What are the white trails behind high-flying jets mostly made of?
AnswerIce crystals formed from water vapour
Contrails form when hot, moist engine exhaust meets very cold air and the water vapour freezes into ice crystals.
Vehicles · Facts & stats
Jet facts & stats
7 fact-checked facts about jets and jet engines, each with the reason behind it. 5 more are in today's round and join this page after it closes.
The basics
What causes jet lag?
AnswerCrossing time zones quickly, unsettling the body clock
Fast travel across time zones puts the body's internal clock out of step with local day and night.
Going deeper
Which British engineer patented a turbojet engine design in 1930?
AnswerFrank Whittle
Frank Whittle patented his turbojet idea in 1930, and his engine powered Britain's first jet flight in 1941.
In which direction do the main jet streams generally blow?
AnswerWest to east
The jet streams are fast high-altitude winds that flow mainly from west to east in both hemispheres.
The phrase 'suck, squeeze, bang, blow' describes which stages of a jet engine?
AnswerIntake, compression, combustion, exhaust
Air is drawn in, compressed, burned with fuel, then blasted out as exhaust to make thrust.
Expert level
Which aircraft made the world's first flight powered by a turbojet engine, in 1939?
AnswerHeinkel He 178
The German Heinkel He 178 flew on 27 August 1939, the first aircraft to fly on turbojet power.
In a turbofan engine, what is 'bypass air'?
AnswerAir moved by the fan that flows around the engine core
Most airliner thrust comes from the large fan pushing bypass air around the core, which is quieter and more efficient.
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