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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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1949

Systematic Investigations of the Effects of Plan Form and Gap between the Fixed Surface and Control Surface on Simple Flapped Wings

Four component measurements of 12 wings of symmetric profile having flaps with chord ratios t(sub R)/t(sub L) = 0.3 and t(sub R)/t(sub L) = 0.2 are treated in this report. As a result of the investigations, the effects of plan form and gap between fixed surface and control surface have been clarified. Lift, drag, pitching moment, and hinge moment were measured in the control-surface deflection range: -23 deg < or = beta < or = 23 deg and the range of angle of attack: -20 deg < or = alpha < or = 20 deg. Six wings with flaps of small chord (t(sub R)/t(sub L) < 0.1) were investigated at large flap settings.

Goethert↗
NASA NTRS1992

Preliminary micrometeoroid and debris effects on LDEF thermal control surfaces

Thermal control surfaces returned from space exhibited synergistic effects of simultaneous exposure to various natural environments. The thermal control surfaces of the Long Duration Exposure Facility (LDEF) were exposed to 5.75 years of low Earth orbit environments. Since LDEF was gravity-gradient stabilized and directionally stable (i.e., no rotation), the effects of each of the environments (meteoroid and space debris impacts, thermal cycling, atomic oxygen, and ultraviolet light exposure) can be distinguished via changes in material responses to hypervelocity impacts. The extent of these impacts are being visually and microscopically characterized using thermal control surfaces archived at NASA Johnson Space Center (JSC) in order to determine the relationship between environment exposure and resulting ring sizes, delamination areas, and penetration diameters. The characterization of these affected areas will provide spacecraft system designers with the information they require to determine degradation of thermal control systems during satellite lifetimes.

Allbrooks, Martha K.↗
NASA NTRS2004

Dynamic Response of X-37 Hot Structure Control Surfaces Exposed to Controlled Reverberant Acoustic Excitation

This document represents a compilation of three informal reports from reverberant acoustic tests performed on X-37 hot structure control surfaces in the NASA Langley Research Center Structural Acoustics Loads and Transmission (SALT) facility. The first test was performed on a carbon-silicone carbide flaperon subcomponent on February 24, 2004. The second test was performed on a carbon-carbon ruddervator subcomponent on May 27, 2004. The third test was performed on a carbon-carbon flaperon subcomponent on June 30, 2004.

Grosveld, Ferdinand W.↗
NASA NTRS1991

Preliminary micrometeoroid and debris effects on LDEF thermal control surfaces

Thermal control surfaces on the Long Duration Exposure Facility (LDEF) were exposed to 5.75 years of low-Earth orbit environments. Since LDEF was gravity gradient stabilized and directionally stable, the effects of each of the environments can be distinguished via changes in material responses to hypervelocity impacts. The extent of these effects are being visually and microscopically characterized using thermal control surfaces archived at Johnson Space Center in order to determine the the relationship between environment exposure and resulting ring sizes, delamination areas, and penetration diameters. The characterization of these affected areas will provide spacecraft system designers with the information they require to determine degradation of thermal control systems during satellite lifetimes.

Allbrooks, Martha K.↗
NASA NTRSDate not supplied

Evaluation of CFD Predictions of CobraMRV Control Surface Effectiveness at the NASA Langley Unitary Plan Wind Tunnel

The ability of CFD simulations to serve as a surrogate for wind tunnel testing at high supersonic speeds has been evaluated for a sub-scale model of the Co-Optimization Blunt-body Re-entry Analysis-Mid-lift-to-drag Rigid Vehicle (CobraMRV) human Mars entry vehicle concept. The vehicle was tested at the Unitary Plan Wind Tunnel (UPWT) at the NASA Langley Research Center under flow conditions and surface control configurations relevant to the entry stage of a flight mission. The CFD simulations were performed prior to gaining access to test results in order to assess how blind predictions obtained using best practices compare to experiments. Solutions of empty tunnel simulations were used as inflow boundary condition for the CobraMRV simulations in a truncated portion of the test section. Different solvers and turbulence models were used by separate teams to assess sensitivity to numerical methods, physics, and users. After release of the test results, the pre-test computations were compared to the experimental results, and additional analyses have been conducted to explain observed discrepancies. The amount of time and resources dedicated to each phase of the computational work was logged for comparison to that required for wind tunnel tests, and to inform planning of future CFD data base development projects.

ARMD↗
NASA NTRS1982

Computer program for post-flight evaluation of the control surface response for an attitude controlled missile

A FORTRAN IV coded computer program is presented for post-flight analysis of a missile's control surface response. It includes preprocessing of digitized telemetry data for time lags, biases, non-linear calibration changes and filtering. Measurements include autopilot attitude rate and displacement gyro output and four control surface deflections. Simple first order lags are assumed for the pitch, yaw and roll axes of control. Each actuator is also assumed to be represented by a first order lag. Mixing of pitch, yaw and roll commands to four control surfaces is assumed. A pseudo-inverse technique is used to obtain the pitch, yaw and roll components from the four measured deflections. This program has been used for over 10 years on the NASA/SCOUT launch vehicle for post-flight analysis and was helpful in detecting incipient actuator stall due to excessive hinge moments. The program is currently set up for a CDC CYBER 175 computer system. It requires 34K words of memory and contains 675 cards. A sample problem presented herein including the optional plotting requires eleven (11) seconds of central processor time.

