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Ejection seat

The meaning of «ejection seat»

In aircraft, an ejection seat or ejector seat is a system designed to rescue the pilot or other crew of an aircraft (usually military) in an emergency. In most designs, the seat is propelled out of the aircraft by an explosive charge or rocket motor, carrying the pilot with it. The concept of an ejectable escape crew capsule has also been tried. Once clear of the aircraft, the ejection seat deploys a parachute. Ejection seats are common on certain types of military aircraft.

A bungee-assisted escape from an aircraft took place in 1910. In 1916, Everard Calthrop, an early inventor of parachutes, patented an ejector seat using compressed air.[1]

The modern layout for an ejection seat was first introduced by Romanian inventor Anastase Dragomir in the late 1920s. The design featured a parachuted cell (a dischargeable chair from an aircraft or other vehicle). It was successfully tested on 25 August 1929 at the Paris-Orly Airport near Paris and in October 1929 at Băneasa, near Bucharest. Dragomir patented his "catapult-able cockpit" at the French Patent Office.[note 1]

The design was perfected during World War II. Prior to this, the only means of escape from an incapacitated aircraft was to jump clear ("bail out"), and in many cases this was difficult due to injury, the difficulty of egress from a confined space, g forces, the airflow past the aircraft, and other factors.

The first ejection seats were developed independently during World War II by Heinkel and SAAB. Early models were powered by compressed air and the first aircraft to be fitted with such a system was the Heinkel He 280 prototype jet-engined fighter in 1940. One of the He 280 test pilots, Helmut Schenk, became the first person to escape from a stricken aircraft with an ejection seat on 13 January 1942 after his control surfaces iced up and became inoperative. The fighter had been being used in tests of the Argus As 014 impulse jets for Fieseler Fi 103 missile development. It had its usual HeS 8A turbojets removed, and was towed aloft from the Erprobungsstelle Rechlin central test facility of the Luftwaffe in Germany by a pair of Bf 110C tugs in a heavy snow-shower. At 2,400 m (7,875 ft), Schenk found he had no control, jettisoned his towline, and ejected.[2] The He 280 was never put into production status. The first operational type built anywhere to provide ejection seats for the crew was the Heinkel He 219 Uhu night fighter in 1942.

In Sweden, a version using compressed air was tested in 1941. A gunpowder ejection seat was developed by Bofors and tested in 1943 for the Saab 21. The first test in the air was on a Saab 17 on 27 February 1944,[3] and the first real use occurred by Lt. Bengt Johansson[note 2] on 29 July 1946 after a mid-air collision between a J 21 and a J 22.[4]

As the first operational military jet in late 1944 to ever feature one, the winner of the German Volksjäger "people's fighter" home defense jet fighter design competition; the lightweight Heinkel He 162A Spatz, featured a new type of ejection seat, this time fired by an explosive cartridge. In this system, the seat rode on wheels set between two pipes running up the back of the cockpit. When lowered into position, caps at the top of the seat fitted over the pipes to close them. Cartridges, basically identical to shotgun shells, were placed in the bottom of the pipes, facing upward. When fired, the gases would fill the pipes, "popping" the caps off the end, and thereby forcing the seat to ride up the pipes on its wheels and out of the aircraft. By the end of the war, the Dornier Do 335 Pfeil — primarily from it having a rear-mounted engine (of the twin engines powering the design) powering a pusher propeller located at the aft end of the fuselage presenting a hazard to a normal "bailout" escape — and a few late-war prototype aircraft were also fitted with ejection seats.

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