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At least 217 records · Page 12

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NASA NTRS1924

The Small Angular Oscillations of Airplanes in Steady Flight

This investigation was carried out by the National Advisory Committee for Aeronautics at the request of the Army Air Service to provide data concerning the small angular oscillations of several types of airplanes in steady flight under various atmospheric conditions. The data are of use in the design of bomb sights and other aircraft instruments. The method used consisted in flying the airplane steadily in one direction for at least one minute, while recording the angle of the airplane with the sun by means of a kymograph. The results show that the oscillations differ but little for airplanes of various types, but that the condition of the atmosphere is an important factor. The average angular excursion from the mean in smooth air is 0.8 degrees in pitch, 1.4 degrees in roll, and 0.9 degrees in yaw, without special instruments to aid the pilot in holding steady conditions. In bumpy air the values given above are increased about 50 per cent. (author)

Norton, F H↗

NASA NTRS1930

The Effect of Supercharger Capacity on Engine and Airplane Performance

This report presents the results of an investigation to determine the effect of different supercharger capacities on the performance of an airplane and its engine . The tests were conducted on a DH4-M2 airplane powered with a Liberty 12 engine. In this investigation four supercharger capacities, obtained by driving a roots type supercharger at 1.615, 1.957, 2.4, and 3 time engine speed, were used to maintain sea-level pressure at the carburetor to altitudes of 7,000, 11,500, 17,000, and 22,000 feet, respectively. The performance of the airplane in climb and in level flight was determined for each of the four supercharger drive ratios and for the unsupercharged condition. The engine power was measured during these tests by means of a calibrated propeller. It was found that very little sacrifice in sea-level performance was experienced with the larger supercharger drive ratios as compared with performance obtained when using the smaller drive ratios. The results indicate that further increase in supercharger capacity over that obtained when using 3:1 drive ratio would give a slight increase in ceiling and in high-altitude performance but would considerably impair the performance for an appreciable distance below the critical altitude. As the supercharger capacity was increased, the height at which sea-level high speeds could be equaled or improved became a larger percentage of the maximum height of operation of the airplane.

Schey, O W↗

NASA NTRS1931

The Pressure Distribution over the Wings and Tail Surfaces of a PW-9 Pursuit Airplane in Flight

This report presents the results of an investigation to determine (1) the magnitude and distribution of aerodynamic loads over the wings and tail surfaces of a pursuit-type airplane in the maneuvers likely to impose critical loads on the various subassemblies of the airplane structure. (2) To study the phenomenon of center of pressure movement and normal force coefficient variation in accelerated flight, and (3) to measure the normal accelerations at the center of gravity, wing-tip, and tail, in order to determine the nature of the inertia forces acting simultaneously with the critical aerodynamic loads. The results obtained throw light on a number of important questions involving structural design. Some of the more interesting results are discussed in some detail, but in general the report is for the purpose of making this collection of airplane-load data obtained in flight available to those interested in airplane structures.

Rhode, Richard↗

NASA NTRS1932

Pressure Distribution Over the Fuselage of a PW-9 Pursuit Airplane in Flight

This report presents the results obtained from pressure distribution tests on the fuselage of a PW-9 pursuit airplane in a number of conditions of flight. The investigation was made to determine the contribution of the fuselage to the total lift in conditions considered critical for the wing structure, and also to determine whether the fuselage loads acting simultaneously with the maximum tail loads were of such a character as to be of concern with respect to the structural design of other parts of the airplane. The results show that the contribution of the fuselage toward the total lift is small on this airplane. Aerodynamic loads on the fuselage are, in general, unimportant from the structural viewpoint, and in most cases they are of such character that, if neglected, a conservative design results. In spins, aerodynamic forces on the fuselage produce diving moments of appreciable magnitude and yawing moments of small magnitude, but opposing the rotation of the airplane. A table of cowling pressures for various maneuvers is included in the report.

Rhode, Richard V↗

NASA NTRS1934

The Aerodynamic Forces and Moments Exerted on a Spinning Model of the NY-1 Airplane as Measured by the Spinning Balance

A preliminary investigation of the effects of changes in the elevator and rudder settings and of small changes in attitude upon the aerodynamic forces and moments exerted upon a spinning airplane was undertaken with the spinning balance in the 5-foot vertical tunnel of the National Advisory Committee for Aeronautics. The tests were made on a 1/12-scale model of the ny-1 airplane. Data by which to fix the attitude, the radius of spin, and the rotational and air velocities were taken from recorded spins of the full-scale airplane. Two spinning conditions were investigated. All six components of the aerodynamic reaction were measured and are presented in coefficient form refereed to airplane axes. The results indicate that the change in yawing moment produced by the rudder with the elevator up was the only component of force or moment produced by the elevator and rudder that could not have been balanced in an actual spin by small changes in attitude and angular velocity.

