Fighter Combat

376 TACTICAL INTERCEPTSalso have the effect of reducing the pilot's visual depth of field. All flightgear, and anything else inside the cockpit, should be dark colored andnonreflective. Otherwise, they will cast light-colored images on thecanopy, severely restricting visibility. Canopies must be kept spotless andfree of scratches. Touching a canopy is a hanging offense. A hard helmetshould be covered with some soft material to avoid canopy scratches.Whenever you're over the lines you have to keep twisting your neck in alldirections every minute, or you're sure to be surprised.Captain Edward V. "Eddie" Rickenbacker, USASRear-view mirrors have been used on many fighters for some time now,generally with good success. When properly placed they can significantlyexpand the pilots' rearward field of view. This is the purpose to which theyshould be put, however; they should not be used as an excuse for notturning the entire head and body to cover those areas that can be seenwithout the aid of the mirrors. Mirror placement is quite important;mirrors must be located outside the canopy or their effectiveness will benullified by canopy glare and reflections. Aircraft designers resist thisplacement because external mirrors mess up the nice, clean lines of theaircraft and increase drag. This is the same mentality that results infighters being designed with low-drag canopies faired into the fuselagerather than with bubble-type canopies, which provide a much better fieldof view.Monitoring aircraft performance can also be facilitated by design. At thevery least, airspeed and altitude instruments should be large, easy tointerpret, and located as high as possible in the cockpit. A better idea is todisplay this and other critical information on some sort of "head-up display"(HUD) that is focused at infinity, so that the pilot is not requiredto look inside the cockpit at critical moments. Coming inside meansrefocusing and adjusting to cockpit lighting conditions, and then refocusingand readjusting when returning the scan to the outside. HUDs areusually incorporated in the fighter's gunsight, but they can also be part ofthe pilot's helmet, with the display projected on the visor. Each methodhas limitations: the pilot must be looking forward to use the gunsight, andhe requires a visor for the helmet unit.Since much of a fighter's combat time is likely to be spent at high G, theeffect of this acceleration on the pilot's vision is an important consideration.As G increases the heart must work against higher gravity forces topump blood to the pilot's head. The greater the height of the pilot's headabove the level of his heart, the lower the blood pressure to his eyes andbrain will be under these conditions. Under protracted high-G conditions,blood tends to pool in the pilot's lower extremities and abdomen area,denying an adequate blood supply to the head, which affects both visionand brain function. The first noticeable effect is normally "tunnel vision,"which is a gradual reduction of the pilot's field of peripheral vision down toa very few degrees directly along his line of sight. Eventually this "tunnel"can close completely, totally blinding the pilot in what is called a "gray-