Pay attention that this page is under construction.
Information inside can be read but shall not be taken as input for any
exam or definite information.
Both helicopter performance and the center of gravity position depends
on proper calculation of it's gross weight and proper balancing of that
weight. This calculation is very important for the safety of a flight.
Based on structural considerations and power availability, every
manufacturer provides specific limiting information on items such as;
Under no circumstances these limitations can be exceeded.
Even though the weight of a helicopter stays within prescribed limits,
if the distribution of this weight has not been made correctly and
center of gravity fall outside of the authorized limits, regardless of
it's weight, such helicopters are categorized as unsafe for flight due
to unsatisfactory balance.
The center of gravity (CG) of a helicopter is the point over which the
helicopter would balance. It directly effects stability and
controllability of the helicopter and should fall within specified
limits established by the manufacturer to ensure safety.
The center of gravity may change over the duration of the flight as the
aircraft's weight changes due to fuel burn or by passengers moving
forward or aft in the cabin.
When the center of gravity is directly under the rotor mast, the
helicopter hangs horizontal; if the CG is too far forward of the mast,
the helicopter hangs with its nose tilted down; if the CG is too far aft
of the mast, the nose tilts up.
When CG is too far forward or aft of the mast due to unsatisfactory
distribution of weight, cyclic inputs are required to compensate center
An aft CG requires forward cyclic input, forward CG requires aft cyclic
input, left CG requires right cyclic input and right CG requires left
cyclic input. The amount of the input depends on the distance of
center of gravity position from datum.
When this distance between CG and datum increases, there comes a CG
position where no more cyclic input is available to compensate. This
situation results with the loss of control of the helicopter.
To avoid this situation, the manufacturers pre-determines the allowable
amount of CG movement that can be safely accepted. The main aim of
weight and balance calculation is to keep the CG inside this safe area.