G-LOC
Enviado: Sáb Dez 08, 2007 2:49 pm
G-Induced Loss of Consciousness
Já que não pudemos discutir esse assunto no tópico aberto sobre a queda do Rafale (fechado prematuramente na minha humilde opiniao), decidi abrir um sobre G-Loc.
As primeiras hipóteses indicam que o piloto perdeu a consciencia e mergulhou de uma altura de 4.000 metros a 900 Km/h, abrindo uma cratera de 10-15 metros, após uma manobra em alto G. Os caças modernos podem manobrar em mais de 9 G's.
Procurei na Wiki (em ingles):
http://en.wikipedia.org/wiki/G-LOC
g-induced Loss Of Consciousness (abbreviated g-LOC) is a condition where a person loses consciousness because g-forces primarily acting along the length of the body move the blood away from the brain to the extent that consciousness is lost.
These conditions are linked to astronauts, pilots of fighter planes and pilots of aerobatic aircraft.
Incidents of acceleration-induced loss of consciousness have caused fatal accidents in aircraft capable of sustaining high-g for considerable periods such as the BAe Hawk, F-16 Falcon and F/A-18 Hornet. As a result, air force training facilities in many countries now include man-rated centrifuges for high-g training in a safe environment. Man-rated centrifuges are made by AMST Systemtechnik in Austria (Austria Metall SystemTechnik), Latacoere in France, the Environmental Tectonics Corporation (EYC) and Wyle Laboratories in the USA.
As g-forces increases, visual effects include loss of colour vision (grey-out), followed by tunnel vision (where peripheral vision is lost, retaining only the centre vision). If g-forces increase further, complete loss of vision will occur, while consciousness remains. These effects are due to a reduction of blood flow to the eyes before blood flow to the brain is lost, because the extra pressure within the eye (intraocular pressure) counters the blood pressure. (The reverse effect is experienced in advanced aerobatic manoeuvres under negative g-forces, where excess blood moves towards the brain and eyes red out.)
The human body has different tolerances for g-forces depending on the acceleration direction. Humans can withstand a positive acceleration forward at a higher g-forces than they can withstand a positive acceleration upwards at the same g-forces. This is because when the body is moving up at such high speeds the blood rushes from the brain which causes loss of consciousness.
A further increase in g-forces will cause g-LOC where consciousness is lost. This is doubly dangerous because, on recovery as g is reduced, a period of several seconds of disorientation occurs, during which the aircraft can dive into the ground. Dreams are reported to follow G-LOC which are brief and vivid.
The g thresholds at which these effects occur depend on the training, age and fitness of the individual. An un-trained individual not used to the g-straining manoevre, can black out between 4 and 6 g, particularly if this is pulled suddenly. A trained, fit individual wearing a g suit and practising the straining manoeuvre, can, with some difficulty, sustain up to 9g without loss of consciousness.
Já que não pudemos discutir esse assunto no tópico aberto sobre a queda do Rafale (fechado prematuramente na minha humilde opiniao), decidi abrir um sobre G-Loc.
As primeiras hipóteses indicam que o piloto perdeu a consciencia e mergulhou de uma altura de 4.000 metros a 900 Km/h, abrindo uma cratera de 10-15 metros, após uma manobra em alto G. Os caças modernos podem manobrar em mais de 9 G's.
Procurei na Wiki (em ingles):
http://en.wikipedia.org/wiki/G-LOC
g-induced Loss Of Consciousness (abbreviated g-LOC) is a condition where a person loses consciousness because g-forces primarily acting along the length of the body move the blood away from the brain to the extent that consciousness is lost.
These conditions are linked to astronauts, pilots of fighter planes and pilots of aerobatic aircraft.
Incidents of acceleration-induced loss of consciousness have caused fatal accidents in aircraft capable of sustaining high-g for considerable periods such as the BAe Hawk, F-16 Falcon and F/A-18 Hornet. As a result, air force training facilities in many countries now include man-rated centrifuges for high-g training in a safe environment. Man-rated centrifuges are made by AMST Systemtechnik in Austria (Austria Metall SystemTechnik), Latacoere in France, the Environmental Tectonics Corporation (EYC) and Wyle Laboratories in the USA.
As g-forces increases, visual effects include loss of colour vision (grey-out), followed by tunnel vision (where peripheral vision is lost, retaining only the centre vision). If g-forces increase further, complete loss of vision will occur, while consciousness remains. These effects are due to a reduction of blood flow to the eyes before blood flow to the brain is lost, because the extra pressure within the eye (intraocular pressure) counters the blood pressure. (The reverse effect is experienced in advanced aerobatic manoeuvres under negative g-forces, where excess blood moves towards the brain and eyes red out.)
The human body has different tolerances for g-forces depending on the acceleration direction. Humans can withstand a positive acceleration forward at a higher g-forces than they can withstand a positive acceleration upwards at the same g-forces. This is because when the body is moving up at such high speeds the blood rushes from the brain which causes loss of consciousness.
A further increase in g-forces will cause g-LOC where consciousness is lost. This is doubly dangerous because, on recovery as g is reduced, a period of several seconds of disorientation occurs, during which the aircraft can dive into the ground. Dreams are reported to follow G-LOC which are brief and vivid.
The g thresholds at which these effects occur depend on the training, age and fitness of the individual. An un-trained individual not used to the g-straining manoevre, can black out between 4 and 6 g, particularly if this is pulled suddenly. A trained, fit individual wearing a g suit and practising the straining manoeuvre, can, with some difficulty, sustain up to 9g without loss of consciousness.
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