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Wind-Tunnel Investigation of the Low-Speed Static Stability and Control Characteristics of a Model of Bell MX-776

Description: An investigation has been made in the Langley stability tunnel to determine the low-speed static stability and control characteristics of a model of the Bell MX-776. The results of the investigation indicated that the basic model configuration was longitudinally stable in the angle-of-attack range from about -16 deg. to 16 deg. but that the stability was a minimum near O deg angle of attack. The data indicated an aerodynamic-center position about 0.64 body diameters behind the center of gravity at low angles of attack. Reduction in the size of the front horizontal fins increased the longitudinal stability. With 20 percent of the span of the normal front horizontal fins cut off the aerodynamic center was about 1.04 body diameters behind the center of gravity, and with front horizontal fins having the same area as the front vertical fins, the aerodynamic center was 2.26 body diameters behind the center of gravity (at low angles of attack).
Date: July 6, 1949
Creator: Queijo, M. J. & Michael, W. H., Jr.
Partner: UNT Libraries Government Documents Department

Supersonic Wave Interference Affecting Stability

Description: Some of the significant interference fields that may affect stability of aircraft at supersonic speeds are briefly summarized. Illustrations and calculations are presented to indicate the importance of interference fields created by wings, bodies, wing-body combinations, jets, and nacelles.
Date: March 8, 1958
Creator: Love, Eugene S.
Partner: UNT Libraries Government Documents Department

Flight Determination of the Longitudinal Stability and Control Characteristics of a 0.125-Scale Rocket-Boosted Model of the Mcdonnell F-101 Airplane at Mach Numbers from 0.82 to 1.84

Description: A flight test has been conducted to determine the longitudinal stability and control characteristics of a 0.125-scale model of the McDonnell F-1OlA airplane for the Mach number range between 0.82 and 1.84. The variation of lift-curve slope with Mach number was gradual with a maximum value of 0.107 occurring at a Mach number of 0.95. The minimum drag coefficient (including base and internal drag) has a value of 0.020 at a Mach number of 0.87. The drag rise begins at a Mach number of 0.90, and at Mach number of 1.10 the minimum drag is 0.070. Above this Mach number there is a gradual increase in minimum drag coefficient to a value of 0.074 when the Mach number is 1.83. The aerodynamic-center location moved from a value of 62 percent mean aerodynamic chord at a Mach number of 0.88 to its most rearward position of 85 percent at a Mach number of 1.40. The all-movable horizontal tail remained an effective control for producing lift and pitching moment with the variation in effectiveness being gradual throughout the Mach number range covered by the test. There were no large or abrupt losses in pitch damping over the Mach number range covered.
Date: July 5, 1955
Creator: Hastings, Earl C , Jr & Mitcham, Grady L
Partner: UNT Libraries Government Documents Department

Flight Determination of the Static Longitudinal Stability Boundaries of the Bell X-5 Research Airplane with 59 Deg Sweepback

Description: During the flight program on the Bell X-5 airplane with 59 deg sweepback to determine the practical Mach number and normal-force coefficient limits of this configuration, a reduction in static longitudinal stability was encountered in maneuvering flight. A determination of the boundary for reduction of longitudinal stability extending to a Mach number of 0.98 is presented in this paper. A reduction of static longitudinal stability existed for all elevator and all stabilizer-executed maneuvers. The reduction of stability existed for maneuvers executed with elevator near a normal-force coefficient of 0.6 for a Mach number range of about 0.31 to 0.76. Above a Mach number of 0.76 the normal-force coefficient for reduction of stability gradually decreased to a value of 0.2 at a Mach number of 0.98. For stabilizer-executed maneuvers the stability boundary was the same as for elevator maneuvers up to a Mach number of 0.88. Above this Mach number the reduction of stability occurred at slightly higher normal-force coefficients decreasing from about 0.51 at a Mach number of 0.92 to a value of 0.311 at a Mach number of 0.97. The airplane has been flown to a Mach number of 1.04 at a normal-force coefficient of about 0.15 without encountering any reduction of stability. The pilot did not consider the reduction of stability to be dangerous at altitudes above 30,000 feet; however, precise flight was impossible. At angles of attack above that at which the reduction of longitudinal stability occurred, directional instability and aileron control overbalance were encountered.
Date: February 20, 1953
Creator: Finch, Thomas W & Walker, Joseph A
Partner: UNT Libraries Government Documents Department

