Aerodynamics for Mars Phoenix Entry Capsule

摘要

The preflight aerodynamic database for the Mars Phoenix entry capsule is presented. The aerodynamic coefficients were generated as a function of total angle of attack and either Knudsen number, velocity, or Mach number, depending on the flight regime. The database was constructed using continuum flowfield computations and data from the Mars Exploration Rover and Viking programs. Hypersonic and supersonic static coefficients were derived from Navier-Stokes solutions on a preflight design trajectory. High-altitude data (free-molecular and transitional regimes) and dynamic pitch damping characteristics were taken from Mars Exploration Rover analysis and testing. Transonic static coefficients from Viking wind-tunnel tests were used for capsule aerodynamics under the parachute. Static instabilities were predicted at two points along the reference trajectory and were verified by reconstructed flight data. During the hypersonic instability, the capsule was predicted to trim at angles as high as 2.5 deg with an onaxis center of gravity. Peak trim angles for an offnominal pitching moment and a 5 mm offaxis center of gravity were predicted to be 4.2 and 4.8 deg, respectively. Finally, hypersonic static coefficient sensitivities to atmospheric density were predicted to be within uncertainty bounds.