Today we are telling the story of Jet Airplanes, it is the “J” invention turn. The jet engine has allowed millions of people now to do something that was barely thinkable just 70 years ago – crossing the Atlantic at speed.
A jet aircraft (or simply jet) is an aircraft (nearly always a fixed-wing aircraft) propelled by jet engines.
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 M 0.8 and around 10,000–15,000 metres (33,000–49,000 ft) or more.
Dr. Hans von Ohain and Sir Frank Whittle are both recognized as being the co-inventors of the jet engine. Each worked separately and knew nothing of the other’s work. Hans von Ohain is considered the designer of the first operational turbojet engine. Frank Whittle was the first to register a patent for the turbojet engine in 1930. Hans von Ohain was granted a patent for his turbojet engine in 1936. However, Hans von Ohain’s jet was the first to fly in 1939. Frank Whittle’s jet first flew in in 1941.
A number of jet power plants were suggested from the first instances of powered flight. René Lorin, Morize, Harris proposed systems for creating a jet efflux. In 1910 the Romanian inventor Henri Coandă filed a patent on a jet propulsion system which used piston-engine exhaust gases to add heat to an otherwise pure air stream compressed by rotating fan blades in a duct.
The “turbojet”, was invented in the 1930s, independently by Frank Whittle and later Hans von Ohain. The first turbojet aircraft to fly was the Heinkel He 178 prototype of the German Air Force, the Luftwaffe, on August 27, 1939 in Rostock (Germany).
The first flight of a jet engined aircraft to come to popular attention was the Italian Caproni Campini N.1 motorjet prototype that flew on August 27, 1940. It was the first jet aircraft recognised by the Fédération Aéronautique Internationale (at the time the German He 178 program was still kept secret). Campini had proposed the motor jet in 1932.
Because of the way they work, the typical exhaust speed of jet engines is transonic or faster, therefore most jet aircraft need to fly at high speeds, either supersonic or speeds just below the speed of sound (“transonic”) so as to achieve efficient flight. Aerodynamics is therefore an important consideration.
Jet aircraft are usually designed using the Whitcomb area rule, which says that the total area of cross-section of the aircraft at any point along the aircraft from the nose must be approximately the same as that of a Sears-Haack body. A shape with that property minimises the production of shockwaves which would waste energy.