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April 12, 1937

Power Jets WU

Frank Whittle runs the experimental Power Jets WU turbojet at Rugby

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Whittle closed the fuel valve and the engine kept accelerating, shrieking, its combustion casing glowing red.

12 April 1937, at the Rugby works

Frank Whittle and Power Jets began running the complete experimental WU turbojet at the British Thomson-Houston works in Rugby on 12 April 1937. Whittle was 29.

The run was alarming rather than smooth. The engine accelerated beyond his control, the combustion-chamber casing showed red-hot patches, and closing the fuel valve did not immediately stop the rise.

The uncontrolled acceleration stopped at about 8,000 rpm and then subsided.

Fuel in the bottom of the chamber

Investigators determined that fuel left pooled in the combustion chamber by earlier pump tests had ignited, causing the runaway.

Financial constraints had forced Whittle to test a complete engine without a full programme of separate component trials.

Another attempt the following evening reportedly produced the same behaviour; modifications were needed before controlled running was achieved, and development continued through the summer.

The disputed first — and an engine that never flew

12 April is the best-supported date, given in Whittle's own James Clayton Lecture and in the Rugby sources, though a National Academy of Engineering biography prints 12 March 1937 without explaining the discrepancy. The place is not in question. The larger dispute is the claim that the run was unquestionably the world's first operating turbojet.

The Smithsonian and the US National Academies place Hans von Ohain's hydrogen-fuelled HeS 1 run in early 1937 or March 1937, potentially before Whittle, while a Cambridge chronology based on Ernst Heinkel's memoir dates that German run to September. Sources also distinguish an experimental hydrogen demonstrator from a liquid-fuelled practical turbojet.

The WU was an experimental bench engine and never powered an aircraft; the later Power Jets W.1 powered the Gloster E.28/39 on Britain's first jet-aircraft flight in 1941.

Sources

Researched 23 Aug 2026 7 sources 3 audit passes, 1 issue open Date disputed

How this was checked

Researched from the web into a fact sheet, rewritten from that sheet, then audited against it by a different model. How the pipeline works →

Date disputed. Sources disagree about when this happened.

What the sources leave uncertain

  • The date and place of Whittle's WU run are strongly attested. The disputed element is the claim that it was unquestionably the world's first operating turbojet.
  • The Smithsonian and US National Academies place Hans von Ohain's hydrogen-fueled HeS 1 run in early 1937 or March 1937, potentially before Whittle. A Cambridge chronology based on Ernst Heinkel's memoir dates that German run to September. Different sources also distinguish between an experimental hydrogen demonstrator and a liquid-fueled practical turbojet.
  • The WU was an experimental bench engine, not a flight-qualified engine intended to be installed in an aircraft.

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