On 15 May 1941 at 7.45pm, he took off from RAF Cranwell, near Sleaford in Lincolnshire in the Gloster E.28/39 (W4041/G) powered by the W.1 engine and flew for 17 minutes, flying at over , impossible for other aircraft at the time in level flight. That Gloster aircraft has been in the Science Museum since 1946. A second aircraft of the same type (W4046/G) would be later demonstrated to Winston Churchill on 17 April 1943, having first flown on 1 March 1943 and later crashed in June 1943.