The Gloster E twenty-eight thirty-nine and the secret jet that changed everything on May fifteenth, nineteen forty-one

On May 15, 1941, test pilot Flight Lieutenant P.E.G. “Gerry” Sayer lifted the Gloster E.28/39 off a grass strip at RAF Cranwell, Lincolnshire, completing a 17-minute flight that proved jet propulsion could power an aircraft. The flight validated over a decade of work by Frank Whittle, whose turbojet concept had been dismissed, defunded, and nearly abandoned by the British government before transforming aviation forever.

Why Was Britain Building a Jet in the Middle of the Blitz?

By spring 1941, Britain was under relentless bombardment. The Luftwaffe dominated the night sky, and the country was fighting for survival. Yet on a closed airfield in the English countryside, a small aircraft with no propeller was being prepared in near-total secrecy. Most of the Royal Air Force didn’t even know it existed.

The E.28/39 was not a fighter or a bomber. It was a flying laboratory, built for a single purpose: to prove that Frank Whittle’s jet engine could make an airplane fly. The Gloster Aircraft Company, under chief designer George Carter, built the airframe around Whittle’s W.1 turbojet engine.

Frank Whittle: The Engineer Nobody Believed

Whittle conceived the jet engine in 1928 as a 21-year-old flight cadet at Cranwell — the same airfield where the E.28/39 would eventually fly. His thesis argued that aviation’s future lay not in bigger, faster propellers but in continuous combustion and turbine-driven thrust.

His instructors found it interesting. The Air Ministry found it impractical. The patent office granted him a patent in 1930, then the government let it lapse because nobody would pay the five-pound renewal fee.

Whittle refused to quit. He secured private funding, founded a company called Power Jets, and built test engines that shook themselves apart on the bench. His first engine ran in April 1937 — and surged so violently that everyone in the room fled as fuel ignited in uncontrolled gouts of flame. The physical and mental toll was enormous. Whittle suffered a breakdown, relying on Benzedrine to work and sedatives to sleep.

Germany Got There First

While Whittle struggled for support, German engineer Hans von Ohain was pursuing the same concept with full government backing. He had a jet engine running on hydrogen in 1937, and on August 27, 1939 — days before the war began — the Heinkel He 178 completed the world’s first jet-powered flight.

Germany’s success finally forced the Air Ministry’s hand. Suddenly very interested, the government contracted Gloster to build an airframe for Whittle’s engine.

What Made the E.28/39 Different?

The aircraft was tiny: a 25-foot wingspan, low-wing monoplane with a bubble canopy that looked almost like a sports plane next to the Spitfires and Hurricanes of the day. The most obvious difference was the absence of a propeller anywhere on the aircraft.

The W.1 engine produced roughly 860 pounds of thrust — modest compared to the Rolls-Royce Merlin’s thousand-plus horsepower in a Spitfire. But the jet eliminated the propeller, the reduction gearbox, and much of the complexity of a piston engine. Its value was not in what it could do that day but in what the technology would become.

The Flight That Changed Everything

Sayer had been conducting high-speed taxi runs for weeks — lifting the tail, even making brief hops where the wheels left the ground. On the evening of May 15, with a small group of officials watching and the airfield closed to all other traffic, he opened the throttle.

Every witness recalled the sound. No hammering pistons. No propeller slap. Just a high, smooth whistle building into a continuous rushing roar. One observer compared it to a giant blowtorch. Another said it sounded like tearing silk, magnified a thousand times.

Sayer flew for 17 minutes, then landed and taxied back. He reportedly called it the simplest, most straightforward airplane he had ever flown — no torque from a spinning propeller, no vibration from piston firing, just smooth continuous thrust. The small group standing on that grass airfield knew they had watched the world change.

A Secret Birth for the Jet Age

Almost nobody was told. The project was classified. There were no newsreels, no headlines, no victory laps. Britain was fighting for its life, and the jet engine was a secret weapon. Whittle couldn’t talk about it. Sayer couldn’t talk about it. The Gloster workers who built the airframe knew only what was strictly necessary.

Over subsequent flights, the E.28/39 reached speeds of approximately 370 mph in level flight — competitive with the best piston-engine fighters of the era, despite being merely a testbed with a modest engine.

Gerry Sayer: The Forgotten First

History has not given Sayer his due. He was Gloster’s chief test pilot — quiet, professional, meticulous. He had flown the Gloster Gladiator, the last biplane fighter in RAF service. He became the first person in Britain to fly a jet aircraft.

On October 21, 1942, Sayer was killed during a routine test flight in a Hawker Typhoon. The aircraft went into the Severn Estuary, and his body was never recovered. He was 37 years old — gone before the jet age he helped launch truly began.

From Testbed to Combat: The Gloster Meteor

The E.28/39 led directly to the Gloster Meteor, the first Allied jet fighter to enter combat. By the summer of 1944, Meteors were intercepting V-1 flying bombs over England. Though they never met the German Me 262 in aerial combat, they proved the Allies had closed the jet gap. Every step traced back to that small aircraft on a grass strip and the engine nobody wanted to fund.

What Happened to Frank Whittle?

After the war, Whittle received a knighthood and £100,000 from the Royal Commission on Awards to Inventors. But real-time credit for one of the most transformative inventions in human history largely eluded him. He spent his later years in the United States, teaching at the U.S. Naval Academy in Annapolis, and died in 1996.

The jet engine now powers every commercial airliner, every military fighter, and every turboprop on a regional commuter. It all began with a thesis nobody believed, an engine that nearly destroyed its creator, and a 17-minute flight over the Lincolnshire countryside.

Where to See the E.28/39 Today

One of the original airframes is on display at the Science Museum in London. The second prototype is at the Jet Age Museum in Gloucester. The Whittle papers are held at the Royal Air Force Museum for those who want to explore the full story.

Key Takeaways

The Gloster E.28/39 made Britain’s first jet flight on May 15, 1941, piloted by Gerry Sayer at RAF Cranwell in a 17-minute sortie.
Frank Whittle conceived the jet engine in 1928 but spent over a decade fighting institutional indifference — the government once let his patent lapse over a five-pound fee.
Germany flew the first jet aircraft (the He 178) in August 1939, which finally spurred British investment in Whittle’s work.
The E.28/39 led directly to the Gloster Meteor, the first Allied jet fighter to see combat in World War II.
Gerry Sayer, Britain’s first jet pilot, was killed in 1942 at age 37 during an unrelated test flight, before the jet age fully arrived.