One of the reasons for why an aircraft stays aloft is that the center of
gravity is located somewhere near the center of lift of the wing. Because the
center of gravity is critical to the aircraft's ability to fly, a determination
of the aircraft's center of gravity and total weight is necessary, and,
required by the FAA, JAR and most other Civil aviation
authorities before every take-off. An overloaded or improperly balanced
aircraft will require more power and greater fuel consumption to maintain
flight, and the stability and controllability will be seriously affected.
Weight
In many general aviation aircraft it is not possible to fill all seats, load
the baggage companment to capacity, carry full fuel, and remain within approved
weight and balance center of gravity (c.g.) limits. In many four-place and
six-place airplanes, the fuel tanks may not be filled to capacity when a full
complement of passengers and their baggage is carried. It will be necessary to
reduce the number of passengers or baggage weight if the proposed flight
distance requires a full fuel load.
Balance
Balance refers to the location of the c.g. along the longitudinal axis of the
aircraft. This is of primary importance to safety of flight. There are forward
and aft limits beyond which the c.g. should not be located for flight. These
limits are established by the aircraft design engineers to assure proper
predictable aircraft control about the horizontal, vertical, and lateral axis.
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