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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

A simulator investigation of parameters affecting helicopter handling qualities in air combat (HAC II)

The Helicopter Air Combat system was used to conduct a pilot simulation study investigating the handling qualities and flight characteristics required for helicopter air-to-air combat. Results indicate that a well-damped directional response, low sideforce caused by sideslip, and some effective dihedral are all desirable for weapon system performance, good handling qualities, and low pilot workload. An angular rate command system was favored over the attitude-type pitch and roll response for most applications, and an enhanced maneuver envelope size over that of current generation aircraft was found to be of advantage.

Lewis, Michael S.↗
NASA NTRS1990

Orbiter utilization as an ACRV

Assuming that a Shuttle Orbiter could be qualified to serve long duration missions attached to Space Station Freedom in the capacity as an Assured Crew Return Vehicle (ACRV), a study was conducted to identify and examine candidate attach locations. Baseline, modified hardware, and new hardware design configurations were considered. Dual simultaneous Orbiter docking accommodation were required. Resulting flight characteristics analyzed included torque equilibrium attitude (TEA), microgravity environment, attitude controllability, and reboost fuel requirements. The baseline Station could not accommodate two Orbiters. Modified hardware configurations analyzed had large TEA's. The utilization of an oblique docking mechanism best accommodated an Orbiter as an ACRV.

Cruz, Jonathan N.↗
NASA NTRS1989

United States orbital transfer vehicle programs

Five U.S. orbital transfer vehicles carrying spacecraft to higher energy orbits than achievable by the Space Shuttle or various expandable launch vehicles are studied. These vehicles are the Payload Assist Module-Delta (PAM-D), an upgraded version designated PAM-DII, the Inertial Upper Stage (IUS), the U.S. Transfer Orbit Stage (TOS), and the Orbital Maneuvering Vehicle (OMV). Capabilities range from providing spacecraft with only a preprogrammed perigee velocity additions to man-in-the-loop remote controlled spacecraft rendezvous, docking, retrieval, and return to a space base. The PAM-D, PAM-DII, and IUS are mature vehicles currently available for mission support. Characteristics, flight records, and costs are defined. The TOS is being commercially developed while the OMV is government developed. The TOS and OMV capabilities, constraints, and costs are reviewed.

Gunn, Charles R.↗
NASA NTRS1990

Grid generation and flow computation about a Martian entry vehicle

A number of vehicles are currently being proposed for a manned mission to Mars. One of these vehicles has a modified blunt-nosed cone configuration. Experimental results were obtained for this vehicle in 1968. They show lift-over-drag ratios comparable to those needed for Mars entry. Computations are performed to verify the earlier results and to further describe the flight characteristics of this vehicle. An analytical method is used to define the surface of this vehicle. A single-block volume grid is generated around the vehicle using the algebraic Two-Boundary Grid Generation algorithm (TBGG) and transfinite interpolation. Euler solutions are then obtained from a Langley Aerodynamic Upward Relaxation Algorithm (LAURA) at Mach 6.0 and angles of attack of 0, 6, and 12 deg. The lift coefficient determined from the LAURA code agree very well with the experimental results. The drag and pitching moment coefficients, however, are underestimated by the code since viscous effects are not considered. Contour plots of the flowfield show no evidence of separation for angles of attack up to 12 deg.

Stewart, J. E.↗
NASA NTRS1991

A powered lift experiment for CFD validation

The transitional flight characteristics of a geometrically simplified STOVL aircraft configuration were measured in the NASA Ames 7- by 10-Foot Wind Tunnel. The experiment is the first in a sequence of tests designed to provide detailed data for evaluating the capability of computational fluid dynamics methods to predict the important flow parameters for powered lift. The model consists of a 60-deg delta wing planform with two circular high-pressure air jets located in a blended fuselage. The measured flows have a maximum freestream Mach number of 0.2. The flow is sonic and at ambient temperature in both jets. The data presented include forces and moments measured using an internal balance, pressures measured at the 281 surface pressure ports, and jet pressures and temperatures. Measurements of the flow are also made in the tunnel test section upstream and downstream of the model and at the jet exists to provide boundary conditions for the planned computations.

