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What changes if the Centre of Gravity (CG) of a helicopter moves to the forward limit?

  • A

    Not enough cyclic to perform take-off translation roll.

  • B

    Air miles decrease as drag increases.

  • C

    Air miles increase as drag decreases.

  • D

    Not enough cyclic input to perform level flight and hover.

Refer to figure.
Parasite drag is present any time the helicopter is moving through the air. This type of drag increases with airspeed. The non-lifting components of the helicopter, such as the cabin, rotor mast, tail and landing gear contribute to parasite drag. Parasite drag varies with the square of the velocity. Doubling the airspeed increases the parasite drag four times.

When the helicopter is loaded to the forward limit it will have a nose down attitude, exposing a bigger area of the non-lifting components as the helicopter moves through the air. This gives us an increase in parasite drag, leading to a higher power required and fuel consumption.

Specific Air Range is a measure of fuel efficiency and tells us the nautical air mile distance travelled per unit of fuel used:

  • SAR = TAS / FUEL FLOW.

Therefore, an increase of the fuel consumption will cause a reduction of Specific Air Range (air miles).

The question states the Centre of Gravity (CG) is close to the forward limit, which is still within the helicopter's CG limits. Therefore, the options of insufficient cyclic control are incorrect.

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