Even before the Gloster Meteor, Britain's first operational jet-powered combat fighter, arrived on the scene in World War 2 (1939-1945) to stake its claim and advance a career that led into the early-Cold War years, the nation needed proof-of concept and test beds to prove the viability of jets and high-speed flight in general. This fell to certain designs of which one, perhaps being the most notable of them all, became the classic Gloster "E.28./39". This single-seat, single-engine product was arranged by the Gloster Aircraft Company through the efforts of the Royal Aircraft Establishment (RAE) and engineer George Carter along with the Whittle turbojet engine's creator himself, Frank Whittle. The result was a pair of flying data-collecting platforms that served to shape the future of jet-powered flight for Britain and prove the nation as a leader in the field of jet propulsion.
The E.28/39, known mainly by its Air Ministry Specification of E.28/39, was also recognized under the names of Gloster G.40, the "Gloster Whittle" and the Gloster "Pioneer". The aircraft became Britain's first aircraft to fly under jet power but followed the German Heinkel He 178 and Italian Caproni-Campini N.1 (both detailed elsewhere on this site) into the air when it joined them in aviation history during its maiden flight in May of 1941.
Work on the design began in August of 1939, a month before the official start of World War 2. Studies then followed that included wind tunnel testing and this work resulted in a very modern-looking aircraft featuring a nose-mounted intake, single-finned tail unit, low-set monoplane wings (straight) and retractable tricycle undercarriage. The sole pilot sat just aft of the nose section and ahead of the mainplanes. The mainplanes were situated ahead of midships. The engine, buried within the aft-section of the fuselage, exhausted through a circular port at the rear, just under and aft of the tail fin.
Dimensions included a length of 25.3 feet, a wingspan of 29 feet and a height of 8.9 feet. Empty weight was 2,885lb against an MTOW of 3,750lb.
Fitted with a Power Jets (the company founded by Whittle) W1X turbojet, taxiing trials were had in April of 1941 and the aircraft went airborne for a short "hop" that month. Under tight security, the official first-flight was then recorded on May 15th, 1941 and proved the design, and its engine, wholly sound. In January of 1942, the airframe received the newer, more powerful Power Jets W1A which promised an output of 1,050lb and, in time, the aircraft was able to consistently reach speeds of 365 miles per hour. The second prototype carried the Rolls-Royce W2B turbojet (1,350lb thrust output) and this example was first-flown on March 1st, 1943 and managed speeds nearing 435 miles per hour.
For June of 1943, an even more powerful turbojet design outputting 1,520lb thrust was fitted and flown with success though, with the increase in performance, engineers had to overcome various speed-related obstacles inherent in high-speed flying so revisions to the airframe were made as needed; both pilots and engineers were to learn the nuances of high-speed flying as this advanced propulsion program evolved.
Before the end, the E.28/39 aircraft managed to record a top speed of 505 miles per hour and reach altitudes beyond 30,000 feet with seemingly relative ease. Testing continued into 1944 by which point the design had more or less completed its project goals and laid the framework for more advanced forms to follow. The first prototype ended its days as a museum piece at the Science Museum of London in 1946. The second prototype was lost during testing due to an aileron failure in flight.
While the E.28/39 was, at one point, seen as a true combat warplane end-product (pending the outcome of its test phase), it was never fitted with the proposed 4 x 7.7mm Browning machine gun battery originally envisioned.