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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 433 records · Page 24
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Summary of flight tests to determine the spin and controllability characteristics of a remotely piloted, large-scale (3/8) fighter airplane model

An unpowered, large, dynamically scaled airplane model was test flown by remote pilot to investigate the stability and controllability of the configuration at high angles of attack. The configuration proved to be departure/spin resistant; however, spins were obtained by using techniques developed on a flight support simulator. Spin modes at high and medium high angles of attack were identified, and recovery techniques were investigated. A flight support simulation of the airplane model mechanized with low speed wind tunnel data over an angle of attack range of + or - 90 deg. and an angle of sideslip range of + or - 40 deg. provided insight into the effects of altitude, stability, aerodynamic damping, and the operation of the augmented flight control system on spins. Aerodynamic derivatives determined from flight maneuvers were used to correlate model controllability with two proposed departure/spin design criteria.

Holleman, E. C.↗
NASA NTRS1976

A simplified application of the method of operators to the calculation disturbed motions of an airplane

A simplified treatment of the application of Heaviside's operational methods to problems of airplane dynamics is given. Certain graphical methods and logarithmic formulas that lessen the amount of computation involved are explained. The problem of representing a gust disturbance or control manipulation is taken up and it is pointed out that in certain cases arbitrary control manipulations may be dealt with as though they imposed specific constraints on the airplane, thus avoiding the necessity of any integration whatever.

Jones, R. T.↗
NASA NTRS1976

The influence of lateral stability on disturbed motions of an airplane with special reference to the motions produced by gusts

Disturbed lateral motions have been calculated for a hypothetical small airplane with various modifications of fin area and dihedral setting. The modifications of the airplane include changes of dihedral and changes of weathercock stability. Fin area and wing dihedral were found to be of primary importance in side gusts. It was found that the rolling action of the wing with as much as 5 deg dihedral was distinctly unfavorable, especially when the weathercock stability was small. It is pointed out that the greatest susceptibility to lateral disturbances lies in the inherent damping and coupling moments developed by the wing.

Jones, R. T.↗
NASA NTRS1976

Review of drag cleanup tests in Langley full-scale tunnel (from 1935 to 1945) applicable to current general aviation airplanes

Results of drag cleanup tests conducted in the Langley full-scale tunnel during the period from 1935 to 1945 are summarized for potential application to current propeller-driven general aviation airplanes. Data from tests on 23 airplanes indicate that the drag increments produced by many individual configuration features - such as, power plant installation, air leakage, cockpit canopies, control surface gaps, and antenna installations - are not large; however, when the increments are summed, the resulting total drag increase is significant. On the basis of results of the investigation, it appears that considerable reduction in drag can be obtained by proper attention to details in aerodynamic design and by adherence to the guidelines discussed.

Coe, P. L., Jr.↗
NASA NTRS1976

A unique formulation of elastic airplane longitudinal equations of motion

Control-configured vehicle technology has increased the demand for detailed analysis of dynamic stability and control, handling and ride qualities, and control system dynamics at early stages of preliminary design. An approximate, but reasonably accurate, set of equations of motion are needed for these early analyses. Such a formulation is developed for the longitudinal dynamics of elastic airplanes. It makes use of only rigid-body aerodynamic stability derivatives in formulating the forces and moments due to elastic motion. Verification of accuracy using data for the B-1 airplane shows very good agreement. Frequencies and damping ratios of the coupled modes corresponding to complex roots of the characteristic equations agree closely with four symmetric elastic modes included.

Swaim, R. L.↗
NASA NTRS1976

A pilot's opinion of the F-8 digital fly-by-wire airplane

The handling qualities of the F-8 digital fly by wire airplane are evaluated by using the Cooper-Harper rating scale. The reasons for the ratings are given, as well as a short description of the flying tasks. It was concluded that the handling qualities of the airplane were good in most situations, although occasional ratings of unsatisfactory were given.

Krier, G. E.↗
NASA NTRS1975

Status of a digital integrated propulsion/flight control system for the YF-12 airplane

The NASA Flight Research Center is engaged in a program with the YF-12 airplane to study the control of interactions between the airplane and the propulsion system. The existing analog air data computer, autothrottle, autopilot, and inlet control system are to be converted to digital systems by using a general purpose airborne computer and interface unit. First, the existing control laws will be programmed in the digital computer and flight tested. Then new control laws are to be derived from a dynamic propulsion model and a total force and moment aerodynamic model to integrate the systems. These control laws are to be verified in a real time simulation and flight tested.

Reukauf, P. J.↗
NASA NTRS1976

Prediction of jump phenomena in roll-coupled maneuvers of airplanes

An easily computerized analytical method is developed for identifying critical airplane maneuvers in which nonlinear rotational coupling effects may cause sudden jumps in the response to pilot's control inputs. Fifth and ninth degree polynomials for predicting multiple pseudo-steady states of roll-coupled maneuvers are derived. The program calculates the pseudo-steady solutions and their stability. The occurrence of jump-like responses for several airplanes and a variety of maneuvers is shown to correlate well with the appearance of multiple stable solutions for critical control combinations. The analysis is extended to include aerodynamics nonlinear in angle of attack.

Schy, A. A.↗
NASA NTRS1976

Flight test evaluation of a separate surface attitude command control system on a Beech 99 airplane

A joint NASA/university/industry program was conducted to flight evaluate a potentially low cost separate surface implementation of attitude command in a Beech 99 airplane. Saturation of the separate surfaces was the primary cause of many problems during development. Six experienced professional pilots made simulated instrument flight evaluations in light-to-moderate turbulence. They were favorably impressed with the system, particularly with the elimination of control force transients that accompanied configuration changes. For ride quality, quantitative data showed that the attitude command control system resulted in all cases of airplane motion being removed from the uncomfortable ride region.

