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  Partner: UNT Libraries Government Documents Department
 Decade: 1940-1949
 Year: 1940
 Serial/Series Title: NACA Technical Memorandums
Aerodynamics of rotating-wing aircraft with blade-pitch control

Aerodynamics of rotating-wing aircraft with blade-pitch control

Date: February 1, 1940
Creator: Pfluger, A
Description: 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.
Contributing Partner: UNT Libraries Government Documents Department
Application of the methods of gas dynamics to water flows with free surface I : flows with no energy dissipation

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

Date: March 1, 1940
Creator: Preiswerk, Ernst
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.
Contributing Partner: UNT Libraries Government Documents Department
Application of the methods of gas dynamics to water flows with free surface II : flows with momentum discontinuities (hydraulic jumps)

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

Date: March 1, 1940
Creator: Preiswerk, Ernst
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.
Contributing Partner: UNT Libraries Government Documents Department
Buckling tests with a spar-rib grill

Buckling tests with a spar-rib grill

Date: September 1, 1940
Creator: Weinhold, Josef
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.
Contributing Partner: UNT Libraries Government Documents Department
The cause of welding cracks in aircraft steels

The cause of welding cracks in aircraft steels

Date: October 1, 1940
Creator: Muller, J
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.
Contributing Partner: UNT Libraries Government Documents Department
Chordwise load distribution of a simple rectangular wing

Chordwise load distribution of a simple rectangular wing

Date: December 1, 1940
Creator: Wieghardt, Karl
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.
Contributing Partner: UNT Libraries Government Documents Department
Constant-pressure blowers

Constant-pressure blowers

Date: January 1, 1940
Creator: Sorensen, E
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.
Contributing Partner: UNT Libraries Government Documents Department
Corrections on the thermometer reading in an air stream

Corrections on the thermometer reading in an air stream

Date: October 1, 1940
Creator: Van Der Maas, H J
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.
Contributing Partner: UNT Libraries Government Documents Department
Creep strength of stabilized wrought-aluminum alloys

Creep strength of stabilized wrought-aluminum alloys

Date: November 1, 1940
Creator: Muller, W
Description: Rohn-type equipment has been mounted on rubber blocks, for the purpose of damping the vibrations of the ground and of rendering the plastic yielding of the test bars less subject to outside interferences. New equipment also included three shockproof creep-testing machines with the Martens mirror instruments for recording the strain curve of the fatigue-tested specimens.
Contributing Partner: UNT Libraries Government Documents Department
DFS dive-control brakes for gliders and airplanes ; and, Analytical study of the drag of the DFS dive-control brake

DFS dive-control brakes for gliders and airplanes ; and, Analytical study of the drag of the DFS dive-control brake

Date: January 1, 1940
Creator: Jacobs, Hans
Description: These two reports are surveys on the progress and present state of development of dive-control flaps for gliders and airplanes. The second article describes how on the basis of wind tunnel and free-flight tests, the drag increase on brake flaps of the type DFS, can be predicted. Pressure records confirm a two-dimensional load distribution along the brake-flap surface Aerodynamically, the location of the brake flaps along the span is of importance for reasons of avoidance of vibration and oscillation phenomena on control and tail surfaces; statically, because of the magnitude of the frontal drag in diving with respect to the bending moments, which may become decisive for the dimensions of the wing attachment and for the wing covering.
Contributing Partner: UNT Libraries Government Documents Department
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