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At least 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
NASA NTRS1956

Theoretical and Experimental Investigation of the Effect of Tunnel Walls on the Forces on an Oscillating Airfoil in Two-Dimensional Subsonic Compressible Flow

This report presents a theoretical and experimental investigation of the effect of wind-tunnel walls on the air forces on an oscillating wing in two-dimensional subsonic compressible flow. A method of solving an integral equation which relates the downwash on a wing to the unknown loading is given, and some comparisons are made between the theoretical results and the experimental results. A resonance condition, which was predicted by theory in a previous report (NACA report 1150), is shown experimentally to exist. In addition, application of the analysis is made to a number of examples in order to illustrate the influence of walls due to variations in frequency of oscillation, Mach number , and ratio of tunnel height to wing semichord.

Runyan, Harry L↗
NASA NTRS1958

Effects of aerodynamic heating on X-15 temperatures

Paper describes examples which show how wind-tunnel model tests of the actual configuration of the aircraft aid in aerothermodynamic analyses and how these tests have made possible increased accuracy in structural temperature prediction. Also, from this and other research, development and design work on the X-15 has been done to accomplish a design consistent with the specified flight requirements. In this work, structural temperatures have been held within acceptable limits by providing sufficient heat sink material. Limited areas of the skin and leading edges are expected to attain temperatures greater than 1,200 degrees F. However, these areas have been carefully investigated for the effect of these higher temperatures on the structure and have been found to be satisfactory.

Kinsler, Martin R↗
NASA NTRS1951

Concerning the flow about ring-shaped cowlings Part VI : further measurements on inlet devices

The present report presents as a supplement to the fourth report (available as ATI 5045, Air Materiel Command) in the series of investigations concerning the flow about ring-shaped cowlings further wind-tunnel measurements on inlet devices which are to show the influence of the radius of the nose of the cowling on the flow conditions. Moreover, a simple rule for the design of such arrangements, containing a hub in the interior, is suggested.

AIR FLOW - ENGINE COWLINGS↗
NASA NTRS1942

Electrical equipment for the experimental study of the dynamics of fluids

This report contains the description of electric anemometers and their application to the study of turbulent fluid flows, of electric tanks for the realization of the analogies between electrology and aerodynamics and their application to the study of varied technical problems, and lastly of the electric condenser type dynamometer and its application to the prediction of the aerodynamic forces on wing and airplane models in wind-tunnel tests and in controlled and spontaneous rotations.

Ferrari, Carlo↗
NASA NTRS1941

Boundary layer removal by suction

Flight-test data and wind-tunnel data on suction profiles are substantially in agreement. The lift values found in the model test can be actually flown and used as a basis for the design. To visualize the action of the suction, the flow conditions with and without suction on the upper surface were photographed; figures 12 to 15 are sections of the film.

Schrenk, O↗
NASA NTRS1938

A New Spinning-test Method

This report contains a description of a new spinning-test arrangement wherein the otherwise customary rotation of the model about a fixed axis is abandoned in favor of a corresponding rotation of the air stream. The advantage of this method lies in the fact that the model is at rest while the spin is recorded. In this manner it is possible to secure systematic results with little loss of time while employing 3- or 6-component wind-tunnel balances. The troublesome equalization of the mass forces is eliminated and the flow phenomena are accessible to direct observation.

Kramer, M↗
NASA NTRS1935

The interdependence of profile drag and lift with Joukowski type and related airfoils

On the basis of a systematic investigation of Gottingen wind-tunnel data on Joukowski type and related airfoils, it is shown in what manner the profile drag coefficient is dependent on the lift coefficient. The individual factors for the construction of the profile drag polars are given. They afford a more accurate calculation of the performance coefficients of airplane designs than otherwise attainable with the conventional assumption of constant drag coefficient.

Muttray, H↗
NASA NTRS1933

Aerodynamic Forces and Moments of a Seaplane on the Water

This report gives the results of wind-tunnel tests with a seaplane model as a contribution to the solution of the aerodynamic problems. In the tests it was assumed that the seaplane rested motionless on the water and was exposed, in various positions with respect to the supposedly flat surface of the water, to a uniform air current 0 to 360 degrees.

Kohler, M↗
NASA NTRS1933

The effect of a gap between elevator and stabilizer on the static stability and maneuverability about the lateral axis in flight

A number of German airplanes have a gap between elevator and stabilizer. The effect of this open space is not generally known, although English wind-tunnel experiments have shown that even a very small gap exerts a profound influence on the elevator action. The purpose of the present free-flight measurements is to ascertain whether fairing over the gap would actually result in an appreciable improvement.

Hubner, Walter↗
NASA NTRS1932

Experimental determination of the thickness of the boundary layer along a wing section

The thickness and course of the boundary layer were measured in flight, in order to determine whether the relations on an airplane and on a shop-made wing can be brought into agreement with the results of wind-tunnel tests and Horst Muller's calculations of the thickness of the boundary layer, as developed from Karman's integral equation for the boundary layer.

Cuno, Otto↗
NASA NTRS1932

Increase in the maximum lift of an airplane wing due to a sudden increase in its effective angle of attack resulting from a gust

Wind-tunnel tests are described, in which the angle of attack of a wing model was suddenly increased (producing the effect of a vertical gust) and the resulting forces were measured. It was found that the maximum lift coefficient increases in proportion to the rate of increase in the angle of attack. This fact is important for the determination of the gust stresses of airplanes with low wing loading. The results of the calculation of the corrective factor are given for a high-performance glider and a light sport plane of conventional type.

Kramer, Max↗
NASA NTRS1932

Problems concerning the stability and maneuverability of airplanes

The stability of an airplane can be easily determined by wind-tunnel tests, especially by simple tests with models mounted wind-vane fashion. However, each stability curve plotted by this method is valid only for a certain setting of the corresponding control surface, i.e., it characterizes the stability of the airplane with the control stick in a given position. The problems thus defined are studied from the point of view of longitudinal and transverse stability. Directional stability is not included in this study.

