An aircraft has a single-wheel nose gear located 25 cm forward of the datum carrying a load of 125 kg, and a two-wheel main gear positioned 180 cm aft of the datum carrying a single wheel load of 6 200 kg. What is the position of the center of gravity in this configuration?
The nose gear wheel load is 125 kg.
The main gear wheels load is 2 x 6200 kg = 12 400 kg (two wheels with a single wheel load of 6200 kg).
The total mass is the mass of the nose gear load plus the load of the main wheels. Total mass = 125 kg + 12 400 kg = 12 525 kg.
Moment is the turning force created by the mass acting over a distance or arm and is calculated by multiplying the arm by the mass or weight:
- Moment = Arm x Mass
Moments aft of the datum are by convention positive and moments forward of the datum are negative:
- Moment of nose gear = -125 kg x 0.25 m (25 cm) = -31.25 kg m (minus because it is located forward of the datum)
- Moment of the two wheels = +(6 200 kg x 2) x 1.80 m = +22 320 kg m (plus because it is located aft of the datum)
The total moment will be 22 320 kg m - 31.25 kg m = 22 288.75 kg m.
- CG = Total Moment / Total Mass = 22 288.75 kg m / 12 525 kg = 1.7795 m = 177.95 cm aft of datum
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