Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “yaw system”

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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
NASA NTRS1997

HARV ANSER Flight Test Data Retrieval and Processing Procedures

Under the NASA High-Alpha Technology Program the High Alpha Research Vehicle (HARV) was used to conduct flight tests of advanced control effectors, advanced control laws, and high-alpha design guidelines for future super-maneuverable fighters. The High-Alpha Research Vehicle is a pre-production F/A-18 airplane modified with a multi-axis thrust-vectoring system for augmented pitch and yaw control power and Actuated Nose Strakes for Enhanced Rolling (ANSER) to augment body-axis yaw control power. Flight testing at the Dryden Flight Research Center (DFRC) began in July 1995 and continued until May 1996. Flight data will be utilized to evaluate control law performance and aircraft dynamics, determine aircraft control and stability derivatives using parameter identification techniques, and validate design guidelines. To accomplish these purposes, essential flight data parameters were retrieved from the DFRC data system and stored on the Dynamics and Control Branch (DCB) computer complex at Langley. This report describes the multi-step task used to retrieve and process this data and documents the results of these tasks. Documentation includes software listings, flight information, maneuver information, time intervals for which data were retrieved, lists of data parameters and definitions, and example data plots.

Yeager, Jessie C.↗
NASA NTRS1984

Space Shuttle separate-surface control-system study

A control system concept is presented that produces proportional control of yaw moment for the space shuttle from early entry to Mach 2 with only software modifications of the vehicle. It uses separate deflections of the inboard and outboard elevon surfaces and is evaluated, by determining the maximum static yawing moment available by considering the deflection limits of the elevon surfaces. A proportional moment slightly in excess of that produced by the most effective reaction control system (RCS) jet for yaw control can be obtained. In addition to the static moment study, a control law is designed which is intended to produce desired flying qualities.

Brown, L. W.↗
NASA NTRS1991

Aerodynamic control using forebody strakes

Aerodynamic control using a rotatable, miniature nose-tip strake system was investigated in a water tunnel with a forebody model. Flow visualization and yawing moment measurements were performed. The results show that the system was highly effective in controlling the forebody vortices and producing controlled yawing moments at moderate-to-high angles of attack. In comparison with the forebody strakes used in several previous studies, the system can potentially be substantially smaller in size, simpler in operation, and effective over wide ranges of angles of attack and sideslip.

Ng, T. Terry↗
NASA NTRS1979

A piloted simulator study on augmentation systems to improve helicopter flying qualities in terrain flight

Four basic single-rotor helicopters, one teetering, on articulated, and two hingeless, which were found to have a variety of major deficiencies in a previous fixed-based simulator study, were selected as baseline configurations. The stability and control augmentation systems (SCAS) include simple control augmentation systems to decouple pitch and yaw responses due to collective input and to quicken the pitch and roll control responses; SCAS of rate-command type designed to optimize the sensitivity and damping and to decouple the pitch-roll due to aircraft angular tate; and attitude-command type SCAS. Pilot ratings and commentary are presented as well as performance data related to the task. SCAS control usages and their gain levels associated with specific rotor types are also discussed.

Chen, R. T. N.↗
NASA NTRS1982

Control of the forebody vortex orientation by asymmetric air injection. Part A: Application to enhance departure/spin recovery of fighter aircraft. Part B: Details of the flow structure

A novel concept which was developed to provide powerful directional control effectiveness for a fighter aircraft at high angles of attack, where more traditional controls have very limited capability is discussed. The concept utilizes the energy concentrated in the strong forebody vortices (which form on slender bodies at high relative incidence) by controlling the lateral orientation of the vortices with respect to the body. The present concept seeks to utilize the inherent sensitivity of the vortex positioning and its bistable nature to an advantage allowing control of the forces which are developed. As it turns out, the direction or sense of the asymmetric vortex pair is much easier to control than to attenuate. The work which was done to develop the concept for application to an aircraft is described and is directed toward the effects of the concept on aircraft forces and moments and on the flight mechanics of the aircraft during maneuvering at high angles of attack. The objective was to utilize the side force associated with asymmetric vortices, in a controlled manner, to enhance the ability of the fighter to recover from a departure from controlled flight. The results from these water tunnel and wind tunnel experiments show that a small amount of tangential blowing along the forebody near the apex can effectively alter the forebody vortex system and generate large restoring yawing moments.

