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  Partner: UNT Libraries Government Documents Department
 Decade: 1930-1939
 Collection: National Advisory Committee for Aeronautics Collection
The Breda wind tunnel

The Breda wind tunnel

Date: December 1, 1939
Creator: Pittoni, Mario
Description: A description of the design and construction of the Breda wind tunnel. The tunnel is equipped with a two-meter throat diameter and a 310 kph velocity potential.
Contributing Partner: UNT Libraries Government Documents Department
Contribution to the aerodynamics of rotating-wing aircraft

Contribution to the aerodynamics of rotating-wing aircraft

Date: December 1, 1939
Creator: Sissingh, G
Description: The chief defect of the investigations up to now was the assumption of a more or less arbitrary "mean" drag coefficient for a section of the blade. This defect is remedied through replacement of the constant coefficient by a function of higher order which corresponds to the polar curve of the employed profile. In that way it is possible to extend the theory to include the entire range from "autogyro" without power input to the driven "helicopter" with forward-tilted rotor axis. The treatment includes the twisted rectangular blade and a non-twisted tapered blade. Proceeding from the air flow and stresses on a section of the blade, the formulas for torque, axial and normal thrust of a linearly twisted rectangular blade, and a non-twisted tapered blade, are derived.
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The Effect of Streamlining the Afterbody of an N.A.C.A. Cowling

The Effect of Streamlining the Afterbody of an N.A.C.A. Cowling

Date: December 1, 1939
Creator: Stickle, George W.; Crigler, John L. & Naiman, Irven
Description: The drag and the power cost associated with the changing of the nose of a nacelle from a streamline shape to a conventional N.A.C.A. cowling shape was investigated in the N.A.C.A. 20-foot tunnel. Full-scale propellers and nacelles were used. The increment of drag associated with the change of nose shapes was found to be critically dependent on the afterbody of the nacelle. Two streamline afterbodies were tested. The results fo the tests with the more streamlined afterbody showed that the added drag due to the open-nose cowling was only one-fourth of the drag increase obtained with the other afterbody. The results of this research indicate that the power cost, in excess of that with a streamline nose, of using an N.A.C.A. cowling in front of a well-designed afterbody to enclose a 1,500-horsepower engine in an airplane with a speed of 300 miles per hour amounts to 1.5 percent of the engine power. If the open-nose cowling is credited with 1 percent because it cools the front of the cylinders, the non-useful power cost amounts to only 0.5 percent of the engine power.
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The Effect of Streamlining the Aterbody of an NACA Cowling

The Effect of Streamlining the Aterbody of an NACA Cowling

Date: December 1, 1939
Creator: Naiman, Irven
Description: None
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Local instability of columns with I-, Z-, channel, and rectangular-tube sections

Local instability of columns with I-, Z-, channel, and rectangular-tube sections

Date: December 1, 1939
Creator: Stowell, Elbridge Z & Lundquist, Eugene E
Description: Charts are presented for the coefficients in the formulas for the critical compressive stress at which cross-sectional distortion begins in thin-wall columns of I-, Z-, channel, and rectangular-tube sections. The energy method of Timoshenko was used in the theoretical calculations required for the construction of the charts. The deflection equations were carefully selected to give good accuracy. The calculation of the critical compressive stress at stresses above the elastic range is briefly discussed in order to demonstrate the use of the formulas and the charts in engineering calculations. Two illustrative problems are included.
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Measurements of the air-flow velocity in the cylinder of an airplane engine

Measurements of the air-flow velocity in the cylinder of an airplane engine

Date: December 1, 1939
Creator: Wenger, Hermann
Description: The object of the present investigation is to determine the velocity in the BMW-VI cylinder of an externally driven single-cylinder test engine at high engine speeds using the hot-wire method of Ulsamer.
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Modern methods of testing

Modern methods of testing

Date: December 1, 1939
Creator: Seeber, F
Description: After a brief survey of the commonly used single-value test methods, the importance of the determination of the incipient knock for the octane number is discussed and improvements suggested for the knock testing in the CFR engine. The DVL supercharge test method with its superiority of direct determination of fuel knock in each single cylinder of an airplane engine without involving structural changes, is described and the advantages of a multiple-value method enumerated. A diagrammatic presentation of the knock characteristics is presented.
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Observations in flight of the region of stalled flow over the blades of an autogiro rotor

Observations in flight of the region of stalled flow over the blades of an autogiro rotor

