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Freeman, Delma C., Jr.

Publications and source records attributed to Freeman, Delma C., Jr..

10 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

Reusable Launch Vehicle Technology Program

Industry/NASA reusable launch vehicle (RLV) technology program efforts are underway to design, test, and develop technologies and concepts for viable commercial launch systems that also satisfy national needs at acceptable recurring costs. Significant progress has been made in understanding the technical challenges of fully reusable launch systems and the accompanying management and operational approaches for achieving a low cost program. This paper reviews the current status of the RLV technology program including the DC-XA, X-33 and X-34 flight systems and associated technology programs. It addresses the specific technologies being tested that address the technical and operability challenges of reusable launch systems including reusable cryogenic propellant tanks, composite structures, thermal protection systems, improved propulsion and subsystem operability enhancements. The recently concluded DC-XA test program demonstrated some of these technologies in ground and flight test. Contracts were awarded recently for both the X-33 and X-34 flight demonstrator systems. The Orbital Sciences Corporation X-34 flight test vehicle will demonstrate an air-launched reusable vehicle capable of flight to speeds of Mach 8. The Lockheed-Martin X-33 flight test vehicle will expand the test envelope for critical technologies to flight speeds of Mach 15. A propulsion program to test the X-33 linear aerospike rocket engine using a NASA SR-71 high speed aircraft as a test bed is also discussed. The paper also describes the management and operational approaches that address the challenge of new cost effective, reusable launch vehicle systems.

Freeman, Delma C., Jr.↗
NASA NTRS1996

Reusable Launch Vehicle Technology Program

Industry/NASA Reusable Launch Vehicle (RLV) Technology Program efforts are underway to design, test, and develop technologies and concepts for viable commercial launch systems that also satisfy national needs at acceptable recurring costs. Significant progress has been made in understanding the technical challenges of fully reusable launch systems and the accompanying management and operational approaches for achieving a low-cost program. This paper reviews the current status of the Reusable Launch Vehicle Technology Program including the DC-XA, X-33 and X-34 flight systems and associated technology programs. It addresses the specific technologies being tested that address the technical and operability challenges of reusable launch systems including reusable cryogenic propellant tanks, composite structures, thermal protection systems, improved propulsion, and subsystem operability enhancements. The recently concluded DC-XA test program demonstrated some of these technologies in ground and flight tests. Contracts were awarded recently for both the X-33 and X-34 flight demonstrator systems. The Orbital Sciences Corporation X-34 flight test vehicle will demonstrate an air-launched reusable vehicle capable of flight to speeds of Mach 8. The Lockheed-Martin X-33 flight test vehicle will expand the test envelope for critical technologies to flight speeds of Mach 15. A propulsion program to test the X-33 linear aerospike rocket engine using a NASA SR-71 high speed aircraft as a test bed is also discussed. The paper also describes the management and operational approaches that address the challenge of new cost-effective, reusable launch vehicle systems.

Freeman, Delma C., Jr.↗
NASA NTRS1996

Mars Pathfinder Status at Launch

The Mars Pathfinder Flight System is in final test, assembly and launch preparations at the Kennedy Space Center in Florida. Launch is scheduled for 2 Dec. 1996. The Flight System development, in particular the Entry, Descent, and Landing (EDL) system, was a major team effort involving JPL, other NASA centers and industry. This paper provides a summary Mars Pathfinder description and status at launch. In addition, a section by NASA's Langley Research Center, a key EDL contributor, is provided on their support to Mars Pathfinder. This section is included as an example of the work performed by Pathfinder team members outside JPL.

