The BT-12 was built of steel sheeting on a tubular frame. Fleetwings argued that spot-welding steel was quicker than riveting aluminium and easier to maintain and, at the same time, that the use of steel saved aluminium. This airframe wears no readable serial but it can only be the XBT-12 prototype, first flown in 1939, which Rudy Arnold also photographed on the ground on 1 May 1941 at Wright Field. It took the company until 1942 to build one more aircraft against an order for 176. 23 were completed in 1943 before the project was cancelled. Not everything got done fast during WWII! Photo by: Rudy Arnold / Smithsonian Institution