High-Speed Hyperspectral Polarimeter for Measuring Parachute Canopy Strain

The parachute development process can be expensive and time-consuming due to the current need for iterative, full-scale flight testing. Although new computational algorithms for parachute modeling are being developed at the U.S. Army Natick Soldier Center, these models must be validated through actual measurements of parachute strain both during the inflation phase and in steady decent. We propose the development of a high-speed strain-imaging system based on optical birefringence properties of the parachute canopy fabric and a technique of hyperspectral polarimetry developed at Lynntech. High-resolution strain data could be recorded in a wind tunnel, drop tower, or during an airdrop. Full-canopy, distortion-free strain maps would be acquired on a millisecond time scale, enabling accurate strain imaging of parachute inflation. No device attachment to the parachute material is required and the fabric would not be structurally modified, thereby obviating measurement-induced alterations in the natural parachute strain. The spatial resolution of the strain map is not limited by the attachment density of massive detection elements and the technique enables strain determination in a highly localized area of the canopy, rather than along the length of a strain gauge. This approach will ultimately reduce the time and expense currently associated with parachute development.