*bing bing bing* Excellent work.
The US wouldn't lend/lease Russia the B-29 because they didn't want to give away their current technology. However, 3 B-29s that were damaged over Japan continues across to the mainland and landed in Soviet territory. The crews were allowed to go home, but the Soviets impounded the aircraft. They took one entirely apart to reverse-engineer it, they flew the heck out of one to see how it performed, and they kept one as a reference standard. In the meantime Tupolev reengineered the plans for metric construction tolerances (and Soviet factory workers), so the Tu-4 is not an exact duplicate in any way. This marked the beginning of the Soviet method of duplicating Western aircraft almost verbatim (look up the Tu-160 for example). The old B-29 copy stayed in active duty well into the late '50s in Russia, with Chinese licensed PLA aircraft like the one here still active into the '60s (note the fitted turboprop engines).
Your go, 911.