Roth, Karlin R.↗
NASA NTRS1991

Mission design strategies for the human exploration of Mars

Conventional mission planning for piloted flights to Mars has been confined to comparing the round-trip energy and flight time requirements of several trajectory classes. This paper addresses these trades in the context of acceptable operational flight characteristics including abort considerations and crew exposure to the interplanetary environment. Quantitative estimates of crew radiation exposure, both during transit and on the surface of Mars, are made and compared to established NASA standards. Time periods spent in zero-gravity during mission transit legs for the various mission options are compared, along with the recovery times in the Mars gravity field. Finally, an integrated mission/abort strategy is proposed, consistent with the expected performance of first-generation nuclear propulsion systems.

Joosten, B. K.↗
NASA NTRS1993

Porous Forebody

Passive device reduces asymmetries in flows and aerodynamic loads. Porous forebody is passive mechanical device, significantly enhancing flight characteristics of all aircraft by minimizing influences of aerodynamics of forebodies upon those characteristics. Leads to safer and better-handling aircraft. Also useful on fast land vehicles and structures or devices subject to high wind.

Wood, Richard M.↗
NASA NTRS1992

Introduction of the M-85 high-speed rotorcraft concept

As a result of studying possible requirements for high-speed rotorcraft and studying many high-speed concepts, a new high-speed rotorcraft concept, designated as M-85, was derived. The M-85 is a helicopter that is reconfigured to a fixed-wing aircraft for high-speed cruise. The concept was derived as an approach to enable smooth, stable conversion between fixed-wing and rotary-wing while retaining hover and low-speed flight characteristics of a low disk loading helicopter. The name, M-85, reflects the high-speed goals of 0.85 Mach number at high altitude. For a high-speed rotorcraft, it is expected that a viable concept must be a cruise-efficient, fixed-wing aircraft so it may be attractive for a multiplicity of missions. It is also expected that a viable high-speed rotorcraft concept must be cruise efficient first and secondly, efficient in hover. What makes the M-85 unique is the large circular hub fairing that is large enough to support the aircraft during conversion between rotary-wind and fixed-wing modes. With the aircraft supported by this hub fairing, the rotor blades can be unloaded during the 100 percent change in rotor rpm. With the blades unloaded, the potential for vibratory loads would be lessened. In cruise, the large circular hub fairing would be part of the lifting system with additional lifting panels deployed for better cruise efficiency. In hover, the circular hub fairing would slightly reduce lift potential and/or decrease hover efficiency of the rotor.

Stroub, Robert H.↗
NASA NTRS1994

Controlling forebody asymmetries in flight: Experience with boundary layer transition strips

The NASA Dryden Flight Research Center has an ongoing program to investigate aircraft flight characteristics at high angles of attack. As part of this investigation, longitudinal boundary layer transition strips were installed on the F-18 HARV forebody, a preproduction F/A-18 radome with a nose-slice tendency, and the X-31 aircraft forebody and noseboom to reduce asymmetric yawing moments at high angles of attack. The transition strips were effective on the F-18 HARV at angles of attack above 60 deg. On the preproduction F/A-18 radome at an angle of attack near 50 deg the strips were not effective. When the transition strips were installed on the X-31 noseboom, a favorable effect was observed on the yawing moment dynamics but the magnitude of the yawing moment was not decreased.

David F Fisher↗
NASA NTRS1994

STOVL CFD model test case

The transitional flight characteristics of a geometrically simplified Short Take-Off Vertical Landing (STOVL) aircraft configuration have been measured in the NASA Ames 7- by 10-Foot Wind Tunnel. The experiment is the first in a sequence of tests designed to provide detailed data for evaluating the capability of computational fluid dynamics methods to predict the important flow parameters for powered lift. The model consists of a 60 deg cropped delta wing platform, blended fuselage and two circular in-line jets that exit perpendicularly from the flat lower surface. The measured flows have a maximum freestream Mach number of 0.2. Model angle of attack is varied between -10 and +20 deg. The flow is ambient temperature in both jet exits and the nozzle pressure ratios are varied between 1 and 3. The data presented includes forces and moments, pressures measured at 281 surface pressure ports and the pressures of the jets. Measurements of the flow are also made in the tunnel test section upstream and downstream of the model and at the jet exits to guide boundary condition selection for the planned computations. Flow visualization and total pressure measurements in the jet plumes provide a description of the three-dimensional jet efflux flowfield.

