<P> The first DH 108 prototype , serial number TG283 , utilising the Vampire fuselage and a 43 ° swept wing , flew on 15 May 1946 at RAF Woodbridge . Designed to investigate low - speed handling , it was capable of only 280 mph ( 450 km / h ) . The de Havilland Chief Test Pilot Geoffrey de Havilland Jr. , son of de Havilland company owner - designer Geoffrey de Havilland , gave a display flight in the DH 108 during the 1946 Society of British Aircraft Constructors ( SBAC ) airshow at Radlett . In later low - speed testing designed to clear the rear fuselage at high angles of attack , the first prototype was fitted with longer Sea Vampire landing gear . </P>
british pilot crashed and was killed while trying to break the sound barrier on september 27th 1946
Geoffrey de Havilland