Ernie Gann didn't do too badly, even though most of his inventing was with a typewriter.
Then there was Benny Howard, whose homebuilt "Mister Mulligan" was the only plane ever to win both the Bendix Trophy (cross-country) race and the Thompson Trophy (closed-course). After losing a leg and nearly his life in a 1936 accident, he developed a line of DGA personal transports, helped Donald Douglas optimize the DC-3 design, then flew initial test flights of the DC-4, DC-6, and A-26 (and also the Budd Conestoga and some Fairchild military transports). In later years he built a low-speed wind tunnel and refined Carroll Shelby's racing car bodies. Also a very witty guy!
