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 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.
Contributing Partner: UNT Libraries Government Documents Department
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.
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.
Contributing Partner: UNT Libraries Government Documents Department
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
Contributing Partner: UNT Libraries Government Documents Department
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
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.
Contributing Partner: UNT Libraries Government Documents Department
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.
Contributing Partner: UNT Libraries Government Documents Department
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.
Contributing Partner: UNT Libraries Government Documents Department
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
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.
Contributing Partner: UNT Libraries Government Documents Department
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.
Contributing Partner: UNT Libraries Government Documents Department
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.
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.
Contributing Partner: UNT Libraries Government Documents Department
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