|Born||7 March 1894
|Died||16 April 1955 aged 61
Northwood, Middlesex, England
University of Nottingham
|Engineering discipline||aero engine designer|
|Significant projects||de Havilland Gipsy|
Major Frank Bernard Halford CBE FRAeS (7 March 1894 – 16 April 1955) was an English aircraft engine designer. He is best known for the series of de Havilland Gipsy engines, widely used by light aircraft in the 1920s and 30's.
Educated at Felsted, In 1913 he left the University of Nottingham before graduating to learn to fly at Brooklands the Bristol Flying School at Brooklands, later becoming a flight instructor for Bristol. In 1914 he joined the Aeronautical Inspection Department of the War Office 
On the outbreak of the [First World War] he joined the Royal Flying Corps where he fought at the front. Recalled to engineering duties he improved and enlarged the water-cooled six-cylinder Austro-Daimler, producing the 230 hp (170 kW) Beardmore Halford Pullinger (BHP). This engine was further developed by Siddeley-Deasy as the Puma.
In 1922 he rode a 4-valve Triumph Ricardo in the Senior TT, finishing 13th. That same year he was commissioned to produce a luxury motorcycle for Vauxhall. Based on aero-engine principles, it featured an in-line unit construction four cylinder engine, with shaft drive to the rear wheel. Four examples were made, one exists in a private collection in the Isle of Man.
In 1923 he set up his own consultancy in London, alongside the equally influential engine designer Harry Ricardo. There he designed the famous de Havilland Gipsy air-cooled inline engines, copying the success of the Cirrus Engine company in the general aviation role.
During this period Frank Halford also designed and had built the AM Halford Special racing car which he raced at Brooklands in the 1926 RAC British Grand Prix, as well as in many other races in 1925 and 1926.
During the 1930s Halford and Harry Ricardo became interested in the sleeve valve as a method of increasing the allowable operating RPM and compression ratio of piston engines, thereby increasing the power from an otherwise smaller engine. Halford worked with Napier & Son on their Sabre design which would go on to be one of the most powerful piston aero engines, producing 3,500 hp (2.6 MW) from only 2200 cubic inches (36 L) in late-war versions.
During the war he became interested in jet engines, and designed a simplified version of Frank Whittle's centrifugal-flow designs with the air intake on the front and "straight-through" combustion chambers. Known initially as the Halford H.1, the project was taken up by de Havilland who produced it as the de Havilland Goblin. Halford's company was eventually purchased outright by de Havilland in 1944. Halford continued working on jets, turboprop and rocket engines.
- Beardmore Halford Pullinger
- ADC Cirrus
- de Havilland Gipsy
- de Havilland Gipsy Major
- Napier Rapier
- Napier Dagger
- Napier Sabre
- Siddeley Puma
- de Havilland H.1 Goblin
- de Havilland H.2 Ghost
- de Havilland H.3 - turbopropeller Gipsy replacement, 500 shp
- de Havilland H.4 Gyron
- de Havilland H.5 - developed Ghost - not built
- de Havilland H.6 Gyron Junior
- de Havilland H.7 - gas generator, later developed as Napier Oryx
- Dictionary of National Biography Oxford: O.U.P.
- Lumsden 2003, p.54.
- Lumsden 2003, p.172.
- J. L. Pritchard, 'Halford, Frank Bernard (1894–1955)', rev. Robin Higham, Oxford Dictionary of National Biography, Oxford University Press, 2004 accessed 9 Sept 2006
- Douglas R. Taylor: Boxkite to jet: the remarkable career of Frank B Halford. Derby: Rolls Royce Heritage Trust, 1999 ISBN 1-872922-16-3 (Rolls Royce Heritage Trust. Historical series; no. 28)
- Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.
- Frank Halford and the Gipsy design office - Flight magazine, 1938
- Jet Propulsion for Civil Aircraft - a 1946 Flight article on a paper presented by Major F. B. Halford, F.R.Ae.S, M.S.A.E.
- "Major F. B. Halford" Flight 1955 obituary
- "Frank Bernard Halford, 1894-1955" a 1959 Flight article on Halford