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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Analytic solution for vertical launch into orbit

An approximate analytic solution is presented for the motion and heating of nonlifting spacecraft launched vertically for ascending flight through the atmosphere into earth orbit. The solution is based on Chapman's Z-function transformation of the equations of motion with the assumption of an exponential atmosphere. The transformed equations have been modified to include the effects of thrusting with mass loss. It is assumed that the vehicle negotiates a gravity turn during ascent so that the thrust vector is aligned in the flight-path direction. Numerical results are presented to document the analytic solution and provide evidence of the useful information generated by it.

Boltz, Frederick W.↗
NASA NTRS1990

Bipropellant engine plume analyses for the Mars Observer scientific spacecraft

This paper discusses the methodology utilized to characterize exhaust plume expansion of the 490 N bipropellant engine and provides an analysis of exhaust plune impingement effects on the Mars Observer oxidizer tank structure. Nozzle and plume continuum flowfields are computed with a method of characteristics solution while transitional and rarefied regions of the exhaust gas flow were defined by a direct simulation Monte Carlo method. Results of this study provide sufficient data for an assessment of spacecraft thermal impacts due to plume heating effects and thrust losses from exhaust plume impingement.

Rattenni, L., Jr.↗
NASA NTRS1990

A comparison of analytical results for 20 K LOX/hydrogen instabilities

Test data from NASA Lewis' Effect of Thrust Per Element on Combustion Stability Characteristics of Hydrogen-Oxygen Rocket Engines test program are used to validate two recently released stability analysis tools. The first tool is a design methodology called ROCCID (ROCket Combustor Interactive Design). ROCCID is an interactive design and analysis methodology that uses existing performance and combustion stability analysis codes. The second tool is HICCIP (High frequency Injection Coupled Combustion Instability Program). HICCIP is a recently developed combustion stability analysis model. Using a matrix of models, results from analytic comparisons with 20 K LOX/H2 experimental data are presented.

Klem, Mark D.↗
NASA NTRS1991

Airframe/propulsion integration at transonic speeds

A significant level of research is ongoing at NASA's Langley Research center on integrating the propulsion system with the aircraft. This program has included nacelle/pylon/wing integration for turbofan transports, propeller/nacelle/wing integration for turboprop transports, and nozzle/afterbody/empennage integration for high-performance aircraft. The studies included in this paper focus more specifically on pylon shaping and nacelle bypass ratio studies for turbofan transports, nacelle and wing contouring, and propeller location effects for turboprop transports, empennage effects, and thrust vectoring for high-performance aircraft. The studies were primarily conducted in NASA Langley's 16-Foot Transonic Tunnel at Mach numbers up to 1.20.

Henderson, W. P.↗
NASA NTRS1991

Experimental investigation of a unique airbreathing pulsed laser propulsion concept

Investigations were conducted into unique methods of converting pulsed laser energy into propulsive thrust across a flat impulse surface under atmospheric conditions. The propulsion experiments were performed with a 1-micron neodymium-glass laser at the Space Plasma Branch of the Naval Research Laboratory. Laser-induced impulse was measured dynamically by ballistic pendulums and statically using piezoelectric pressure transducers on a stationary impulse surface. The principal goal was to explore methods for increasing the impulse coupling performance of airbreathing laser-propulsion engines. A magnetohydrodynamic thrust augmentation effect was discovered when a tesla-level magnetic field was applied perpendicular to the impulse surface. The impulse coupling coefficient performance doubled and continued to improve with increasing laser-pulse energies. The resultant performance of 180 to 200 N-s/MJ was found to be comparable to that of the earliest afterburning turbojets.

Myrabo, L. N.↗
NASA NTRS1991

Techniques for developing approximate optimal advanced launch system guidance

An extension to the authors' previous technique used to develop a real-time guidance scheme for the Advanced Launch System is presented. The approach is to construct an optimal guidance law based upon an asymptotic expansion associated with small physical parameters, epsilon. The trajectory of a rocket modeled as a point mass is considered with the flight restricted to an equatorial plane while reaching an orbital altitude at orbital injection speeds. The dynamics of this problem can be separated into primary effects due to thrust and gravitational forces, and perturbation effects which include the aerodynamic forces and the remaining inertial forces. An analytic solution to the reduced-order problem represented by the primary dynamics is possible. The Hamilton-Jacobi-Bellman or dynamic programming equation is expanded in an asymptotic series where the zeroth-order term (epsilon = 0) can be obtained in closed form.

