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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1978

Comparison of concurrent strain gage- and pressure transducer-measured flight loads on a lifting reentry vehicle and correlation with wind tunnel predictions

Concurrent strain gage and pressure transducer measured flight loads on a lifting reentry vehicle are compared and correlated with wind tunnel-predicted loads. Subsonic, transonic, and supersonic aerodynamic loads are presented for the left fin and control surfaces of the X-24B lifting reentry vehicle. Typical left fin pressure distributions are shown. The effects of variations in angle of attack, angle of sideslip, and Mach number on the left fin loads and rudder hinge moments are presented in coefficient form. Also presented are the effects of variations in angle of attack and Mach number on the upper flap, lower flap, and aileron hinge-moment coefficients. The effects of variations in lower flap hinge moments due to changes in lower flap deflection and Mach number are presented in terms of coefficient slopes.

Tang, M. H.↗
NASA NTRS1980

Torque equilibrium attitude control for Skylab reentry

The method of torque equilibrium attitude control used to control the reentry of Skylab to an altitude below 150 km without the use of thruster fuel once the attitude was established is discussed. The Skylab attitude and pointing control system, which included rate gyros, sun sensors, star tracker, the Apollo telescope mount digital computer, control moment gyros and cold-gas attitude thrusters, is presented. The 12 torque equilibrium attitudes found at which aerodynamic, gravity gradient and gyroscopic torques would balance are indicated, and the three of those at which the solar power supply would be adequate for attitude control are illustrated. The equilibrium seeking method employed is then examined, and the operation and performance of the torque equilibrium attitude control system during the three weeks prior to Skylab reentry are discussed. It is concluded that the torque equilibrium attitude control method developed for Skylab was successful in performing its assigned mission, and will be valuable for the design of future, low-altitude spacecraft or tethered vehicles.

Glaese, J. R.↗
NASA NTRS1984

The next generation of reentry vehicles: NASA's view

The term reentry vehicle is used in the broad sense. The vehicles addressed include not only those that return from orbit to the Earth's surface, but also aeroassisted orbit transfer vehicles that use aerodynamic forces generated during atmospheric passes to achieve orbital changes with a smaller expenditure of energy than is required for an all-propulsion vehicle. Advanced reusable launch vehicles with special emphasis on system concepts and the influence of advanced technology on entry vehicle configuration are considered. Three categories of orbital transfer vehicles discussed: synergetic plane-change vehicles, planetary aerocapture vehicles, and LEO to GEO orbital transfer vehicles. While the orbital transfer and planetary vehicles are quite different from conventional winged Earth entry vehicles, synergetic plane change and high cross-range Earth entry vehicles have many similarities. Finally, a possible scenario for the development of the next generation of reentry vehicles is presented.

Walberg, G. D.↗
NASA NTRS1983

Residual mechanical properties of Ti-6Al-4V after simulated Space Shuttle reentry

Oxidation and embrittlement are concerns in use of titanium foils for shielding advanced space transportation system vehicles during Earth reentry. Ti-6Al-4V in 0.003 in. and 0.035 in. thicknesses were exposed to multiple cycles of simulated space transportation system ascent/reentry conditions at temperatures ranging from 1000 F to 1200 F. Residual mechanical tests and metallurgical analyses were made on the specimens after exposure. Results show that tensile elongation is the mechanical property most affected by the reentry environment. Results are presented to show a comparison of residual properties of foil specimens from static oxidation exposure and cyclic oxidation exposure.

Clark, R. K.↗
NASA NTRS1983

Capture and real-time display of selected Space Shuttle reentry data

Because the flight planning for the orbital flight test (OFT) flights of the NASA Space Shuttle required several months, there was very little time to analyze data from one flight before it was necessary to start final planning for the next flight. Real-time and selected immediate postflight data display of the reentry data minimized the postflight computer analysis time required so that the rigid time restraints imposed by the program could be met. This paper describes the methods used to decommutate and provide real-time and immediate postflight data display of selected Space Shuttle reentry data.

