Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Reentry”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

A steepest descents method for reentry optimization

A steepest descents optimization program is applied to the problem of a lifting vehicle entering the earth's atmosphere. The program employs penalty functions representing terminal conditions and inflight inequality constraints. During each iteration, it reduces a single performance measure which is the sum of the performance index and the penalty functions. Therefore, only one set of adjoint equations must be integrated per iteration. Values of weight factors, multiplying the penalty functions, are automatically adjusted before each iteration in order that the penalty functions will approach acceptable values. This method is shown to be a form of the classical Lagrange multiplier methods.

Andrus, J. F.↗
NASA NTRS1975

Thermostructural test facilities for reentry vehicle nose tip materials

To provide a cost effective means of assessing the thermostructural performance of nosetip materials, the Air Force has developed and utilized two types of thermostructural facilities: ground simulation facilities and laboratory facilities. The capabilities of the currently available test facilities are summarized and compared.

Budde, C. L.↗
NASA NTRS1976

Estimates of nitric oxide production for lifting spacecraft reentry

An approximate analysis to estimate the quantity of nitric oxide that could be formed in the wake of a reentering lifting spacecraft is reported. Three different approaches are undertaken: two simplified analytical models utilizing the sudden-freezing concept named the 'trailing-edge-freezing' and 'wake-freezing' approximations, and a computer calculation involving numerical integration of chemical rate equations. The three methods predict a maximum nitric oxide production equivalent to 6, 9.5 and 8% of the mass of the spacecraft, respectively. Thus, the amount of nitric oxide expected to be produced by future space activities is negligibly small compared with that produced by the natural processes.

Park, C.↗
NASA NTRS1978

Research study: Thermal curtain permeability and thermal response test for SRB reentry

Nine inch diameter samples of the material which will provide thermal and acoustic protection between the nozzle and outer skirt on the space shuttle solid rocket boosters were subjected to heating tests to determine the porosity of the material and the thermal response to a step change in heating. For the porosity measurements a steady state flow of air at 70 F, 500 F, and 1000 F was passed through a sample of the curtain material and measurements of the flow rates were made at different pressure drops across the sample. For the transient measurements, a sample of the curtain material was subjected to a step change in temperature as air was passed through the sample. Measurements of the heat flow through the sample were made as a function of time after the input of the heat pulse. The sample consisted of three layers of curtain panels. Each panel was made of combinations of quartz and fiberglass cloth between which a fiberfrax filler material had been stitched. The hardware design and test procedures were described. Data are provided in engineering units for the flow conditions and and temperatures at which measurements were conducted.

Fuller, C. E.↗
NASA NTRS1978

Optimum reentry trajectories of a lifting vehicle

The optimum maneuver of a space shuttle vehicle reentering a spherical, stationary, and locally exponential atmosphere was investigated. The use of Chapman's modified variables and a rescaled lift-drag polar leads to the formulation of a set of dimensionless equations of motion for flight analysis. The resulting equations are exact in the sense that they are also valid for flight in the vacuum. For planar flight several typical optimum maneuvers are investigated at different altitude ranges, low, moderate and very high. For three-dimensional flight, the procedure to solve the optimum trajectory for maximum cross range is discussed. Finally, using the equilibrium glide condition the maximum cross ranges for entry from circular speed, for several values of E*, and the footprint for E* = 1.5 are computed in this reduced problem.

Chern, J. S.↗
NASA NTRS1980

Development of the reentry flight dynamics simulator for evaluation of space shuttle orbiter entry systems

A nonlinear, six degree of freedom, digital computer simulation of a vehicle which has constant mass properties and whose attitudes are controlled by both aerodynamic surfaces and reaction control system thrusters was developed. A rotating, oblate Earth model was used to describe the gravitational forces which affect long duration Earth entry trajectories. The program is executed in a nonreal time mode or connected to a simulation cockpit to conduct piloted and autopilot studies. The program guidance and control software used by the space shuttle orbiter for its descent from approximately 121.9 km to touchdown on the runway.

Rowell, L. F.↗
NASA NTRS1981

Sonic boom measurement test plan for Space Shuttle STS-2 reentry

Procedures and system specifications associated with the space shuttle STS-2 sonic boom measurement program are described. Specifically included are details such as mobile data acquisition station locations, measurement systems calibration levels, predicted sonic boom overpressure levels, overpressure level assignment for each data acquisition station, data recording times on and off, universal coordinate time, and measurement system descriptions.

