Aerothermodynamics of a Parashield Re-Entry Vehicle

摘要

Feasibility and performance are investigated for a baseline configuration of a parashield re-entry vehicle, so named because it combines features of a parasol in a folding heatshield that might also be used as a landing parachute. The flowfield properties and heat transfer response are calculated for a 150-kg, 2.6-m-diam baseline parashield vehicle on a re-entry trajectory from low Earth orbit. The re-entry shield is formed from high-temperature cloth stretched over rigid folding spars and has a very low ballistic coefficient. Calculations show that a parashield made of 3M-brand Nextel™ 312 AF-10 ceramic fabric deployed over 12 Al 2024 arced spars designed for 15-deg angle of attack could withstand the re-entry aerothermodynamic stagnation-point heating load from a 122-km circular orbit. During this re-entry, the vehicle would experience a maximum 3.4 g of deceleration and would have a payload mass fraction of up to 45% with great packaging flexibility. Panel and spar heating, shield permeability, angle-of-attack misprediction, and free shear layer impingement are shown to be manageable design issues for a flexible cloth shield. It is also shown that the baseline vehicle could be scaled upward in size by at least a factor of 10 for increased payload volume and mass.