3. Aircraft Accessories – A Weighty Problem

Paper

Abstract

The actual completed weight of today’s airplane, whether its intended function be mi1itry or commercial, is a vital factor not only in performance, but also in its utility to the customer. The answer to the question: ‘how much should it weigh?’ is estimated by the weight engineer; ‘How much may it weigh’ is specified by the aerodynamicist; ‘How much must it weigh?’ is determined by the design, the service, and the structural engineers; but the final weight when the finished article is put on the scales is a compromise answer to these and other important questions, and is the responsibility of practically every man in the organization.
There are five basic engineering principles which enter into the design or the component parts of the airplane: (1) DESIGN, which requires the part to perform its function satisfactorily, to lend itself to economical service and maintenance, and to incorporate aerodynamic refinements where necessary for reduction of drag; (2) SAFETY, demanding structural strength and stiffness consistent with the purpose for which the craft is intended; (3) ECONOMY, which insists on efficient use of material to maintain a high strength/weight ratio; (4) PRODUCTION, requiring adaptability to modern production methods; and (5) COST, which establishes a control to insure a profit commensurate with the capital investment. To combine these principles into a single definition, it might be said that ‘The ideal airplane is one which furnishes maximum utility to the customer, achieves adequate strength with a minimum ‘expenditure of material, and which can be fabricated by production methods at a cost permitting a reasonable profit.’