Spear, A. J.↗
NASA NTRS1995

Single-stage-to-orbit: Meeting the challenge

There has been and continues to be significant discussion about the viability of fully reusable, single-stage-to-orbit (SSTO) concepts for delivery of payloads to orbit. Often, these discussions have focused in detail on performance and technology requirements relating to the technical feasibility of the concept, with only broad generalizations on how the SSTO will achieve its economic goals of greatly reduced vehicle ground and flight operations costs. With the current industry and NASA Reusable Launch Vehicle Technology Program efforts underway to mature and demonstrate technologies leading to a viable commercial launch system that also satisfies national needs, achieving acceptable recurring costs becomes a significant challenge. This paper reviews the current status of the Reusable Launch Vehicle Technology Program including the DC-XA, X-33, and X-34 flight systems and associated technology programs. The paper also examines lessons learned from the recently completed DC-X reusable rocket demonstrator program. It examines how these technologies and flight systems address the technical and operability challenges of SSTO whose solutions are necessary to reduce costs. The paper also discusses the management and operational approaches that address the challenge of a new cost-effective, reusable launch vehicle system.

Freeman, Delma C., Jr.↗
NASA NTRS1992

HL-20 personnel launch system - A concept definition case study

For several years, the NASA Langley Research Center has been involved in defining options for future space transportation systems. As part of this effort, for the past 2 years, an analysis of a candidate Personnel Launch System to deliver and return people and small payloads to and from Space Station Freedom has been conducted. This effort has involved a government/industry/university team in conducting an indepth analysis of the HL-20 lifting body concept to provide a technically viable, affordable Personnel Launch System. This paper will use the HL-20 PLS definition activity to illustrate the process that is used by Langley to mature vehicle concepts to identify technical/development risks and costs for future transportation systems.

Freeman, Delma C., Jr.↗
NASA NTRS1991

Advanced manned launch system study status

Various concepts for advanced manned launch systems (AMLS) are examined for delivery missions to Space Station and polar orbit. Included are single- and two-stage winged systems with rocket and/or airbreathing propulsion systems. For near-term technologies, two-stage, reusable rocket systems are favored over single-stage rocket or airbreathing/rocket systems. Advanced technologies enable viable single-stage-to-orbit (SSTO) concepts. Although two-stage rocket systems continue to be lighter in dry weight than SSTOs, advantages in simpler operations may make SSTOs more cost-effective over the life cycle. Generally, rocket systems maintain a dry weight advantage over airbreathing systems at advanced technology levels, but to a lesser degree than when near-term technologies are used. More detailed understanding of vehicle systems and associated ground and flight operations requirements and procedures is essential in determining quantitative discrimination between these latter concepts.

Freeman, Delma C., Jr.↗
NASA NTRS1990

Manned Mars aerobrake vehicle design issues

The paper examines the preliminary definition of the stagnation region aerothermodynamic environment, the effect of convective/radiative effect of trim angle-of-attack mispredictions, packaging issues, and the implications of wake flow for vehicles not having an aft aeroshell. The implications of each of these factors for a Mars aerobrake configuration with a L/D in the range of 0.3-0.5 is evaluated. It is shown that packaging and wake flow requirements have a significant impact on the final design of a low L/D aerobrake. Due to the large proportion of carbonaceous species in the Martian atmosphere, radiative heating is seen to play a more dominant role in the stagnation region aerothermodynamics than for an equivalent earth entry. It is concluded that this radiation amplification is an additional reason to consider a multiple aerobrake system.

Freeman, Delma C., Jr.↗
NASA NTRS1989

Lifting-body option for a Space Station rescue vehicle

With the proposed development of the Space Station Freedom, the need for an assured crew return capability (ACRC) has been identified. During the past 2 years within NASA, there has been an ongoing activity to establish the design requirements for such a vehicle and to identify candidate vehicle concepts that can satisfy these requirements. From this activity, three primary design reference missions and four candidate vehicle concepts have been identified. In support of this activity, the emphasis at Langley has been to assess the potential application of a lifting-body concept derived from work on the HL-10 and X-24 programs in the late sixties. A vehicle systems analysis has been completed including wind-tunnel tests, aerodynamic heating predictions, six-degree-of-freedom entry simulations, and a global landing opportunities assessment. This report summarizes the results of work at Langley over the past 2 years to define the candidate lifting-body ACRC vehicle and provides insight into potential benefits of the higher cross range of this concept in accomplishing the Space Station rescue mission.

Hook, W. Ray↗