This paper presents development of allowable stress estimation methods specifically tailored to
preliminary design weight prediction. The paper presents a unique analytical technique for projecting
test results to cover a large variety of material/temperature combinations, including composite materials.
It is shown how this approach overcomes inaccuracies and limitations associated with stress ratioing
techniques by providing accountability for material strength limitations such as plasticity. Methods for
compression, tension/fatigue and shear are developed. Discussions are limited to primary wing, tail and
body structure. Method application examples are included in the paper.