Editing Boeing B-29 Superfortress (section)

===Soviet Tupolev Tu-4===
{{Main|Tupolev Tu-4}}
[[File:Tupolev Tu-4 01 red (10255123433).jpg|thumb|Tupolev Tu-4 at [[Central Air Force Museum|Monino]] museum]]
At the end of WWII, Soviet development of modern four-engine heavy bombers lagged behind the West. The [[Petlyakov Pe-8]]—the sole heavy bomber operated by the [[Soviet Air Forces]]—first flew in 1936. Intended to replace the obsolete [[Tupolev TB-3]], only 93 Pe-8s were built by the end of WWII. During 1944 and 1945, four B-29s made emergency landings in Soviet territory after bombing raids on Japanese Manchuria and Japan. In accordance with [[Soviet–Japanese Neutrality Pact|Soviet neutrality in the Pacific War]], the bombers were interned by the Soviets despite American requests for their return. Rather than return the aircraft, the Soviets [[reverse engineering|reverse engineered]] the American B-29s and used them as a pattern for the [[Tupolev Tu-4]].<ref name=Monino/>

On 31 July 1944, ''Ramp Tramp'' ([[United States military aircraft serials|serial number]] 42-6256), of the United States Army Air Forces [[462d Strategic Aerospace Wing|462nd (Very Heavy) Bomb Group]] was diverted to [[Vladivostok]], [[Russia]], after an engine failed and the propeller could not be [[Propeller (aircraft)#Feathering|feathered]].{{efn|The drag of the windmilling propeller critically reduced the range of the B-29. Because of this "Ramp Tramp" was unable to reach home base at [[Chengdu]], China, and the pilot opted to head for Vladivostok.{{cn|date=August 2023}} }} This B-29 was part of a 100-aircraft raid against the Japanese Showa steel mill in [[Anshan]], [[Manchuria]].<ref name=Monino>[http://www.moninoaviation.com/40a.html "Tu-4 "Bull" and ''Ramp Tramp''."] {{Webarchive|url=https://web.archive.org/web/20090218234551/http://moninoaviation.com/40a.html |date=18 February 2009 }} ''Monino Aviation''. Retrieved: 1 November 2009.</ref> On 20 August 1944, ''Cait Paomat'' (42-93829), flying from Chengdu, was damaged by anti-aircraft gunfire during a raid on the Yawata Iron Works. Due to the damage it sustained, the crew elected to divert to the Soviet Union. The aircraft crashed in the foothills of [[Sikhote-Alin]] mountain range east of [[Khabarovsk]] after the crew bailed out.

On 11 November 1944, during a night raid on Omura in Kyushu, Japan, the ''General H. H. Arnold Special'' (42-6365) was damaged and forced to divert to Vladivostok in the Soviet Union. The crew was interned.<ref name=ColdWar /> On 21 November 1944, ''Ding How'' (42-6358) was damaged during a raid on an aircraft factory at Omura and was also forced to divert to Vladivostok.<ref>{{cite magazine |title=Made in the U.S.S.R. |first=Von |last=Hardesty |date=March 2001|magazine= Smithsonian |url=https://www.smithsonianmag.com/air-space-magazine/made-in-the-ussr-38442437/ |access-date=8 December 2024}}</ref>

The interned crews of these four B-29s were allowed to escape into American-occupied Iran in January 1945, but none of the B-29s were returned after Stalin ordered the [[Tupolev]] [[OKB]] to examine and copy the B-29 and produce a design ready for quantity production as soon as possible.<ref name=ColdWar>Lednicer, David. [http://mysite.ncnetwork.net/res12e522/ColdWar.html "Intrusions, Overflights, Shootdowns and Defections During the Cold War and Thereafter".] David Lednicer, 16 April 2011. Retrieved: 31 July 2011.</ref>{{efn|''Ramp Tramp'' was also used during 1948–49 as a drop ship for underwing launching of 346P glider. The 346P was a development of the German [[DFS 346]] rocket-powered aircraft. The complete wing and engines of ''Cait Paomat'' were later incorporated into the sole [[Tupolev Tu-70]] transport aircraft.{{cn|date=August 2023}} }}

Because aluminum in the USSR was supplied in different gauges from that available in the US (metric vs imperial),<ref name=Monino/> the entire aircraft had to be extensively re-engineered. In addition, Tupolev substituted his own favored airfoil sections for those used by Boeing, with the Soviets themselves already having their own [[Wright R-1820]]-derived 18 cylinder radial engine, the [[Shvetsov ASh-73]] of comparable power and displacement to the B-29's Duplex Cyclone radials available to power their design. In 1947, the Soviets debuted both the Tupolev Tu-4 ([[NATO]] ASCC code named Bull), and the [[Tupolev Tu-70]] transport variant. The Soviets used tail-gunner positions similar to the B-29 in many later bombers and transports.<ref>{{cite web|url=http://www.rb-29.net/HTML/03RelatedStories/03.03shortstories/03.03.10contss.htm |title=Russian B-29 Clone – The TU-4 Story. |access-date=2 November 2004 |url-status=dead |archive-url=https://web.archive.org/web/20080809222956/http://www.rb-29.net/HTML/03RelatedStories/03.03shortstories/03.03.10contss.htm |archive-date=9 August 2008  }} ''B-29.net''. Retrieved: 20 July 2011.</ref>{{efn| The Soviets interned another B-29 when, on 29 August 1945, a Soviet Air Force Yak-9 damaged a B-29 dropping supplies to a POW camp in Korea, and forced it to land at Konan (now [[Hŭngnam]]), North Korea. The 13-man crew of the B-29 was not injured in the attack and was released after being interned for 13 days.<ref>Streifer, Bill and Irek Sabitov. [http://www.my-jia.com/The_Flight_of_the_Hog_Wild/ "The Flight of the Hog Wild B-29 (WWII): The day the world went cold."] ''Jia Educational Products, Inc.'', 2011. Retrieved: 28 November 2011.</ref>}}