Yakovlev Yak 11 MooseYak 11 Moose airplane model. The Yakovlev Yak 11 was an advanced trainer. It flew in the air forces of all Warsaw pact countries, the middle east, China and Austria. In the Czechoslovakian republic, Let Aircraft built this famous plane under license. In 1944, Alexander Yakovlev based this new construction on the Yak 9 fighter. Different than its predecessor, a radial engine ASch 21 was used instead of the V engines used previously. As is typical of