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  Partner: UNT Libraries Government Documents Department
 Decade: 1940-1949
 Year: 1940
 Serial/Series Title: NACA Special Report
An Approximate Method of Calculation of Relative Humidity Required to Prevent Frosting on Inside of Aircraft Pressure Cabin Windows, Special Report

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

Date: December 5, 1940
Creator: Jones, Alun R.
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.
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Boundary-Layer Transition on the N.A.C.A. 0012 and 23012 Airfoils in the 8-Foot High-Speed Wind Tunnel, Special Report

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

Date: January 1, 1940
Creator: Becker, John V.
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 ...
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Comparison of Three Exit-Area Control Devices on an N.A.C.A. Cowling, Special Report

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

Date: May 1, 1940
Creator: McHugh, James G.
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.
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The Effect of Initial Displacement of the Center Support on the Buckling of a Column Continuous over Three Supports

The Effect of Initial Displacement of the Center Support on the Buckling of a Column Continuous over Three Supports

Date: November 1, 1940
Creator: Lunquist, Eugene E. & Kotanchik, Joseph N.
Description: The test indicate that "an indiscriminate single application of the Southwell method (for analyzing Exp. Observations in problems of elastic stability)--can result in definite and measurable errors" The test also indicate "that the effect of curvature due to bending on the critical load for the compression flange material of a box beam is probably small and can be neglected." We have not found this to be true in our tests. It is believed that the effect of curvature, together with a small amount of fixity at the ribs, tends to force the stiffeners to bow in each bay thus effectively increasing their end fixity and thereby raising their allowable loads.
Contributing Partner: UNT Libraries Government Documents Department
The Effects of Aerodynamic Heating on Ice Formations on Airplane Propellers

The Effects of Aerodynamic Heating on Ice Formations on Airplane Propellers

Date: August 1, 1940
Creator: Rodert, Lewis A.
Description: An investigation has been made of the effect of aerodynamic heating on propeller-blade temperatures. The blade temperature rise resulting from aerodynamic heating was measured and the relation between the resulting blade temperatures and the outer limit of the iced-over region was examined. It was found that the outermost station at which ice formed on a propeller blade was determined by the blade temperature rise resulting from the aerodynamic heating at that point.
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Experimental Determination of Exhaust Gas Thrust, Special Report

Experimental Determination of Exhaust Gas Thrust, Special Report

Date: February 1, 1940
Creator: Pinkel, Benjamin & Voss, Fred
Description: This investigation presents the results of tests made on a radial engine to determine the thrust that can be obtained from the exhaust gas when discharged from separate stacks and when discharged from the collector ring with various discharge nozzles. The engine was provided with a propeller to absorb the power and was mounted on a test stand equipped with scales for measuring the thrust and engine torque. The results indicate that at full open throttle at sea level, for the engine tested, a gain in thrust horsepower of 18 percent using separate stacks, and 9.5 percent using a collector ring and discharge nozzle, can be expected at an air speed of 550 miles per hour.
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A Flight Investigation of Exhaust-Heat De-Icing, Special Report

A Flight Investigation of Exhaust-Heat De-Icing, Special Report

Date: September 1, 1940
Creator: Rodert, Lewis A. & Jones, Alun R.
Description: The National Advisory Committee for Aeronautics has conducted exhaust-heat de-icing tests inflight t o provide data needed in the application of this method of ice prevention. Thc capacity to extract heat from the exhaust gas for de-icing purposes, the quantity of heat required, and other factors were examined. The results indicate that a wing-heating system employing a spanwise exhaust tube within the leading edge of the wing will make available for de-icing purposes between 30 and 35 percent of the exhaust-gas heat. Data are given by which the heat required for ice prevention can be calculated. Sample calculations have been made, on a basis of existing engine power over wing area ratios, to show that sufficient heating can be obtained for ice protection on modern transport airplanes,.
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Flight Tests of Exhaust Gas Jet Propulsion, Special Report

Flight Tests of Exhaust Gas Jet Propulsion, Special Report

Date: November 1, 1940
Creator: Pnkel, Benjamin & Turner, L. Richard
Description: Flight test s were conducted on the XP-41 airplane, equipped with a Pratt & Whitney R1830-19, 14-cylinder, air-cooled engine, to determine the increase in flight speed obtainable by the use of individual exhaust stacks directed rearwardly to obtain exhaust-gas thrust. Speed increases up to 18 miles per hour at 20,000 feet altitude were obtained using stacks having an exit area of 3.42 square inches for each cylinder. A slight increase in engine power and decrease in cylinder temperature at a given manifold pressure were obtained with the individual stacks as compared with a collector-ring installation. Exhaust-flame visibility was quite low, particularly in the rich range of fuel-air ratios.
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Full-Scale Tests of 4- and 6-Blade, Single- and Dual-Rotating Propellers, Special Report

Full-Scale Tests of 4- and 6-Blade, Single- and Dual-Rotating Propellers, Special Report

Date: August 1, 1940
Creator: Biermann, David & Hartman, Edwin P.
Description: Test of 10-foot diameter, 4- and 6-blade single- and dual-rotating propellers were conducted in the 20-foot propeller-research tunnel. The propellers were mounted at the front end of a streamline body incorporating spinners to house the hub portions. The effect of a symmetrical wing mounted in the slipstream was investigated. The blade angles investigated ranged from 20 degrees to 65 degrees; the latter setting corresponds to airplane speeds of over 500 miles per hour. The results indicate that dual-rotating propellers were from 0 to 6% more efficient than single-rotating ones; but when operating in the presence of a wing the gain was reduced about one-half. Other advantages of dual-rotating propellers were found to include greater power absorption and greater efficiency at the low V/nD operating range of high pitch propellers.
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Full-Scale Tests of Several Propellers Equipped with Spinners, Cuffs, Airfoil and Round Shanks, and NACA 16-Series Sections, Special Report

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

Date: October 1, 1940
Creator: Biermann, David; Hartman, Edwin P. & Pepper, Edward
Description: 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 ...
Contributing Partner: UNT Libraries Government Documents Department
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