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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 541 records · Page 30

All sources NASA NTRS DOE OSTI

NASA NTRS1981

The effects of lateral aerodynamic uncertainties on the handling qualities of the space shuttle orbiter at Mach numbers of 1.5 and .6

The effects of aerodynamic uncertainties on the handling qualities of the space shuttle orbiter were investigated with the use of six-degree-of-freedom, nonlinear equations of motion on the hybrid computer system. Flight condition characteristics for Mach numbers of 1.5 and .6 for the nominal and off nominal angle of attack conditions were selected for this investigation. Results revealed that at the low Mach number condition (.6), only a few problems existed for the angle of attack range considered and the many combinations of large aerodynamic variations considered. Moreover, none of these problems were considered to be related to poor handling qualities. For the angle of attack conditions considered at the high Mach number (1.5) problems existed with reduction of roll rate which can result in roll reversal conditions. In many cases, sideslip became proverse and increased rudder deflections and yaw jets were required.

Brown, L. W.↗

NASA NTRS2008

Autonomous Formation Flight: Project Overview

Objectives: a) Map the vortex effects; b) Formation Auto-Pilot Requirements. Two NASA F/A-18 aircraft in formation: a) NASA 845 Systems Research Aircraft; b) NASA 847 Support Aircraft. Flight Conditions: M = 0.56, 25000 feet (Subsonic condition); b) M = 0.86, 36000 feet (Transonic condition). Nose-To-Tail (N2T) Distances: 20, 55, 110 and 190 feet. Lessons learned: a) Controllable flight in vortex is possible with pilot feedback (displays); b) Position hold at best C(sub D), is attainable; c) Best drag location is close to max rolling moment; e) Drag reductions demonstrated up to 22% (WFE up to 20%); f) Induced drag results compare favorably with simple prediction model; g) "Sweet Spot" (lateral & vertical area > 25%) is larger than predicted; h) Larger wing overlaps result in sign reversals in roll, yaw; i) As predicted, favorable effects degrade gradually with increased nose-to-tail distances after peaking at 3 span lengths aft; and j) Demonstrated - over 100 N mi (>15%) range improvement and 650 lbs (14%) fuel savings on actual simulated F/A-18 cruise mission.

Cole, Jennifer↗

NASA NTRS1991

Reusable Reentry Satellite (RRS) system design study. Phase B, appendix E: Attitude control system study

A study which consisted of a series of design analyses for an Attitude Control System (ACS) to be incorporated into the Re-usable Re-entry Satellite (RRS) was performed. The main thrust of the study was associated with defining the control laws and estimating the mass and power requirements of the ACS needed to meet the specified performance goals. The analyses concentrated on the different on-orbit control modes which start immediately after the separation of the RRS from the launch vehicle. The three distinct on-orbit modes considered for these analyses are as follows: (1) Mode 1 - A Gravity Gradient (GG) three-axis stabilized spacecraft with active magnetic control; (2) Mode 2 - A GG stabilized mode with a controlled yaw rotation rate ('rotisserie') using three-axis magnetic control and also incorporating a 10 N-m-s momentum wheel along the (Z) yaw axis; and (3) Mode 3 - A spin stabilized mode of operation with the spin about the pitch (Y) axis, incorporating a 20 N-m-s momentum wheel along the pitch (Y) axis and attitude control via thrusters. To investigate the capabilities of the different controllers in these various operational modes, a series of computer simulations and trade-off analyses have been made to evaluate the achievable performance levels, and the necessary mass and power requirements.

Source record↗

NASA NTRS1944

A theoretical investigation of the rolling oscillations of an airplane with ailerons free

Cohen, Doris↗

DOE OSTI2025

Data for "Implications of Zoning Ordinances for Rural Utility-Scale Solar Deployment and Power System Decarbonization in the Great Lakes Region".

This dataset includes the Energy Zoning Database and geographic shapefiles used to identify suitable rural areas for utility-scale solar development. Additionally, it contains the input data required for the capacity expansion model, including information on existing electric generators and their associated costs, solar resource potential, and transmission infrastructure data. These datasets collectively support the analysis presented in the paper, ensuring a comprehensive assessment of zoning regulations, land suitability, and the economic and technical feasibility of solar deployment in rural areas.

