Captain Frank Sowter Barnwell OBE AFC FRAeS BSc (1880 – 2 August 1938) was an aeronautical engineer, who performed the first powered flight in Scotland and later went on to a career as an aircraft designer.
He was the Chief Designer for the Bristol Aeroplane Co from 1911 til 1938. He designed 150 aircraft, including the Bristol Blenheim (1936). 
Educated at Fettes College in Edinburgh and the University of Glasgow.
From 1898 to 1904 he worked for Fairfield Shipbuilding and Engineering Co before going abroad for two years.
1906 he joined his brother Harold in business and established the Grampian Motor and Engineering Co in Stirling where between 1908 and 1909 they set about building a prototype aeroplane.
1909 Harold piloted the first powered flight in Scotland, in a field in Causewayhead under the Wallace Monument.
1914 Henri Coandă was succeeded as chief engineer of British and Colonial Aeroplane Co by Frank Barnwell, who was to become one of the world's foremost aeronautical engineers. One of Barnwell's first designs, the Bristol Scout, was one of the very first fighter aircraft to enter British service. Later in the war came the mass-produced two-seat Bristol F.2 Fighter, which was one of the backbones of the Royal Flying Corps (RFC), later the Royal Air Force (RAF).
1920 The company became Bristol Aeroplane Co.
1936 He designed the Bristol Blenheim amongst other aircraft.
1938 Barnwell was killed in a plane crash in 1938. He was piloting a small aircraft he had designed and built himself, the Barnwell B.S.W., when it struck a bump taking off from Bristol (Whitchurch) Airport and stalled crashing onto a nearby road.
Frank and Marjorie (nee Sandes) Barnwell had three sons who all lost their lives in the second world war:
- Pilot Officer David Usher Barnwell DFC, RAFVR, of No. 607 Squadron RAF died aged 19 on 14 October 1941.
- Flight Lietenant Richard Antony Barnwell, RAF of No. 102 Squadron RAF died aged 24 on 29 October 1940.
- Pilot Officer John Sandes Barnwell, RAF of No. 29 Squadron RAF died aged 20 on 19 June 1940.
Honours and awards
- 7 June 1918 - Captain Frank Sowter Barnwell. Aeroplane Designer, The British and Colonial Aeroplane Company, Limited to be an Officer of the Order of the British Empire for services in connection with the War.
- 1 September 1918 - Capt. Frank Sowter Barnwell, OBE awarded the Air Force Cross in recognition of distinguished service.