Chiles, H. R.↗
NASA NTRS1985

Supersonic aerodynamic characteristics of some reentry concepts for angles of attack up to 90 deg

Past studies of reentry vehicles tested to high angles of attack (up to 90 deg) in the Mach number range from 2 to 4.8 have provided some fundamental insights into the aerodynamic characteristics of such vehicles. Two basic planforms are considered in this paper: highly swept deltas, and circular. The delta concepts include variations in cross section (and thus volume) and in camber distribution. The effectiveness of various types of aerodynamic control devices is also included. The purpose of the paper is to examine the characteristics of the vehicles with a view toward the potential usefulness of such concepts in a flight regime that would include reentry from space into the atmosphere, followed by a transition to sustained atmospheric flight.

Spearman, M. L.↗
NASA NTRS1985

Supersonic aerodynamic characteristics of some reentry concepts for angles of attack to 90 deg

Past studies of reentry vehicles tested to high angles of attack (up to 90 deg) in the Mach number range from 2 to 4.8 are reviewed. Two basic planforms are considered: highly-swept deltas and circular. The delta concepts include variations in cross section (and thus volume) and in camber distribution. The effectiveness of various types of aerodynamic control devices is also included. The purpose of the paper is to examine the characteristics of the vehicles with a view toward the potential usefulness of such concepts in a flight regime that would include reentry from space into the atmosphere followed by a transition to sustained atmospheric flight.

Spearman, M. L.↗
NASA NTRS1985

Residual mechanical properties of Ti-6Al-2Sn-4Zr-2Mo after simulated Space Shuttle reentry

Oxidation and embrittlement are concerns in use of titanium foils for shielding advanced space transportation system vehicles during earth reentry. Ti-6Al-4V in 0.003 in. and 0.035 in. thicknesses were exposed to multiple cycles of simulated space transportation system ascent/reentry conditions at temperatures ranging from 1000 F to 1200 F. Residual mechanical tests and metallurgical analyses were made on the specimens after exposure. Results show that tensile elongation is the mechanical property most affected by the reentry environment. Results are presented to show a comparison of residual properties of foil specimens from static oxidation exposure and cyclic oxidation exposure.

Clark, R. K.↗
NASA NTRS1986

Finite-element reentry heat-transfer analysis of space shuttle Orbiter

A structural performance and resizing (SPAR) finite-element thermal analysis computer program was used in the heat-transfer analysis of the space shuttle orbiter subjected to reentry aerodynamic heating. Three wing cross sections and one midfuselage cross section were selected for the thermal analysis. The predicted thermal protection system temperatures were found to agree well with flight-measured temperatures. The calculated aluminum structural temperatures also agreed reasonably well with the flight data from reentry to touchdown. The effects of internal radiation and of internal convection were found to be significant. The SPAR finite-element solutions agreed reasonably well with those obtained from the conventional finite-difference method.

Ko, William L.↗
NASA NTRS1987

Thermal stress analysis of space shuttle orbiter subjected to reentry aerodynamic heating

A structural performance and resizing (SPAR) finite-element computer program and NASA structural analysis (NASTRAN) finite-element computer programs were used in the thermal stress analysis of the space shuttle orbiter subjected to reentry aerodynamic heating. A SPAR structural model was set up for the entire left wing of the orbiter, and NASTRAN structural models were set up for: (1) a wing segment located at midspan of the orbiter left wing, and (2) a fuselage segment located at midfuselage. The thermal stress distributions in the orbiter structure were obtained and the critical high thermal stress regions were identified. It was found that the thermal stresses induced in the orbiter structure during reentry were relatively low. The thermal stress predictions from the whole wing model were considered to be more accurate than those from the wing segment model because the former accounts for temperature and stress effects throughout the entire wing.

