Unsourced material may be challenged and removed. Ballast is removable or permanently installed weight in an aircraft used to bring the center of gravity into the allowable range. The Center of gravity formula pdf limits are indicated in the airplane flight manual.

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. The location of the reference datum is established by the manufacturer and is defined in the aircraft flight manual. The horizontal reference datum is an imaginary vertical plane or point, placed 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, and it may be located forward of the nose of the aircraft. 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┬áinches 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. The further an object is from this point, the greater the force it exerts. Moment is calculated by multiplying the weight of an object by its arm. A specific chord line of a tapered wing. At the mean aerodynamic chord, the center of pressure has the same aerodynamic force, position, and area as it does on the rest of the wing.