Southern California industrialist E.M. Smith formed Emsco Aero Engine Co. 1928 to build 1,000-hp diesel, and in 1929 bought Zenith Aircraft to form Emsco Aircraft Corp., Downey (Los Angeles), producing trimotor Challenger, 2-seat Cirrus, 8-seat high-wing B-3, 9-seat B-3A, 2-seat B-7, fast Arctic Tern amphibian and incomplete B-10 STOL flying wing.