Date: December 1, 1939
Creator: Bailey, F J , Jr & Gustafon, F B
Description: The flow over the inner halves of the rotor blades on a Kellet YG-1B autogiro was investigated in flight by making camera records of the motion of silk streamers attached to the upper surfaces of the blades. These records were analyzed to determine the boundaries of the region within which the flow over the blade sections was stalled for various tip-speed ratios. For the sake of comparison, corresponding theoretical boundaries were obtained. Both the size of the stalled area and its rate of growth with increasing tip-speed ratio were found to be larger than the theory predicted, although experiment agreed with theory with regard to shape and general location of the stalled area. The stalled region may be an important factor in both the rotor lift-drag ratio and the blade flapping motion at the higher tip-speed ratios. The method of study used in this paper should be useful in further studies of the problem, including the reduction of the size of the region.
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Pressure-distribution measurements on a rectangular wing with a partial-span split flap in curved flight

Pressure-distribution measurements on a rectangular wing with a partial-span split flap in curved flight

Date: December 1, 1939
Creator: Rokus, Frank G
Description: Pressure-distribution tests were made on the 32-foot whirling arm of the Daniel Guggenheim Airship Institute of a rectangular wing of NACA 23012 section to determine the rolling and the yawing moment due to angular velocity in yaw. The model was tested at 0 and 5 degree pitch; 0, +/- 5, and +/- 10 degrees yaw; and with no flap and with split flaps 25, 50 and 75 percent of the wing span and deflected 60 degrees. The results are given in the form of span load distributions and as calculated moment coefficients. The experimental values of rolling- and yawing-moment coefficients were in fairly close agreement with theory.
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Profile-Drag Investigation of an Airplane Wing Equipped with Rubber Inflatable De-Icer

Profile-Drag Investigation of an Airplane Wing Equipped with Rubber Inflatable De-Icer

Date: December 1, 1939
Creator: Rodert, Lewis A. & Jones, Alun R.
Description: The National Advisory Committee for Aeronautics has made profile-drag measurements in flight of a wing which was equipped with a rubber inflatable de-icer and to which various stimulated ice formations were attached. Tuft observations at the stalling speed of the wing with the various drag conditions were made in order to determine the influence on the maximum lift coefficient. The de-icer installation caused an increase of from 10-20% in the profile drag of the plain wing and reduced CL(sub max) about 6%. Simulated ice, when confined to the leading-edge region of the de-icer, had no measurable influence upon the profile drag at the cruising speed. This ice condition, however, reduced the value of CL(sub max) to about three-fourths that of the plain wing. Simulated ice in the form of a ridge along the upper and lower de-icer cap-strips increased the profile drag by about 360% at cruising speed. This condition reduced the CL(sub max) to approximately one-half that of the plain wing value.
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A recurrence formula for shear-lag problems

A recurrence formula for shear-lag problems

Date: December 1, 1939
Creator: Kuhn, Paul
Description: The analysis of the bending action in box beams with appreciable shear deformation of the flanges becomes very difficult in the general case of variable cross section and loading. This paper presents a convenient method of solving the problem by the familiar method of dividing the beam into a number of bays that can be assumed to have constant cross section and loading. Application of formerly derived shear-lag formulas leads to a general equation closely analogous in form to the well-known three-moment equation. A numerical example and two comparisons between calculation and experimental results are included.
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Stress concentration around an open circular hole in a plate subjected to bending normal to the plane of the plate

Stress concentration around an open circular hole in a plate subjected to bending normal to the plane of the plate

Date: December 1, 1939
Creator: Dumont, C
Description: An aluminum-alloy plate containing an open circular hole of diameter large compared with the thickness of the plate was subjected to bending forces normal to the plane of the plate. Deflection and strain measurements were taken for two different loads. Stress concentrations occurred at the edge of the hole and the maximum stresses were tangential to the hole at the ends of the transverse diameter. The maximum stress at the edge of the hole was 1.59 times the computed stress on the net section and 1.85 times the computed stress in a solid plate of the same dimensions subjected to the same bending forces. The maximum deflections were about 20 percent greater than the corresponding deflection for a solid plate of the same size subjected to the same bending forces. The smallest edge distance was equal to 2-1/2 times the diameter of the hole and the stress concentration on this side of the hole was the same as on the side where the edge distance was about 4-1/2 diameters. A theoretical analysis of the problem shows that, for an aluminum plate of infinite width, the stress concentration at the edge of the hole would be 1.87 times the stress in ...
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Corrugated metal diaphragms for aircraft pressure-measuring instruments

