Around the end of the fifteenth century were written what must have been about the first set of airworthiness requirements ever compiled. These were notebooks of Leonardo da Vinci in which he discussed the physics of flight and the design of flying machines. In one of these notebooks he wrote:—“ In constructing wings one should make one cord to bear the strain and a looser one in the same position so that if the one breaks under the strain the other is in position to serve the same function.”

No abstract

Development of the supersonic transport is involving a wide variety of activities in the structural field. Although Concorde is designed for Mach 2, a speed at which aluminum alloys can continue to be used for the primary structure, evaluation of the chosen alloys under complex temperature-stress histories involves considerable laboratory effort. Although many aircraft have already operated under these conditions, none has previously had to last for 50,000 hr. The most significant new design considerations are creep and thermal fatigue. Creep affects the choice of basic material, the design of joints, and the design of structures through its interaction with fatigue life. Thermal stresses, arising from differential expansions within the structure, have a more important effect on fatigue design than on static strength. While the experimental techniques involved are novel, practical methods of accelerated thermal testing using convective heating and cooling are described.

No abstract

No abstract