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 Decade: 1940-1949
 Year: 1940
 Collection: National Advisory Committee for Aeronautics Collection
Aerodynamic heating and the deflection of drops by an obstacle in an air stream in relation to aircraft icing

Aerodynamic heating and the deflection of drops by an obstacle in an air stream in relation to aircraft icing

Date: October 1, 1940
Creator: Kantrowitz, Arthur
Description: Two topics of interest to persons attempting to apply the heat method of preventing ice formation on aircraft are considered. Surfaces moving through air at high speed are shown, both theoretically and experimentally, to be subject to important aerodynamic heating effects that will materially reduce the heat required to prevent ice. Numerical calculations of the path of water drops in an air stream around a circular cylinder are given. From these calculations, information is obtained on the percentage of the swept area cleared of drops.
Contributing Partner: UNT Libraries Government Documents Department
Analysis of wind-tunnel data on directional stability and control

Analysis of wind-tunnel data on directional stability and control

Date: September 1, 1940
Creator: Pass, H R
Description: None
Contributing Partner: UNT Libraries Government Documents Department
Mechanism of flutter.a theoretical and experimental investigation of the flutter problem

Mechanism of flutter.a theoretical and experimental investigation of the flutter problem

Date: January 1, 1940
Creator: Theodorsen, Theodore & Garrick, I E
Description: The results of the basic flutter theory originally devised in 1934 and published as NACA Technical Report no. 496 are presented in a simpler and more complete form convenient for further studies. The paper attempts to facilitate the judgement of flutter problems by a systematic survey of the theoretical effects of the various parameters. A large number of experiments were conducted on cantilever wings, with and without ailerons, in the NACA high-speed wind tunnel for the purpose of verifying the theory and to study its adaptability to three-dimensional problems. The experiments included studies on wing taper ratios, nacelles, attached floats, and external bracings. The essential effects in the transition to the three-dimensional problem have been established. Of particular interest is the existence of specific flutter modes as distinguished from ordinary vibration modes. It is shown that there exists a remarkable agreement between theoretical and experimental results.
Contributing Partner: UNT Libraries Government Documents Department
Flame speeds and energy considerations for explosions in a spherical bomb

Flame speeds and energy considerations for explosions in a spherical bomb

Date: January 1, 1940
Creator: Fiock, Ernest F; Marvin, Charles F , Jr; Caldwell, Frank R & Roeder, Carl H
Description: Simultaneous measurements were made of the speed of flame and the rise in pressure during explosions of mixtures of carbon monoxide, normal heptane, iso-octane, and benzene in a 10-inch spherical bomb with central ignition. From these records, fundamental properties of the explosive mixtures, which are independent of the apparatus, were computed. The transformation velocity, or speed at which flame advances into and transforms the explosive mixture, increases with both the temperature and the pressure of the unburned gas. The rise in pressure was correlated with the mass of charge inflamed to show the course of the energy developed.
Contributing Partner: UNT Libraries Government Documents Department
The unsteady lift of a wing of finite aspect ratio

The unsteady lift of a wing of finite aspect ratio

Date: January 1, 1940
Creator: Jones, Robert T
Description: Unsteady-lift functions for wings of finite aspect ratio have been calculated by correcting the aerodynamic inertia and the angle of attack of the infinite wing. The calculations are based on the operational method.
Contributing Partner: UNT Libraries Government Documents Department
Effect of exit-slot position and opening on the available cooling pressure for NACA nose-slot cowlings

Effect of exit-slot position and opening on the available cooling pressure for NACA nose-slot cowlings

Date: January 1, 1940
Creator: Stickle, George W; Naiman, Irven & Crigler, John L
Description: Report presents the results of an investigation of full-scale nose-slot cowlings conducted in the NACA 20-foot wind tunnel to furnish information on the pressure drop available for cooling. Engine conductances from 0 to 0.12 and exit-slot conductances from 0 to 0.30 were covered. Two basic nose shapes were tested to determine the effect of the radius of curvature of the nose contour; the nose shape with the smaller radius of curvature gave the higher pressure drop across the engine. The best axial location of the slot for low-speed operation was found to be in the region of maximum negative pressure for the basic shape for the particular operating condition. The effect of the pressure operating condition on the available cooling pressure is shown.
Contributing Partner: UNT Libraries Government Documents Department
Determination of ground effect from tests of a glider in towed flight

Determination of ground effect from tests of a glider in towed flight

Date: January 1, 1940
Creator: Wetmore, J W & Turner, L I , Jr
Description: Report presents the results of an investigation made to find the effect of ground on the aerodynamic characteristics of a Franklin PS-2 glider. The lift, the drag, and the angle of attack of the glider in towed flight were determined at several heights from 0.14 to 1.19 span lengths and at various speeds for each height. Two wing arrangements were tested: the plain wing, and the wing with a nearly full-span 30-percent-chord split flap deflected 45 degrees. The experimental results for the plain wing were in good agreement with theoretical values calculated by the method of Wieselsberger for both the angle of attack and the drag coefficient at a height of 0.21 span length; Tani's refinements of the theory had a practically negligible effect on the computed values in this case.
Contributing Partner: UNT Libraries Government Documents Department
Effective gust structure at low altitudes as determined from the reactions of an airplane

Effective gust structure at low altitudes as determined from the reactions of an airplane

Date: January 1, 1940
Creator: Donely, Philip
Description: Measurements of gust structure and gust intensity were made in the lower levels of the atmosphere (0 to 3,500 ft.). An Aeronca C-2 airplane was used as the measuring instrument, the gust structure being derived from the recorded motions of the airplane. Data were also obtained on wind velocities and temperatures as functions of altitude for use in attempting to correlate the gust-structure data with various meteorological quantities. The results indicated little or no correlation between the gust velocity and the gradient distance. The data, however, did indicate that an airplane the size of the Aeronca will respond most frequently to gusts having gradient distance of the order of 30 feet. The maximum true gust velocity measured during the investigation was 25 feet per second.
Contributing Partner: UNT Libraries Government Documents Department
Free-spinning wind-tunnel tests of a low-wing monoplane with systematic changes in wings and tails V : effect of airplane relative density

Free-spinning wind-tunnel tests of a low-wing monoplane with systematic changes in wings and tails V : effect of airplane relative density

Date: January 1, 1940
Creator: Seidman, Oscar & Neihouse, A I
Description: 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.
Contributing Partner: UNT Libraries Government Documents Department
Annual report of the National Advisory Committee for Aeronautics (25th).administrative report including Technical Report nos. 645 to 680

Annual report of the National Advisory Committee for Aeronautics (25th).administrative report including Technical Report nos. 645 to 680

Date: January 1, 1940
Creator: unknown
Description: Report includes the National Advisory Committee for Aeronautics letter of submittal to the President, summaries of the committee's activities and research accomplished, bibliographies, and financial report.
Contributing Partner: UNT Libraries Government Documents Department
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