The impact of dynamic loads on the design of military aircraft

The layout of military aircraft structures is strongly influenced by dynamic loads from the early development phase onwards up to final design and clearance phase. Different dynamic loads have to be considered namely dynamic gust loads, buffet loads on wing, fin, fuselage and also buffet loads from airbrakes, cavities and blisters, gunfire loads mainly at attachment frames and panels, Hammershock loads for air intake, bird strike and ammunition impact, acoustic loads for outer air intake and missile bays. Also dynamic loads from landing, jettison, brake chute and rough runway induced loads as well as wake induced loads may be designing. Dynamic loads resulting from flight test excitation like bunker input, stick jerks and control surface sweeps also have to be considered. For some of the designing dynamic loads examples are given to explain their derivation and significance both for design of aircraft structural parts and related clearance aspects. Methods to derive dynamic design loads for different application by using analytical and experimental tools will be presented. Validation methods for various design loads using dynamic model test results, windtunnel model and flight rest results are mentioned. Main purpose of this presentation is to indicate where dynamic loads would be dimensioning structures of future high performance combat airplanes and how to approach the problem of integrating all aspects into an optimum design.