47 Fun Facts About Jet Engines

Which fighter takes off vertically by swivelling the four nozzles of its Pegasus turbofan?

The Hawker Siddeley Harrier points its Pegasus engine's four nozzles down to lift off and back to fly; needing no runway, it could be dispersed in wartime away from airfields that were open to attack.

Which German physicist designed the turbojet that became the first to power an aircraft in flight?

Hans von Ohain built his first model with a garage mechanic, Max Hahn; unlike Whittle, he had an aircraft maker funding his work from 1936, and his engine flew in 1939.

What was the world's first aircraft to fly purely on turbojet power, on 27 August 1939?

The Heinkel He 178 made the first purely turbojet flight at Rostock-Marienehe on 27 August 1939; air ministry officials who watched a later demonstration were reportedly unimpressed, and it stayed a one-off experiment.

What was the world's first operational jet fighter, powered by Junkers Jumo 004 engines?

The Messerschmitt Me 262 Schwalbe entered service with Erprobungskommando 262 in April 1944, months before any Allied jet; Hitler insisted it also be reworked as a fighter-bomber.

Which British jet fighter was the only Allied jet aircraft to see combat in the Second World War?

The Gloster Meteor joined 616 Squadron in July 1944, but its pilots were long forbidden to fly over enemy-held territory in case a downed jet handed its secrets to the Germans or the Soviets.

Why did Whittle's original jet engine patent lapse in January 1935?

Whittle let the patent lapse in January 1935 because he could not afford the £5 renewal fee and the Air Ministry declined to pay it; Cranwell friends helped him found a company the next year.

What was the name of the company Whittle formed with two retired RAF servicemen to build his engine?

Power Jets Ltd was formed in 1936 with retired officers Rolf Dudley-Williams and James Tinling; its WU engine first ran on 12 April 1937 and the firm was nationalised in 1944.

What was the first British aircraft to fly with a turbojet, on 15 May 1941?

The Gloster E.28/39 flew officially from RAF Cranwell on 15 May 1941 with Gerry Sayer at the controls; weeks earlier it had already left the ground in short hops during taxi tests.

What was the first US-built jet aircraft, powered by American copies of a British engine?

The Bell P-59 Airacomet first flew in October 1942 on GE-built copies of a Whittle engine flown over from Britain; on the ground it wore a dummy propeller to hide the secret that it needed none.

Jumo 004 designer Anselm Franz later led work on the turbine engine of which US tank?

The M1 Abrams runs on the 1,500-horsepower AGT1500, which grew out of a tank turbine project Franz led at Lycoming in the 1960s; being a turbine, it can burn several fuels, from diesel to jet fuel.

What is the name of the thermodynamic process gas-turbine jet engines operate on?

The Brayton cycle is named for American engineer George Brayton, who built piston engines on the principle from 1872, decades before anyone got a gas turbine to run.

Which component gives a high-bypass airliner engine most of its thrust?

A large fan that pushes air around the core supplies most of the thrust; that slower bypass air is what makes a turbofan far more efficient than a turbojet at airliner speeds.

Which airliner, in service from 1970 with four JT9D engines, first carried passengers on high-bypass turbofans?

The Boeing 747 entered service in January 1970 on Pratt & Whitney JT9Ds, an engine that Boeing and the engine maker had teamed up to develop specially for the new jumbo.

What was the world's first production turbofan engine?

The Rolls-Royce Conway was the first turbofan to enter service, around 1960, but with a bypass ratio of only about 0.3 it was soon overtaken by American engines with bigger fans.

Which aircraft was the first production high-bypass turbofan, the GE TF39, designed to power?

GE designed the TF39 for the Lockheed C-5 Galaxy, promising twice the power of any jet engine then running; its core went on to become the CF6 used on wide-body airliners.

Which airliner engine is rated at about 115,000 lbf of thrust?

The General Electric GE90-115B is rated at about 115,000 lbf and reached 127,900 lbf on test, a record at the time; it became the only engine offered on the longest-range versions of its twin-jet.