Flight, analog-simulator, and analytical studies of an automatically controlled interceptor which uses a bank-angle-error computer for lateral commands

Description: Report presenting the tracking performance of an automatically controlled interceptor in which the deflection channel incorporated a bank-angle-error computer that commanded rolling velocities of the interceptor proportional to the computed bank-angle errors. Results regarding gravity terms included in bank-angle-error computation and a comparison of modified system using bank-angle-error computer with the prototype system are provided.
Date: August 11, 1958
Creator: Cheatham, Donald C. & Brissenden, Roy F.
Partner: UNT Libraries Government Documents Department

The flexible mounting of an airplane engine

Description: Discussed here is the suggested installation of the 'unbalanced' 8-cylinder VE-engine. The suggestion was that a flexible mounting be used instead of bolting the engine rigidly to the airplane structure. It was concluded that a flexible connection between the engine and the airplane is probably possible. A flexible connection primarily diminishes the vibrations due to inertia and, to a lesser degree, those due to torque variation. However, engines vibrate more when freely suspended than when rigidly mounted, and this vibration has a detrimental effect on all connections between the engine and the airplane. Therefore, in view of the relatively insignificant advantages which may be derived from the elastic suspension of the engine, the present rigid mounting is to be preferred. Vibration reduction can be achieved by incorporating in the fuselage as many of the rigid airplane parts as possible.
Date: July 1923
Creator: Kutzbach, K.
Partner: UNT Libraries Government Documents Department

Flight measurements of the dynamic longitudinal stability of several airplanes and a correlation of the measurements with pilots' observations of handling characteristics

Description: The dynamic longitudinal stability characteristics of eight airplanes as defined by the period and damping of the longitudinal oscillations were measured in flight to determine the degree of stability that may be expected in conventional airplanes. An attempt was made to correlate the measured stability with pilots' opinions of the general handling characteristics of the airplanes in order to obtain an indication of the most desirable degree of dynamic stability. The results of the measurements show that the period of oscillation increases with speed. At low speeds a range of periods from 11 to 23 seconds was recorded for the different airplanes. At high speeds the periods ranged from 23 to 64 seconds. The damping showed no definite trend with speed.
Date: July 15, 1936
Creator: Soulé, Hartley A.
Partner: UNT Libraries Government Documents Department

Flight Measurements of the Stability Characteristics of the Bell X-5 Research Airplane in Sideslips at 59 Deg Sweepback

Description: Flight measurements of the stability characteristics of the Bell X-5 research airplane at 59 deg sweepback were made in steady sideslips at Mach numbers from 0.62 to 0.97 at altitudes ranging between 35,000 and 40,000 feet. The results showed that the apparent directional stability was positive and increased at Mach numbers above 0.90. The apparent effective dihedral was positive and high, increasing at Mach numbers above 0.75. The cross-wind force coefficient per degree of sideslip was positive and increased rapidly at Mach numbers above 0.94.
Date: February 11, 1953
Creator: Childs, Joan M
Partner: UNT Libraries Government Documents Department

Flight measurements of the velocity distribution and persistence of the trailing vortices of an airplane

Description: Report regarding the measurement of velocity distribution and persistence of the trailing vortices of a propeller-driven fighter-type airplane. Vortex strength did not decrease appreciably up to 35 seconds after the vortices had been shed. When flying in the trailing wake of another airplane, the pilot reported that it was difficult to maintain a precise course and that the disturbance was similar to severe turbulence.
Date: March 1955
Creator: Kraft, Christopher C., Jr.
Partner: UNT Libraries Government Documents Department

An investigation of a supersonic aircraft configuration having a tapered wing with circular-arc sections and 40 degree sweepback: Static longitudinal stability and control characteristics at a Mach number of 1.59

Description: Report presenting an investigation in the 4- by 4-foot supersonic tunnel to determine the static longitudinal stability and control characteristics of a supersonic aircraft configuration at a Mach number of 1.59. The model had a 40 degree sweptback tapered wing with 10-percent-thick circular-arc sections normal to the quarter-chord line.
Date: June 29, 1950
Creator: Spearman, M. Leroy & Hilton, John H., Jr.
Partner: UNT Libraries Government Documents Department