Owusu-Obeng, Papa Yaw (ORCID:0000000334385183)↗

NASA NTRS1983

Inherent spiral stability in a fixed wing aircraft by means of a simplified pneumatic wing tip control system

The concept of the lateralizer device is to sense the difference in wing tip static pressures (differential pressures being created by wing tip venturis) produced when any deviation from straight to level flight occurs. In a steady state turn the low slow wing tip experiences less venturi suction than the high fast wing tip. This signal activates the appropriate servos connected to the ailerons to produce a wing leveling restoring moment. If the wing is subjected to rolling velocities due to changes of the local angle of attack at the tip, the downgoing wing tip operates at a higher angle than the upgoing one. If with an increase in the angle of attack the signal is such that it increases the venturi pressure, then the servos are activated to produce the most negative signal to an upgoing aileron which results in a wing leveling restoring moment. In other words, any deviation from straight and level flight in either roll or yaw is exploited and the difference signal from the differential pressures activates the servo to effect or produce the necessary corrective action to null the signal.

Goglia, G. L.↗

NASA NTRS2000

Transient cardio-respiratory responses to visually induced tilt illusions

Although the orthostatic cardio-respiratory response is primarily mediated by the baroreflex, studies have shown that vestibular cues also contribute in both humans and animals. We have demonstrated a visually mediated response to illusory tilt in some human subjects. Blood pressure, heart and respiration rate, and lung volume were monitored in 16 supine human subjects during two types of visual stimulation, and compared with responses to real passive whole body tilt from supine to head 80 degrees upright. Visual tilt stimuli consisted of either a static scene from an overhead mirror or constant velocity scene motion along different body axes generated by an ultra-wide dome projection system. Visual vertical cues were initially aligned with the longitudinal body axis. Subjective tilt and self-motion were reported verbally. Although significant changes in cardio-respiratory parameters to illusory tilts could not be demonstrated for the entire group, several subjects showed significant transient decreases in mean blood pressure resembling their initial response to passive head-up tilt. Changes in pulse pressure and a slight elevation in heart rate were noted. These transient responses are consistent with the hypothesis that visual-vestibular input contributes to the initial cardiovascular adjustment to a change in posture in humans. On average the static scene elicited perceived tilt without rotation. Dome scene pitch and yaw elicited perceived tilt and rotation, and dome roll motion elicited perceived rotation without tilt. A significant correlation between the magnitude of physiological and subjective reports could not be demonstrated.

NASA Center JSC↗

DOE OSTI2020

Validation of Numerical Models of the Offshore Wind Turbine From the Alpha Ventus Wind Farm Against Full-Scale Measurements Within OC5 Phase III

The main objective of the Offshore Code Comparison Collaboration Continuation, with Correlation (OC5) project is validation of aero-hydro-servo-elastic simulation tools for offshore wind turbines (OWTs) through comparison of simulated results to the response data of physical systems. Phase III of the OC5 project validates OWT models against the measurements recorded on a Senvion 5M wind turbine supported by the OWEC Quattropod from the alpha ventus offshore wind farm. The following operating conditions of the wind turbine were chosen for the validation: (1) idling below the cut-in wind speed, (2) rotor-nacelle assembly (RNA) rotation maneuver below the cut-in wind speed, (3) power production below and above the rated wind speed, and (4) shutdown. A number of validation load cases were defined based on these operating conditions. The following measurements were used for validation: (1) strains and accelerations recorded on the support structure and (2) pitch, yaw, and azimuth angles, generator speed, and electrical power recorded from the RNA. Strains were not directly available from the majority of the OWT simulation tools; therefore, strains were calculated based on out-of-plane bending moments, axial forces, and cross-sectional properties of the structural members. The simulation results and measurements were compared in terms of time series, discrete Fourier transforms, power spectral densities, and probability density functions of strains and accelerometers. A good match was achieved between the measurements and models setup by OC5 Phase III participants.

17 WIND ENERGY↗

NASA NTRS2000

Emergency Multiengine Aircraft System for Lateral Control Using Differential Thrust Control of Wing Engines

Development of an emergency flight control system is disclosed for lateral control using only differential engine thrust modulation of multiengine aircraft is currently underway. The multiengine has at least two engines laterally displaced to the left and right from the axis of the aircraft. In response to a heading angle command psi(sub c) is to be tracked. By continually sensing the heading angle psi of the aircraft and computing a heading error signal psi(sub e) as a function of the difference between the heading angle command psi(sub c) and the sensed heading angle psi, a track control signal is developed with compensation as a function of sensed bank angle phi. Bank angle rate phi, or roll rate p, yaw rate tau, and true velocity produce an aircraft thrust control signal ATC(sub psi(L,R)). The thrust control signal is differentially applied to the left and right engines, with equal amplitude and opposite sign, such that a negative sign is applied to the control signal on the side of the aircraft. A turn is required to reduce the error signal until the heading feedback reduces the error to zero.

