Stanley Hiller designed the first successful coaxial helicopter at the age if 15. In 1941 (at 17) he got contract from the Army to build his XH-44 "Hiller-Copter" design. First flying untethered on July 4, 1944, it allowed Hiller Industries to partner with Henry J. Kaiser to become United Helicopters in 1945. The company was re-named Hiller Helicopters in 1948. The XH-44 was donated to the Smithsonian in 1953.