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 Collection: National Advisory Committee for Aeronautics Collection
Air resistance measurements on actual airplane parts

Air resistance measurements on actual airplane parts

Date: November 1, 1923
Creator: Weiselsberger, C
Description: For the calculation of the parasite resistance of an airplane, a knowledge of the resistance of the individual structural and accessory parts is necessary. The most reliable basis for this is given by tests with actual airplane parts at airspeeds which occur in practice. The data given here relate to the landing gear of a Siemanms-Schuckert DI airplane; the landing gear of a 'Luftfahrzeug-Gesellschaft' airplane (type Roland Dlla); landing gear of a 'Flugzeugbau Friedrichshafen' G airplane; a machine gun, and the exhaust manifold of a 269 HP engine.
Contributing Partner: UNT Libraries Government Documents Department
A preliminary investigation of a new method for testing aerofoils in free flight

A preliminary investigation of a new method for testing aerofoils in free flight

Date: January 1, 1922
Creator: Norton, F H
Description: This report is a description of a new method of testing aerofoils in free flight devised by the National Advisory Committee for Aeronautics. The method consists in lowering below a flying airplane a large inverted aerofoil on three small steel wires in such a way that the lift on the aerofoil always keeps the wires tight. The resultant force is measured by the tension in the wires, and the direction of the resultant by the amount the wing trails backwards. A test was made on an aerofoil of the N.A.C.A. #64 section, 6 ft. in span and the results are compared with a similar section tested in the wind tunnel. This investigation indicates that by the use of suitable recording apparatus aerofoils may be accurately and conveniently tested at a Reynolds number, a velocity and a degree of turbulence, comparable with that on the full-sized airplane. Satisfactory experiments were also made in trailing a sphere and a streamlined body on single wires.
Contributing Partner: UNT Libraries Government Documents Department
Variation in the number of revolutions of air propellers

Variation in the number of revolutions of air propellers

Date: March 1, 1923
Creator: Achenbach, W
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Experiments with fabrics for covering airplane wings, to determine effect of method of installation

Experiments with fabrics for covering airplane wings, to determine effect of method of installation

Date: December 1, 1923
Creator: Proll, A
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Notes on the construction and testing of model airplanes

Notes on the construction and testing of model airplanes

Date: January 1, 1922
Creator: Diehl, Walter S
Description: Here, it is shown that the construction of an airplane model can and should be simplified in order to obtain the most reliable test data. General requirements for model construction are given, keeping in mind that the general purpose of wind tunnel tests on a model airplane is to obtain the aerodynamic characteristics, the static balance, and the efficiency of controls for the particular combination of wings, tail surfaces, fuselage, and landing gear employed in the design. These parts must be exact scale reproductions. Any appreciable variation from scale reproduction must be in the remaining parts of the model, i.e., struts, wires, fittings, control horns, radiators, engines, and the various attachments found exposed to the wind in special airplanes. Interplane bracing is discussed in some detail.
Contributing Partner: UNT Libraries Government Documents Department
Reduction in efficiency of propellers due to slipstream

Reduction in efficiency of propellers due to slipstream

Date: December 1, 1923
Creator: Munk, Max M
Description: In the slipstream behind a propeller there is a considerable amount of kinetic energy which has been imparted to it by the engine without producing any corresponding propeller thrust. The increased absorption of power reduces the propeller efficiency. Attention has been previously directed to this question by Bendemann and Madelung and other writers. Their contribution serves to verify a simple method of calculating the reduction in the propeller efficiency due to the slip stream. That method of calculation is given here. Explanations and examples are given for as single propeller and for two propellers mounted in tandem.
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Compressive strength of tapered airplane struts

Compressive strength of tapered airplane struts

Date: December 1, 1923
Creator: Lewe, V
Description: None
Contributing Partner: UNT Libraries Government Documents Department
The N.A.C.A. recording tachometer and angle of attack recorder

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

Date: August 1, 1923
Creator: Reid, H J E
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.
Contributing Partner: UNT Libraries Government Documents Department
A Simple Method of Estimating the Subsonic Lift and Damping in Roll of Sweptback Wings

A Simple Method of Estimating the Subsonic Lift and Damping in Roll of Sweptback Wings

Date: April 1, 1949
Creator: Polhamus, Edward C.
Description: A method of modifying existing correction factors of lifting-surface theory to account approximately for the effects of sweep was derived, and these factors were applied to existing lifting-line theories for the lift and damping in roll of swept wings. Despite the simplicity of the resulting formulas the agreement with experimental data for low speeds is very good. The equation for lift is expressed entirely in terms of the geometric characteristics of the wing and the section-lift-curve; the necessity for any charts is thereby eliminated. The equation for the damping in roll, however, requires a chart for the determination of the effective lateral center of pressure for rolling moment due to rolling. If the Glauert-Prandtl transformation is used, the formulas obtained can be applied to swept wings at subsonic speeds below the critical speed.
Contributing Partner: UNT Libraries Government Documents Department
Empirical relation between induced velocity, thrust, and rate of descent of a helicopter rotor as determined by wind-tunnel tests on four model rotors

Empirical relation between induced velocity, thrust, and rate of descent of a helicopter rotor as determined by wind-tunnel tests on four model rotors

Date: October 1, 1951
Creator: Castles, Walter, Jr. & Gray, Robin B.
Description: The empirical relation between the induced velocity, thrust, and rate of vertical descent of a helicopter rotor was calculated from wind tunnel force tests on four model rotors by the application of blade-element theory to the measured values of the thrust, torque, blade angle, and equivalent free-stream rate of descent. The model tests covered the useful range of C(sub t)/sigma(sub e) (where C(sub t) is the thrust coefficient and sigma(sub e) is the effective solidity) and the range of vertical descent from hovering to descent velocities slightly greater than those for autorotation. The three bladed models, each of which had an effective solidity of 0.05 and NACA 0015 blade airfoil sections, were as follows: (1) constant-chord, untwisted blades of 3-ft radius; (2) untwisted blades of 3-ft radius having a 3/1 taper; (3) constant-chord blades of 3-ft radius having a linear twist of 12 degrees (washout) from axis of rotation to tip; and (4) constant-chord, untwisted blades of 2-ft radius. Because of the incorporation of a correction for blade dynamic twist and the use of a method of measuring the approximate equivalent free-stream velocity, it is believed that the data obtained from this program are more applicable to free-flight calculations than ...
Contributing Partner: UNT Libraries Government Documents Department