 Armament comprised four 20mm Hispano Mk V cannon located underneath the nose; from the onset of the design phase, even when the aircraft was officially intended to serve only as an experimental aircraft, the provision for the cannon armament had been included.On 20 September 1943, the first DH.100 prototype, serial number "LZ548/G", conducted its maiden flight from Hatfield Aerodrome; it was piloted by Geoffrey de Havilland Jr., the company's chief test pilot and son of the company's founder.This flight took place only six months after the Meteor had performed its own maiden flight; the first flight had been delayed due to the need to dispatch the only available engine suitable for flight to America to replace one destroyed in ground engine runs in Lockheed's prototype XP-80 jet fighter.