Statistical Engineering for Wind Tunnel Testing of Mars Parachute Designs

Abstract

Formal experiment design and analysis techniques featuring design of experiments were applied to a Mars parachute wind tunnel test. The experiments were part of an extensive study conducted in 2014 by the NASA Engineering and Safety Center to evaluate the performance of two candidate parachute systems. Reduced scale models of the legacy Disk-Gap-Band (DGB) parachute and new Supersonic Ringsail (SSRS) were compared for both model fidelity and performance measures. Two tests, conducted in the NASA Langley Transonic Dynamics Tunnel, are described with emphasis on statistical engineering principles. The first test compared drag coefficients between models of the same canopy at Earth atmospheric pressure but at mission dynamic pressures. The experiment proved that any manufacturing differences between models were not detectable in drag coefficient measurements. The second test focused on parachute drag coefficient modeling for both canopy designs and two fabric permeabilities over a representative range of mission dynamic pressures and Mach numbers. The SSRS was found to have higher drag coefficients in comparison to the DGB for both canopy material permeabilities over the operational range of Mach numbers and dynamic pressures.