A MATHEMATICAL-MODEL OF G-TIME-TOLERANCE

We propose a model to explain experimentally observed effects of Gz on set rates and levels on the time of occurrence of loss of vision and/o r consciousness. The model is based on the existence of two generally accepted parameters: a G limit beyond which cerebral perfusion ceases, and a buffer time between loss of perfusion and loss of function. Whe n applied to ramp onset G profiles, the model predicts a generally hyp erbolic locus of end-points, similar to the well-known Stoll curve, ex cept for the dip. The advantage of the model is its applicability to a ny G onset profile. Data from the literature support the assumptions o f the model and its results, including the absence of the dip in the l ocus for a ramp onset. The results call into question some concepts us ed to design G avoidance inflight strategies and the usefulness of som e experimental centrifuge methods. The model may enable an increase in the accuracy of predictions of the time of visual or cerebral loss of function under various G profiles.