Ko, William L.↗
NASA NTRS1989

Improved Monte Carlo turbulence simulation for Shuttle reentry studies

A turbulence model for Space Shuttle reentry simulation is presented, which may be used to improve redline selection. It is suggested that the turbulence model in current use is overly conservative because it assumes severe turbulence from reentry altitude to the earth's surface. Two improved versions of the turbulence simulation equations are presented. These are third and fifth order approximations to the von Karman spectrum. The equations are in a form suitable for digital simulation. Both sets of equations can be used to generate a probability distribution of fuel remaining at landing.

Campbell, C. Warren↗
NASA NTRS1990

Project EGRESS: Earthbound Guaranteed Reentry from Space Station. the Design of an Assured Crew Recovery Vehicle for the Space Station

Unlike previously designed space-based working environments, the shuttle orbiter servicing the space station will not remain docked the entire time the station is occupied. While an Apollo capsule was permanently available on Skylab, plans for Space Station Freedom call for a shuttle orbiter to be docked at the space station for no more than two weeks four times each year. Consideration of crew safety inspired the design of an Assured Crew Recovery Vehicle (ACRV). A conceptual design of an ACRV was developed. The system allows the escape of one or more crew members from Space Station Freedom in case of emergency. The design of the vehicle addresses propulsion, orbital operations, reentry, landing and recovery, power and communication, and life support. In light of recent modifications in space station design, Project EGRESS (Earthbound Guaranteed ReEntry from Space Station) pays particular attention to its impact on space station operations, interfaces and docking facilities, and maintenance needs. A water-landing medium-lift vehicle was found to best satisfy project goals of simplicity and cost efficiency without sacrificing safety and reliability requirements. One or more seriously injured crew members could be returned to an earth-based health facility with minimal pilot involvement. Since the craft is capable of returning up to five crew members, two such permanently docked vehicles would allow a full evacuation of the space station. The craft could be constructed entirely with available 1990 technology, and launched aboard a shuttle orbiter.

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NASA NTRS1991

Radioactive satellites - Intact reentry and breakup by debris impact

There is a substantial mass of radioactive material in nuclear reactors or radioisotope thermal generators (RTGs) in orbit about the earth. This paper examines the reentry of intact nuclear fuel cores and RTGs and the fragmentation and subsequent radioactive debris cloud deposition and evolution resulting from the impact of orbital debris upon an orbiting reactor, fuel core, or RTG. To assess the intact reentry, decay rates and a predicted decay date using historical and projected orbital decay data, are estimated. The current NASA debris environment model is utilized to estimate impact rates and debris cloud evolution of a fragmentation event. Results of these analyses are compared and concepts are tendered which would tend to minimize the radiological debris hazard to personnel and structures both on the earth's surface and in low earth orbit.

Anz-Meador, P. D.↗
NASA NTRS1992

Low-to-high altitude predictions of three-dimensional ablative reentry flowfields

A new coupled-chemistry PNS scheme has been developed to study 3D hypersonic reentry flows over sphere cones at small angles of attack. A new quasi-steady ablation model for Teflon was used to predict ablative reentry flow fields under laminar, transitional, and turbulent conditions. This solution scheme uses a new two-step solution scheme for solving the species conservation equations under low-altitude conditions. As an example, the scheme is used to study hypersonic flow over a 6-deg sphere-cone configuration at 50 and 125 kft conditions under zero and nonzero angle of attack conditions.

Bhutta, Bilal A.↗
NASA NTRS1992

An evaluation of three anti-G suit concepts for shuttle reentry

A study was conducted to compare the standard anti-G launch-entry suit (LES) with a reentry full-coverage anti-G suit (REAGS) and a REAGS without an abdominal bladder (AB). (The inflated AB is the most uncomfortable G-suit component). Intravenous Lasix, a diuretic, was used to induce the fluid loss seen during space flight. Using the Armstrong Laboratory Centrifuge, data collected from seven subjects have shown that less anti-G suit pressure is required to maintain eye-level systolic blood pressure above 70 mmHg when the REAGS or REAGS without AB is worn during simulated shuttle reentry G-profiles when compared to the current LES G-suit. The REAGS without AB was significantly more comfortable than the standard anti-G suit.

