1. Parachute testing at altitudes between 30 and 90 kilometers.
2. Preisser, J. S., Eckstrom, C. V., and Murrow, H. N. "Flight Test of a 31.2-Foot-Diameter Modified Ringsail Parachute Deployed at a Mach Number of 1.39 and a Dynamic Pressure of II.0 Pounds Per Square Foot/' TM X-1414, Aug. 1967, NASA.