Biche, Jean↗
NASA NTRS1931

The dangerous flat spin and the factors affecting it

This report deals first with the fundamental data required for the investigation. These are chiefly the aerodynamic forces and moments acting on an airplane in a flat spin. It is shown that these forces and moments depend principally on the angle of attack and on the rotation about the path axis, and can therefore either be measured in a wind tunnel or calculated from wind-tunnel measurements of lift, drag and moment about the leading edge of the wing of an airplane model at rest. The lift, drag and moments about the span axis are so greatly altered by the rapid rotation in a flat spin, that they can no longer be regarded as independent of rotation. No substantial change in the angles of attack and glide occurring in a flat spin is involved. The cross-wind force, as compared with the lift and drag, can be disregarded in a flat spin.

Fuchs, Richard↗
NASA NTRS1950

Tests of a Northrop XSSM-A-3 Missile in the Ames 40- by 80-Foot Wind Tunnel: Stability and Control

This report presents the results of wind-tunnel force tests which were conducted to determine the low-speed stability and control characteristics of a full-scale Northrop XSSM-A-3 missile. Tests were made through a range of angles of attack, sideslip, and control deflection, and at various Reynolds numbers. Characteristics of the complete missile are compared with the characteristics of the missile with the landing skids extended, with the vertical tail removed, and with the fuselage alone. No analysis of the data has been made in order to make the results available as soon as possible.

Maki, Ralph L.↗
NASA NTRS1940

Full-Scale Tests of Several Propellers Equipped with Spinners, Cuffs, Airfoil and Round Shanks, and NACA 16-Series Sections, Special Report

Wind-tunnel tests of several propeller, cuff, and spinner combinations were conducted in the 20 foot propeller-research tunnel. Three propellers, which ranged in diameter from 8.4 to 11.25 feet, were tested at the front end of a streamline body incorporating spinners of two diameters. The tests covered a blade angle range from 20 deg to 65 deg. The effect of spinner diameter and propeller cuffs on the characteristics of one propeller was determined. Test were also conducted using a propeller which incorporated aerodynamically good shank sections and using one which incorporated the NACA 16 series sections for the outer 20 percent of the blades. Compressibility effects were not measured, owing to the low testing speeds. The results indicated that a conventional propeller was slightly more efficient when tested in conjunction with a 28 inch diameter spinner than with a 23 inch spinner, and that cuffs increased the efficiency as well as the power absorption characteristics. A propeller having good aerodynamic shanks was found to be definitely superior from the efficiency standpoint to a conventional round-shank propeller with or without cuffs; this propeller would probably be considered structurally impracticable, however. The propeller incorporating the NACA 16 series sections at the tims were found to have a slightly higher efficiency than a conventional propeller; the take-off characteristics appeared to be equally good. The effects noted above probably would be accentuated at helical speeds at which compressibility effects would enter.

Biermann, David↗
NASA NTRS1939

Preliminary Model Tests of a Wing-Duct Cooling System for Radial Engines, Special Report

Wind-tunnel tests were conducted on a model wing-nacelle combination to determine the practicability of cooling radial engines by forcing the cooling air into wing-duct entrances located in the propeller slipstream, passing the air through the engine baffles from rear to front, and ejecting the air through an annular slot near the front of the nacelle. The tests, which were of a preliminary nature, were made on a 5-foot-chord wing and a 20-inch-diameter nacelle. A 3-blade, 4-foot-diameter propeller was used. The tests indicated that this method of cooling and cowling radial engines is entirely practicable providing the wing of the prospective airplane is sufficiently thick to accommodate efficient entrance ducts , The drag of the cowlings tested was definitely less than for the conventional N.A.C.A. cowling, and the pressure available at low air speed corresponding to operation on the ground and at low flying speeds was apparently sufficient for cooling most present-day radial engines.

Biermann, David↗
NASA NTRS1939

Preliminary Tests of Blowers of Three Designs Operating in Conjunction with a Wing-Duct Cooling System for Radial Engines, Special Report

This paper is one of several dealing with methods intended to reduce the drag of present-day radial engine installations and improve the cooling at zero and low air speeds, The present paper describes model wind-tunnel tests of blowers of three designs tested in conjunction with a wing-nacelle combination. The principle of operation involved consists of drawing cooling air into ducts located in the wing root at the point of maximum slipstream velocity, passing the air through the engine baffles from rear to front, and exhausting the air through an annular slot located between the propeller and the engine with the aid of a blower mounted on the spinner. The test apparatus consisted essentially of a stub wing having a 5-foot chord and a 15-foot span, an engine nacelle of 20 inches diameter enclosing a 25-horsepower electric motor, and three blowers mounted on propeller spinners. Two of the blowers utilize centrifugal force while the other uses the lift from airfoils to force the air out radially through the exit slot. Maximum efficiencies of over 70 percent were obtained for the system as a whole. Pressures were measured over the entire flight range which were in excess of those necessary to cool present-day engines, The results indicated that blowers mounted on propeller spinners could be built sufficiently powerful and efficient to warrant their use as the only, or chief, means of forcing air through the cooling system, so that cooling would be independent of the speed of the airplane.

Biermann, David↗
NASA NTRS1941

A Remote Indicating Hinge-Moment Balance, Special Report

This report describes an electrical hinge-moment balance for use with wind-tunnel models of aircraft. A brief description of the principle of operation and operating experience with the balance is given in part I. Part II gives constructional details and part III gives theoretical considerations. Extensive constructional information is given to enable the reproduction of the equipment.

Stoller, Morton J.↗