Tech Briefs

AFRL develops a new aerodynamic analysis program.

Dr. Abate's new method employs instantaneous position, motion state, physical properties, and environmental conditions to determine aeroballistic parameters. His novel approach subsequently evolved into a fully developed software analysis package called AeroSolve (see figure). AeroSolve runs in the Microsoft® Windows® operating environment and is accessible via a graphical user interface. AeroSolve segments measured flight data into user-defined Mach number ranges in which aeroballistic parameters are assumed to vary slowly. This approach avoids both the problem associated with extreme nonlinearity of aeroballistic parameters at Mach 1 and that related to trajectory matching with extremely long trajectories.

Test engineers using the new approach acquire experimental flight data from two different sources: (1) a radar-based system that measures the projectile's velocity in the earth-fixed frame of reference, and (2) an onboard instrumentation suite that measures the projectile's Euler angles (excluding roll) and roll rate in the bodyfixed reference frame. Test engineers process the radar-based data to extract the projectile's position and acceleration, whereas they use the data acquired on board to determine the projectile's angular rates (pitch and yaw) and angular accelerations. Not only do the radar-based and onboard data sources reflect different spatial reference frames, they operate at different sampling rates as well. Therefore, test engineers must convert the collected data into a common time frame. The result of this conversion is a listing of position, velocity, acceleration, Euler angles, body rates, and body angular accelerations at discrete time increments over the duration of the flight.