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Aerodynamic characteristics of horizontal tail surfaces

Description: From Summary: "Collected data are presented on the aerodynamic characteristics of 17 horizontal tail surfaces including several with balanced elevators and two with end plates. Curves are given for coefficients of normal force, drag, and elevator hinge moment. A limited analysis of the results has been made. The normal-force coefficients are in better agreement with the lifting-surface theory of Prandtl and Blenk for airfoils of low aspect ratio than with the usual lifting-line theory. Only partial agreement exists between the elevator hinge-moment coefficients and those predicted by Glauert's thin-airfoil theory."
Date: 1940
Creator: Silverstein, Abe & Katzoff, S

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

Description: From Summary: "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."
Date: October 1940
Creator: Kantrowitz, Arthur

Aerodynamics of rotating-wing aircraft with blade-pitch control

Description: From Introduction: "In the present report, with the aid of the usual computation methods, a rotor is investigated the pitch of whose blades is capable of being controlled in such a manner that it varies linearly with the flapping angle. To test the effect of this linkage on the aircraft performance, the theory is applied to an illustrative example."
Date: February 1940
Creator: Pfluger, A

The aileron as an aid to recovery from the spin

Description: From Introduction: "In order to afford a means of comparison and to obtain a clear understanding of the results, a study of the effects of normal angular deflections of the ailerons, with and against the spin, was included in the investigation. Ailerons deflected with the spin means that the ailerons are deflected with right aileron up and left aileron down in a right spin. The results of the investigation are discussed in this paper."
Date: September 1940
Creator: Neihouse, A. I.

Analysis of cylinder-pressure-indicator diagrams showing effects of mixture strength and spark timing

Description: An investigation was made to determine the effect of mixture strength and of normal as well as optimum spark timing on the combustion, on the cylinder temperature, and on the performance characteristics of an engine. A single-cylinder test unit utilizing an air-cooled cylinder and a carburetor and operating with gasoline having an octane rating of 92 was used. The investigation covered a range of fuel-air ratios from 0.053 to 0.118. Indicator diagrams and engine-performance data were taken for each change in engine conditions. Examination of the indicator shows that for fuel-air ratios less than and greater than 0.082 the rate and the amount of effective fuel burned decreased. For a fuel-air ratio of 0.118 the combustion efficiency was only 58 percent. Advancing the spark timing increased the rate of pressure rise. This effect was more pronounced with leaner mixtures.
Date: August 1940
Creator: Gerrish, Harold C & Voss, Fred

Analysis of wind-tunnel data on directional stability and control

Description: From Summary: "This paper does not attempt to establish criterions for directional stability and control; rather, the emphasis is placed on providing some basis for design to specified criterions. An example applying the design methods has been included."
Date: September 1940
Creator: Pass, H R

Application of the methods of gas dynamics to water flows with free surface I : flows with no energy dissipation

Description: The application is treated in sufficient detail to facilitate as much as possible its application by the engineer who is less familiar with the subject. The present work was undertaken with two objects in view. In the first place, it is considered as a contribution to the water analogy of gas flows, and secondly, a large portion is devoted to the general theory of the two-dimensional supersonic flows.
Date: March 1940
Creator: Preiswerk, Ernst

Application of the methods of gas dynamics to water flows with free surface II : flows with momentum discontinuities (hydraulic jumps)

Description: In this paper an introduction to shock polar diagrams is given which then leads into an examination of water depths in hydraulic jumps. Energy loss during these jumps is considered along with an extended look at elementary solutions of flow. An experimental test set-up is described and the results presented.
Date: March 1940
Creator: Preiswerk, Ernst

An Approximate Method of Calculation of Relative Humidity Required to Prevent Frosting on Inside of Aircraft Pressure Cabin Windows, Special Report

Description: This report has been prepare in response to a request for information from an aircraft company. A typical example was selected for the presentation of an approximate method of calculation of the relative humidity required to prevent frosting on the inside of a plastic window in a pressure type cabin on a high speed airplane. The results of the study are reviewed.
Date: December 5, 1940
Creator: Jones, Alun R.

An Autunite Deposit in the Rosamond Hills, Kern County, California

Description: From introduction: An autunite deposit in the SW 1/4 sec. 25, T. 10 N., R. 13 W. San Bernardino meridian, was visited by F. M. Chace on May 6 and 15, 1950. The deposit is about 100 yards west of a north-south country road and is at an altitude of approximately 2,775 feet. The autunite-bearing tuffaceous sandstone strikes N. 35-40 W. and dips 20 -25 SW. It has been traced about 40 feet along the strike at the base of the outcrop and for about 20 feet up the dip. Insufficient work was done to give an accurate idea of the size of the deposit or to determine if other autunite-bearing beds are present.
Date: August 1940
Creator: Chace, F. M.

