Thursday, October 30, 2008

Weight and balance calculations

From Wikipedia, the free encyclopedia

When determining whether an aircraft is properly loaded, the pilot must answer two questions:

  1. Is the gross weight less than or equal to the maximum allowable gross weight?
  2. Is the center of gravity within the allowable CG range, and will it stay within the allowable range as fuel is burned off?

To answer the first question, just add the weight of the items comprising the useful load (pilot, passengers, fuel, oil, if applicable, cargo, and baggage) to the basic empty weight of the aircraft. Check that the total weight does not exceed the maximum allowable gross weight.

To answer the second question, the pilot needs to use CG or moment information from loading charts, tables, or graphs in the manual. Then calculate the loaded moment and/or loaded CG and verify that it falls within the allowable CG range, also shown in the manual.

The location of the reference datums is established by the manufacturer and is defined in the aircraft flight manual. The horizontal reference datum is an imaginary vertical plane or point, arbitrarily fixed somewhere along the longitudinal axis of the aircraft, from which all horizontal distances are measured for weight and balance purposes. There is no fixed rule for its location. For helicopters, it may be located at the rotor mast, the nose of the helicopter, or even at a point in space ahead of the helicopter. While the horizontal reference datum can be anywhere the manufacturer chooses, most small training helicopters have the horizontal reference datum 100 inches forward of the main rotor shaft centerline. This is to keep all the computed values positive. The lateral reference datum, is usually located at the center of the helicopter.[3]

See also

References

  1. ^ "Aircraft Flying Handbook" (PDF). Federal Aviation Administration (2004).
  2. ^ a b "Aircraft Weight and Balance Handbook" (PDF). Federal Aviation Administration (2007).
  3. ^ "Rotorcraft Flying Handbook" (PDF). Federal Aviation Administration (2000).

External links

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