The need of a counter pressure jerkin in the JAS 39 Gripen anti-G protection system

Authors:

  • Grönkvist Mikael
  • Bergsten Eddie
  • Eiken Ola

Publish date: 2006-01-01

Report number: FOI-R--2177--SE

Pages: 17

Written in: Swedish

Abstract

Background. Positive pressure breathing (PPB) is used in JAS 39 Gripen as part of the anti-G ensemble (AGE-39). PPB is used in combination with a chest-counter pressure (CCP), which consists of an inflatable bladder covering the frontal aspects of the thorax. CCP is expected to lower the expiratory work of breathing, reduce the risk for lung rupture, and increase G-tolerance. In a previous study we did not find any effect of CCP on G-tolerance. The aim of this study was to investigate the effects of the CCP on work of breathing and risk for lung rupture. Methods. Eight male test subjects were exposed to 20 sec of PPB at 1.0 G and seven subjects at 5.6, 7.0, and 8.0 G. Each G-level was accomplished twice, with and without pressurization of the chest bladder. Measurements and calculations were done of the transpulmonary pressure and the work and power of moving the lungs. Results. The transpulmonary pressure was marginally larger without than with CCP at 1.0 G, while CCP did not affect transpulmonary pressure at increased G-load. Nor did the CCP affect work or power of breathing at any G load. Summary. Inflation of the chest bladder does not seem to have any effects on G-tolerance, work of breathing or risk for lung rupture during PPB at high G-loads, and can from these aspects be removed from the AGE-39.