Krutz, R. W., Jr.↗
NASA NTRS1991

Reusable Reentry Satellite (RRS): Telemetry, Tracking, and Command (TT/C) Coverage Tradeoff Study

The Reusable Reentry Satellite (RRS) Telemetry, Tracking & Command (TT&C) Coverage Tradeoff Study described herein was performed during Part 1 of the RRS Phase B contract. This report is one of several that describes the results of various trade studies performed to arrive at a recommended design for the RRS satellite system. The overall RRS Phase B Study objective is to design a relatively inexpensive satellite to access space for extended periods of time, with eventual recovery of experiments on Earth. The RRS will be capable of: (1) being launched by a variety of expendable launch vehicles; (2) operating in low earth orbit as a free flying unmanned laboratory; and (3) executing an independent atmospheric reentry and soft landing. The RRS will be designed to be refurbished and reused up to three times a year for a period of 10 years. The expected principal use for such a system is research on the effects of variable gravity (0 to 1.5 g) and radiation on small animals, plants, lower life forms, tissue samples, and materials processes. This Summary Report provides a description of the RRS Telemetry, Tracking & Command Analysis performed to study the ground station coverage available to meet RRS requirements. Concepts were considered that used off-the-shelf technology, had generous margins of capability, and high reliability, were easily maintained, cost effective, and were compatible with existing support networks. From this study, a recommended RRS TT&C configuration will be developed.

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NASA NTRS1991

Vehicle/payload interface specification for the reusable reentry satellite

This document describes the common interface requirements between the Vehicle Segment and the Payload Segment of the Reusable Reentry Satellite (RRS) system. The system consists of a single transport vehicle design that provides a uniform, unidirectional payload gravitational environment which is selectable during on-orbit operations over the range of 10(exp -5) (microgravity) to 1.5 g's. The initial Reusable Reentry Vehicle/Payload Module (RRV/PM) integration and checkout will occur at the launch base unless otherwise agreed to in a mission-unique addendum to this specification. Pre-integration interface qualification shall be done using emulators as described.

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NASA NTRS1990

Reusable Reentry Satellite (RRS): Propulsion system trade study

The purpose of the Reusable Reentry Satellite (RRS) Propulsion System Trade Study described in this summary report was to investigate various propulsion options available for incorporation on the RRS and to select the option best suited for RRS application. The design requirements for the RRS propulsion system were driven by the total impulse requirements necessary to operate within the performance envelope specified in the RRS System Requirements Documents. These requirements were incorporated within the Design Reference Missions (DRM's) identified for use in this and other subsystem trade studies. This study investigated the following propulsion systems: solid rocket, monopropellant, bipropellant (monomethyl hydrazine and nitrogen tetroxide or MMH/NTO), dual-mode bipropellant (hydrazine and nitrogen tetroxide or N2H4/NTO), liquid oxygen and liquid hydrogen (LO2/LH2), and an advanced design propulsion system using SDI-developed components. A liquid monopropellant blowdown propulsion system was found to be best suited for meeting the RRS requirements and is recommended as the baseline system. This system was chosen because it is the simplest of all investigated, has the fewest components, and is the most cost effective. The monopropellant system meets all RRS performance requirements and has the capability to provide a very accurate deorbit burn which minimizes reentry dispersions. In addition, no new hardware qualification is required for a monopropellant system. Although the bipropellant systems offered some weight savings capability for missions requiring large deorbit velocities, the advantage of a lower mass system only applies if the total vehicle design can be reduced to allow a cheaper launch vehicle to be used. At the time of this trade study, the overall RRS weight budget and launch vehicle selection were not being driven by the propulsion system selection. Thus, the added cost and complexity of more advanced systems did not warrant application.

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