Technology & Medicine › Electric age › The airplane (Wright brothers' first flight)
Jet engine
1937 (Whittle, von Ohain); first jet flight 1939· Invention or discovery· Transport & space
Mostly agreedGood evidence; some details, dates or numbers uncertain.
The jet engine drives an aircraft forward by blasting hot gas backward, letting planes fly faster and higher than propellers allow.
See it on the Technology & Medicine map →How it works
A jet sucks in air, squeezes it with a spinning compressor, burns fuel in it, and blasts the hot gas out the back; on the way out the gas spins a turbine that drives the compressor. Frank Whittle in Britain patented the idea in 1930 and ran an engine in April 1937. Hans von Ohain in Germany ran his later in 1937 and powered the first jet flight, the Heinkel He 178, in August 1939. Jet airliners began with the de Havilland Comet in 1952.
Why it mattered
Jets made air travel fast and affordable, opening mass tourism and global business. The Boeing 707 (1958) and 747 (1970) shrank the world.
Think of it like
Like a balloon let go: air rushing out the back pushes it forward. A jet keeps refilling and heating that air.
How we know
Whittle's 1930 patent and test records, von Ohain's Heinkel papers, and the surviving Gloster E.28/39, Britain's first jet (1941), in London's Science Museum.
Still unknown or debated
Why Britain's Air Ministry was slow to back Whittle, letting Germany fly a jet first, is still debated. The two inventors became friends after the war.
Connections (3)
▸Petroleum industry fuels the Jet engineWell documented
The connection
Jet engines burn kerosene, a petroleum product first refined for lamps in the 1850s. It packs much energy per pound, stays liquid in high-altitude cold, and is safer to handle than gasoline. Jet fuel is now roughly 7% of world oil use, and fuel is one of an airline's biggest costs.
When and how
Kerosene refining from the 1850s in Pennsylvania and Baku; standard jet fuels from the 1940s–50s; Jet A and Jet A-1 power airliners worldwide today.
How we know
Fuel specifications, refinery output data and airline cost reports document the dependence; the airline trade body IATA puts fuel at roughly a quarter of operating costs.
Debates and open questions
Whether sustainable aviation fuels made from waste oils or plants, or hydrogen, can replace petroleum at scale and at an affordable cost is a major open question.
▸The airplane (Wright brothers' first flight) was transformed by the Jet engineWell documented
The connection
Propellers lose efficiency near the speed of sound and in thin, high-altitude air. Whittle saw in 1928 that a gas turbine pushing a jet could fly far higher and faster. Jets nearly doubled airliner speeds and let planes cruise above most weather.
When and how
RAF College Cranwell, England, 1928 (Whittle's idea); first jet flight near Rostock, Germany, August 27, 1939 (Heinkel He 178); jet fighters in combat from 1944.
How we know
Aircraft performance and test-flight records; the de Havilland Comet (1952) and Boeing 707 (1958) cut long-distance flight times dramatically.
Debates and open questions
Early jet airliners had grave problems: 1954 Comet crashes were traced to metal fatigue around window corners, and how to balance speed and safety shaped later designs.
▸Heron's aeolipile (steam toy) shared its reaction principle with the Jet engineMostly agreed
The connection
The aeolipile spun because steam rushing out of its nozzles pushed the sphere the opposite way: action and reaction, later stated as Newton's third law (1687). A jet engine works the same way, compressing air, burning fuel in it and blasting hot gas out the back to push the aircraft forward. The link is shared physics, not direct descent.
When and how
Alexandria about AD 60; England (Frank Whittle) and Germany (Hans von Ohain) in 1937; first jet flight, Heinkel He 178, 1939.
How sure are we?
Engineering histories routinely cite the aeolipile as the first reaction turbine; the physics matches, though Whittle built on gas-turbine work, not Heron.
Debates and open questions
Some argue the aeolipile is closer to a rocket or a reaction steam turbine than a jet; calling it an 'ancestor' is mainly a teaching device.