[Effects of extended flight factors on +Gz tolerance]

Tolerance of single-seat fighter pilots to +Gz loads in long missions was evaluated. In centrifuge experiments, after 5-hr flight simulation 6 test-subjects were exposed to +Gz with a growth rate of 0.1 u/s using muscular relaxation but not anti-G suit (AGS), and to complex-profile ultimate +Gz (2.0 to 9.0 units) with a growth rate of 1.0 u/s with AGS-3 and anti-G straining maneuvers. Pre-experimental data about the subjects' tolerance to +Gz by similar protocols were used as control. Hemodynamic parameters were measured during and immediately after centrifugation. Strength of the leg muscular effort was determined during the centrifuge runs. External respiration and gas exchange parameters were evaluated immediately after centrifugation. Results of the experiments made it evident that 5-hr flight simulation impairs pilot's functional state and tolerance of high +Gz loads, as incidence and severity of visual disorders and cardiac arrhythmias rose and energy expenditure and cervical muscles fatigue increased pointing to the necessity to develop a special purpose preventive system.