This is nonsense.
the Tu-4; It is obviously based on the B-29, that is not denied by anyone, however there are major differences in their construction.
Soviet engineers were tasked with reverse-engineering the several B-29s the USSR had in it’s possession; impounded USAF bombers (under the terms of the 1941 Soviet-Japanese Neutrality treaty) which were forced to land in Soviet territory after flying bombing missions against Japan.
The B-29’s fuselage was made of an 1/16 inch thick plates, or 1.5875 mm. The Soviets used a metric system, so there was no way or logic to produce/use such plates, only 1.5 or 1.6mm. This meant that it could not be applied directly to the original B-29 plans because of mass, length and rigidity changes in the air-frame. So Tu-4 air-frame was redesigned, (increasing and redefining size and dimensions) with the plating being made of 1.8 and 0.8mm plates.
Other differences also existed. The Tu 4 used 20mm guns in its defensive mounts, and later mounted 23mm guns, (both of which were far more effective at defense, having a longer range, able to contend in distance with the 30 and 25 millimeter guns of fighters of the time), and with a heavy enough hit to seriously damage attackers with explosive force, rather than the cleanly punched holes the .50 M2 left. Or the engines; the Tu-4’s ASh-73 radial engines were not copies of the B-29’s Wright R-3350 “Duplex Cyclone” radial engines as is often (falsely) claimed. The two engines were in fact separately developed from the same “grandparent”: the R-3350 was an evolutionary development of the Wright R-1820 Cyclone engine, whereas the ASh-73TK was an evolutionary development of the Shvetsov M-25 which was a licensed copy of that same engine. This common ancestry meant that many parts were similar or even interchangeable between the two engines, but the only component of the Duplex Cyclone engine which the Soviets actually copied was the turbo-supercharger unit. The Tu-4s engines did not include the R-3350’s lightweight magnesium-alloy crankcase, which increased weight but also eliminated the Duplex Cyclone’s infamous tendency towards engine fires so catastrophically hot that they could melt the wing spars in literal seconds. The differences are seen in capability as well. The Tu-4 was about 750kg heavier, 10 mph slower (big difference that is) and carried only 6000kg (Post too long. Click here to view the full text.