G-suit
From Wikipedia, the free encyclopedia
A G-suit is worn by aviators and astronauts subject to high levels of acceleration in order to prevent a blackout and g-LOC (g-induced Loss Of Consciousness). Various concepts of the G-suit have been developed. The first two, the Franks Mark I (for the RAF) and Franks Mark II (for the USAF and RCAF) were both hydrostatic and used water filled bladders around the lower body and legs. Later concepts used controlled compressed air to do the same thing because the suits themselves were lighter but this required complex control mechanisms in the aircraft. Recent developments such as the Swiss designed Libelle G-suit designed for use with the Eurofighter have reverted to hydrostatic liquid.
In both hydrostatic and active pneumatic systems the pressure prevents the wearer's blood from pooling in the lower areas of the body and protects the brain from deprivation of blood leading to hypoxia. Hypoxia causes first a brownout (a dimming of the vision), followed by tunnel-vision and ultimately a blackout (unconsciousness).
[edit] History
As early as 1917, there were documented cases of loss of consciousness due to g-forces in pilots. In 1931 a Professor of Physiology from the University of Sydney described a new way of determining the center of gravity of the human body. This made it possible to describe the displacement of mass within the body under acceleration. The first G-suit was developed by a team led by Wilbur R. Franks at the University of Toronto's Banting and Best Institute in 1941, used water filled bladders around the legs and were made to be used by Royal Air Force Hurricane and Spitfire pilots during World War II. U.S. fighter pilots also tested the Franks suit during 1944, but Eighth Air Force pilots found the water system too uncomfortable and were issued an air-inflatable design known as the Berger suit beginning in September 1944.
During the war the German Henschel Hs 132 jet and US XP-79 Flying Ram both had prone positions to minimise G effects. After the end of the Second World War, the British experimented with prone flying positions on a modified Gloster Meteor fighter as a means of overcoming the effects but the development of a practical g-suit terminated the experiments.
the first g-suits were water bags under the pilots legs to keep the blood from pooling up in their legs.
The later fighter jets such as the Eurofighter are much more demanding but by using a modern g-suit such as the Libelle suit a pilot can now be expected to withstand flight forces of 9 to 10g.
Astronauts wear similar G-suits to aviators but face different challenges due to the effects of microgravity. Aviator G-suits apply uniform pressure to the lower legs to minimise the effects of high acceleration but research from the Canadian Space Agency implies there might be a benefit in having a suit for astronauts that uses a "milking action" to increase blood flow to the upper body.