Roth, Karlin R.↗
NASA NTRS1994

Photovoltaic electric power applied to Unmanned Aerial Vehicles (UAV)

Photovoltaic electric-powered flight is receiving a great deal of attention in the context of the United States' Unmanned Aerial Vehicle (UAV) program. This paper addresses some of the enabling technical areas and their potential solutions. Of particular interest are the long-duration, high-altitude class of UAV's whose mission it is to achieve altitudes between 60,000 and 100,000 feet, and to remain at those altitudes for prolonged periods performing various mapping and surveillance activities. Addressed herein are studies which reveal the need for extremely light-weight and efficient solar cells, high-efficiency electric motor-driven propeller modules, and power management and distribution control elements. Since the potential payloads vary dramatically in their power consumption and duty cycles, a typical load profile has been selected to provide commonality for the propulsion power comparisons. Since missions vary widely with respect to ground coverage requirements, from repeated orbiting over a localized target to long-distance routes over irregular terrain, we have also averaged the power requirements for on-board guidance and control power, as well as ground control and communication link utilization. In the context of the national technology reinvestment program, wherever possible we modeled components and materials which have been qualified for space and defense applications, yet are compatible with civilian UAV activities. These include, but are not limited to, solar cell developments, electric storage technology for diurnal operation, local and ground communications, power management and distribution, and control servo design. And finally, the results of tests conducted by Wright Laboratory on ultralight, highly efficient MOCVD GaAs solar cells purchased from EPI Materials Ltd. (EML) of the UK are presented. These cells were also used for modeling the flight characteristics of UAV aircraft.

Geis, Jack↗
NASA NTRS1996

Structural dynamic model obtained from flight use with piloted simulation and handling qualities analysis

The ability to use flight data to determine an aircraft model with structural dynamic effects suitable for piloted simulation. and handling qualities analysis has been developed. This technique was demonstrated using SR-71 flight test data. For the SR-71 aircraft, the most significant structural response is the longitudinal first-bending mode. This mode was modeled as a second-order system, and the other higher order modes were modeled as a time delay. The distribution of the modal response at various fuselage locations was developed using a uniform beam solution, which can be calibrated using flight data. This approach was compared to the mode shape obtained from the ground vibration test, and the general form of the uniform beam solution was found to be a good representation of the mode shape in the areas of interest. To calibrate the solution, pitch-rate and normal-acceleration instrumentation is required for at least two locations. With the resulting structural model incorporated into the simulation, a good representation of the flight characteristics was provided for handling qualities analysis and piloted simulation.

Powers, Bruce G.↗
NASA NTRS1996

Development of Three-Dimensional Flow Code Package to Predict Performance and Stability of Aircraft with Leading Edge Ice Contamination

In the work reported herein, a simplified, uncoupled, zonal procedure is utilized to assess the capability of numerically simulating icing effects on a Boeing 727-200 aircraft. The computational approach combines potential flow plus boundary layer simulations by VSAERO for the un-iced aircraft forces and moments with Navier-Stokes simulations by NPARC for the incremental forces and moments due to iced components. These are compared with wind tunnel force and moment data, supplied by the Boeing Company, examining longitudinal flight characteristics. Grid refinement improved the local flow features over previously reported work with no appreciable difference in the incremental ice effect. The computed lift curve slope with and without empennage ice matches the experimental value to within 1%, and the zero lift angle agrees to within 0.2 of a degree. The computed slope of the un-iced and iced aircraft longitudinal stability curve is within about 2% of the test data. This work demonstrates the feasibility of a zonal method for the icing analysis of complete aircraft or isolated components within the linear angle of attack range. In fact, this zonal technique has allowed for the viscous analysis of a complete aircraft with ice which is currently not otherwise considered tractable.

