North and South Atlantic Routes – During WWII, the Soviet Union received almost 15,000 U.S. built aircraft under the Lend-Lease program. About half of these were delivered by sea via the North Atlantic or were flown across the South Atlantic Ocean to the U.S.S.R. via North Africa. Each method was difficult.

The North Atlantic route was subject to attack by German submarines and aircraft and the African route suffered from exposure to desert sand which reduced the life of engines and other aircraft components. Eventually aircraft deliveries shifted to a more direct course via Alaska to Siberia, the ALSIB route.

ALSIB Route – Almost 8,000 aircraft were ferried over the ALSIB route, usually by Air Transport Command pilots, through Great Falls, Montana to Fairbanks, Alaska. There, Soviet pilots took over and flew the aircraft to Nome, Alaska and then to Siberia.

Winter ground temperatures of minus 50º Fahrenheit, the threat of being forced down in remote wilderness, hazardous flying weather, spartan living conditions, and a lack of sufficient hangar space which sometimes forced mechanics to work outside under cruel winter conditions made life difficult for personnel assigned to duty along the ALSIB route.

Neither the Red Army Museum in Moscow nor the Soviet Air Force Museum makes any mention of Soviet use of American aircraft during WWII or that the Western Allies even participated in that war. This is even more interesting when comparing a P-63 flight manual page from the Soviet version and the American original.

Following American and British aircraft were officially delivered to USSR as lend-lease deliveries (numbers as received in USSR; numbers dispatched bigger, as considerable numbers were lost in transit):

P-39 Airacobra 4952
P-63 Kingcobra 2400
P-40 Tomahawk and Warhawk (in Russia called Kittyhawk) 2397 (part of which redirected from UK)
P-47 Thunderbolt 195
NA Mustang I 10 (from UK)
Hurricane 2952
Spitfire 1351
AW Albemarle 14
A-20 Havoc 2908 (including “Boston III” aircraft redirected from UK)
B-25 Mitchell 862
HP Hampden 23 (originally intended for lend-lease delivery; left behind in Northern Russia by 144 and 455 Sq.)
DH Mosquito 1
C-46 Commando 1
C-47 Dakota 707
C-52 Owl 19
AT-6 Texan 82
PBN-1 Nomad 137
PBY-5A Catalina approx. 20
PBY-6A Catalina 48
OS2U Kingfisher 2

In addition a number of various Western aircraft crashed on Soviet or Soviet-occupied territory were repaired and tested (or even used operationally) by the Soviet Air Forces:

P-38 Lightning >2
B-24 Liberator approx. 20
B-17 Flying Fortress approx. 20
B-29 Superfortress >3
Avro Lancaster >2
Short Stirling >2?
Supermarine Walrus >1

Note: above are only the main types listed; in USSR a big number of modifications were made (two-seater modifications, installation of Soviet engines and cooling systems, machine guns and cannons, bombs
and rockets etc).