Experimental Investigation of NASA Orion Pilot Chute Drag Characteristics

摘要

The planned replacement for NASA's Space Shuttle, the Orion Multi-Purpose Crew Vehicle (MPCV), utilizes a three-stage parachute system to safely bring the re-entry vehicle and its astronauts back to the earth's surface. Integral to this system is the effective deployment of the three pilot chutes. The purpose of the pilot chutes is to produce enough aerodynamic drag to pull the main chutes into clean air away from the bluff body Orion wake. Due to reduced dynamic pressures in the wake of the Orion MPCV, it is important to quantify the drag deficit experienced by the pilot chutes at various trailing distances behind the vehicle in order to determine if they can successfully pull the main chutes into clean air. Tasked by the NASA Johnson Space Center (JSC) Applied Aeroscience and Computational Fluid Dynamics branch, the Air Force Academy Department of Aeronautics determined the drag characteristics of the pilot chute for freestream and "in wake" conditions and experimentally defined the drag loss resulting from the "in wake" condition. With a test section speed of Mach 0.4, a rigid pilot chute wind tunnel model was swept laterally through the Orion wake at trailing distances of 4, 4.5, 5, 5.5, 6, and 6.5 Orion heat shield diameters behind a 2% scale Orion model. Results showed a maximum drag loss of 15.86% in the wake of the Orion at 4 diameters aft. The drag loss decreased as distance aft increased, resulting in a 7.66% maximum drag loss in the wake at 6.5 diameters aft. These drag loss values will aid NASA in the determination of the optimal pilot chute size and shroud line length.