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
As the Crew Exploration Vehicle (CEV) program developed, NASA decided to provide the parachute portion of the landing system as Government Furnished Equipment (GFE) and designated NASA Johnson Space Center (JSC) as the responsible NASA center based on JSC's past experience with the X-38 program. JSC subsequently chose to have the Engineering Support contractor Jacobs Sverdrup to manage the overall program development.After a detailed source selection process Jacobs chose Irvin Aerospace Inc (Irvin) to provide the parachutes and mortars for the CEV Parachute Assembly System (CPAS). Thus the CPAS development team, including JSC, Jacobs and Irvin has been formed. While development flight testing will have just begun at the time this paper is submitted, a number of significant design decisions relative to the architecture for the manned spacecraft will have been completed. This paper will present an overview of the approach CPAS is taking to providing the parachute system for CEV, including: system requirements, the preliminary design solution, and the planned/completed flight testing. AbstractThe CEV is an element of the Constellation Program that includes launch vehicles, spacecraft, and ground systems needed to embark on a robust space exploration program. As an anchoring capability of the Constellation Program, the CEV shall be human-rated and will carry human crews and cargo from Earth into space and back again. Coupled with transfer stages, landing vehicles, and surface exploration systems, the CEV will serve as an essential component of the architecture that supports human voyages to the Moon and beyond. In addition, the CEV will be modified, as required, to support International Space Station (ISS) mission requirements for crewed and pressurized cargo configurations.
Human rating begins with design. Converging on the requirements and identifying the risks as early as possible in the design process is essential. Understanding of the interaction between the recovery system and the spacecraft will in large part dictate the achievable reliability of the final design. Component and complete system full-scale flight testing is critical to assure a realistic evaluation of the performance and reliability of the parachute system. However, because testing is so often difficult and expensive, comprehensive analysis of test results and correlation to accurate modeling completes the human rating process. The National Aeronautics and Space Administration (NASA) Orion program uses parachutes to stabilize and decelerate the Crew Exploration Vehicle (CEV) spacecraft during subsonic flight in order to deliver a safe water landing. This paper describes the approach that CEV Parachute Assembly System (CPAS) will take to human rate the parachute recovery system for the CEV. Human rating begins with design. Converging on the requirements and identifying the risks as early as possible in the design process is essential. Understanding of the interaction between the recovery system and the spacecraft will in large part dictate the achievable reliability of the final design. Component and complete system full-scale flight testing is critical to ensure a realistic evaluation of the performance and reliability of the parachute system. However, because testing is so often difficult and expensive, comprehensive analysis of test results and correlation to accurate modeling completes the human rating process. The National Aeronautics and Space Administration (NASA) Orion program uses parachutes to stabilize and decelerate the Crew Exploration Vehicle (CEV) spacecraft during subsonic flight in order to deliver a safe water landing. This paper describes the approach that the CEV Parachute Assembly System (CPAS) will take to human rate the parachute recovery system.
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