Burken, John J.↗

NASA NTRS2024

Optimal Control Allocation for Distributed Electric Propulsion in a Series/Parallel Partial Hybrid Powertrain

The SUbsonic Single Aft eNgine (SUSAN) Electrofan is a NASA concept jet transport aircraft with a 2040 entry-into-service date. It utilizes electrified aircraft propulsion (EAP) to enable propulsive and aerodynamic benefits to reduce fuel usage, emissions, and cost. The powertrain consists of a single thrust producing, boundary layer-ingesting (BLI) turbofan gas turbine engine (GTE) with generators driving a series/parallel partial hybrid EAP system. The architecture includes 16 underwing contrarotating BLI fans, eight on each side, in a mailslot configuration. The 16 fans run on power extracted from the GTE through four 5 MW motor/generators connected to the Low-Pressure Spool, and a single 1 MW motor/generator on the High-Pressure Spool. The distributed fans can be used by the flight control to augment or replace the rudder function. At top of climb, the power extracted from the GTE for the fans is boosted by batteries. The design provides redundancy, and the capacity for boost means that the fans are designed to be able to provide additional thrust when necessary. These features can be leveraged in case of a fan or generator failure. This paper sets up the optimal control problem of setpoint determination for individual fans in the distributed propulsion system, accounting for electrical string efficiencies, saturations, and failures. The solution minimizes power consumption while maintaining thrust and torque on the airframe for maneuvering. Additionally, thrust that would have been lost due to temporary fan speed or power saturation is optimally redistributed to maintain overall desired thrust and torque on the aircraft. The power extraction range constraints derive from the gas turbine engine design and the small amount of variation allowed for the engine to maintain operability. The problem formulation allows the number and location of fan failures for which the thrust and torque can be maintained to be investigated, which has implications for certification. Simulations of a coordinated turn utilizing the distributed electric propulsion for yaw rate control under different failure scenarios demonstrate the robustness of the powertrain design to failures and help define its limitations.

Distributed Electric Propulsion↗

NASA NTRS2004

Geoscience Laser Altimeter System (GLAS) Loop Heat Pipes: An Eventual First Year On-Orbit

Goddard Space Flight Center's Geoscience Laser Altimeter System (GLAS) is the sole scientific instrument on the Ice, Cloud and land Elevation Satellite (ICESat) that was launched on January 12, 2003 from Vandenberg AFB. A thermal control architecture based on propylene Loop Heat Pipe technology was developed to provide selectable/stable temperature control for the lasers and other electronics over the widely varying mission environment. Following a nominal LHP and instrument start-up, the mission was interrupted with the failure of the first laser after only 36 days of operation. During the 5-month failure investigation, the two GLAS LHPs and the electronics operated nominally, using heaters as a substitute for the laser heat load. Just prior to resuming the mission, following a seasonal spacecraft yaw maneuver, one of the LHPs deprimed and created a thermal runaway condition that resulted in an emergency shutdown of the GLAS instrument. This paper presents details of the LHP anomaly, the resulting investigation and recovery, along with on-orbit flight data during these critical events.

Grob, E.↗

NASA NTRSDate not supplied

Momentum Management Strategies for Solar Cruiser and Beyond (ISSS 2023)