Bamber, M J↗

NASA NTRS1934

Maneuverability Investigation of an O3U-1 Observation Airplane

This report presents the results of maneuverability tests of an O3U-1 observation airplane. This investigation is the third in a series of similar investigations requested by the Bureau of Aeronautics (Navy) for the purpose of comparing the maneuverability of different airplane types and to provide quantitative data for use in establishing a criterion or method for rating the maneuverability of an airplane. The two former investigations were conducted with the fighter types designated F6C-3 and F6C-4 and have been reported previously. Measurement of the air speed, the angular velocity, the linear acceleration, and positions of the controls were made during abrupt single-control maneuvers with three stop positions for each control, during steady horizontal turns for the determination of minimum radius, and during 180 degree turns by various methods. Flight-path coordinates in two dimensions were determined for the 180 degree turns by means of a special camera obscura designed for the previous investigation of the F6C-4 airplane. All maneuvers were performed at an altitude of approximately 3,000 feet.

Thompson, F L↗

NASA NTRS1935

A flight investigation of the effect of mass distribution and control setting on the spinning of the XN2Y-1 airplane

The investigation of the effect of mass distribution on the spinning of airplanes initiated with tests on the NY-1 airplane has been continued by tests on another airplane in order to increase the scope of the information and to observe particularly the behavior of an airplane that shows considerable change in sideslip angle for its various conditions of spinning. The XN2Y-1 naval training biplane was used for the present tests in which changes of ballast along the longitudinal and lateral axes and changes of aileron, stabilizer, and elevator settings were made. The effects of these changes on the steady spin were measured in flight.

Scudder, N F↗

NASA NTRS1937

The effect of lateral controls in producing motion of an airplane as computed from wind-tunnel data

This report presents the results of an analytical study of the lateral controllability of an airplane in which both the static rolling and yawing moments supplied by the controls and the reactions due to the inherent stability of the airplane have been taken into account. The investigation was undertaken partly for the purpose of coordinating the results of a long series of wind-tunnel investigations with phenomena observed in flight tests; for this reason a hypothetical average airplane, embodying the essential characteristics of both wind-tunnel models and the full-size test airplanes, was assumed for the study.

Weick, Fred E↗

NASA NTRS1937

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

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.

Soule, Hartley A↗

NASA NTRS1937

Spinning Characteristics of the XN2Y-1 Airplane Obtained from the Spinning Balance and Compared with Results from the Spinning Tunnel and from Flight Tests

Report presents the results of tests of a 1/10-scale model of the XN2Y-1 airplane tested in the NACA 5-foot vertical wind tunnel in which the six components of forces and moments were measured. The model was tested in 17 attitudes in which the full-scale airplane had been observed to spin, in order to determine the effects of scale, tunnel, and interference. In addition, a series of tests was made to cover the range of angles of attack, angles of sideslip, rates of rotation, and control setting likely to be encountered by a spinning airplane. The data were used to estimate the probable attitudes in steady spins of an airplane in flight and of a model in the free-spinning tunnel. The estimated attitudes of steady spin were compared with attitudes measured in flight and in the spinning tunnel. The results indicate that corrections for certain scale and tunnel effects are necessary to estimate full-scale spinning attitudes from model results.

Bamber, M J↗

NASA NTRS1939

General airplane performance

Equations have been developed for the analysis of the performance of the ideal airplane, leading to an approximate physical interpretation of the performance problem. The basic sea-level airplane parameters have been generalized to altitude parameters and a new parameter has been introduced and physically interpreted. The performance analysis for actual airplanes has been obtained in terms of the equivalent ideal airplane in order that the charts developed for use in practical calculations will for the most part apply to any type of engine-propeller combination and system of control, the only additional material required consisting of the actual engine and propeller curves for propulsion unit. Finally, a more exact method for the calculation of the climb characteristics for the constant-speed controllable propeller is presented in the appendix.

Rockfeller, W C↗

NASA NTRS1940

Free-Spinning Wind-Tunnel Tests of a Low-Wing Monoplane with Systematic Changes in Wings and Tails V : Effect of Airplane Relative Density

The reported tests are a continuation of an NACA investigation being made in the free-spinning wind tunnel to determine the effects of independent variations in load distribution, wing and tail arrangement, and control disposition on the spin characteristics of airplanes. The standard series of tests was repeated to determine the effect of airplane relative density. Tests were made at values of the relative-density parameter of 6.8, 8.4 (basic), and 12.0; and the results were analyzed. The tested variations in the relative-density parameter may be considered either as variations in the wing loading of an airplane spun at a given altitude, with the radii of gyration kept constant, or as a variation of the altitude at which the spin takes place for a given airplane. The lower values of the relative-density parameter correspond to the lower wing loadings or to the lower altitudes of the spin.

