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Activity title

AG-300 V.35 Ground and Flight Test Methods Used to Assure Aeroelastic Stability of Fixed Wing Aircraft

Activity Reference

SCI-314

Panel

Systems Concepts and Integration

Security Classification

PUBLIC RELEASE

Status

Planning

Activity type

AG

Start date

2019

End date

2021

Keywords

Aerostructures, Aircraft, Data processing, Excitation, Flight Testing, Flutter, Instrumentation, Structures

Background

The process of substantiating the aeroelastic stability of modern aircraft requires a combination of numerical and empirical analysis. The ground and flight testing required to collect the empirical data is arduous at best and extremely hazardous at worst. There are a number of phenomenon that fall into the area of aeroelasticity. The most notable of which is flutter. Limit Cycle Oscillation is a non-linear form of flutter in which a nonlinearity, either in the structure or the aerodynamics, limits the amplitude of the oscillation. Divergence is similar to flutter except that it is non-oscillatory. Control reversal occurs when the force from the deflection of a control surface, normally the aileron, causes the wing to twist in the opposite direction to the point that the control surface and wing twist net effect is in the opposite direction intended by the pilot. Aerodynamic buzz is the vibration of a control surface due to unsteady aerodynamics and/or unsteady shock waves on the control surface. Buffet is a shaking or shuddering of the aircraft structure caused by separated flow or vortex shedding. These phenomenon have impacted all NATO nations conducting flight operations, particularly with varying aircraft store configurations.

Objectives

This AGARDograph is to document the best practices across NATO nations for certifying that an aircraft is free of aeroelastic instabilities with particular attention given to conducting ground and flight testing targeted at collecting the empirical data needed for this substantiation.

Topics

The topics will cover the certification process for aircraft with regard to flutter, Limit Cycle Oscillation, divergence, control reversal, buzz, buffet, aeroservoelasticity, and aerothermalelasticity..

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