The General Electric GE9X was developed exclusively for which airliner?

The GE9X was built solely for the Boeing 777X and set a thrust record of 134,300 lbf on test, but a compressor redesign in 2019 pushed the airliner's first flight back to January 2020.

What is the simplest type of air-breathing jet engine, having no moving parts in the engine proper?

A ramjet has no moving parts in the engine proper; it relies on the vehicle's forward speed to compress intake air, so it cannot produce thrust from a standstill.

What is the defining feature of a scramjet?

Air stays supersonic through the combustor instead of being slowed down first, which only pays off above about Mach 5; a scramjet makes no thrust at low speed, so test vehicles ride a rocket booster first.

Which NASA scramjet test vehicle reached nearly Mach 10 in 2004, a record for an air-breathing aircraft?

The X-43A hit about Mach 9.6, nearly 7,000 mph, on 16 November 2004; a carrier aircraft and a rocket booster took it to speed, and its scramjet then burned for only about ten seconds.

Which German weapon that struck London from June 1944 was propelled by an Argus pulsejet?

The V-1 flying bomb's pulsejet fired about 50 times a second, a drone Londoners learned to fear less than the sudden silence that meant the engine had cut out and the bomb was coming down.

What does an afterburner do?

An afterburner sprays extra fuel into the hot exhaust, where it burns for a burst of thrust; it drinks fuel so fast that pilots light it only for take-off, combat or going supersonic.

What was the world's first commercial jet airliner, which entered service in 1952?

The de Havilland Comet entered BOAC service in May 1952 with four Ghost turbojets buried in the wing roots; three fatal in-flight break-ups in 1953–54 grounded it and handed the market to American rivals.

What phenomenon, poorly understood at the time, made two early jet airliners break up in flight in 1954?

Metal fatigue cracked the pressurised cabin skin at the corners of cut-outs; investigators proved it by sinking a whole fuselage in a water tank and pressurising it again and again until it split.

The aeolipile described by Hero of Alexandria, often called the first reaction engine, spun on jets of what?

Steam from a heated vessel shot out of two bent nozzles and spun the sphere by the same action and reaction that drives a jet; described in the first century AD, and no practical use of it is recorded.

US Airways Flight 1549 ditched in the Hudson River in 2009 after both engines swallowed which birds?

Canada geese, identified from remains in the engines, are heavier than the birds an airliner engine is built to swallow and keep running; both engines failed at about 2,800 feet, yet all 155 aboard survived.

What did British Airways Flight 9 fly through in 1982 that stopped all four of its engines?

A cloud of volcanic ash from Indonesia's Mount Galunggung melted inside the engines and choked them; as the airliner glided down into clear air the ash hardened and broke away, and the crew restarted all four.

The white contrails behind high-flying jets form mainly from which product of burning jet fuel?

Water vapour in the exhaust condenses and freezes into ice crystals in the cold air at cruising height; a trail may vanish in seconds in dry air or linger and spread when the air is humid.

What was the first production afterburning turbofan, which powered the F-111 Aardvark and F-14 Tomcat?

The Pratt & Whitney TF30 was the first production afterburning turbofan, powering the F-111 from 1967 and the original F-14A; later Tomcats switched to the GE F110.

Which Soviet interceptor exceeded Mach 2.8 on two Tumansky R-15 turbojets?

The MiG-25's two Tumansky R-15 turbojets pushed it past Mach 2.8; Viktor Belenko's 1976 defection to Japan let Western engineers examine one closely.

Which turbofan-powered car set the first supersonic land speed record in 1997?

ThrustSSC reached 763 mph in Nevada's Black Rock Desert on two afterburning Rolls-Royce Speys of the type fitted to British Phantoms; RAF pilot Andy Green drove it, 50 years and a day after Chuck Yeager's first supersonic flight.

What was the first aircraft to fly powered solely by propfan engines?

The Antonov An-70 transport, first flown in December 1994, is powered by four Progress D-27 propfans driving contra-rotating propellers; Western propfan testbeds like the MD-80/GE36 flew one demonstrator engine only.

