The Tupolev Tu-4, the reversed copy of the B-29 Superfortress .

Joseph Stalin ordered the development of a comparable bomber. The United States  declined to supply the Soviets with B-29s under the Lend Lease Act of March 11,1941. On three occasions during 1944 ,B-29s made emergency landings in Soviet territory after bombing raids on Manchukro and Japan . In accordance with the Soviet Japanese Neutrality Pact the Soviets were neutral in the Pacific War. The bombers were interned  by the Soviets , despite American demands for their return.
  All three planes  were flown to  Tupolev OKB in Moscow .The  first B-29 was fully dismantled and reversed engineered .The aircraft that evolved was the  four engine Tupolev -T4 ( NATO reporting name ; Bull ) a piston engined strategic bomber that served in the Soviet Air Force from the late 1940s to the mid 1960s. The second aircraft was used for flight testing and the third plane was left as a standard for cross reference . Soviet industry  was able to produce twenty copies of this aircraft in two years.
Additional information welcomed

The one thing the Sovs couldn't replicate was the tires. There was simply no machinery in the USSR that could make such things. So Soviet agents went to the U.S. and discretely purchased surplus B-29 tires. 
The 29s weak spot was the engines, something the USAF didn't resolve until about 1949 with new engines. The Soviets replicated the original engines and experienced the same problems.
I think the B-29/TU-4 story is a great one.

It would be interesting to inspect one of the surviving Tu-4's to see how much of these stories are true.
 
Marty

An in-depth article on the genesis of the Tu-4 can be found at the link below.  It confirms a few of the rumors and dispells others.
http://www.airspacemag.com/military-aviation/USSR.html?c=y&page=1

 
Comparing fully armed bomber production versions with B-29, B-29A (in WWII configuration) vs the Tu-4:
 
major design differences  Wright R-3350 engines replaced by ASH-73TK 2,300 hp engine designed by A.D. Shvetsov, crew communication tunnel was omitted; aluminum skin thicknesses changed – overall weight increased; 23mm cannons replaced the M2 0.50” mgs in all gun positions, changes to computers to develop new firing solutions for 23mm cannons; control cabling and piping differences; different instruments, IFF and radios; and?
 
The Tu-4 entered Soviet service in 1949, ahead of the RAF B-29s in 1950.
 
 
Other copy jobs:
 
 
  US JB-2 Loon was a development of the German V-1 Buzz Bomb from captured missiles from which drawings were made.  The JB-2 was a larger vehicle with an improved guidance system.  Some 1,200? were built; Republic built the airframe and Ford Motor Co the engine; production delivery began in Jan 1945, and was cancelled on VJ Day; the first JB-2 was test flown at Eglin Field, FL in Oct 1944.  Just before the end of the war, JB-2s were aboard an aircraft carrier enroute to the Pacific for possible use in the proposed invasion of the Japanese home islands.
 
France, Sweden and the USSR also built versions of the V-1.
 
The Germans developed anti-tank weapons based on the US Bazookas they captured in N Africa.
 
 
There are probably many other reverse engineered examples.
 
 
Neat idea: obtain a Tu-4 from Com China to be referbed in the Seattle Museum of Flight to be displayed along side their B-29.  There are probably many still living air and crew in Russia – they could be contacted to give a narrative of their experience with the Tu-4 and possibly help with the referb.  A deal could also be made to obtain a Tu-16 from China to display along side the museum’s B-47.
 
 
the best,
 
Tony