2455. Weighing a Beluga (A300-600ST) Nose Up to Determine the Vertical Center of Gravity

Paper

Abstract

Federal Aviation Administration regulations require that all civil aircraft are weighed to determine the center of gravity (CG) location and the empty weight in order to establish a basis for weight and balance computations. Normally the weighing is conducted prior to ground vibration tests, first flight or delivery of the aircraft. From the weighing results Manufacturer Weight Empty (MWE), Operational Weight Empty (OWE) and the CG of the aircraft are calculated and provided to the customer. In order to determine the weight and the longitudinal center of gravity weighing the aircraft in level attitude is sufficient and common practice. For the A300-600ST Beluga the knowledge of the longitudinal CG is not enough. The unconventional shape and the variety of payloads which are transported mostly in the main cargo compartment requires also knowledge of the vertical CG of the empty aircraft. The position of the vertical CG is necessary for airplane control and stability investigations and the determination of ground loads. Dynamic braking, for example, a load case which occurs when the take off with maximum take off weight is aborted, causes the maximum nose landing gear load and the maximum compression in the upper front fuselage sections. To determine the CG in the z-direction it is necessary to weigh the aircraft in two different attitudes. At first the weighing is performed with the aircraft in level attitude. Then the aircraft is lifted at the nose wheel and weighed again in the nose up position. Lifting the aircraft at the nose landing gear was one part of the challenge, the other was to measure precisely nose up angle and wheel-base for the final calculation. This paper describes the methodology that was developed and the weighing of aircraft number four which took place in May 1998 in Toulouse, France.