Corrugated metal diaphragms for aircraft pressure-measuring instruments

Date: November 1, 1939
Creator: Goerke, V H & Wildhack, W A
Description: None
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The effect of compressibility on the pressure reading of a Prandtl pitot tube at subsonic flow velocity

The effect of compressibility on the pressure reading of a Prandtl pitot tube at subsonic flow velocity

Date: November 1, 1939
Creator: Walchner, O
Description: Errors arising from yawed flow were also determined up to 20 degrees angle of attack. In axial flow, the Prandtl pitot tube begins at w/a approx. = 0.8 to give an incorrect static pressure reading, while it records the tank pressure correctly, as anticipated, up to sonic velocity. Owing to the compressibility of the air, the Prandtl pitot tube manifests compression shocks when the air speed approaches velocity of sound. This affects the pressure reading of the instrument. Because of the increasing importance of high speed in aviation, this compressibility effect is investigated in detail.
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The effect of the slipstream on an airplane wing

The effect of the slipstream on an airplane wing

Date: November 1, 1939
Creator: Franke, A & Weinig, F
Description: The conditions which must be met at the slipstream boundary are developed, after which it is shown with the aid of the reflection method how these limiting conditions may be complied with in the case of an airfoil in a propeller slipstream in horizontal flow as well as for the propeller in yaw and with allowance for the slipstream rotation. In connection herewith, it is shown how the effective angles of attack and the circulation distribution with due regard to slipstream effect can be predicted and what inferences may be drawn therefrom for the distribution of lift, drag, and pitching moment.
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Engine Operation in Flight for Minimum Fuel Consumption

Engine Operation in Flight for Minimum Fuel Consumption

Date: November 1, 1939
Creator: Reuter, George
Description: Engine and airplane performance data have been gathered from various sources and analyzed to determine indications of the most economical methods of flight operation from a consideration of fuel expenditure. The analysis includes the influence of such facts as fuel-air ratio, engine speed, engine knock, altitude, cylinder cooling, spark timing, and limits of cruising brake mean effective pressure. The results indicate that the cheapest power is obtained with approximately correct mixture at low engine speed and highest permissible manifold pressure. If more power is desired, the methods of obtaining it are, in order of fuel economy: (a) increasing the engine speed and maintaining safe cylinder temperatures by cooling; (b) retarding the spark or cooling further to permit higher manifold pressure; and, (c) riching the mixture. The analysis further shows that the maximum time endurance of flight occurs at the air speed corresponding to minimum thrust horsepower required and with minimum practicable engine speed. Maximum mileage per pound of fuel is obtained at slightly higher air speed. The fuel-air ratio should be approximately the theoretically correct ratio in both cases. For an engine equipped with a geared supercharger, as in the example presented, and with knock as the limiting condition, a ...
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The enlarged N.A.C.A. tank, and some of its work

The enlarged N.A.C.A. tank, and some of its work

Date: November 1, 1939
Creator: Truscott, Starr
Description: The most conspicuous of the features of the enlarged N.A.C.A. tank are derived directly from those of the original tank and owe their present form not only to the reasons for their first use but also to the experience obtained with them. As in the original tank, there are: 1) A basin of great length (new 2,880 feet); 2) Rails made of structural H beams, without machining; 3) A towing carriage of very high speed (now 80 mph maximum); 4) Rubber tires on all the wheels, pneumatic on the running wheels and solid on the guide wheels.
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An Investigation of the Prevention of Ice on the Airplane Windshield

An Investigation of the Prevention of Ice on the Airplane Windshield

Date: November 1, 1939
Creator: Rodert, Lewis A.
Description: An investigation has been completed on several methods for the prevention and removal of ice on an airplane windshield. Tests were made on the use of electric heating, hot-air heating, and an alcohol-dispensing, rotating wiper blade. The results showed that vision through the airplane windshield could be maintained during severe icing conditions by the use of heat. When put in operation prior to the formation of ice on the windshield, the rotating wiper blade prevented the formation of ice. A combination system that employs the use of heated air and a rotating wiper blade would appear to give protection against the formation of ice on the windshield exterior, prevent frost on the interior, and provide for the removal of rainfall.
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Photoelastic analysis of three-dimensional stress systems using scattered light

