HGU-68 COMBAT EDGE
The HGU 68 Combat Edge (Combined Advanced Technology Enhanced Design G Ensemble) was tested by the Swiss AF in the early 2000's.
Combat Edge components act in unison to sense and respond to
high-G conditions. The G-valve sends a signal to the oxygen regulator to increase mask pressure up to 80 millibar (1.2 psi) above ambient.
This same pressure is routed to the occipital bladder in the back of the helmet, causing it to inflate and push the pilot’s face into the oxygen mask.
This same pressure is also sent to the counter-pressure vest to
balance the breathing pressure supplied to the lungs.
Ultimately, Combat Edge maintains pressure in the pilot’s chest cavity to help the heart pump blood to the eyes and brain while
inhibiting the downward blood flow.
The K-12 stencilling at the back of the helmet is in fact the test pilot's nickname.
At the ALSE shop, (the tests/ evaluations took place in the US) during the handover of the CE equipment, it was realized that his name was longer than the maximum number of letters - 12 - the device for printing labels was able to manage.
So, his family name beginning with the letter K, the pilot was pragmatically "awarded" by the K-12 nickname, which he still uses today.
At the same time, the SAF tested the "Libelle" flying suit.
“Libelle” is German for “dragonfly,” because the suit is based on the same principles that protect a dragonfly from the 30-G accelerations the insect generates in flight.
The suit uses 1.13 liters (0.3 US gallons) of liquid to exert counterpressure during acceleration. When acceleration forces push blood toward the lower part of the body, it also pushes the liquid inside the suit in the same direction, providing a counter-pressure that is automatically adjusted by the G-load itself.
The suit uses fluid-filled channels traversing the arms, torso, and legs to tension its snug-fitting fabric. The suit is an autonomous, stand-alone system that does not require air or power from the aircraft.
The suit was tested on the centrifuge at the German Air Force Institute of Aviation Medicine in Königsbrück and in more than
200 flights in SAF Learjets, F-5F's and Mirage III's.
Both tests were stopped due to SAF changes in operational philosopy.