Aircraft icing↗
NASA NTRS1996

Further Study of 'Pop-Up' Vortex Generators

The model is a replica of a modified MAX-103 kit aircraft that our Parks College of St. Louis University Student Design Group built and modified from a tail wheel to a tricycle configuration. A model was tested in the Parks College low-speed wind tunnel. I hope to initiate flight-testing upon my second return to. St. Louis. The combined data using wind tunnel, water tunnel, RC, flight-testing and analytical results will be very valuable for assessing the correlation between the different methods of analyses, since at present it is almost impossible to accurately predict flight characteristics from anything but in-situ tests. Unfortunately, political/financial reasons dictated using a generic wing rather than a specific model in the NASA-DFRC water tunnel.

Manor, David↗
NASA NTRS1975

Analysis of the Flight Motions of a Small Deployable Glider Configuration

An investigation was conducted at the request of the U.S. Air Force Avionics Laboratory to analyze the flight characteristics of a small uncontrolled glider with folding wings. The study consisted of wind-tunnel tests of an actual glider and a theoretical analysis of the performance, stability, and trimmability of the configuration.

Coe, Paul L., Jr.↗
NASA NTRS1999

Current Testing Capabilities at the NASA Ames Ballistic Ranges

Capabilities for designing and performing ballistic range tests at the NASA Ames Research Center are presented. Computational tools to assist in designing and developing ballistic range models and to predict the flight characteristics of these models are described. A CFD code modeling two-stage gun performance is available, allowing muzzle velocity, maximum projectile base pressure, and gun erosion to be predicted. Aerodynamic characteristics such as drag and stability can be obtained at speeds ranging from 0.2 km/s to 8 km/s. The composition and density of the test gas can be controlled, which allows for an assessment of Reynolds number and specific heat ratio effects under conditions that closely match those encountered during planetary entry. Pressure transducers have been installed in the gun breech to record the time history of the pressure during launch, and pressure transducers have also been installed in the walls of the range to measure sonic boom effects. To illustrate the testing capabilities of the Ames ballistic ranges, an overview of some of the recent tests is given.

Ramsey, Alvin↗
NASA NTRS2000

Flying Qualities Evaluation of a Commuter Aircraft With an Ice Contaminated Tailplane

During the NASA/FAA (Federal Aviation Administration) Tailplane Icing Program, pilot evaluations of aircraft flying qualities were conducted with various ice shapes attached to the horizontal tailplane of the NASA Twin Otter Icing Research Aircraft. Initially, only NASA pilots conducted these evaluations, assessing the differences in longitudinal flight characteristics between the baseline or clean aircraft, and the aircraft configured with an Ice Contaminated Tailplane (ICT). Longitudinal tests included Constant Airspeed Flap Transitions, Constant Airspeed Thrust Transitions, zero-G Pushovers, Repeat Elevator Doublets, and Simulated Approach and Go-Around tasks. Later in the program, guest pilots from government and industry were invited to fly the NASA Twin Otter configured with a single full-span artificial ice shape attached to the leading edge of the horizontal tailplane. This shape represented ice formed due to a 'Failed Boot' condition, and was generated from tests in the Glenn Icing Research Tunnel on a full-scale tailplane model. Guest pilots performed longitudinal handling tests, similar to those conducted by the NASA pilots, to evaluate the ICT condition. In general, all pilots agreed that longitudinal flying qualities were degraded as flaps were lowered, and further degraded at high thrust settings. Repeat elevator doublets demonstrated reduced pitch damping effects due to ICT, which is a characteristic that results in degraded flying qualities. Pilots identified elevator control force reversals (CFR) in zero-G pushovers at a 20 deg flap setting, a characteristic that fails the FAR 25 no CFR certification requirement. However, when the same pilots used the Cooper-Harper rating scale to perform a simulated approach and go-around task at the 20 deg flap setting, they rated the airplane as having Level I and Level II flying qualities respectively. By comparison, the same task conducted at the 30 deg flap setting, resulted in Level II flying qualities for the approach portion, and Level III for the go-around portion.The results of this program indicate that safe and acceptable flying qualities with an ICT condition, can be effectively assessed by task-oriented pilot maneuvers. In addition, other maneuvers such as repeat elevator doublets provide good qualitative and quantitative assessments of pitch damping and elevator effectiveness, which are characteristics that correlate well with pilot task ratings. The results of this testing indicate that the FAR 25 zero-G pushover maneuver, which requires no CFR during its execution, may be an overly conservative pass/fail criteria for aircraft certification.

Ranaudo, Richard J.↗