Gee, S. W.↗
NASA NTRS1976

Landing practices of general aviation pilots in single-engine light airplanes

The methods and techniques used by a group of general aviation pilots during the landing phase of light airplane operations are documented. The results of 616 landings made by 22 pilots in 2 modern, four-place, single-engine, flight airplanes (one having a low wing and the other, a high wing) are presented. The landings were made on both a long runway (1524 m (5000 ft)) and a short runway (762 m (2500 ft)); both runways were considered typical of those used in general aviation. The results generally show that most of the approaches were fast with considerable floating during the flares and with touchdowns that were relatively flat or nose-low.

Goode, M. W.↗
NASA NTRS1976

Low speed wind tunnel investigation of flight spoilers as trailing-vortex-alleviation devices on an extended-range wide body tri-jet airplane model

An investigation was made in the Langley V/STOL tunnel to determine, by the trailing wing sensor technique, the effectiveness of various segments of the existing flight spoilers on an extended-range wide-body tri-jet transport airplane model when they were deflected as trailing-vortex-alleviation devices. On the transport model with the approach flap configuration, the four combinations of flight-spoiler segments investigated were effective in reducing the induced rolling moment on the trailing wing model by as much as 25 to 45 percent at downstream distances behind the transport model of 9.2 and 18.4 transport wing spans. On the transport airplane model with the landing flap configuration, the four combinations of flight-spoiler segments investigated were effective in reducing the induced rolling moment on the trailing wing model by as much as 35 to 60 percent at distances behind the transport model of from 3.7 to 18.4 transport wing spans, 18.4 spans being the downstream limit of distances used.

Croom, D. R.↗
NASA NTRS1976

A forebody design technique for highly integrated bottom-mounted scramjets with application to a hypersonic research airplane

A rapid and simple inviscid technique for designing forebodies which produce uniformly precompressed flows at the entrance for bottom-mounted scramjets was developed so that geometric constraints resulting from design trade-offs can be effectively evaluated. The flow fields resulting from several forebody designs generated in support of a conceptual design for a hypersonic research airplane have been analyzed in detail. Three-dimensional characteristics calculations were used to verify the uniform flow conditions. For the designs analyzed, uniform flow was maintained over a wide range of flight conditions (Mach numbers from 4 to 10; angles of attack of 6 and 10 deg) corresponding to the scramjet operation flight envelope of the research airplane.

Edwards, C. L. W.↗
NASA NTRS1977

Lateral aerodynamic parameters extracted from flight data for the F-8C airplane in maneuvering flight

Flight test data are used to extract the lateral aerodynamic parameters of the F-8C airplane at moderate to high angles of attack. The data were obtained during perturbations of the airplane from steady turns with trim normal accelerations from 1.5g to 3.0g. The angle-of-attack variation from trim was negligible. The aerodynamic coefficients extracted from flight data were compared with several other sets of coefficients, and the extracted coefficients resulted in characteristics for the Dutch roll mode (at the highest angles of attack) similar to those of a set of coefficients that have been the basis of several simulations of the F-8C.

Suit, W. T.↗
NASA NTRS1976

Wind-tunnel tests of a 1/4 scale model of the Bell XS-1 transonic airplane. 1: Longitudinal stability and control characteristics

A 1/4 scale model of the Bell XS-1 transonic aircraft was tested in the Langley 300 mile-per-hour 7 by 10 foot tunnel to determine its low speed longitudinal stability and control characteristics. Pertinent longitudinal flying qualities expected of the XS-1 research airplane were estimated from the results of these tests including the effects of compressibility likely to be encountered at speeds below the force break. It appears that the static longitudinal stability and elevator control power will be adequate, but that the elevator control force gradient in steady flight will be undesirably low for all configurations. It is suggested that a centering spring be incorporated in the elevator control system of the airplane in order to increase the control force gradient in steady flight and in maneuvers.

Donlan, C. J.↗
NASA NTRS1976

Estimated transonic flying qualities of a tailless airplane based on a model investigation, 8 June 1949

Flying qualities of a tailless airplane with the wing quarter chord line swept back 35 deg were analyzed in the Mach number range from 0.40 to 0.91 based on tests of a model of this airplane in the Langley high speed 7 by 10 foot tunnel. The results indicate that longitudinal control position instability exists at transonic speeds but the accompanying trim changes are not large. Control position maneuvering stability, however, is present for all speeds. Longitudinal and lateral control appear adequate, but the damping of the short period longitudinal and lateral oscillations at high altitudes is poor and would probably require artificial damping.

Donlan, C. J.↗
NASA NTRS1977

A unique formulation of elastic airplane longitudinal equations of motion

Control-configured vehicle technology has increased the demand for detailed analysis of dynamic stability and control, handling and ride qualities, and control system dynamics at early stages of preliminary design. An approximate but reasonably accurate set of equations of motion are needed for these early analyses. Such a formulation is developed for the longitudinal dynamics of elastic airplanes. It makes use of only rigid-body aerodynamic stability derivatives in formulating the forces and moments due to elastic motion. Verification of accuracy using data for the B-1 airplane shows very good agreement. Frequencies and damping ratios of the coupled modes corresponding to complex roots of the characteristic equations agree closely with four symmetric elastic modes included.

Swaim, R. L.↗
NASA NTRS1977

Flight test results for an advanced technology light airplane

A single-engine light airplane was modified by the installation of a wing with reduced area, Fowler flaps, Kruger flaps, and spoilers. Flight test results show that zero-lift drag was reduced 13.8% and a trimmed maximum lift coefficient of 2.73 was achieved. Gust response was significantly reduced and excellent roll control was achieved with spoilers. Several design features employed in the new wings have excellent potential for incorporation in future light airplanes.

Kohlman, D. L.↗