canopy glass was a common problem for the Soviets throughout the war.Another thing worth adding is that production radial Lavochkins, at least up to the La-5FN, overheated the cockpit, sometimes even in the winter, and the firewall also leaked dangerous carbon monoxide gasses in the cockpit, while the sliding canopy was not always great in optical quality.
For all these reasons, radial engine Lavochkins, up to and including the La-5FN, were mostly flown in combat with the canopy fully open, even in the dead of winter. This probably cut at least 20 km/h from most of the speed data shown in this thread.
What is remarkable is that despite this handicap, The La-5FNs below 4.5 km still were faster, canopy open, than Me-109Gs without MW-50 injection, as the G-6 without MW-50 had a dogleg in its speed that made it fairly slow below about 13 000 ft.
The La-5FN in combat, canopy open, was still about 10-20 km/h faster than the G-6 below 13 000 ft, so that should give a rough ballpark of how much the open canopy cut into its figures down low, which can then be extrapolated to speed losses higher up.
The open canopy issue should not infer the Lavochkins were badly made. In fact the wood surfaces were remarkable for their quality right from the early Lagg-3 production. But the adaptation of a radial engine, that was not intended from the start, meant there were engineering issues that were only sorted out later on. Probably the worst thing about La-5s were their short fuel endurance: Significantly shorter than 109s.