Feeley, Timothy S.↗
NASA NTRS1958

Effect of Target-type Thrust Reverser on Transonic Aerodynamic Characteristics of a Single-engine Fighter Model

A brief investigation of a target-type thrust reverser on a single-engine fighter model has been conducted in the Langley 16-foot transonic tunnel at Mach numbers from 0.20 to 1.05.At Mach numbers of 0.80, 0.92, and 1.05, a hydrogen peroxide turbojet-engine simulator was operated with the thrust reverser extended. The angle of attack was varied from 0 degrees to 5 degrees at these Mach numbers. The Reynolds number of the free stream, based on the mean aerodynamic chord, was about 5 x 10(6). It was estimated that reversed jet operations separated the model boundary-layer flow over the upper surface of the horizontal tail and upper part of the afterbody. This resulted in a positive pitch increment due to reversed jet operation. Jet-on operation also tended to stabilize the severe lateral oscillations which occurred with the reverser extended and the jet off. It appeared that these jet-off oscillations were the result of an alternating separation and reattachment of the flow on the rearmost portions of the fuselage afterbody.

Swihert, John M↗
NASA NTRS1993

Trajectory optimization for the national aerospace plane

During the past six months the research objectives outlined in the last semi-annual report were accomplished. Specifically, these are: three-dimensional (3-D) fuel-optimal ascent trajectory of the aerospace plane and the effects of thrust vectoring control (TVC) on the fuel consumption and trajectory shaping were investigated; the maximum abort landing area (footprint) was studied; preliminary assessment of simultaneous design of the ascent trajectory and the vehicle configuration for the aerospace plane was also conducted. The work accomplished in the reporting period is summarized.

Lu, Ping↗
NASA NTRS1993

Experimental performance of a ventral nozzle with pitch and yaw vectoring capability for SSTOVL aircraft

Aircraft with supersonic, short takeoff and vertical landing capability have been proposed to replace some of the current high-performance aircraft. Several of these configurations use a ventral nozzle in the lower fuselage, aft of the center of gravity, for lift or pitch control. Internal vanes canted at 20 deg were added to a swivel-type ventral nozzle and tested at tailpipe to ambient pressure ratios up to 5.0 on the Powered Lift Facility at NASA Lewis Research Center. The addition of sets of four or seven vanes decreased the discharge coefficient of the nozzle by at least 6 percent and did not effect the thrust coefficient. Side force produced by the nozzle with vanes was 14 percent or more of the vertical force. In addition, this side force caused only a smalll loss in vertical force in comparison to the nozzle without vanes. The net thrust force was 8 deg from the vertical for four vanes and 10.5 deg for seven.

Esker, Barbara S.↗
NASA NTRS1996

Design of a mixer for the thrust-vectoring system on the high-alpha research vehicle

One of the advanced control concepts being investigated on the High-Alpha Research Vehicle (HARV) is multi-axis thrust vectoring using an experimental thrust-vectoring (TV) system consisting of three hydraulically actuated vanes per engine. A mixer is used to translate the pitch-, roll-, and yaw-TV commands into the appropriate TV-vane commands for distribution to the vane actuators. A computer-aided optimization process was developed to perform the inversion of the thrust-vectoring effectiveness data for use by the mixer in performing this command translation. Using this process a new mixer was designed for the HARV and evaluated in simulation and flight. An important element of the Mixer is the priority logic, which determines priority among the pitch-, roll-, and yaw-TV commands.