An instrument for recording the position of airplane control surfaces

Description: N.A.C.A. has developed an instrument which makes a continuous record of the angular position of the control surfaces of an airplane, not only in steady flight but during acrobatics as well. It has proven useful in researches into stability and controllability, and from records obtained from it many otherwise obscure details of piloting technique have been available for the instruction of pilots, from novices to seasoned experts.
Date: August 1923
Creator: Ronan, K. M.
Partner: UNT Libraries Government Documents Department

Investigation of a Spoiler-Type Lateral Control System on a Wing with Full-Span Flaps in the Langley 19-Foot Pressure Tunnel

Description: Tests of a partial-span model of a large bomber-type air1ane were conducted to determine the. aerodynamic characteristics of the wing equipped with full-span flaps and a retractable spoiler end aileron lateral control system. The arrangement consisted of (1) a double slotted flap extending over aproximate1y 86 percent of the wing semispan, (2) a 20-percent constant-percentage-chord aileron extending from the outboard end of the flap to the wing tip, and (3) a retractable spoiler, located at the 65-percent wing-chord station and extending from approximately 63 percent of the wing semispan to the wing tip. In addition, tests were made of a wing vent (of 1 and 2 percent of the wing chord located directly behind the spoiler), perforations in the spoiler, a blot or cut-out along the lower edge of the spoiler and spoilers of various spans. With full-span flaps deflected and with the 2-percent vent open or closed the initial stalling of the wing occurred at the tips, but with the vents closed there probably would be no appreciable loss in lateral control until maximum lift was reached. The l-percent vent increased the rolling effectiveness of the spoiler at small spoi1er deflections, particularly at high angles of attack with flaps deflected. With flaps deflected the 2-percent vent caused a large reduction in both the wing lift and rolling effectiveness of the spoiler at large angles of attack. However, at small angle of attack the 2-percent vent increased the rolling effectiveness of the spoiler at small spoiler deflections. The simultaneous operation of the spoiler and vent (in contrast to a vent fixed in the wing) would result in a large increase in the effectiveness of the spoiler and would avoid any loss in wing lift as in a fixed vent arrangement. The tests of the spoiler modifications revealed that (1) the ...
Date: August 1, 1947
Creator: Deters, Owen J & Russell, Robert T
Partner: UNT Libraries Government Documents Department

An exploratory investigation of some types of aeroelastic instability of open and closed bodies of revolution mounted on slender struts

Description: Report presenting an investigation of aeroelastic instability phenomena of isolated open and closed rigid bodies of revolution free to move under elastic restraint at low speeds. Results regarding speeds at which flutter or divergence occurs, the flutter-speed coefficient, and speed coefficients are provided.
Date: November 1954
Creator: Clevenson, S. A.; Widmayer, E., Jr. & Diederich, Franklin W.
Partner: UNT Libraries Government Documents Department

Exploratory investigation of leading-edge chord-extensions to improve the longitudinal stability characteristics of two 52 degree sweptback wings

Description: Report presenting exploratory testing obtained with leading-edge wing chord-extensions on two 52 degree sweptback wings. The wings had the same aspect ratio but different airfoil sections. Results regarding force characteristics and flow characteristics are provided.
Date: March 10, 1950
Creator: Furlong, G. Chester
Partner: UNT Libraries Government Documents Department

Initial flight tests of the NACA FR-2, a high-velocity rocket-propelled vehicle for transonic flutter research

Description: Report presenting initial flight tests of two simplified flutter vehicles. Test results were in agreement with the results of the freely-falling-body test in that the wing failures in the transonic range occurred at velocities greater than the flutter velocity calculated from the two-dimensional theory.
Date: March 4, 1948
Creator: Barmby, J. G. & Teitelbaum, J. M.
Partner: UNT Libraries Government Documents Department

Inherent stability of helicopters

Description: The equilibrium, in still air, of a "stationary" helicopter (i.e., of one having neither vertical nor translational velocity, but a tendency to remain practically motionless within restricted limits of space) presents some difficulty in practice and justifies a theoretical investigation of its "inherent stability," i.e., independent of the pilot.
Date: October 1923
Creator: Crocco, G. Arturo
Partner: UNT Libraries Government Documents Department

Investigation of low-speed, power-off stability and control characteristics of a model with a 35 degree sweptback wing in the Langley free-flight tunnel

