A CSU/15P anti-G suit has been acquired which is fed compressed air through a series of electric valves.

The rate of suit inflation is determined by three valves, each of which allows a different rate of airflow. By arranging the valves in a binary format, where the most significant bit allows the most air to pass, and the least significant bit the lowest, a total of 8 different suit inflation rates can be set.

The variable containing the number being sent to the G meter is constantly sampled and triggers the valves beginning at about 4 Gs. The higher the G reading, the faster the suit inflates. When any of the feeder air valves activate, a set of three vent valves close, which allows the suit to pressurize. When the G reading falls below 4 Gs, the feeder valves close and the three vent valves open, thus enabling rapid deflation of the suit.

A safety valve from a real G suit control valve unit has been incorporated into the system. This prevents the suit from over-inflating/bursting and/or crushing the pilot. The effect of being squeezed during high G maneuvers is quite dramatic!

The same pneumatic system also feeds the oxygen diluter-demand control head. This control head is fully functional and indicates the overall system pressure accurately with its built-in meter while feeding ambient or pressurized air to the oxygen mask. The flow indicator also functions correctly and appears whenever the pilot inhales from the mask. I considered feeding pure oxygen into the diluter-demand regulator panel, but backed off when considering the flammability risk of a possible pure oxygen leak.

A pressure sensing switch is also part of the pneumatic system. When pressure from the air compressor falls below 70 PSI, the "OXY LOW" light on the central warning light assembly illuminates until pressure above 70 PSI is restored. Both the G suit and oxygen systems can be disabled from the G suit control panel and powering down the sim will also result in automatic cutoff of air supplied from the compressor and all sim pneumatic systems being vented.

The entire flight gear ensemble features flight coveralls, CSU/15 Anti-G suit, HGU/55P helmet with MBU/12 oxygen mask connected to a CRU-60 which is in turn connected to the ejection seat emergency oxygen system and cockpit's oxygen connection block. I didn't bother to acquire the flight gear until just recently since all of the G suit and oxygen mask systems had to be designed, built and installed first. Naturally, the electronics in the helmet have been traced through all of the interconnecting cables so that the comm system can be made to work.

With the diluter demand set to 100% oxygen you can really hear the air rushing into the mask every time you inhale. When the G suit compresses it squeezes the abdomen, which makes breathing laborious. You can hear the labored breathing through the mask when struggling against the compressing G suit and it creates an incredible overall effect. The HGU-55 helmet is extremely light-weight and can easily rest against the ejection seat which creates a "rumbling" sound since there is a sub-woofer built into the seat kit. I underestimated the dramatic effects of wearing a functional helmet, G suit and oxygen mask and am still amazed at how these items enhance the overall sim experience!