1202. Sensitivity of Combat Aircraft Mass to Changes in Structural Design Safety Factors

Paper

Abstract

This paper makes a case for reviewing the level of flight safety factor. The evaluation of the flight safety factor and the area of influence on modern fighter structures are discussed.
The potential savings achievable by reducing flight safety factor from the present level of 1.5 towards unity are evaluated for a range of strike fighter configurations, using both analytical and computer aided design techniques. Also examined is the influence of the potential savings of other design constraints, materials, aircraft configuration and mission.
The particular causes examined demonstrate the trends and orders of savings. However, it is clear from the analysis that the savings can be significantly influenced by the above design parameters and that meaningful generalization cannot be made. It is apparent, however, that significant savings are possible if the design is sized around reduced flight safety factor at the project stage. The examples considered yield savings at combat in the order of 10% if the safety factor is reduced to 1.3, the maximum reduction possible using conventional aluminum alloys. Although limited experience of composites exists, the indications are that comparable or even greater mass savings should be possible.
The current on-going technology research programs such as Active Control Technology (ACT) and advanced structural analysis, make that reduction in flight safety factor on the next generation of aircraft a real possibility.
The proposal is made that flight safety factors should be progressively reviewed, starting with selected areas where there is a high level of confidence in the design and analysis techniques currently practiced.