ANTI-G GARMENTS

Although there is no limit to the speed a human can endure in straight and level flight in an aircraft, changing speed or direction can produce inertia to which the body has a sharply limited tolerance. In the case of extreme stresses exerted by forces of the type met in seat ejection, ditching, or parachute opening shock, the short duration of the force restricts its effects. However, changing the direction of flight often produces stress forces equal to several times the normal value of gravity for periods longer than a second. These forces can have dangerous effects.

At 5 g's (five times the force of gravity), the pilot's body is exposed to a force that increases its weight and that of its components five times. This increased weight has many effects. The pilot is pushed down into his seat. His arms and legs feel like lead, and manipulation of the controls becomes more difficult. In addition, the extra weight of the internal organs causes abdominal and chest discomfort. Most important, however, is the effect on the circulatory system.

At 5 g's the pressure exerted by the column of blood between the head and the heart becomes just about equal to the blood pressure in the arteries. As a result, the pressure supplied by the heart is not great enough to pump an adequate supply of blood to the head.

To counteract these effects, the pressure in the arteries must be increased above the heart level. At the same time, distended vessels and tissue and fluid spaces in the regions below the heart must be restored to normal. This is accomplished by the anti-g garment.

With the anti-g system, compressed air is metered to the garment in proportion to the gravitational force being exerted. The bladders of the garment inflate, compressing the legs and abdomen of the wearer by an amount also proportional to the gravitational force. Thus, the garment prevents blood collecting in the abdomen and lower extremities and forces blood from the lower to the upper part of the body. This effect increases blood flow to the heart and increases resistance to the shifting of blood to the lower limbs. In addition, it raises the diaphragm, decreasing the distance between the heart, the eyes, and the brain. Altogether, it increases the tolerance of the pilot an average of about 2 g's.

Without an anti-g garment, the average pilot can withstand 4.5 to 5.5 g's without losing vision or blacking out. With a garment, he is capable of withstanding 6.0 to 7.0 g's. However, this protection is available only for sustained accelerations of 4 to 5 seconds or longer in maneuvers other than snap maneuvers.

Anti-g equipment does not offer protection in snap maneuvers where 10 to 12 g's can be applied in approximately 1 second. Such brief forces are not as harmful to the body as lesser forces sustained for a number of seconds.

CSU-15/P ANTI-G GARMENT

The CSU-15/P anti-g garment (fig. 4-11) consists of a fire-resistant Aramid cloth outer shell, which houses a bladder. It is cut away at the buttocks, groin, and knees. The outer shell has waist and leg entrance slide fasteners, six adjustment lacing areas with lacing covers, and two easily detached leg pockets with slide fastener closures. The bladder system is constructed of polyurethane-coated nylon cloth and covers the abdomen, thighs, and calves. The bladder system is fitted with a hose for connecting directly to the aircraft anti-g system. This anti-g garment is available in six sizes.

CSU-15/P anti-g garments are issued to individual aircrew members, and are used in conjunction with standard Navy personal equipment.

Fitting the CSU-15/P Anti-g Garment

The CSU-15/P anti-g garment is fitted and adjusted to the aircrew member on a best-fit basis.

Figure 4-11.-CSU-15/P anti-g garment.

The cords are laced in the same direction as the applicable lacing slide fastener closure. With a proper fit, the lace adjustment should be tightened approximately halfway, and the cutout should expose the knees, groin, and buttocks without binding or hindering movement. The garment should fit snugly, but not tight, with the bladder deflated. The inflated bladder should compress the waist, thighs, and calves firmly and evenly.

With bladder deflated, lace adjustments are tightened to provide a snug (not tight) comfortable fit, especially at the waist.

Installing The CSU-15/P Anti-g Garment Hose

This anti-g hose also must be cut to size, and an end fitting installed after correct garment size has been determined. To fit the anti-g hose, proceed as follows:

Have the aircrew member don the anti-g garment and sit in the aircraft. Attach the quick disconnect on the hose to the aircraft supply system. If the hose is too long, measure it and mark where to cut it.

Lay the hose out flat. In a single operation, cut the outer covering, inner hose, and spacer/reinforcement at the mark. Sear completely around the end of the outer cover to prevent fraying.

Remove the tape, clamp, and severed portion of hose from the quick-disconnect connector.

Position the spacer/reinforcement on the rubber extension of the connector (fig. 4-12). Butt the end against the raised portion of the connector, and cover it with three turns of electrical tape.

Slide the inner hose (bladder material) over the connector and butt it against the raised portion of the connector. Ensure the spacer/reinforcement is not twisted. Secure it with three turns of tape.

NOTE: In some instances it may be necessary to build up the outside diameter of the hose area under the clamp with three to six turns of tape to get the clamp tight.

Slide the outer cover of the hose over the inner hose until it butts against the raised portion of the connector. Install a clamp as shown in figure 4-12. Cover the clamp with three turns of tape

or a heat-shrinkable insulation sleeve.

Figure 4-12.-Assembly of hose and quick-disconnect fitting.

Finally, ensure that the fitting is properly inserted in the hose, and clamp it properly positioned between the raised bead and the body. Ensure that the clamp is tightened sufficiently by grasping the hose and fitting and jerking sharply.