National Advisory Committee for Aeronautics (NACA) - 1,272 Matching Results

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Wind tunnel tests on airfoil boundary control using a backward opening slot

Description: This report presents the results of an investigation to determine the effect of boundary layer control on the lift and drag of an airfoil equipped with a backward opening slot. Various slot locations, widths of opening, and pressures, were used. The tests were conducted in the Five-Foot Atmospheric Wind Tunnel of the Langley Memorial Aeronautical Laboratory. The greatest increase in maximum lift was 96 per cent, the greatest decrease in minimum drag was 27 per cent, and the greatest increase in the ratio, maximum lift coefficient/minimum drag coefficient, was 151 per cent.
Date: October 1, 1929
Creator: Knight, Montgomery & Bamber, Millard J
Partner: UNT Libraries Government Documents Department

Wind tunnel tests on an airfoil equipped with a split flap and a slot

Description: The investigation described in this report is concerned with the changes in the aerodynamic characteristics of an airfoil which are produced by a gauze-covered suction slot, located near the leading edge, and connected by an air passage to a split flap at the trailing edge. The tests were conducted at the Langley Memorial Aeronautical Laboratory. At the larger values of lift coefficient where the action of the slot might be expected to be most effective, the pressure differences were such that the air flowed out of the slot rather than in through it, and in consequence, the maximum lift coefficient was decreased.
Date: October 1, 1929
Creator: Bamber, Millard J
Partner: UNT Libraries Government Documents Department

Soaring flight in Guinea

Description: The term soaring is applied here to the flight of certain large birds which maneuver in the air without moving their wings. The author explains the methods of his research and here gives approximate figures for the soaring flight of the Egyptian Vulture and the African White backed Vulture. Figures are given in tabular form for relative air speed per foot per second, air velocity per foot per second, lift/drag ratio, and selected coefficients. The author argues that although the figures given were taken from a very limited series of observations, they have nevertheless thrown some light on the use by birds of the internal energy of the air.
Date: August 1, 1920
Creator: Idrac, P.
Partner: UNT Libraries Government Documents Department

The determination of the effective resistance of a spindle supporting a model airfoil

Description: An attempt was made to determine the effect of spindle interference on the lift of the airfoil by measuring moments about the axis parallel to the direction of air flow. The values obtained are of the same degree as the experimental error, and for the present this effect will be neglected. The results obtained using a U.S.A. 15 wing (plotted here) show that the correction is nearly constant from 0 degrees to 10 degrees incidence and that at greater angles its value becomes erratic. At such angles, however, the wing drag is so high that the spindle correction and its attendant errors become relatively small and unimportant.
Date: January 1, 1921
Creator: Davidson, W E & Bacon, D L
Partner: UNT Libraries Government Documents Department

Determination of the lift and drag characteristics of an airplane in flight

Description: Flight tests to determine lift and drag characteristics are discussed. A review is given of the fundamental principles on which the tests are based and on the forces acting on an airplane in the various conditions of steady flight. Glide with and without propeller thrust and the relation between angle of attack and the indicated airspeed for different conditions of steady flight are discussed. The glide test procedure and the problem of the propeller are discussed.
Date: August 1, 1925
Creator: Green, Maurice W
Partner: UNT Libraries Government Documents Department

The determination of several spray characteristics of a high-speed oil engine injection system with an oscilloscope

Description: An investigation was conducted to determine the injection lag, duration of injection, and spray start and cut-off characteristics of a fuel injection system operated on an engine and injecting fuel into the atmosphere.
Date: September 1, 1928
Creator: Hicks, Chester W & Moore, Charles S
Partner: UNT Libraries Government Documents Department

The comparison of well-known and new wing sections tested in the variable density wind tunnel

Description: Three groups of airfoils have been tested in the variable density wind tunnel. The first group contains three airfoils. The second group is a systematic series of twenty-seven airfoils. The third group consists of several frequently used wing sections.
Date: May 1, 1925
Creator: Higgins, George J
Partner: UNT Libraries Government Documents Department

Model supports and their effects on the results of wind tunnel tests

Description: The airflow about a model while being tested is often sufficiently affected by the model support to lead to erroneous conclusions unless appropriate corrections are used. In this paper some new material on the subject is presented, together with a review of the airfoil support corrections used in several other laboratories.
Date: February 1, 1923
Creator: Bacon, David L
Partner: UNT Libraries Government Documents Department

The N.A.C.A. recording tachometer and angle of attack recorder

Description: This note contains photos and descriptions of airplane flight apparatus for use in conjunction with a recording galvanometer. In measuring the angle of attack a variable resistance is used, being controlled by a vane in the airstream. Thus it is only necessary to measure the change of resistance.
Date: August 1, 1923
Creator: Reid, H J E
Partner: UNT Libraries Government Documents Department

The NACA CYH airfoil section

Description: The NACA CYH airfoil section is described and its aerodynamic characteristics are given as tested in the NACA variable density wind tunnel at twenty atmosphere pressure. This section has a low drag, a high maximum lift, and a small travel of center of pressure.
Date: June 1, 1926
Creator: Higgins, George J
Partner: UNT Libraries Government Documents Department