Henderson, H. R.↗
NASA NTRS1981

Preflight reentry heat transfer analysis of Space Shuttle

Preflight predictions of the structural temperature distributions during entry are compared with data from the initial Shuttle flight. Finite element thermal analysis programming was used to model the heat flow on Shuttle structures and actual gas properties of air were employed in the analyses of aerodynamic heating. Laminar, separated, and turbulent heat fluxes were calculated for varying locations on the craft using velocity-attitude and angle-of-attack projections taken from the nominal STS-1 trajectory. Temperature time histories of the first flight are compared with laminar and turbulent flow assumptions and an unpredicted rapid cooling 1800 sec into entry is credited to inaccurate assumptions of structural heat dissipative properties or flow conditions in that time phase of the flight; additional discrepancies in descriptions of heating of the upper fuselage are attributed to a lack of knowledge of the complex flow patterns existing over that area of the Shuttle body.

Ko, W. L.↗
NASA NTRS1982

Radiative properties of a nickel based superalloy: Inconel 617 - After simulated earth reentry

Experimental results are presented to show the effect of environmental simulation exposures of convective heating and of radiant heating on the spectral (1.0 to 14 micrometers) and total emittance of oxidized Inconel 617. Convective heating exposures were conducted in an arc heated supersonic wind tunnel using a wedge-shaped specimen configuration. Radiant tests were conducted in dry air at a flow velocity of several meters per second. Convective heating specimens were subjected to 8, 20 and 38 heating cycles of 15-minutes duration and radiant heating specimens were tested for 10, 20, 50 and 100 one-half hour heating cycles. Changes in radiative properties are discussed in terms of changes in composition and morphology resulting from the exposure tests. Total normal emittance did not significantly change from the statically oxidized condition after either type of exposure, and it remained above 0.80 at 1260K for all cases. Although spectral changes were observed on post exposure specimens at wavelengths less than 2.0 micrometers and greater than 15 micrometers, these changes have no influence on total emittance at 1260K.

Cunnington, G. R.↗
NASA NTRS1981

Sonic boom measurement test plan for Space Shuttle STS-1 reentry

Formal documentation for measurement procedures and system specifications, and general information are relating to the Space Shuttle STS-1 Sonic Boom Measurement Program are supplied. This test plan is designed to provide information, guidance, and assignment of responsibilities for the acquisition of sonic boom and atmospheric measurements, timing correlation, communications and other necessary supporting tasks. Specifically included are details such as mobile data acquisition station locations, measurement systems calibration levels, predicted sonic boom overpressure levels, overpressure level assignment for each data acquisition station, data recording times on and off, universal coordinated time, and measurement system descriptions.

Henderson, H. R.↗
NASA NTRS1982

Sonic boom measurement test plan for Space Shuttle STS-4 reentry

Formal documentation for measurement procedures and system specifications, and general information relating to the Space Shuttle STS-4 Sonic Boom Measurement Program are supplied. This test plan is designed to provide information, guidance, and assignment of responsibilities for the acquisition of sonic boom and atmospheric measurements, timing correlation, communications and other necessary supporting tasks. Specifically included are details such as mobile data acquisition station locations, measurement systems calibration levels, predicted sonic boom overpressure levels, overpressure level assignment for each data acquisition station, data recording times on and off, universal coordinated time, and measurement system descriptions.

Henderson, H. R.↗
NASA NTRS1983

Non-intrusive flow measurements on a reentry vehicle

This study evaluates the utility of various non-intrusive techniques for the measurement of the flow field on the windward side of the Space Shuttle or a similar re-entry vehicle. Included are linear (Rayleigh, Raman, Mie, Laser Doppler Velocimetry, Resonant Doppler Velocimetry) and nonlinear (Coherent Anti-Stokes Raman, Laser Induced Fluorescence) light scattering, electron beam fluorescence, thermal emission and mass spectroscopy. Flow field properties are taken from a nonequilibrium flow model by Shinn, Moss and Simmonds at NASA Langley. Conclusions are, when possible, based on quantitative scaling of known laboratory results to the conditions projected. Detailed discussion with researchers in the field contributed further to these conclusions and provided valuable insights regarding the experimental feasibility of each of the techniques.

Miles, R. B.↗
NASA NTRS1982

Space shuttle solid rocket booster reentry and decelerator system loads and dynamics

Recovery of the space shuttle solid rocket boosters required development of a heavy duty large decelerator subsystem. Successful recovery of the first launch pair of boosters demonstrated the adequacy of the design. Flight data consisting of accelerometers and parachute attach point loads provide a basis for evaluation of the decelerator subsystem performance. These results are summarized and compared to preflight predictions.

Moog, R.↗