2 lines about jetplanes
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Answer:
A jet aircraft (or simply jet) is an aircraft (nearly always a fixed-wing aircraft) propelled by jet engines.
EXAMPLE :-McDonnell Douglas DC-10 of Northwest Airlines.
USAF Lockheed Martin F-35 Lightning II
Whereas the engines in propeller-powered aircraft generally achieve their maximum efficiency at much lower speeds and altitudes, jet engines and aircraft achieve maximum efficiency at speeds close to or even well above the speed of sound. Jet aircraft generally cruise at faster than about Mach 0.8 (609 mph, 981 km/h or 273 m/s) at altitudes around 10,000–15,000 metres (33,000–49,000 ft) or more.
The idea of the jet engine was not new, but the technical problems involved did not begin to be solved until the 1930s. Frank Whittle, an English inventor and RAF officer, began development of a viable jet engine in 1928,[1] and Hans von Ohain in Germany began work independently in the early 1930s. In August 1939 the turbojet powered Heinkel He 178, the world's first jet aircraft, made its first flight. A wide range of jet aircraft exist, both for civilian and military purposes.