NACA flight-path angle and air-speed recorder

Description: A new trailing bomb-type instrument for photographically recording the flight-path angle and air speed of aircraft in unaccelerated flight is described. The instrument consists essentially of an inclinometer, air-speed meter and a film-drum case. The inclinometer carries an oil-damped pendulum which records optically the flight-path angle upon a rotating motor-driven film drum. The air-speed meter consists of a taut metal diaphragm of high natural frequency which is acted upon by the pressure difference of a Prandtl type Pitot-static tube. The inclinometer record and air-speed record are made optically on the same sensitive film. Two records taken by this instrument are shown.
Date: April 1, 1926
Creator: Coleman, Donald G
Partner: UNT Libraries Government Documents Department

The use of wheel brakes on airplanes

Description: The results of tests to determine the effect of wheel brakes on the landing run of an airplane under conditions of load and at various wind velocities are presented.
Date: July 1, 1929
Creator: Carroll, Thomas & Defrance, Smith J
Partner: UNT Libraries Government Documents Department

Wall interference in closed type wind tunnels

Description: A series of tests has been conducted by the National Advisory Committee for Aeronautics, in the variable density wind tunnel on several airfoils of different sizes and sections to determine the effect of tunnel wall interference and to determine a correction which can be applied to reduce the error caused thereby. The use of several empirical corrections was attempted with little success. The Prandtl theoretical correction gives the best results and its use is recommended for correcting closed wind tunnel results to conditions of free air.
Date: March 1, 1927
Creator: Higgins, George J
Partner: UNT Libraries Government Documents Department

A warning concerning the take-off with heavy load

Description: A successful take-off can be made with an airplane so heavily loaded that it cannot climb to a height greater than the span of its wings. The explanation is that the power required to maintain level flight at an altitude of the order of the wing span may be as much as 50 per cent greater than that necessary when the airplane is just clear of the ground. The failure of heavily loaded airplanes to continue climbing at the rate attained immediately after the actual take-off is a grave hazard and has resulted in great risk or catastrophe in three notable cases which are cited.
Date: July 1, 1927
Creator: Reid, Elliott G & Carroll, Thomas
Partner: UNT Libraries Government Documents Department

Tests of rotating cylinders

Description: Tests were made in the no. 1 wind tunnel at Langley Memorial Aeronautical Laboratory to determine the air forces acting on rotating cylinders with axes perpendicular to the direction of motion. One cylinder had a circular cross-section, the other that of a greek cross.
Date: December 1, 1924
Creator: Reid, Elliott G
Partner: UNT Libraries Government Documents Department

The formation of ice upon airplanes in flight

Description: This report describes the atmospheric conditions under which ice is formed upon the exposed parts of airplanes in flight. It identifies the formation found under different conditions, and describes some studies of preventative means.
Date: August 1, 1929
Creator: Carroll, Thomas & Mcavoy, William H
Partner: UNT Libraries Government Documents Department

The formation of ice upon exposed parts of an airplane in flight

Description: In order to experimentally study the conditions leading to ice formation on aircraft surfaces, an aircraft was equipped with small auxiliary surfaces and aerodynamic shapes similar to struts, wires, Pitot heads, etc. This airplane was flown at an altitude where a temperature of 32 F was encountered, at such times as cloud formations could be found at the coincident altitude. Here it was discovered that ice formed rapidly in regard to quantity,character, shape, and rapidity of formation. An examination of this data, which confirms observations of pilots, indicates that the weight of ice collected can very possibly be sufficient to force the airplane to rapidly lose altitude on account of the increased loads. However, it is more evident that the malformation of the aerodynamic shapes may so increase the drag and reduce the lift so as to produce a loss of altitude even greater in consequence, the combination of the two working in the same direction having a double effect. Other adverse consequences are noted. The recommendation for the guidance of those who must encounter these conditions appears to lie entirely along the lines of avoidance.
Date: July 1, 1928
Creator: Carroll, Thomas & Mcavoy, Wm H
Partner: UNT Libraries Government Documents Department

Langley Field wind tunnel apparatus

Description: The difficulties experienced in properly holding thin tipped or tapered airfoils while testing on an N.P.L. type aerodynamic balance even at low air speeds, and the impossibility of holding even solid metal models at the high speeds attainable at the National Advisory Committee's wind tunnel, necessitated the design of a balance which would hold model airfoils of any thickness and at speeds up to 150 m.p.h. In addition to mechanical strength and rigidity, it was highly desirable that the balance readings should require a minimum amount of correction and mathematical manipulation in order to obtain the lift and drag coefficients and the center of pressure. The balance described herein is similar to one in use at the University of Gottingen, the main difference lying in the addition of a device for reading the center of pressure directly, without the necessity of any correction whatsoever. Details of the design and operation of the device are given.
Date: October 1, 1921
Creator: Bacon, D L
Partner: UNT Libraries Government Documents Department

Static testing and proposed standard specifications

Description: Static tests fall into two groups, the first of which is designed to load all members of the structure approximately in accordance with the worst loads which they carry in flight, while the second is directed to the testing of specific members which are suspected of weakness and which are difficult to analyze mathematically. The nature of the loading in the second type is different for every different test, but the purpose of the first is defined clearly enough to permit the adoption of some standard set of loading specifications, at least for airplanes of normal design. Here, an attempt is made to carry through an analysis leading to such a standard, the goal being the determination of a load which will simultaneously impose on every member of the airplane structure a stress equal to the worst it will carry in flight.
Date: July 1, 1920
Creator: Warner, E P
Partner: UNT Libraries Government Documents Department