Photoelastic analysis of three-dimensional stress systems using scattered light

Date: November 1, 1939
Creator: Weller, R & Bussey, J K
Description: A method has been developed for making photoelastic analyses of three-dimensional stress systems by utilizing the polarization phenomena associated with the scattering of light. By this method, the maximum shear and the directions of the three principal stresses at any point within a model can be determined, and the two principal stresses at a free-bounding surface can be separately evaluated. Polarized light is projected into the model through a slit so that it illuminates a plane section. The light is continuously analyzed along its path by scattering and the state of stress in the illuminated section is obtained. By means of a series of such sections, the entire stress field may be explored. The method was used to analyze the stress system of a simple beam in bending. The results were found to be in good agreement with those expected from elementary theory.
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Pressure-distribution investigation of an N.A.C.A. 0009 airfoil with a 50-percent-chord plain flap and three tabs

Pressure-distribution investigation of an N.A.C.A. 0009 airfoil with a 50-percent-chord plain flap and three tabs

Date: November 1, 1939
Creator: Street, William G & Ames, Milton B
Description: Pressure-distribution tests of an N.A.C.A. 0009 airfoil with a 50-percent-chord plain flap and three plain tabs, having chords 10, 20, and 30 percent of the flap chord, were made in the N.A.C.A. 4- by 6- foot vertical tunnel. The tests supplied aerodynamic section data that may be applied to the design of horizontal and vertical tail surfaces. The results are presented as resultant-pressure diagrams for the airfoil with the flap and the 20-percent-chord tab. Plots are also given of increments of normal-force and hinge-moment coefficients for the airfoil, the flap, and the three tabs. The experimental results and values computed by analytical methods are in good agreement for small flap and tab deflections. The results of the tests indicated that the effectiveness of all three tab sizes in reducing flap hinge moments decreased with increasing flap deflection.
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Pressure-distribution measurements on a tapered wing with a partial-span split flap in curved flight

Pressure-distribution measurements on a tapered wing with a partial-span split flap in curved flight

Date: November 1, 1939
Creator: Troller, TH & Rokus, F
Description: Pressure-distribution tests were made on the 32-foot whirling arm of the Daniel Guggenheim Airship Institute of a tapered wing to determine the rolling and the yawing moments due to an angular velocity in yaw. The model was tested at 0 degree and 5 degree pitch; 0 degree, 5 degree, and 10 degree yaw; and with split flaps covering 25, 50, 75, and 100 percent of the wing span and deflected 60 degrees. The results are given in the form of load distributions and as calculated moment coefficients. The experimental values of rolling- and yawing- moment coefficients were in fairly close agreement with theory.
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Pressure Distribution on the Fuselage of a Midwing Airplane Model at High Speeds

Pressure Distribution on the Fuselage of a Midwing Airplane Model at High Speeds

Date: November 1, 1939
Creator: Delano, James B.
Description: The pressure distribution on the fuselage of a midwing airplane model was measured in the NACA 8-foot high speed wind tunnel at speeds from 140 to 440 miles per hour for lift coefficients ranging from -0.2 to 1.0. The primary purpose of the tests was to provide data showing the air pressures on various parts of the fuselage for use in structural design. The data may also be used for the design of scoops and vents. The results show that the highest negative pressures occurred near the wing and were more dependent on the wing than on the fuselage. At high speeds, the magnitude of the pressure coefficients as predicted from pressure coefficients determined experimentally at low speeds by application of the theoretical factor 1/(square root)1-M(exp 2) (where M is the ratio of the air speed to the speed of sound in air) may misrepresent the actual conditions. At the points where the maximum negative pressures ocurred, however, the variation of the pressure coefficients was in good agreement with the theoretical factor, indicating that this factor may afford satisfactory predictions of critical speed, at least for fuselages similar to the shape tested.
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Report on ice formation on aircraft

Report on ice formation on aircraft

Date: November 1, 1939
Creator: unknown
Description: The physical phenomena involved in the icing of aircraft have been analyzed and measured. Recommendations on warning devices are made as well as the different types of ice and glazing that can occur on airplanes are examined and discussed.
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Tidewater and weather-exposure tests on metals used in aircraft

Tidewater and weather-exposure tests on metals used in aircraft

Date: November 1, 1939
Creator: Mutchler, Willard & Galvin, W G
Description: Tidewater and weather-exposure tests on various aluminum alloys, magnesium alloys, and stainless steels are now being conducted by the National Bureau of Standards. Exposures were begun in June 1938 and, according to present plans, are to continue over a 3-year period. The methods of exposure and the materials being investigated are described and the more important results obtained up to the conclusion of the first year's exposure are reported.
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