Jet aircraft
Jet aircraft generally cruise most efficiently at about Mach 0.8 (981 km/h (610 mph)) and at altitudes around 10,000–15,000 m (33,000–49,000 ft) or more.
A wide range of different types of jet aircraft exist, both for civilian and military purposes.
[2] After other jet engines had been run, Romanian inventor Henri Coandă claimed to have built a jet-powered aircraft in 1910, the Coandă-1910.
[3] In fact the ducted-fan engine backfired, setting the aircraft on fire before any flights were ever made, and it lacked nearly all of the features necessary for a jet engine - including a lack of fuel injection, and any concern about hot jet efflux being directed at a highly flammable fabric surface.
Rocket-engine research was being carried out in Germany and the first aircraft to fly under rocket power was the Lippisch Ente, in 1928.
The first turbojet aircraft to fly was the Heinkel He 178, on August 27, 1939 in Rostock (Germany), powered by von Ohain's design.
[7][8] The first flight of a jet-propelled aircraft to come to public attention was the Italian Caproni Campini N.1 motorjet prototype which flew on August 27, 1940.
[9] It was the first jet aircraft recognised by the Fédération Aéronautique Internationale (at the time the German He 178 program was still kept secret).
[10] The United States Bell XP-59A flew on October 1, 1942, using two examples of a version of the Whittle engine built by General Electric.
The Messerschmitt Me 262 was the first operational jet fighter,[15] manufactured by Germany during World War II and entering service on 19 April 1944 with Erprobungskommando 262 at Lechfeld just south of Augsburg.
An Me 262 scored the first combat victory for a jet fighter on 26 July 1944, the day before the British Gloster Meteor entered operational service.
The Me 262 had first flown on April 18, 1941, but mass production did not start until early 1944, with the first squadrons operational that year, too late for any effect on the outcome of the World War II.
[citation needed] Around this time, mid 1944, the United Kingdom's Meteor was being used for defence of the UK against the V-1 flying bomb – the V-1 itself a pulsejet-powered aircraft and direct ancestor of the cruise missile – and then ground-attack operations over Europe in the last months of the war.
In 1944 Germany introduced the Arado Ar 234 jet reconnaissance and bomber aircraft into service, though chiefly used in the former role, with the Heinkel He 162 Spatz single-jet light fighter appearing at the end of 1944.
The Imperial Japanese Navy also developed jet aircraft in 1945, including the Nakajima J9Y Kikka, a modified, and slightly smaller version of the Me 262 that had folding wings.
Brown, flying in an F-80, intercepted two North Korean MiG-15s near the Yalu River and shot them down in the first jet-to-jet dogfight in history.
BOAC operated the first commercial jet service, from London to Johannesburg, in 1952 with the de Havilland Comet jetliner.
However, due to a design defect, and use of aluminium alloys, the aircraft suffered catastrophic metal fatigue which led to several crashes,[16] which gave time for the Boeing 707 to enter service in 1958 and thus to dominate the market for civilian airliners.
The underslung engines were found to be advantageous in the event of a propellant leak, and so the 707 looked rather different from the Comet: the 707 has a shape that is effectively the same as that of contemporary aircraft, with marked commonality still evident today for example with the 737 (fuselage) and A340 (single deck, swept wing, four below-wing engines).
Turbofan aircraft with far greater fuel efficiency began entering service in the 1950s and 1960s, and became the most commonly used type of jet.
The Space Shuttle, while far faster than the X-43 or X-15, was not regarded as an aircraft during ascent as it was carried ballistically by rocket thrust, rather than the air.
The Bell 533 (1964), Lockheed XH-51 (1965), and Sikorsky S-69 (1977-1981) are examples of compound helicopter designs where jet exhaust added to forward thrust.
Jet-powered wingsuits exist – powered by model aircraft jet engines – but of short duration and needing to be launched at height.
For a long range jet operating in the stratosphere, the speed of sound is constant, hence flying at fixed angle of attack and constant Mach number causes the aircraft to climb, without changing the value of the local speed of sound.
