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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

FLEXSTAB: A computer program for the prediction of loads and stability and control of flexible aircraft

Capabilities of the FLEXSTAB Computer Program System are described and illustrated. Aeroelastic analysis of a wide variety of aircraft configurations is performed. The aerodynamic theory used in FLEXSTAB is applicable to both steady and unsteady, subsonic and supersonic flow for multiple wing-body tail nacelle configurations with a plane of symmetry. For unsteady flow calculations, an unsteady aerodynamic theory is used which is appropriate for the low reduced frequencies associated with aircraft flight dynamics. The aircraft is modeled as either a rigid or flexible structure. The computer trims the aircraft in steady reference flight and computes both static and dynamic stability and control derivatives and the stability behavior about the trim condition. The airplane lifting pressure distribution, aerodynamic and inertia loads and deflected shape are also computed.

Perkin, B. R.↗
NASA NTRS1973

Explicit determination of lateral-directional stability and control derivatives by simutaneous time vector analysis of two maneuvers

An extension of the time vector technique for determining stability and control derivatives from flight data is formulated. The technique provides for explicit determination of derivatives by means of simultaneous analysis of two maneuvers which differ by a dependent control input. The control derivatives for the dependent input are also explicitly determined. This extended technique is preferable to the application of the time vector method to single maneuvers in that no estimates of derivatives are required. An example illustrating the application of the technique is given.

Gilyard, G. B.↗
NASA NTRS2017

Low-Speed Stability and Control Test of a "Double-Bubble" Transport Configuration

A test in the Langley 12-Foot Low-Speed Tunnel was conducted as a risk mitigation effort to quickly obtain some low-speed stability and control data on a "double-bubble" or D8 transport configuration. The test also tested some configuration design trades. A 5-percent scale model was tested with stabilizer, elevator, rudder and aileron control deflections. This report summarizes the test results.

Vicroy, Dan D.↗
NASA NTRS1986

Flight test report of the NASA icing research airplane: Performance, stability, and control after flight through natural icing conditions

Flight test results are presented documenting the effect of airframe icing on performance and stability and control of a NASA DHC-6 icing research aircraft. Kohlman System Research, Inc., provided the data acquisition system and data analysis under contract to NASA. Performance modeling methods and MMLE techniques were used to determine the effects of natural ice on the aircraft. Results showed that ice had a significant effect on the drag coefficient of the aircraft and a modest effect on the MMLE derived longitudinal stability coefficients (code version MMLE). Data is also presented on asymmetric power sign slip maneuvers showing rudder floating characteristics with and without ice on the vertical stabilizer.

Jordan, J. L.↗
NASA NTRS1982

Development and flight evaluation of an augmented stability active controls concept: Executive summary

A pitch active control system (PACS) was developed and flight tested on a wide body jet transport (L-1011) with a flying horizontal stabilizer. Two dual channel digital computers and the associated software provide command signals to a dual channel series servo which controls the stabilizer power actuators. Input sensor signals to the computer are pitch rate, column trim position, and dynamic pressure. Control laws are given for the PACS and the system architecture is defined. Discussions are given regarding piloted flight simulation and vehicle system simulation and vehicle system simulation tests that are performed to verify control laws and system operation prior to installation on the aircraft. Modifications to the basic aircraft included installation of the PACS, addition of a c.g. management system to provide a c.g. range from 25 to 39% mac, and downrigging of the geared elevator to provide the required nose down control authority for aft c.g. flight test conditions. Three pilots used the Cooper-Harper Rating Scale to judge flying qualities of the aircraft with PACS on and off. The handling qualities with the c.g. at 39% mac (41% stability margin) and PACS operating were judged to be as good as the handling qualities with the c.g. at 25% mac (+15% stability margin) and PACS off.

Guinn, W. A.↗
NASA NTRSDate not supplied

Rapid Aero Modeling of a Lift+Cruise UAM Configuration for Stability and Control Using Overset Grid CFD

This talk will address some aspects of an effort to develop both static and dynamic stability and control derivatives of a generic Lift+Cruise Urban Air Mobility vehicle. In particular, the use of NASA overset grid CFD packages OVERFLOW and Chimera Grid Tools allowed for rapid grid and solution generation while varying many database factors. Approach details include coarse gridding and control effectors, rotor disk modeling, convergence evaluation, and parallel execution on a midrange compute resource. A brief *description of the Rapid Aero Modeling (RAM) approach, including design of experiments and response surface modeling, will be given, and recent simulations of powered and unpowered dynamic multisine maneuvers will be presented.

