Flight Testing the Parachute System for the Space Station Crew Return Vehicle

Abstract

NASA has developed and tested a large parafoil for use in landing the International Space Station crew return vehicle. A series of tests using low-velocity airdrop pallets and prototype lifting bodies ights has demonstrated that the parafoil recovery system is a viable option for safely landing a crewed vehicle. The aerodynamic characteristics of the parafoil system have been determined through a series of ight-test maneuvers and subsequently successfully modeled using an eight-degree-of-freedom simulation program. An introduction to the requirements for the crew return vehicle, a description of the parafoil system, an overview of the testing performed including several signi cant ndings, a description of the techniques used to assess the aerodynamic performance of the parafoil system, and a discussion of the simulation of the parafoil system are presented. Nomenclature AR= aspect ratio b= parafoil span C L ; C D = lift and drag coef cients Cm c=4= parafoil system pitching moment coef cient about c=4 Cn r = yawing moment due to yaw rate Cn ± f = yawing moment due to control line de ection difference between left and right aps c = parafoil chord c=4 = quarter chord point on the parafoil keel HR = velocity vector heading rate HR wc = wind-corrected heading rate N q = dynamic pressure RA, µ r = parafoil rigging angle (X pf to parafoil keel) R=b = line length ratio (average suspension line length divided by span) S = parafoil reference area t = time, where t 1 is time at rst data point and t 2 time at second data point V h wc = wind-corrected horizontal velocity V tot = total velocity V w = wind velocity V x = east velocity V y = north velocity V z = vertical velocity W pf = weight of the parafoil system, including rigging, but not payload W sys = weight of the parafoil system and payload W =S = wing loading (payload weight divided by parafoil area) X cg ; Y cg = distance from the con uence to the parafoil system c.g. in parafoil coordinates X PL = payload body axis parallel to payload's bottom surface X pf ; Z pf = parafoil coordinate system, Z axis originating at the con uence point with Z extending up through c=4 Z c=4 = distance from the con uence to the c=4 ® = parafoil angle of attack relative to keel ® PL = payload angle of attack relative to X PL°= wind-corrected ight-path angle (V wc to horizon) ± f = control line de ection delta µ = parafoil pitch angle (X pf to horizon) ½ = atmospheric density Á w = direction of the wind measured from the north, that is, wind is coming from Á w 9 & b = body yaw rate

Substantiation of the choice of materials for the wing of tourist class suborbital reusable space vehicle

“…However, the effort to develop a reliable man-rated system is illustrated by the X-38's four-year flight test program which consisted of 26 drops using 3 different size parafoils and 4 different test vehicles dropped from C-130 and B-52 aircraft. 14 Parachutes. Parachutes are limited to landing weights less than about 40,000 lbs (12,200 kg).…”

On the Development of a Scalable 8-DoF Model for a Generic Parafoil-Payload Delivery System

“…(The flight test results of the developed fullscale X-38 system were discussed in details nine years later by Iacomimi et al, Martin, Madsen and Cerimele. [17][18][19][20][21][22][23]…”

“…Machin et al developed and thoroughly investigated low-order degree of freedom models for longitudinal and lateral channels (separately) of the large-scale ARS (X-38) for the space station crew recovery vehicle. 22 They presented a method of extracting system longitudinal and lateral-directional aero data to feed these models. These data/models were further applied to a NASA Johnson Space Center 8-DoF simulator to receive a reasonable dynamic response match between simulations and flight-test data.…”

A Multivariate Optimal Control Strategy for the Attitude Tracking of a Parafoil-UAV System

“…Hence, parafoil systems are well suited for fixed-wing unmanned aerial vehicles (UAV) that need to land on unprepared terrain accurately [1]. In recent years, this type of system has been used in several UAVs, including Developmental Sciences Corp.'s SkyEye, Israel Aerospace Industries' Eyeview and NASA's X-38 [2], [3]. However, the parafoil-UAV system has a unique issue called the pendulumswing problem.…”