Seidman, Oscar↗

NASA NTRS1940

Preliminary Investigation of the Flying Qualities of Airplanes

The National Advisory Committee for Aeronautics is undertaking an investigation of the flying qualities of airplanes. The work consists in the determination of the significant qualities susceptible of measurement, the development of the instruments required to make the measurements, and the accumulation of data on the flying qualities of existing airplanes, which data are to serve as a basis for quantitative specifications for the flying qualities of future designs. A tentative schedule of measurable flying qualities has been prepared and the instruments needed for their measurements have been assembled. A trial of the schedule and the instruments has been made using the Stinson SR-8e airplane. The results showed that, although the original schedule and instruments are basically satisfactory some further development is required to eliminate nonessential items and to expedite flight testing. The report describes and discusses the work done with this airplane.

Soule, H A↗

NASA NTRS1948

Correlation of the Drag Characteristics of a Typical Pursuit Airplane Obtained from High-Speed Wind-Tunnel and Flight Tests

In order to obtain a correlation of drag data from wind-tunnel and flight tests at high Mach numbers, a typical pursuit airplane, with the propeller removed, was tested in flight at Mach numbers up to 0.755, and the results were compared with wind-tunnel tests of a 1/3-scale model of the airplane. The tests results show that the drag characteristics of the test airplane can be predicted with satisfactory accuracy from tests in the Ames 16-foot high-speed wind tunnel of the Ames Aeronautical Laboratory at both high and low Mach numbers. It is considered that this result is not unique with the airplane.

Nissen, James M↗

NASA NTRS1949

Sound-Level Measurements of a Light Airplane Modified to Reduce Noise Reaching the Ground

An Army liaison-type airplane, representative of personal airplanes in the 150 to 200 horsepower class, has been modified to reduce propeller and engine noise according to known principles of airplane-noise reduction. Noise-level measurements demonstrate that, with reference to an observer on the ground, a noisy airplane of this class can be made quiet -- perhaps more quiet than necessary. In order to avoid extreme and unnecessary modifications, acceptable noise levels must be determined.

Vogeley, A W↗

NASA NTRS1951

Analysis of the effects of boundary-layer control in the take-off and power-off landing performance characteristics of a liaison type of airplane

A performance analysis has been made to determine whether boundary-layer control by suction might reduce the minimum take-off and landing distances of a four-place or five-place airplane or a liaison type of airplane below those obtainable with conventional high-lift devices. The airplane was assumed to have a cruise duration of 5 hours at 60-percent power and to be operating from airstrips having a ground friction coefficient of 0.2 or a combined ground and braking coefficient of 0.4. The payload was fixed at 1500 pounds, the wing span was varied from 25 to 100 feet, the aspect ratio was varied from 5 to 15, and the power was varied from 300 to 1300 horsepower. Maximum lift coefficients of 5.0 and 2.8 were assumed for the airplanes with and without boundary-layer-control --equipment weight was included. The effects of the boundary-layer control on total take-off distance, total power-off landing distance, landing and take-off ground run, stalling speed, sinking speed, and gliding speed were determined.

Horton, Elmer A↗

NASA NTRS1956

Effect of interaction on landing-gear behavior and dynamic loads in a flexible airplane structure

The effects of interaction between a landing gear and a flexible airplane structure on the behavior of the landing gear and the loads in the structure have been studied by treating the equations of motion of the airplane and the landing gear as a coupled system. The landing gear is considered to have nonlinear characteristics typical of conventional gears, namely, velocity-squared damping, polytropic air-compression springing, and exponential tire force-deflection characteristics. For the case where only two modes of the structure are considered, an equivalent three-mass system is derived for representing the airplane and landing-gear combination, which may be used to simulate the effects of structural flexibility in jig drop tests of landing gears. As examples to illustrate the effects of interaction, numerical calculations, based on the structural properties of two large airplanes having considerably different mass and flexibility characteristics, are presented.

Cook, Francis E↗

NASA NTRS1953

Review and investigation of unsatisfactory control characteristics involving in stability of pilot-airplane combination and methods for predicting these difficulties from ground tests

A number of examples are presented of control difficulties not completely covered by existing handling-qualities requirements. 520/3:*:These control difficulties appear to result from a tendency for dynamic instability of the combination of pilot, control system, and airplane. The unsatisfactory characteristics involved have been encountered most frequently with hydraulic-power control systems. The nature of the difficulties may range from a slight interference with the ability of the pilot to hold precisely straight and level flight to a dangerous tendency toward divergent short-period oscillations which require constant attention of the pilot to control. Tests of a bomber and a fighter airplane with experimental power control systems have been made to study this problem further. The results of the investigation show that control difficulties of the type considered have always been associated with a marked phase difference between the pilot's control force and the associated control-surface deflection. The presence of static friction in the control valves of hydraulic-power control systems was found to be the explanation for unsatisfactory characteristics in several airplanes equipped with such systems. The valve friction may cause a phase lag between the pilot's control force and the associated control-surface deflection approaching 180 degrees at small control deflections. Definite limits or simple rules for the tolerable amount of valve friction appear to be difficult to establish because of the large number of variables which may influence the problem.The control characteristics of the airplanes tested were strongly influenced by minor design details of the power control systems.

Phillips, William H↗