Flight Test Techniques for Quantifying Pitch Rate and Angle of Attack Rate Dependencies

Area of Science:

• Aerospace Engineering
• Flight Dynamics
• Aerodynamics

Background:

• Accurate estimation of stability and control derivatives is crucial for understanding aircraft flight dynamics.
• Quantifying the contributions of pitch rate and angle of attack rate to the pitching moment coefficient is essential for flight control system design.
• Existing methods may not sufficiently isolate these contributions, leading to potential inaccuracies in analysis and simulation.

Purpose of the Study:

• To develop and demonstrate novel flight maneuvers for separately quantifying pitch rate and angle of attack rate contributions to the nondimensional aerodynamic pitching moment coefficient.
• To accurately estimate stability and control derivatives, specifically $$, from flight test data.
• To provide a methodology applicable to various aircraft types for enhanced flight dynamics analysis.

Main Methods:

• Designed three distinct maneuver types combining pilot inputs and automatic multisine excitations.
• Conducted flight tests using subscale T-2 and Bat-4 airplanes at the NASA AirSTAR flight test facility.
• Employed advanced data analysis techniques to estimate aerodynamic and stability derivatives from recorded flight data.

Main Results:

• Successfully demonstrated the designed maneuvers on the T-2 and Bat-4 aircraft.
• Accurately estimated key stability and control derivatives, including $$, from the flight test data.
• Validated the effectiveness of the maneuvers in isolating pitch rate and angle of attack rate contributions.

Conclusions:

• The developed maneuvers provide a reliable method for quantifying pitch rate and angle of attack rate effects on the pitching moment coefficient.
• These maneuvers enhance physical insight into flight dynamics and allow for more accurate comparisons with wind tunnel and numerical simulations.
• The methodology can be applied to a wide range of aircraft, improving simulation prediction fidelity and overall flight dynamics understanding.