Human Tolerance Of Vertical Axis G Force
The tolerance of G forces by human body depends on the magnitude of the g-force, the length of time for which it is applied, its direction and location of application and as well as the posture of the body. In this article we will take a look at the effect of Vertical Axis G Force on humans.
The human body, as we know is flexible and supple. To some extent, g-tolerance can be trainable, but some illnesses, particularly relating to cardiovascular problems, reduce the g-tolerance. Let us know more about Vertical Axis G Force.
Aircraft, in particular, applies g-force along the axis aligned with the spine. This vertical axis G Force causes major variation in blood pressure along the length of the subject's body. This limits the maximum g-forces that can be endured by the human body.
Going in depth on the effect of Vertical Axis G Force on humans, the “upward" g, forces the blood to move downward to the feet of a seated or standing person. The resistance to positive g varies with different individuals. A typical person can bear about 5 g (49m/s²) before G-LOC. But the combination of special g-suits and efforts to strain muscles work together to force blood back into the brain. Today, modern pilots can handle 9 g (88 m/s²) sustained.
The resistance to "negative" or "downward" g, which forces the blood towards the head, is much lower and is typically in the range of −2 to −3 g , or −20 m/s² to −30 m/s² range. The person can experience his vision turning red, which is also known as a red out. This is probably because the capillaries in the eyes swell up or burst under the increased blood pressure.
The g-forces in aircraft are often positive, forcing the blood towards the feet and away from the head. This can lead to problems with the eyes and brain in particular. As vertical axis G force is progressively increased the pilot may experience, a grey-out vision, Tunnel vision, a blackout, which is a loss of vision or a redout, with a reddening of the vision. He may also experience G-LOC a loss of consciousness or even death, if g-forces are not quickly reduced.