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What is the ratio Take-off mass to Rotor disc area used to calculate?

  • A
    The coning angle.
  • B
    Disc area density.
  • C
    Rotor disc loading.
  • D
    Power ratio kw to m2.

Refer to figure.
Disc loading is a measure of the amount of weight that a rotor disk must support, and is calculated by dividing the weight of the aircraft by the rotor disk area. It is an important factor in helicopter design, as it affects the helicopter's performance, stability, and maximum weight capacity.

The higher the disc loading, the more weight the rotor disk must support, and the greater the stress on the rotor system. This can make the helicopter more difficult to control and limit its performance capabilities. High disc loading also requires a larger rotor disk area, which increases the size and weight of the helicopter.

Low disc loading, on the other hand, makes the helicopter more stable and easier to control, and allows for a smaller rotor disk area and a lighter helicopter. However, a low disc loading also means that the helicopter is limited in terms of maximum weight capacity.

The formula for helicopter disc loading is:

  • Disc loading = Total Mass / (π * R^2)

Where:

  • Total mass is the total mass of the helicopter, including the weight of the rotorcraft, fuel, and any payload
  • R is the disc area radius
  • π (pi) is a mathematical constant (approximately 3.14)

The equation provides the loading in pounds per square foot (lb/ft²). The rotor diameter is used as the reference area for the loading calculation.

It's important to note that the formula assumes that the load is distributed evenly over the rotor disc, which is not always the case in reality.

In summary, Disc loading is a measure of the amount of weight that a rotor disk must support, and is calculated by dividing the weight of the aircraft by the rotor disk area. It affects the helicopter's performance, stability and maximum weight capacity.

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