Skow, A. M.↗
NASA NTRS1983

Control of the forebody vortex orientation by asymmetric air injection. Part A: Application to enhance departure/spin recovery of fighter aircraft and Part B: Details of the flow structure

A concept developed to provide powerful directional control effectiveness for a fighter aircraft at high angles of attack is described. The concept utilizes the energy concentrated in the strong forebody vortices (which form on slender bodies of high relative incidence) by controlling the lateral orientation of the vortices with respect to the body. The objective was to utilize the side force associated with asymmetric vortices, in a controlled manner, to enhance the ability of the fighter to recover from a departure from controlled flight. The results from water tunnel and wind tunnel experiments show that a small amount of tangential blowing along the forebody near the apex can effectively alter the forebody vortex system and generate large restoring yawing moments. Six degree of freedom digital simulation results show that this concept can substantially enhance recovery characteristics of fighter aircraft with long, slender forebodies. Also, the results of experiments which were conducted on a cone model are discussed where the principal test objective was to develop an understanding of the fluid mechanics involved in the process of vortex control. Knowledge gained in these more generic tests should allow the concept to be applied to a wider range of configurations.

Skow, A. M.↗
NASA NTRS1984

Advanced AFCS developments on the XV-15 tilt rotor research aircraft

The design criteria and control and handling qualities of the Automatic Flight Control System (AFCS), developed in the framework of the XV-15 tilt-rotor research aircraft, are evaluated, differentiating between the stability and control criteria. A technically aggressive SCAS control law was implemented, demonstrating that significant benefits accrue when stability criteria are separated from design criteria; the design analyses for application of the control law are presented, and the limit bandwidth for stabilization in hovering flight is shown to be defined by rotor or control lag functions. Flight tests of the aircraft resulted in a rating of 3 on the Cooper-Harper scale; a possibility of achieving a rating of 2 is expected if the system is applied to the yaw and heave control modes.

Churchill, G. B.↗
NASA NTRS2012

Pilot-in-the-Loop Evaluation of a Yaw Rate to Throttle Feedback Control with Enhanced Engine Response

This paper describes the implementation and evaluation of a yaw rate to throttle feedback system designed to replace a damaged rudder. It can act as a Dutch roll damper and as a means to facilitate pilot input for crosswind landings. Enhanced propulsion control modes were implemented to increase responsiveness and thrust level of the engine, which impact flight dynamics and performance. Piloted evaluations were performed to determine the capability of the engines to substitute for the rudder function under emergency conditions. The results showed that this type of implementation is beneficial, but the engines' capability to replace the rudder is limited.

Litt, Jonathan S.↗
NASA NTRS1971

Experiment D010: Ion sensing attitude control

The feasibility of an attitude control system that uses environmental positive ions and an electrostatic detection system to measure spacecraft pitch and yaw is studied. The secondary objective was to measure the spatial and temporal variations of ambient positively charged particles along the orbital path of the Gemini 10 and 12 spacecrafts. The results proved that the use of a horizon detector in conjunction with pitch and yaw sensors would facilitate complete description of the spacecraft position and attitude. Furthermore, with the addition of a servosystem, the unit could be used as a complete automatic attitude-control system that would be applicable from the lowest satellite altitudes up to at least 10 earth radii. Also, results established that the charge density along the trajectory of the satellite could be determined by transmission of output voltages from the individual electrometers.

Sagalyn, R. C.↗
NASA NTRS1979

Simulator study of stall/post-stall characteristics of a fighter airplane with relaxed longitudinal static stability

A real-time piloted simulation was conducted to evaluate the high-angle-of-attack characteristics of a fighter configuration based on wind-tunnel testing of the F-16, with particular emphasis on the effects of various levels of relaxed longitudinal static stability. The aerodynamic data used in the simulation was conducted on the Langley differential maneuvering simulator, and the evaluation involved representative low-speed combat maneuvering. Results of the investigation show that the airplane with the basic control system was resistant to the classical yaw departure; however, it was susceptible to pitch departures induced by inertia coupling during rapid, large-amplitude rolls at low airspeed. The airplane also exhibited a deep-stall trim which could be flown into and from which it was difficult to recover. Control-system modifications were developed which greatly decreased the airplane susceptibility to the inertia-coupling departure and which provided a reliable means for recovering from the deep stall.