Which Mach 2 airliner got about 63% of its thrust from its air intakes?

Concorde's intakes slowed Mach 2 air to subsonic speed before it reached the engines, and the pressure that built up inside them pushed the airframe forward, leaving the engines themselves about 8% of the thrust.

Which twin-engine airliner flew the first 120-minute ETOPS transatlantic service, for TWA in 1985?

The Boeing 767 opened TWA's Boston–Paris ETOPS route in February 1985; in-flight engine shutdowns, once about 40 per 100,000 flight hours, were falling towards fewer than one, which made twin-jets safe to cross oceans.

What limit pushed engineers toward jets before the Second World War?

Propeller tips nearing the speed of sound lose efficiency, which capped how fast piston aircraft could fly; a gas turbine that drives its own compressor from the exhaust offered a way past that barrier.

Which gas fuelled Germany's first experimental jet engine, the HeS 1 rig of 1937?

Hydrogen let the designers put off the hard problem of burning liquid fuel steadily and prove the turbine first; the 1937 HeS 1 was a bench rig, never meant to fly.

Which type of compressor did Whittle ultimately concentrate on for his engines?

Whittle concentrated on the centrifugal compressor, the type already proven in superchargers and the simpler choice, while Junkers and BMW in Germany went for slimmer axial designs.

Jet A-1, the standard fuel for jet airliners, is a highly refined form of what?

Kerosene is far less volatile than petrol, with a flash point of about 38°C, so it is safer to store and handle; jet grades are also refined to stay liquid in the deep cold at cruising height.

The hottest turbine blades in a modern jet engine are cast from superalloys based on which metal?

Nickel superalloys keep their strength at extreme heat, and many blades are grown as a single crystal so there are no grain boundaries to creep apart; cooling air and ceramic coatings do the rest.

Why was the teenage Whittle first turned down as an RAF apprentice in 1923?

He was too short: only five feet tall, Whittle failed the RAF medical, built himself up on a physical training instructor's diet and exercise plan, and was accepted as an apprentice later in 1923.

What was the world's first operational jet bomber, powered by two Jumo 004s?

The Arado Ar 234 Blitz flew its first mission in August 1944, a reconnaissance run over the Normandy beachhead; at about 735 km/h it simply outran the piston-engined fighters sent after it.

Which US aircraft's J58 engines burned JP-7, a fuel made deliberately hard to ignite?

The SR-71 Blackbird flew so fast that its airframe grew hot and its fuel doubled as coolant, so JP-7 had to resist igniting; starting the engines took a shot of triethylborane, which burns on contact with air.

Which Soviet fighter flew on the Klimov VK-1, derived from the Rolls-Royce Nene?

The MiG-15's Klimov VK-1 descended from Rolls-Royce Nene engines that Britain agreed in 1946 to sell to the USSR; the fighter was meeting US F-86 Sabres over Korea by late 1950.

Which US bomber, introduced in 1955, flies on eight jet engines paired in four underwing pods?

The B-52 Stratofortress has kept its eight-engine layout for seven decades; in 2021 the US Air Force chose new Rolls-Royce F130 engines to replace its 1960s TF33s and keep it flying into the 2050s.

The sawtooth chevrons cut into the rear edge of some jet engine nozzles are there to reduce what?

Noise falls because the sawtooth edges smooth the mixing of hot core exhaust with the cooler air from the fan, calming the turbulence that makes a jet roar; NASA helped develop them with engine makers.

The sound from shockwaves at a turbofan's supersonic fan-blade tips at takeoff is nicknamed what?

The 'buzz saw' sound comes from shockwaves off supersonic fan-blade tips at take-off power; it replaced the raw roar of pure turbojets once high-bypass turbofans arrived.

Which was the first US-built jet airliner to enter service, in October 1958?

Pan Am's Boeing 707 began New York–Paris service on 26 October 1958; Boeing had staked $16 million of its own money on the prototype after the Air Force showed no interest in a jet tanker.