Boundary-Layer Transition on the N.A.C.A. 0012 and 23012 Airfoils in the 8-Foot High-Speed Wind Tunnel, Special Report

Description: Determinations of boundary-layer transition on the NACA 0012 and 2301 airfoils were made in the 8-foot high-speed wind tunnel over a range of Reynolds Numbers from 1,600,000 to 16,800,000. The results are of particular significance as compared with flight tests and tests in wind tunnels of appreciable turbulence because of the extremely low turbulence in the high-speed tunnel. A comparison of the results obtained on NACA 0012 airfoils of 2-foot and 5-foot chord at the same Reynolds Number permitted an evaluation of the effect of compressibility on transition. The local skin friction along the surface of the NACA 0012 airfoil was measured at a Reynolds Number of 10,000,000. For all the lift coefficient at which tests were made, transition occurred in the region of estimated laminar separation at the low Reynolds Numbers and approach the point of minimum static pressure as a forward limit at the high Reynolds Numbers. The effect of compressibility on transition was slight. None of the usual parameters describing the local conditions in the boundary layer near the transition point served as an index for locating the transition point. As a consequence of the lower turbulence in the 8-foot high-speed tunnel, the transition points occurred consistently farther back along the chord than those measured in the NACA full-scale tunnel. An empirical relation for estimating the location of the transition point for conventional airfoils on the basis of static-pressure distribution and Reynolds Number is presented.
Date: January 1, 1940
Creator: Becker, John V.

Buckling tests with a spar-rib grill

Description: The present report deals with a comparison of mathematically and experimentally defined buckling loads of a spar-rib grill, on the assumption of constant spar section, and infinitely closely spaced ribs with rigidity symmetrical to the grill center. The loads are applied as equal bending moments at both spar ends, as compression in the line connecting the joints, and in the spar center line as the assumedly uniformly distributed spar weight.
Date: September 1, 1940
Creator: Weinhold, Josef

The calculated effect of various hydrodynamic and aerodynamic factors on the take-off of a large flying boat

Description: Report presents the results of an investigation made to determine the influence of various factors on the take-off performance of a hypothetical large flying boat by means of take-off calculations. The factors varied in the calculations were size of hull (load coefficient), wing setting, trim, deflection of flap, wing loading, aspect ratio, and parasite drag. The take-off times and distances were calculated to the stalling speeds and the performance above these speeds was separately studied to determine piloting technique for optimum take-off.
Date: January 1, 1940
Creator: Olson, R E & Allison, J M

The cause of welding cracks in aircraft steels

Description: The discussion in this article refers to gas welding of thin-walled parts of up to about 3 mm thickness. It was proven that by restricting the sulphur, carbon, and phosphorous content, and by electric-furnace production of the steel, it was possible in a short time to remove this defect. Weld hardness - i.e., martensite formation and hardness of the overheated zone - has no connection with the tendency to weld-crack development. Si, Cr, Mo, or V content has no appreciable effect, while increased manganese content tends to reduce the crack susceptibility.
Date: October 1, 1940
Creator: Muller, J

Chordwise load distribution of a simple rectangular wing

Description: The chordwise distribution theory was taken over from the theory of the infinite wing. Since in this work a series expansion in b/t was used, the computation converges only for large aspect ratios. In this paper a useful approximate solution will be found also for wings with large chord - i.e., small aspect ratio.
Date: December 1, 1940
Creator: Wieghardt, Karl

Coal-Mine Accidents in the United States, 1937

Description: Report compiled by the U.S. Bureau of Mines including statistics on fatal and non-fatal accidents in coal mines located in the United States as well as data regarding the various operations (e.g., number of miners employed and average production). The information is organized into tables for comparison and the text draws some overall conclusions in the summary.
Date: 1940
Creator: Adams, William W.; Geyer, L. E. & Parry, M. G.

Comparison of Three Exit-Area Control Devices on an N.A.C.A. Cowling, Special Report

Description: Adjustable cowling flaps, an adjustable-length cowling skirt, and a bottom opening with adjustable flap were tested as means of controlling the rate of cooling-air flow through an air-cooled radial-engine cowling. The devices were tested in the NACA 20-foot tunnel on a model wing-nacelle-propeller combination, through an airspeed range of 20 to 80 miles per hour, and with the propeller blade angle set 23 degrees at 0.75 of the tip radius. The resistance of the engine to air flow through the cowling was simulated by a perforated plate. The results indicated that the adjustable cowling flap and the bottom opening with adjustable flap were about equally effective on the basis of pressure drop obtainable and that both were more effective means of increasing the pressure drop through the cowling than the adjustable-length skirt. At conditions of equal cooling-air flow, the net efficiency obtained with the adjustable cowling flaps and the adjustable-length cowling skirt was about 1% greater than the net efficiency obtained with the bottom opening with adjustable flap.
Date: May 1, 1940
Creator: McHugh, James G.

Constant-pressure blowers

Description: The conventional axial blowers operate on the high-pressure principle. One drawback of this type of blower is the relatively low pressure head, which one attempts to overcome with axial blowers producing very high pressure at a given circumferential speed. The Schicht constant-pressure blower affords pressure ratios considerably higher than those of axial blowers of conventional design with approximately the same efficiency.
Date: January 1, 1940
Creator: Sorensen, E.

Corrections on the thermometer reading in an air stream

Description: A method is described for checking a correction formula, based partly on theoretical considerations, for adiabatic compression and friction in flight tests and determining the value of the constant. It is necessary to apply a threefold correction to each thermometer reading. They are a correction for adiabatic compression, friction and for time lag.
Date: October 1, 1940
Creator: Van Der Maas, H J & Wynia, S