Captain Frank Sowter Barnwell OBE AFC FRAeS BSc was a Scottish aeronautical engineer. With his elder brother Harold, he built the first successful powered aircraft made in Scotland and later went on to a career as an aircraft designer with the Bristol Aeroplane Company, designing aircraft such as the Bristol Fighter, the Bulldog and the Blenheim.

Richard Harold Barnwell was an English aviation pioneer, who began as an aircraft builder. He died while test-flying an early Vickers fighter aircraft.