Description: Report presenting an investigation in the free-flight tunnel to determine the low-speed, power-off dynamic stability and control characteristics of a model with a 35 degree sweptback wing. The investigation consisted of force and flight tests of the model and calculations of the lateral oscillatory stability with wing-tip fuel tanks off and on.
Date: October 28, 1948
Creator: Schade, Robert O.
Partner: UNT Libraries Government Documents Department

A method for measuring the product of inertia and the inclination of the principal longitudinal axis of inertia of an airplane

Description: Report presenting a simple method of experimentally determining the product of inertia and the inclination of the principal longitudinal axis of inertia of an airplane. The results of the method are provided and a description of the equipment and techniques are given for a simple model and a conventional airplane. Results regarding moments of inertia about the body reference area, the product of inertia and inclination of the principal axis, and the principal moments of inertia are provided.
Date: April 1954
Creator: Boucher, Robert W.; Rich, Drexel A.; Crane, Harold L. & Matheny, Cloyce E.
Partner: UNT Libraries Government Documents Department

A method for estimating variations in the roots of the lateral-stability quartic due to changes in mass and aerodynamic parameters of an airplane

Description: Report presenting a method for estimating variations in the roots of the lateral-stability quartic due to changes in mass and aerodynamic parameters of an airplane. The method is applied to three high-speed airplanes and the changes in their lateral stability characteristics are determined by considering increments in various airplane parameters.
Date: January 1954
Creator: Gates, Ordway B., Jr. & Woodling, C. H.
Partner: UNT Libraries Government Documents Department

NACA Conference on Aircraft Loads, Structures, and Flutter

Description: This document contains reproductions of technical papers on some of the most recent research results on aircraft loads, flutter, and structures from the NACA laboratories. These papers were presented by members of the staff of the NACA laboratories at the Conference held at the Langley Aeronautical Laboratory March 5, 6, and 7, 1957. The primary purpose of this Conference was to convey to contractors of the military services and others concerned with the design of aircraft these recent research results and to provide those attending an opportunity to discuss the results. The papers in this document are in the same form in which they were presented at the Conference in order to facilitate their prompt distribution. The original presentation and this record are considered as complementary to, rather than as substitutes for, the Committee?s more complete and formal reports. Accordingly, if information from this document is utilized it is requested that this document not be listed as a reference. Individual reports dealing with most of the information presented at the Conference will subsequently be published by NACA and will therefore be suitable as reference material.
Date: March 5, 1957
Partner: UNT Libraries Government Documents Department

The motions of rolling symmetrical missiles referred to a body-axis system

Description: Report presenting the linearized equations of motion have been derived for a rolling missile with slight aerodynamic asymmetries. Time histories of rolling-missile motions referred to a body-axis system have been prepared to show the types of missile motions that can be encountered.
Date: November 1956
Creator: Nelson, Robert L.
Partner: UNT Libraries Government Documents Department

Matrix methods for determining the longitudinal-stability derivatives of an airplane from transient flight data

Description: Three matrice methods are developed and presented for determining the longitudinal-stability derivatives from transient flight data. In these methods the expressions for some of the stability derivatives are in the form generally used in stability calculations. The first method requires the combination of four measurements in time-history form, two of which must be incremental elevator deflection and incremental tail load and the other two measurements can be chosen from a possible three, namely incremental load factor, pitching velocity, and angle of attack. The method demonstrates the use of the tail load to separate the pitching-moment derivatives and to determine the downwash derivative. (author).
Date: 1954
Creator: Donegan, James J.
Partner: UNT Libraries Government Documents Department

Matrix method of determining the longitudinal-stability coefficients and frequency response of an aircraft from transient flight data

Description: From Summary: "A matrix method is presented for determining the longitudinal-stability coefficients and frequency response of an aircraft from arbitrary maneuvers. The method is devised so that it can be applied to time-history measurements of combinations of such simple quantities as angle of attack, pitching velocity, load factor, elevator angle, and hinge moment to obtain the over-all coefficients. Although the method has been devised primarily for the evaluation of stability coefficients which are of primary interest in most aircraft loads and stability studies, it can be used also, with a simple additional computation, to determine the frequency-response characteristics. The entire procedure can be applied or extended to other problems which can be expressed by linear differential equations."
Date: December 15, 1950
Creator: Donegan, James J. & Pearson, Henry A.
Partner: UNT Libraries Government Documents Department