With the approach of WW2 the de Havilland Aerodrome at Hatfield went
through a major expansion, concentrating on Mosquito production and
development. The Company also pioneered the production and development
of jet engines led by Major Frank Halford, leading to the Vampire jet
fighter. Early commercial aircraft were the Dove and Heron, but the
major pioneering program was the Comet, the world's first commercial jet
airliner, which first flew on 27 July 1949 and entered service with BOAC
on 2 May 1952. The DH.108 tailless research aircraft based on the
Vampire fuselage was used to investigate the effects of the speed of
sound, exceeding Mach 1 on 9 September 1948. The de Havilland jet
airliner developed through the Trident, which was the first aircraft
capable of automatic landing with passengers in all weathers, leading to
the BAe 146 Whisper Jet, Britain's most successful jet airliner. In
addition to developing turbojet engines, the Engine Company also
developed rocket engines. The Propeller Company developed air-to-air
guided missiles and the Blue Streak stage 1 booster space rocket. Other
types developed by de Havilland at Hatfield were the Sea Vixen naval
strike fighter and the DH 125 Business Jet.