Dynamic Aerodynamic Coefficients for Aircraft
the proper dynamic terms for aerodynamics math models
representing fighter aircraft during high-angle-of-attack maneuvers is
limited by the ability to quantify the necessary dynamic coefficients from
either computations or experiments. The traditional approach uses small-amplitude forced-oscillation (assumes linear variation of aerodynamic
coefficients with rotation rate) and rotary-balance wind tunnel
tests. Data from these experiments are then combined with various
methods of superposition to approximate the actual flight response.
uniquely acquired the appropriate static and dynamic force and
moment data in RHRC's water tunnel with motions from one to three
degrees of freedom in pitch, yaw, roll and velocity-vector roll without
the usual constraints of assuming linear aerodynamics. Static
experiments were performed to identify "critical states" in
the flow field (such as
rapid changes in forces due to vortex breakdown) which introduce
dramatic departures from a locally linear aerodynamic behavior during
RHRC's water tunnel has the unique capability to
perform multi-axis dynamic force/moment tests with simultaneously flow visualization.
RHRC used a 65 degrees delta wing model, which allows direct
comparison to results from advanced wind tunnel to acquire non-linear
dynamic data, and an F/A-18E model,
a more complex configuration representing modern fighter aircraft.