Photo shows NX21755 after it was rebuilt following a collision with a Lockheed Sirius while landing at Downey. The most obvious change was the fully enclosed cowling it first had was replaced by a more conventional cowling for a radial engine. Went into limited production as the P-66 Vanguard but was soon rejected by the USAAC, the RAF and the Chinese air force which received them. Photo by: Rudy Arnold / Smithsonian Institution

First flown on 9 September 1939, the prototype of the Vultee V-48 / P-66 Vanguard fighter initially had a pointed nose housing an R-1830 radial engine, which overheated, and a normal radial cowling was fitted instead. The type also had stability issues. A Swedish order for 144 Vanguards was embargoed and 129 of these were sent to China via Karachi, but only 79 reached Chengdu to see action with the Chinese air force. Photo from: San Diego Air & Space Museum