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The Role of Buffet in the Structural Design of Combat Aircraft
Wolfgang Gerold Luber

Last modified: 2023-05-15


The application of buffet loads in the design of military aircraft structures are discussed and results from special detailed investigations of a high performance combat aircraft structural design are presented.

High dynamic vortex induced loads, called buffet loads and severe structural vibrations resulting in so-called buffeting loads can be induced in wing and empennage of high performance aircraft flying at high angle of attack and through airbrake deflections in front of tails by vortices originating from wing leading edge extensions and front fuselage/canard and the airbrake.

The resulting wing/fin dynamic loads may lead to increased material fatigue and require an augmented effort in aircraft maintenance. By introduction of the complete buffet forces and the resulting dynamic buffet induced loads in the structural design of an aircraft at the beginning of the project, the fatigue problem can be alleviated.

The airbrake induced maximum fin buffet pressures are similar to the wing vortex induced buffet pressures at high incidence. However due to the different exposure times of airbrake deflected and not deflected the fin fatigue loads for the airbrake deflected case are dramatically higher.

The presentation shows the process of the structural design and vibration prediction using wind tunnel unsteady buffet measurements, their application in the dynamic response analysis, the validation of the buffet forces by comparison of different wind tunnel measurements and the verification of the buffeting vibration and dynamic loads prediction through flight test results.