Nguyen, L. T.↗
NASA NTRS1979

Behavior of aircraft antiskid braking systems on dry and wet runway surfaces. A slip-velocity-controlled, pressure-bias-modulated system

The braking and cornering response of a slip velocity controlled, pressure bias modulated aircraft antiskid braking system is investigated. The investigation, conducted on dry and wet runway surfaces, utilized one main gear wheel, brake, and tire assembly of a McDonnell Douglas DC 9 series 10 airplane. The landing gear strut was replaced by a dynamometer. The parameters, which were varied, included the carriage speed, tire loading, yaw angle, tire tread condition, brake system operating pressure, and runway wetness conditions. The effects of each of these parameters on the behavior of the skid control system is presented. Comparisons between data obtained with the skid control system and data obtained from single cycle braking tests without antiskid protection are examined.

Stubbs, S. M.↗
NASA NTRS2013

Dexterous Humanoid Robotic Wrist

A humanoid robot includes a torso, a pair of arms, a neck, a head, a wrist joint assembly, and a control system. The arms and the neck movably extend from the torso. Each of the arms includes a lower arm and a hand that is rotatable relative to the lower arm. The wrist joint assembly is operatively defined between the lower arm and the hand. The wrist joint assembly includes a yaw axis and a pitch axis. The pitch axis is disposed in a spaced relationship to the yaw axis such that the axes are generally perpendicular. The pitch axis extends between the yaw axis and the lower arm. The hand is rotatable relative to the lower arm about each of the yaw axis and the pitch axis. The control system is configured for determining a yaw angle and a pitch angle of the wrist joint assembly.

Ihrke, Chris A.↗
NASA NTRS1998

Static Performance of a Wing-Mounted Thrust Reverser Concept

An experimental investigation was conducted in the Jet-Exit Test Facility at NASA Langley Research Center to study the static aerodynamic performance of a wing-mounted thrust reverser concept applicable to subsonic transport aircraft. This innovative engine powered thrust reverser system is designed to utilize wing-mounted flow deflectors to produce aircraft deceleration forces. Testing was conducted using a 7.9%-scale exhaust system model with a fan-to-core bypass ratio of approximately 9.0, a supercritical left-hand wing section attached via a pylon, and wing-mounted flow deflectors attached to the wing section. Geometric variations of key design parameters investigated for the wing-mounted thrust reverser concept included flow deflector angle and chord length, deflector edge fences, and the yaw mount angle of the deflector system (normal to the engine centerline or parallel to the wing trailing edge). All tests were conducted with no external flow and high pressure air was used to simulate core and fan engine exhaust flows. Test results indicate that the wing-mounted thrust reverser concept can achieve overall thrust reverser effectiveness levels competitive with (parallel mount), or better than (normal mount) a conventional cascade thrust reverser system. By removing the thrust reverser system from the nacelle, the wing-mounted concept offers the nacelle designer more options for improving nacelle aero dynamics and propulsion-airframe integration, simplifying nacelle structural designs, reducing nacelle weight, and improving engine maintenance access.

