| [[Image:|300px|The first E.28/39 prototype]]|
The first E.28/39 prototype
|First flight||May 15, 1941|
|Manufacturer||Gloster Aircraft Company|
|Length||25 ft 4 in||7.74 m|
|Wingspan||29 ft 0 in||8.84 m|
|Height||8 ft 10 in||2.70 m|
|Wing area||146 ft²||13.6 m²|
|Empty||2,886 lb||1,309 kg|
|Maximum takeoff||3,748 lb||1,700 kg|
|Engine||1 × Power Jets W.1|
|Power (each)||860 lbf||3.8 kN|
|Maximum speed||466 mph||750 km/h|
|Range||410 mi||660 km|
|Ceiling||32,000 ft||9,755 m|
|Rate of climb||1,363 ft/min||6.9 m/s|
The Gloster E.28/39 was the first British jet powered aircraft that was used during World War II.[N 1] The first of two examples, with serial number W4041/G[N 2], was initially flown on 15th May 1941 by Garry Sayer, two years after the first flight of the German Heinkel He 178, which was the first jet aircraft ever made. The aircraft was able to reach speeds of up to 544 km/h.
In early 1939 Frank Whittle, who had originally developed the idea behind the jet engine in the late 1920s, roughed out a preliminary design for a completely new aircraft, which would be powered solely by the jet engine, rather than use an existing aircraft to test the engine first, as was usually the case. Whittle chose this course of action as he knew his engine had to power the testbed in order to maximise it's impact. 
This was built under Specification E.28/39, which called for two aircraft with tricycle undercarriage featuring a steerable nose wheel. This was issued by the Air Ministry to Gloster on 3rd February 1940. The first of the two prototypes was ready for taxiing trails just over a year later, undertaken by test pilot P. E. G. Sayer at Gloster's airfield at Hucclecote on 7th April 1941, followed by a few shirt hops the following day. After being fitted with a new nose wheel unit, the first prototype was dismantled and taken by road to the airfield at Cranwell in Lincolnshire, as it was felt that the longer runways would be an advantage during flight trials, which began with a 17 minute flight on 15th May 1941.[N 3]
- ↑ The E.28/39 was designed and built with provision for a quartet of machine guns. This was to allow studies of the interaction between the guns and the jet intake and not, as has been widely reported, to allow the aircraft to form the basis of a jet fighter. In the event, the guns were never fitted, and the E.28/39 was used solely as an experimental aircraft, to test the operation of the jet engine.
- ↑ The /G (Guard) suffix was used to indicate a military aircraft which needed to be kept under armed guard while on the ground.
- ↑ In fact the E.28/39 became airborne in 1,800ft (550 m).