[Evaluation of +Gz tolerance following simulation of 8-hr flight]

Tolerance of +Gz (head-pelvis) centrifugation of pilots was evaluated following simulation of a long flight on single-seat fighter. The experiment involved 5 test-subjects who were exposed to +Gz before and after simulated 8-hr flight with a growth gradient of 0.1 u/s without anti-g suits and muscles relaxed; in addition, limiting tolerance of intricate profile +Gz loads of 2.0 to 9.0 units with a growth gradient of 1.0 u/s of test-subjects in anti-g suits (AGS) with a change-over pressure valve in the peak mode using muscle straining and breathing maneuvers. To counteract the negative effects of extended flight, various seat configurations: with a back inclination at 30 degrees to the +Gz vector and changeable geometry with a back inclination at 55 degrees to the vector. The other counter-measures applied were cool air shower, suit ventilation, physical exercises, lower body massage with AGS, electrostimulation of the back and lumber region, profiling of the supporting and soft parts of the seat, and 30-s exposure to +5 Gz. Hemodynamic and respiration parameters as well as body temperature were measured in the course of 8 hrs of flight and during and shortly after centrifugation. According to the results of the investigation, seat inclination at 55 degrees to the +Gz vector and tested system of countermeasures prevent degradation of tolerance of large (9 u.) loads following 8-hr flight simulation with the use of the modern anti-g gear,