Re: respectable clone of the B29
In 1947 the Soviet Union bought Rolls-Royce Derwent and Nene engines from the British and the Russians cloned them in their MiG-15 and La-15 jet fighters. Stalin had been skeptical that Britain would sell these engines. Stalin reportedly said "What kind of fool would be willing to sell his secrets!". But the British government agreed to the sale anyway.
Stalin and the Bomb, page 235.