Gloster E.28/39 - Testing

Testing

Although the initial flight tests were relatively early in the Second World War, the German Heinkel He 178 had been first test flown on 27 August 1939, at Rostock-Marienehe on the Baltic Coast, days before the outbreak of the war.

The E.28/39 was delivered to Brockworth for ground tests beginning on 7 April 1941, using a non-flightworthy version of the Power Jets W.1 engine. These included some short "hops" of about 6 ft in height from the grass airfield. With these initial tests satisfactorily completed, the aircraft was fitted with a flightworthy engine rated for 10 hours use, and then transferred to Cranwell which had a long runway. On 15 May 1941, Gloster's Chief Test Pilot, Flight Lieutenant Gerry Sayer flew the aircraft under jet power for the first time from RAF Cranwell, near Sleaford in Lincolnshire, in a flight lasting 17 minutes.

Over the following months, tests continued with increasingly refined versions of the engine. Later in the test program small, auxiliary fins were added near the tips of the tailplanes to provide additional stability in high-speed flight.

On 21 October 1942, Gloster Chief Test Pilot Gerry Sayer disappeared during an acceptance test flight in a Hawker Typhoon, presumed killed, and his assistant took over testing of the E.28/39. The oil system had been changed before he flew; after it was proven, the aircraft was handed over to the RAE for testing by service pilots.

The second prototype E.28/39 (W4046) - initially powered by a Rover W2B engine - joined the test programme on 1 March 1943. Testing had revealed problems with engine oil and lubricants. Flying of W4046 was by Gloster pilots John Grierson and John Crosby Warren, because Michael Daunt was then involved with the F.9/40 (the Meteor). In April 1943, W4046 flew to Hatfield for a demonstration in front of the Prime Minister and members of the Air Staff. It was taken to Farnborough and fitted with a 1,500 lbf (6.7 kN) W2.B. It achieved 466 mph. On 30 July 1943, while on a high altitude test flight, the second prototype was destroyed in a crash resulting from an aileron failure. The accident was attributed to the use of the wrong type of grease in the aileron controls; one aileron had "stuck in position, sending the aircraft out of control". The test pilot successfully bailed out from 33,000 ft.

The first prototype was fitted with the 1,700 lbf (7.6 kN) thrust W2/500. It was flown successfully to 42,000 ft, but level speed at altitude was not attempted due to fuel shortage. The pilot commented in his report on a need for cockpit heating and a larger fuel tank. It continued flight tests until 1944. By that time, more advanced turbojet-powered aircraft were available. The Gloster E.28/39 was not able to achieve high speeds, but it proved to be a capable experimental platform and exhibited a "good climb rate and ceiling". Experience with the E.28/39 paved the way for Britain's first operational jet fighter aircraft, the Gloster Meteor. The Meteor used the Rolls-Royce Welland engine, the next stage from the Power Jets W.1.