Overset Grid CFD↗
NASA NTRS1998

High Stability Engine Control (HISTEC): Flight Demonstration Results

Future aircraft turbine engines, both commercial and military, must be able to accommodate expected increased levels of steady-state and dynamic engine-face distortion. The current approach of incorporating sufficient design stall margin to tolerate these increased levels of distortion would significantly reduce performance. The High Stability Engine Control (HISTEC) program has developed technologies for an advanced, integrated engine control system that uses measurement- based estimates of distortion to enhance engine stability. The resulting distortion tolerant control reduces the required design stall margin, with a corresponding increase in performance and/or decrease in fuel burn. The HISTEC concept was successfully flight demonstrated on the F-15 ACTIVE aircraft during the summer of 1997. The flight demonstration was planned and carried out in two parts, the first to show distortion estimation, and the second to show distortion accommodation. Post-flight analysis shows that the HISTEC technologies are able to successfully estimate and accommodate distortion, transiently setting the stall margin requirement on-line and in real-time. Flight demonstration of the HISTEC technologies has significantly reduced the risk of transitioning the technology to tactical and commercial engines.

Delaat, John C.↗
NASA NTRS1998

Flight Stability and Control and Performance Results from the Linear Aerospike SR-71 Experiment (LASRE)

The Linear Aerospike SR-71 Experiment (LASRE) is presently being conducted to test a 20-percent-scale version of the Linear Aerospike rocket engine. This rocket engine has been chosen to power the X-33 Single Stage to Orbit Technology Demonstrator Vehicle. The rocket engine was integrated into a lifting body configuration and mounted to the upper surface of an SR-71 aircraft. This paper presents stability and control results and performance results from the envelope expansion flight tests of the LASRE configuration up to Mach 1.8 and compares the results with wind tunnel predictions. Longitudinal stability and elevator control effectiveness were well-predicted from wind tunnel tests. Zero-lift pitching moment was mispredicted transonically. Directional stability, dihedral stability, and rudder effectiveness were overpredicted. The SR-71 handling qualities were never significantly impacted as a result of the missed predictions. Performance results confirmed the large amount of wind-tunnel-predicted transonic drag for the LASRE configuration. This drag increase made the performance of the vehicle so poor that acceleration through transonic Mach numbers could not be achieved on a hot day without depleting the available fuel.

Moes, Timothy R.↗
NASA NTRS1948

Measurements of the Longitudinal Stability and Control and Stalling Characteristics of a North American P-51H Airplane (AAF No. 4-64164)

Flight tests have been made to determine the longitudinal stability and control and stalling characteristics of a North American P-51H airplane. The results indicate that the airplane has satisfactory longitudinal stability in all the flight conditions tested at normal loadings up to 25,000 feet altitude. At Mach numbers above 0.7, the elevator push force required for longitudinal trim decreased somewhat because of compressibility effects. The elevator stick force per g in accelerated turns at the forward center-of-gravity position of 24 percent mean aerodynamic chord above 250 miles per hour was in excess of the required limits at both 5,000 and 25,OOO feet altitude. The longitudinal-trim-force changes due to flaps and power were small, but the rudder-trim-force change with power change was high. The stalling characteristics in all the conditions tested were satisfactory.

Kraft, Christopher C., Jr.↗
NASA NTRS1972

Effects of an in-flight thrust reverser on the stability and control characteristics of a single-engine fighter airplane model

The changes in thrust minus drag performance as well as longitudinal and directional stability and control characteristics of a single-engine jet aircraft attributable to an in-flight thrust reverser of the blocker-deflector door type were investigated in a 16-foot transonic wind tunnel. The longitudinal and directional stability data are presented. Test conditions simulated landing approach conditions as well as high speed maneuvering such as may be required for combat or steep descent from high altitude.

Mercer, C. E.↗