The Development of Manoeuvre Load Criteria for Agile Aircraft,
ADVISORY GROUP FOR AEROSPACE RESEARCH AND DEVELOPMENT NEUILLY-SUR-SEINE (FRAN CE)
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Design manoeuvre load regulations in the Nato nations have evolved from crude assumptions of single control surface movement to relatively complicated series of pilot inputs in all three axes. These inputs need to be standardized to permit the assessment of structural loads with reasonable effort, but with the advent of active control technology the hiatus between standardized control inputs for load assessment and actual pilot practice with agile aircraft is rapidly increasing. A solution of this dilemma may be to design flight control systems such that they provide carefree handling , that is a system which even for the wildest pilot inputs does not lead to structural damage. But this solution has also disadvantages a structural designers lose the wealth of experience contained in previous design practice and with it their basis for initial dimensioning of the airframe. This affects a large portion of the aircraft mass and later re-design may be impossible. b Structural safety becomes crucially dependent on the functioning of black boxes and their connections. As long as we have no technically feasible direct load sensing and controlling system, a compromise is proposed Use the best combination of the old criterial for initial design but allow for a long development period flight control system adjustments of load critical functions to fully exploit the manoeuvre capability of the aircraft without structural damage. This will require a flexible system of operational clearances where the user can not have a complete definition of the manoeuvre capabilities at the start of a programme.
- Military Aircraft Operations