High-altitude testing of parachutes; a low-cost methodology for parachute evaluation using consumer electronics Iain C. Waugh * , Edward A. Moore * , Daniel G. T. Strange * , John Cormack * and Fergus Noble * CUSF, University of Cambridge, Cambs., CB2 1PZ, United Kingdom John C. Underwood † Vorticity Ltd, Chalgrove, Oxfordshire, OX44 7RW, United Kingdom This paper presents a low-cost method for testing the inflation behaviour of small (< 5m) parachutes at high-altitude and high subsonic Mach numbers. A small and light drop vehicle (11.7kg) was developed and used to test a 2.55m ringslot parachute at a velocity of 210.5m/s (Mach 0.71), an altitude of 22.2km (72, 800ft) and an atmospheric density of 0.056kg/m 3 . Sensors and cameras mass-produced for consumer electronics are used in a custom avionics package because they are small, low-cost, lightweight and low power. Acceleration, rotation rate and dynamic pressure data are recorded at 2kHz, and high- speed video at 300fps, during inflation and descent. The per-launch expendable costs (balloon, helium etc.) are of the order of several thousand pounds (GBP). This provides an extremely cost effective way of testing small parachutes for stability and performance at the design Mach number and appropriate mass ratio. I. Introduction This paper describes a low-cost method for the experimental verification of parachutes designed for low- density, high-speed deployment, such as those required for planetary entry or sample return. There are various methods for evaluating parachutes in these regimes, but there are few physical test data that match both the mass ratios and dynamic pressures for deployment at the required Mach numbers. The available test data in the literature stem mostly from four NASA programmes completed in the 1960s; namely the Planetary Entry Parachute Program 1–3 (PEPP), the Supersonic Planetary Entry Decel- erator Program 4 (SPED-I), the Supersonic High Altitude Parachute Experiment 5 (SHAPE) and the Balloon Launched Decelerator Tests (BLDT). The results from these tests are summarised in Cruz and Lingard 6 . There are some additional data available from the successful descents of recent planetary probes, although appropriate instrumentation on the crafts was limited. The data from the NASA tests span Mach numbers of 1.16 to 3.31, for several parachute configurations (disk gap-band, cruciform and ring sail). The NASA tests demonstrated that the opening performance of such parachutes is strongly dependent on Mach number, particularly in the transient behaviour following deployment. Due to the costs associated with the NASA programmes only 16 tests were completed, so additional experimental data are required to verify the effects of scaling and Mach number on high-speed parachute performance. More recently, the high-altitude test program for a Mars Subsonic Parachute 7 (MSP) used a balloon lofted vehicle to evaluate the inflation characteristics of a 33.5m ringsail parachute. For these subsonic tests, rocket boosters were not necessary; the vehicle was simply lofted to 36km and dropped. This method is cost-effective for subsonic tests, in that the mission costs were of the order of several hundred thousand dollars rather than several million dollars for the NASA PEPP tests. A similar method is presented in this paper, at a smaller scale, with mission costs of the order of several thousand dollars. The MSP high-altitude tests highlighted several design inadequacies that were not identified with low- altitude tests, due to the difference in inflation conditions. For parachute testing to be representative, * Student, AIAA Student Member. † Principal Engineer, AIAA Senior Member. 1 of 12 American Institute of Aeronautics and Astronautics