Asbury, Scott C.↗
NASA NTRS2020

Solar Cruiser Technology Maturation Plans

The NASA Marshall Space Flight Center (MSFC) developed the Solar Cruiser mission concept to mature solar sail technology for use in future Heliophysics missions, as well as missions of interest across a broad user community (e.g., space weather and Earth polar observatories). Solar Cruiser will serve as a pathfinder for missions that observe the solar environment from unique vantage points such as a high inclination solar mission opening a fundamentally new range of observational capabilities for the Heliophysics Program and for space weather monitoring. Sustained observations away from the Sun-Earth line (SEL) present unique opportunities for answering the outstanding science questions of Heliophysics, improving space-weather monitoring and prediction, and revealing new information about our Sun and solar system. Propellantless solar sails can be used to create artificial equilibria and maintain indefinite station-keeping at locations sunward of L1 along the SEL, or at any desired offset from the SEL leading or trailing the Earth in its orbit. They can change the heliocentric inclination of a spacecraft from the ecliptic to as high as solar polar, stopping and remaining at any intermediate inclination orbit in between. Sails can be used to hover over the Earth’s poles, using solar photon pressure to offset the Earth’s gravitational attraction, creating functional equivalents of geostationary earth orbits. The Solar Cruiser mission would fly a small spacecraft with a large (>1,600 square meter) solar sail containing embedded reflectivity control devices (RCDs) and photovoltaic cells. The mission concept includes successful deployment of the solar sail, validation of all sail subsystems, controlled station-keeping inside of the Sun-Earth L1 point, attitude control of the sail with the RCDs (including spinning and de-spinning), demonstration of pointing performance for science imaging, and an increase in heliocentric inclination (out of the ecliptic). To demonstrate the requisite sail technology, the Solar Cruiser project will design, fabricate, deploy, and fly the Solar Sail Propulsion Element (SSPE). The SSPE incorporates the following three systems: • The Solar Sail System (SSS) provides the large propulsive surface required for acceleration and smaller reflectivity-changing surfaces for roll control. • The Active Mass Translator System (AMT) provides SSPE motion with respect to the sailcraft bus for pitch and yaw control. • The Solar Sail Attitude Determination and Control System (SSADCS) consists of embedded software to 1) provide autonomous sailcraft attitude estimation, attitude pointing control, and reaction wheel momentum management following sail deployment and 2) execute the uplinked inertial attitude pointing commands to maintain the desired sailcraft trajectory. The plans for maturing each of these technology systems to TRL 5 and beyond are described herein.

Solar Sail↗
NASA NTRS1982

Investigation of correlation between full-scale and fifth-scale wind tunnel tests of a Bell helicopter Textron Model 222

Reasons for lack of correlation between data from a fifth-scale wind tunnel test of the Bell Helicopter Textron Model 222 and a full-scale test of the model 222 prototype in the NASA Ames 40-by 80-foot tunnel were investigated. This investigation centered around a carefully designed fifth-scale wind tunnel test of an accurately contoured model of the Model 222 prototype mounted on a replica of the full-scale mounting system. The improvement in correlation for drag characteristics in pitch and yaw with the fifth-scale model mounted on the replica system is shown. Interference between the model and mounting system was identified as a significant effect and was concluded to be a primary cause of the lack of correlation in the earlier tests.

Squires, P. K.↗
NASA NTRS1981

Limited evaluation of an F-14A airplane utilizing an aileron-rudder interconnect control system in the landing configuration

A flight test was conducted for preliminary evaluation of an aileron-rudder interconnect (ARI) control system for the F-14A airplane in the landing configuration. Two ARI configurations were tested in addition to the standard F-14 flight control system. Results of the flight test showed marked improvement in handling qualities when the ARI systems were used. Sideslip due to adverse yaw was considerably reduced, and airplane turn rate was more responsive to pilot lateral control inputs. Pilot comments substantiated the flight data and indicated that the ARI systems were superior to the standard control system in terms of pilot capability to make lateral offset corrections and heading changes on final approach.

Kelley, W. W.↗
NASA NTRS1994

Computational analysis of forebody tangential slot blowing on the high alpha research vehicle

Current and future fighter aircraft can maneuver in the high-angle-of-attack flight regime while flying at low subsonic and transonic freestream Mach numbers. However, at any flight speed, the ability of the vertical tails to generate yawing moment is limited in high-angle-of-attack flight. Thus, any system designed to provide the pilot with additional side force and yawing moment must work in both low subsonic and transonic flight. However, previous investigations of the effectiveness of forebody tangential slot blowing in generating the desired control forces and moments have been limited to the low subsonic freestream flow regime. In order to investigate the effectiveness of tangential slot blowing in transonic flight, a computational fluid dynamics analysis was carried out during the grant period. Computational solutions were obtained at three different freestream Mach numbers and at various jet mass flow ratios. All results were obtained using the isolated F/A-18 forebody grid geometry at 30.3 degrees angle of attack. One goal of the research was to determine the effect of freestream Mach number on the effectiveness of forebody tangential slot blowing in generating yawing moment. The second part of the research studied the force onset time lag associated with blowing. The time required for the yawing moment to reach a steady-state value from the onset of blowing may have an impact on the implementation of a pneumatic system on a flight vehicle.

Gee, Ken↗