Knauber, R. N.↗
NASA NTRS1976

Wind-tunnel investigation of control-surface characteristics. 5: The use of a beveled trailing edge to reduce the hinge moment of a control surface

Wind tunnel tests have been made to investigate the possibility of reducing the hinge moments of a control surface by beveling the trailing edge. The tests were made with a 9 percent thick airfoil having a 30 percent chord plain flap. A faired beveled shape, 5 percent of the airfoil chord in width and having a thickness of 21/2 percent of the airfoil chord, was found to give approximately 50 percent reduction in the hinge moment caused by a given deflection of the flap and 80 percent reduction in the hinge moment due to the angle of attack of this airfoil for a wide range of angles. Elliptical trailing edge shapes were also tried but were found to be somewhat less effective.

Jones, R. T.↗
NASA NTRS1976

Active control technology and the use of multiple control surfaces

Needed criteria for active control technology applications in commercial transports are lacking. Criteria for redundancy requirements, believed to be consistent with certification philosophy, are postulated to afford a discussion of the relative value of multiple control surfaces. The control power and frequency bandpass requirements of various active control technology applications are shown to be such that multiple control surfaces offer advantages in minimizing the hydraulic or auxiliary power for the control surface actuators.

Hart, J. E.↗
NASA NTRS1984

On orbit surfacing of thermal control surfaces

Substrates to be contaminated and contamination source were prepared. Additional information on paint spray method apparatus was obtained. Silver teflon second surface mirror samples and S 13 GLO paint samples were mounted, photographed under the microscope and measured to establish baseline data. Atomic oxygen cleaning and spray painting are being considered. Electrostatic powder and plasma spray coating systems appear to have serious drawbacks.

Racette, G. W.↗
NASA NTRS1992

Initial materials evaluation of the thermal control surfaces experiment (S0069)

The Thermal Control Surface Experiment (TCSE) was flown on the NASA Long Duration Exposure Facility (LDEF) with the basic objective of determining the effects of the near-earth orbital environment and the LDEF induced environment on spacecraft thermal control surfaces. The TCSE was a comprehensive experiment that combined in-space measurements with extensive post-flight analyses of thermal control surfaces to determine the effects of exposure to the low earth orbit space environment. The TCSE is the first space experiment to measure the optical properties of thermal control surfaces the way they are routinely measured in the laboratory. The specific mission objectives of the TCSE were to: (1) determine the effects of the natural and induced space environment on thermal control surfaces; (2) provide in-space performance data on thermal control surfaces; (3) provide in-space comparison to ground-based environmental testing of materials; and (4) develop and prove instrumentation to perform in-space optical testing of materials. Various aspects of the experiment are discussed.

Donald R. Wilkes↗
NASA NTRS1995

Trend analysis of in-situ spectral reflectance data from the Thermal Control Surfaces Experiment (TCSE)

The Thermal Control Surfaces Experiment (TCSE) on the LDEF was a comprehensive experiment that combined in-space measurements with extensive pre- and post-flight analyses of thermal control surfaces to determine the effects of exposure to the low earth orbit (LEO) space environment. The TCSE is the first space experiment to directly measure in-situ total hemispherical reflectance of thermal control surfaces in the same way they are routinely measured in the laboratory. In-space optical measurements performed by the TCSE provide the unique opportunity for trend analysis of the performance of materials in the space environment. Such trend analysis of flight data offers the potential to develop an empirical life time prediction model for several thermal control surfaces. For material research, trend analysis of the TCSE flight data, particularly the spectral data, can provide insight into the damage mechanisms of space exposure. Trend analysis for the TCSE samples has been limited to those materials that were not significantly eroded by the atomic oxygen (AO) environment. The performance of several materials on the LDEF mission was dominated by AO effects. Trend analysis was performed on both the detailed spectral reflectance measurements (in-space, pre-flight, and post-flight) and on the integrated solar absorptance. Results of this analysis for the five selected TCSE materials are presented along with the spectral flight data. Possible degradation and effects mechanisms will be discussed to better understand and predict the behavior of these materials in the LEO space environment.

Wilkes, Donald R.↗
NASA NTRS1989

Control surface spanwise placement in active flutter suppression systems

All flutter suppression systems require sensors to detect the movement of the lifting surface and to activate a control surface according to a synthesized control law. Most of the work performed to date relates to the development of control laws based on predetermined locations of sensors and control surfaces. These locations of sensors and control surfaces are determined either arbitrarily, or by means of a trial and error procedure. The aerodynamic energy concept indicates that the sensors should be located within the activated strip. Furthermore, the best chordwise location of a sensor activating a T.E. control surface is around the 65 percent chord location. The best chordwise location for a sensor activating a L.E. surface is shown to lie upstream of the wing (around 20 percent upstream of the leading edge), or alternatively, two sensors located along the same chord should be used.

Nissim, E.↗