Pahle, Joseph W.↗
NASA NTRS1953

Wind-Tunnel Investigation at Low Speed of the Pitching Stability Derivatives of a 1/9-Scale Powered Model of the Convair XFY-1 Vertically Rising Airplane, TED No. NACA DE 373

An experimental investigation has been conducted in the Langley stability tunnel at low speed to determine the pitching stability derivatives of a 1/9-scale powered model of the Convair XFY-1 vertically rising airplane. Effects of thrust coefficient, control deflections, and propeller blade angle were investigated. The tests were made through an angle-of-attack range from about -4deg to 29deg, and the thrust coefficient range was from 0 to 0.7. In order to expedite distribution of these data, no analysis of the data has been prepared for this paper.

Queijo, M. J.↗
NASA NTRS1969

Scaled Lunar Module Jet Erosion Experiments

An experimental research program was conducted on the erosion of particulate surfaces by a jet exhaust. These experiments were scaled to represent the lunar module (LM) during landing. A conical cold-gas nozzle simulating the lunar module nozzle was utilized. The investigation was conducted within a large vacuum chamber by using gravel or glass beads as a simulated soil. The effects of thrust, descent speed, nozzle terminal height, particle size on crater size, and visibility during jet erosion were determined. Results indicate that, from an erosion and visibility standpoint, the best landing mode for a lunar module type of vehicle would involve: site inspection and selection above the incipient erosion height, and a fast descent to the highest drop-in altitude that the vehicle structure could withstand. A slow and cautious descent with hovering just above the lunar surface would greatly increase crater size and impair visibility.

Experiments↗
NASA NTRS2015

A Simple Analytical Fuselage-Induced Velocity Model for Comprehensive Rotor Codes

A simple analytical model to account for fuselage-induced velocities at rotor blade elements and at rotor wake nodes is described. The method is applied to three different fuselage configurations. Results obtained with a comprehensive rotor code show the fuselage effect on rotor trim controls, comparing the isolated rotor with inclusion of the fuselage for the same trim. This is compared to a simple analytical estimate of the fuselage effect using blade element/momentum theory. It is found that in forward flight the lateral control is mainly affected by fuselage effects. Rotor thrust can be varied by the presence of the fuselage, depending on its angle of attack, and the fuselage influence generally increases with flight speed.

Velocity Model↗
NASA NTRS1935

The Effect of Lateral Inclination of the Thrust Axis and of Sweepback of the Leading Edge of the Wing on Propulsive and Net Efficiencies of a Wing-Nacelle-Propeller Combination

This report describes and gives the results of tests made to determine the effect of lateral inclination of the propeller thrust axis to the direction of flight. A wing-nacelle-propeller combination with the nacelle axis located successively parallel to and at 15 degrees to the perpendicular to the leading edge of a wing was tested with the combination at several angles of yaw. Tests of the wing alone at the same angles of yaw were also made. The data are presented in the usual graphic form. An increase in propulsive efficiency with increase in angle of the thrust axis was found. The change in net efficiency, found by charging the whole nacelle drag to the power unit, was negligible, however, within the range of the tests.

Wood, Donald H.↗
NASA NTRS1983

A simulation investigation of the effects of engine-and thrust-response characteristics on helicopter handling qualities

A multi-phase program is being conducted to study, in a generic sense and through ground simulation, the effects of engine response, rotor inertia, rpm control, excess power, and vertical damping on specific maneuvers included in nap-of-the-Earth (NOE) operations. The helicopter configuration with an rpm-governed gas-turbine engine are considered. Handling-qualities-criteria data are considered in light of aspects peculiar to rotary-wing and NOE operations. The results of three moving-based piloted simulation studies are summarized and the frequency, characteristics of the helicopter thrust response which set it apart from other VTOL types are explained. Power-system response is affected by both the engine-governor response and the level of rotor inertia. However, results indicate that with unlimited power, variations in engine response can have a significant effect on pilot rating, whereas changes in rotor inertia, in general, do not. The results also show that any pilot interaction required to maintain proper control can significantly degrade handling qualities. Data for variations in vertical damping and collective sensitivity are compared with existing handling-qualities specifications, MIL-F-83300 and AGARD 577, and show a need for higher minimums for both damping and sensitivity for the bob-up task. Results for cases of limited power are also shown.

Corless, L. D.↗