Trim angle measurements in free-flight facilitiesThe aerodynamic cofficients and trim angle for an aerobrake at Mach 9.2 and 11.8 were found using a combination of experiment and computation. Free-flight tests were performed at NASA Ames Research Center's Hypervelocity Free-Flight Aerodynamic Facility, and the forebody pressure distribution was calculated using a three-dimensional Navier-Stokes code with an effective specific heat ratio. Using the computed drag, lift, and moments to prescribe the number of terms in the aerodynamic coefficient expansions and to specify the values of the higher order terms, the experimental aerodynamic coefficients and trim angle were found using a six-degree-of-freedom, weighted, least-squares analysis. The experimental and computed aerodynamic coefficients and trim angles are in good agreement. The trim angle obtained from the free-flight tests, 14.7 deg, differs from the design trim angle, 17 deg, and from the Langley wind tunnel results, 12 deg in air and 17 deg in CF4. These differences are attributable to real-gas effects.
Document ID
19910058938
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Yates, Leslie A. (NASA Ames Research Center Moffett Field, CA, United States)
Venkatapathy, Ethiraj (NASA Ames Research Center Moffett Field; Eloret Institute, Palo Alto, CA, United States)