janneh,
La-5 was powered by ASh-82A with max output of 1700hp. Has a raised rear fuselage, ala Spit, 109. First saw combat at Stalingrad.
La-5F was powered ASh-82F, which had same output as ASh-82A, but offered improved performance above 5000ft. Rear fuselage was cut down, incorporating a bubble canopy (this change was standard for all subsequent versions of La-5). -5F was built simultaneously with the La-5FN, because development of the ASh-82 radial was an ongoing, and uncertain, process. Saw combat in early to mid '43.
La-5FN was powered by the ASh-82FN with a maximum output of 1850hp. Was nearly 400lbs. lighter than previous La-5s. Came out at the same time as the -5F.
La-7 powerplant was unchanged, but the La-5 shape was aerodynamically refined, and lightened by a further 300lbs. In 1945, some aircraft were equipped with three 20mm B-20 cannons. Saw combat in mid 1944.
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leonid, aka grisha
129 IAP VVS RKKA