Solar Cruiser is a small (ESPA-class) satellite Technology Demonstration Mission (TDM) to mature solar sail propulsion technology using a solar sail larger than 1600 square meters, demonstrating performance both as a propulsion system and a stable pointing platform for science observations in an artificial halo orbit sunward of the Sun-Earth Lagrange Point 1 (sub-L1). To ensure attitude control throughout the mission, momentum accumulated on the reaction wheels (RWs) used for attitude control must be managed such that the sailcraft does not lose control due to RW momentum saturation. Momentum builds up on the wheels from environmental disturbance torques caused by solar radiation pressure combined with a center of mass (CM)/center of pressure (CP) offset, deformed sail shape, and an off-sun pointing angle, plus other factors. Solar Cruiser mitigates this momentum build up by utilizing an Active Mass Translator (AMT) that maintains pitch and yaw momentum by trimming the CM/CP offsets, and thrusters to maintain roll momentum. A survey was conducted by the Solar Cruiser team to assess the feasibility and tradeoffs of novel momentum management concepts such as Reflectivity Control Devices (RCD’s), different thruster configurations, and control vanes and other articulated control surfaces. In addition, techniques to reduce disturbance torque buildup, such as reducing boom tip deflections and clock angle control, were assessed. Similar sailcraft momentum management strategies can be used for future missions such as space weather monitoring and Earth magnetotail science missions

Solar Sail↗

NASA NTRS1944

A Theoretical Investigation of the Rolling Oscillations of an Airplane with Ailerons Free

An analysis is made of the stability of an airplane with ailerons free, with particular attention to the motions when the ailerons have a tendency to float against the wind. The present analysis supersedes the aileron investigation contained in NACA Report No. 709. The equations of motion are first written to include yawing and sideslipping, and it is demonstrated that the principal effects of freeing the ailerons can be determined without regard to these motions. If the ailerons tend to float against the wind and have a high degree of aerodynamic balance, rolling oscillations, in addition to the normal lateral oscillations, are likely to occur. On the basis of the equations including only the rolling motion and the aileron deflection, formulas are derived for the stability and damping of the rolling oscillations in terms of the hinge moment derivatives and other characteristics of the ailerons and airplane. Charts are also presented showing the oscillatory regions and stability boundaries for a fictitious airplane of conventional proportions. The effects of friction in the control system are investigated and discussed. If the ailerons tend to trail with the wind, the condition for stable variation of stick force with aileron deflection is found to determine the amount of aerodynamic balance that may be used. If the ailerons tend to float against the wind, the period and damping of the rolling oscillations are found to be satisfactory (in a mass-balanced system) so long as the restoring moment is not completely balanced out. Unbalanced mass behind the hinge, however, has an unfavorable effect on the damping of the oscillations and so shifts the boundary that close aerodynamic balance may not be attainable.

Cohen, Doris↗

NASA NTRS2008

Experimental Measurement of RCS Jet Interaction Effects on a Capsule Entry Vehicle

An investigation was made in NASA Langley Research Center s 31-Inch Mach 10 Tunnel to determine the effects of reaction-control system (RCS) jet interactions on the aft-body of a capsule entry vehicle. The test focused on demonstrating and improving advanced measurement techniques that would aid in the rapid measurement and visualization of jet interaction effects for the Orion Crew Exploration Vehicle while providing data useful for developing engineering models or validation of computational tools used to assess actual flight environments. Measurements included global surface imaging with pressure and temperature sensitive paints and three-dimensional flow visualization with a scanning planar laser induced fluorescence technique. The wind tunnel model was fabricated with interchangeable parts for two different aft-body configurations. The first, an Apollo-like configuration, was used to focus primarily on the forward facing roll and yaw jet interactions which are known to have significant aft-body heating augmentation. The second, an early Orion Crew Module configuration (4-cluster jets), was tested blowing only out of the most windward yaw jet, which was expected to have the maximum heating augmentation for that configuration. Jet chamber pressures and tunnel flow conditions were chosen to approximate early Apollo wind tunnel test conditions. Maximum heating augmentation values measured for the Apollo-like configuration (>10 for forward facing roll jet and 4 for yaw jet) using temperature sensitive paint were shown to be similar to earlier experimental results (Jones and Hunt, 1965) using a phase change paint technique, but were acquired with much higher surface resolution. Heating results for the windward yaw jet on the Orion configuration had similar augmentation levels, but affected much less surface area. Numerical modeling for the Apollo-like yaw jet configuration with laminar flow and uniform jet outflow conditions showed similar heating patterns, qualitatively, but also showed significant variation with jet exit divergence angle, with as much as 25 percent variation in heat flux intensity for a 10 degree divergence angle versus parallel outflow. These results along with the fabrication methods and advanced measurement techniques developed will be used in the next phase of testing and evaluation for the updated Orion RCS configuration.

