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The Air Force Medical Services worked first on the "partial-pressure suit," which covers the trunk, arms and legs but leaves the hands and head free. The Navy took the job of trying to devise a full (i.e., overall) pressure suit without the disadvantages of "frozen" joints and clubfingers. Now the Air Force is trying to improve on the Navy's work, and under military security both services are testing suits that they believe are markedly superior to any models the public has been told about. In everyday use, the "partial" suit is worn with a pressurized crash helmet, and the two are hooked together to give an almost full pressure suit, still leaving the hands free. But this rig will not give as much protection against the bends or the boiling of blood as an overall pressure suit.
Another type of suit is needed to counteract the effect of gravity forces. "G suits" do that job in the crudest way possible—by restricting the flow of blood. The G suit looks like a pair of close-fitting overalls, with five rubber bladders set in: one over the belly, two over the thighs, and a pair around the calves. Automatically inflated, these check the footward blood flow, and they can be deflated for straightaway flight.
Theoretically, the G suit makes it possible for a pilot to tolerate as much as two Gs more than human nature in the raw. In practice, however, any flyer tenses his belly muscles when he is going into a tight turn, and this tends to dam the blood stream. Some authorities question whether it really gives any more protection than good muscle tone, properly used. The Navy's Captain Charles F. Gell believes that the answer to G forces is not a suit but a reclining seat. At the Johnsville (Pa.) Air Development Center, he has experimented with tilt-back models which would enable a pilot to take the stresses fore and aft instead of up and down. But this makes for difficulties in seeing out and handling the controls.
On top of a G suit and a pressure suit, plus helmet and gloves, the pilot must wear protection against cold and immersion (he might have to bail out over the ocean). This means a quilted "liner," much like the Chinese army's winter gear (gadgeteers are trying to save weight and bulk by getting rid of the quilting), with a waterproof suit worn over everything.
By this time the pilot is wearing so many protective layers that he is in danger of stewing in his own juices, so researchers of the U.S.A.F. Air Research and Development Command at Wright Air Force Base have developed a cooling suit to be worn under everything but the underwear. This consists of two layers of rubberized nylon, quilted together, with two sets of air holes. A hose from a valve near the pilot's navel hooks the suit into the plane's air-conditioning system, and cooled air pours through small holes around his body. Warmed and spent, it escapes through larger holes and a set of dump valves.