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G Forces
Most maneuvers create only slight, brief G forces. Aerobatics, however, can impose strong, rapidly changing G forces typically ranging from 4–6 positive Gs to minus 3–4 Gs. Competitive aerobatics can produce even greater G loads. Such G loads are more than just uncomfortable—they can incapacitate a pilot who is not trained to handle them. Positive GsRapid pullups and steeply banked, level turns create positive Gs—forces acting in the direction of the pilot's feet. They displace blood and the body's organs toward the lower extremities. As the blood circulation to the brain decreases under positive Gs, the pilot's visual field narrows. If positive Gs increase, the pilot loses color vision and eventually loses consciousness. Negative GsRapid pushovers and "outside" aerobatic maneuvers create negative Gs—forces acting toward the pilot's head. Depending on forces involved and individual tolerance, a pilot may experience discomfort, headache, "redout" caused by excessive blood flow in the eyes, and even unconsciousness. Most people have a much lower tolerance for negative Gs than for positive Gs. Coping With GsPeople adapt to the G forces of flight, so the best strategy for coping with high G loads is to practice aerobatic maneuvers, gradually building up to those that impose the highest G loads. Airshow and competitive aerobatic pilots fly regularly to maintain their G tolerance. They also maintain excellent overall fitness, which helps them handle the physical stress of aerobatic flight. |
When an
aircraft climbs, turns, or changes speed, it experiences G forces—changes in apparent
gravity. For example, a level turn with a 60-degree bank imposes a 2G load on an airplane
and its occupants. Both they and the airplane seem to weigh twice as much as they do when
at rest.