988. Designing for Growth Using the Growth Probability Concept

Paper

Abstract

This paper proposes, and demonstrates the feasibility of, a technique for evaluating aircraft growth potential during conceptual design. This technique, the Growth Probability Concept, integrates baseline configuration characteristics with technology innovations yielding growth capacity in terms of technology time period and performance retention probabilities.
As will be shown, the probability of retaining or improving performance can be defined for parameters (range, thrust/weight, etc.) individually, in combination, or in total. Data not only indicates growth potential but also gives an indication of design ‘forgiveness’ in the face of prediction errors (weight or performance). The Growth Probability Concept also provides insight into the asymptotic weight growth function described in reference A.
Paragraph 2.0 sets the stage for the Growth Probability Concept by discussing weight growth philosophy. The types and origins of weight growth are illustrated. Effects of technology innovation on growth capability are also discussed. Technology projections with probability of achievement are proposed and described.
Paragraph 3.0 gives the mathemtica1 development of the Growth Probability Concept. The general expression for relating performance variables to performance is developed and the statistical relationships and probability theory are described.
Paragraph 4.0 demonstrates the feasibility of the Growth Probability Concept by showing the results of applying the technique to two distinctly different VTOL configurations (Jet Augmented Wing and Lift + Lift/Cruise) sized for the same mission. Data are shown for various combinations of performance parameters.
Paragraph 5.0 presents the conclusions resulting from use of the Growth Probability Concept. The primary conclusion drawn is that the Growth Probability Concept can be used effectively as part of a design synthesis process.
Paragraph 6.0 suggests further efforts which should prove beneficial in understanding and using the Growth Probability Concept.