Buck, Gregory M.↗

NASA NTRS1973

Effects of the air breathing propulsion system on space shuttle orbiter subsonic stability and control characteristics (OA71A)

Experimental aerodynamic investigations were conducted on an 0.0405 scale representation of the -89B (2A) Space Shuttle Orbiter in a 7.75 x 11.00 ft low speed wind tunnel during the time period from July 27, 1973 to August 3, 1973. The primary test objective was to investigate the aerodynamic effects of engine nacelle grouping and location on the orbiter ferry mission configuration. Five nacelles were tested, both individually mounted as well as mounted in a podded configuration, at the baseline position and moved 45.0 in. aft (full scale). Orbiter control effectiveness, both with and without nacelles, was recorded at elevon deflections of 0 deg, 5 deg, 10 deg, -10 deg and -20 deg and aileron deflections, about 0 deg elevon, of 0 deg, 5 deg, 10 deg, and 15 deg. The model was sting mounted on a 2.5 inch diameter internal strain gage balance entering through the base region. The nominal angle of attack range was -4 deg or = alpha or = 30 deg. Yaw polars were recorded over the beta range of -10 deg or = beta or = at fixed angles of attack of 0 deg and 10 deg.

Mennell, R. C.↗

NASA NTRS1989

Flight/propulsion control integration for V/STOL fighter/attack aircraft

A NASA-defined technology program investigating integrated flight/propulsion control system design for vertical and short takeoff and landing (V/STOL) aircraft is outlined, and initial fixed-base simulation experiments for two V/STOL aircraft are covered. It is shown that transition performance can be characterized by the minimum climb or level-flight acceleration that can be achieved. Level-1 flying qualities can be achieved for deceleration to hover in instrument conditions, and for shore-based and shipboard landing when attitude and velocity stabilization and command augmentation modes are provided. Level-1 and Level-2 flying qualities can be expected when only attitude command is provided. During vertical landing aboard a destroyer in heavy seas, substantial bleed flow rates are reported for a control arrangement employing reaction control for the pitch, roll, and yaw axes. Peak bleed flows can be reduced for a control arrangement using lateral-thrust transfer for roll control.

Franklin, James A.↗

NASA NTRS1981

On the motion of a flexible shallow spherical shell in orbit

A mathematical model for the motion of a large, flexible shallow spherical shell in a circular orbit is presented. For small elastic displacements and attitude angles the linearized equations for the roll and yaw (out-of-plane) motions completely separate from the pitch (in-plane) and elastic motions. However, the pitch and only the axisymmetric elastic modes are seen to be coupled in the linear range. With the shell's symmetry axis following the local vertical, the structure undergoes a static deformation under the influence of gravity and inertia. Further, the pitch and roll motions are unstable due to the unfavorable moment of inertia distribution. A rigid lightweight dumbbell with heavy tip masses and connected to the shell at its apex by a spring loaded double gimbal joint is proposed to gravitationally stabilize the structure. It is noted that the dumbbell motion can excite only those elastic modes having one nodal diameter. A sensitivity study of the system response characteristics to the key system parameters is carried out.

Kumar, V. K.↗

NASA NTRS1990

Prediction of forces and moments for flight vehicle control effectors. Part 1: Validation of methods for predicting hypersonic vehicle controls forces and moments

Many types of hypersonic aircraft configurations are currently being studied for feasibility of future development. Since the control of the hypersonic configurations throughout the speed range has a major impact on acceptable designs, it must be considered in the conceptual design stage. The ability of the aerodynamic analysis methods contained in an industry standard conceptual design system, APAS II, to estimate the forces and moments generated through control surface deflections from low subsonic to high hypersonic speeds is considered. Predicted control forces and moments generated by various control effectors are compared with previously published wind tunnel and flight test data for three configurations: the North American X-15, the Space Shuttle Orbiter, and a hypersonic research airplane concept. Qualitative summaries of the results are given for each longitudinal force and moment and each control derivative in the various speed ranges. Results show that all predictions of longitudinal stability and control derivatives are acceptable for use at the conceptual design stage. Results for most lateral/directional control derivatives are acceptable for conceptual design purposes; however, predictions at supersonic Mach numbers for the change in yawing moment due to aileron deflection and the change in rolling moment due to rudder deflection are found to be unacceptable. Including shielding effects in the analysis is shown to have little effect on lift and pitching moment predictions while improving drag predictions.

Maughmer, Mark D.↗