1,437 Matching Results

Search Results

Investigation of boundary layers on an airplane wing in free flight

Description: "This report describes the equipment and method developed for recording the boundary layers on the surface of an airfoil in free flight. The results are in close agreement with the wind-tunnel tests of other experimenters. The intensity of the turbulent boundary layer, even at the much higher Reynolds Numbers reached, is determinable with Gruschwitz's formulas, although it was impossible to definitely establish a direct relationship between the turbulent boundary layer and the Reynolds Number within the limits of the obtained accuracy. The observations on the transition from laminar to turbulent flow check with previous wind-tunnel tests and calculations" (p. 1).
Date: August 1934
Creator: Stüper, J.
Partner: UNT Libraries Government Documents Department

Reduction of lift of a wing due to its drag

Description: This analysis computes for a predetermined airfoil and given Reynolds Number the course of the "displacement thickness," i.e., the course of the layer by which the streamlines of the potential flow are pushed away from the wing through the frictional layer. The result is, to a certain extent, a new wing contour.
Date: November 1935
Creator: Stüper, J
Partner: UNT Libraries Government Documents Department

Contribution to the problem of airfoils spanning a free jet

Description: After a brief discussion of the work done up to now on an unwarped wing of constant chord spanning a free jet, the computation of the circulation and lift distribution for different forms of warped wings spanning rectangular and circular jets was carried out. The computed values are compared with test values and the agreement is found to be good. The effect of placing the wing eccentrically is slight and may be applied as a correction factor to the data obtained for wing placed in middle of jet.
Date: June 1936
Creator: Stüper, J.
Partner: UNT Libraries Government Documents Department

Effect of propeller slipstream on wing and tail

Description: The results of wind tunnel tests for the determination of the effect of a jet on the lift and downwash of a wing are presented in this report. In the first part, a jet without rotation and with constant velocity distribution is considered - the jet being produced by a specially designed fan. Three-component, pressure distribution, and downwash measurements were made and the results compared with existing theory. The effect of a propeller slipstream was investigated in the second part. In the two cases the jet axis coincided with the undisturbed wind direction. In the third part the effect of the inclination of the propeller axis to the wing chord was considered, the results being obtained for a model wing with running propeller.
Date: August 1938
Creator: Stüper, J
Partner: UNT Libraries Government Documents Department

Recent Results on High-Pressure Axial Blowers

Description: "Considerable progress has, in recent times, been attained in the development of the high-pressure axial blower by well-planned research. The efforts are directed toward improving the efficiencies, which are already high for the axial blower, and in particular the delivery pressure heads. For high pressures multistage arrangements are used. Of fundamental importance is the careful design of all structural parts of the blower that are subject to the effects of the flow. In the present report, several recent results and experiences are reported, which are based on results of German engine research" (p. 1).
Date: April 1947
Creator: Eckert, B.
Partner: UNT Libraries Government Documents Department

Experiences with flow-direction instruments

Description: "The method of recording the direction of flows on the basis of the hydrodynamic zero-point measurement has now reached a certain limit, in spite of the good results achieved. While the available flow-direction devices are accurate enough for many purposes, they are all insufficient for perfectly exact prediction of the flow direction. The next problem will be to achieve a point-by point flow-direction record, whereby the test procedure must be simplified, accelerated, and the degree of accuracy of the test data improved" (p. 1).
Date: March 1941
Creator: Eckert, B.
Partner: UNT Libraries Government Documents Department

Possibilities of Reducing the Length of Axial Superchargers for Aircraft Motors

Description: Axial blowers are gaining importance as aircraft engine superchargers. However, the pressure head obtainable per stage is small. Due to the necessary great number of stages, the physical length of the blower becomes too great for an airworthy device. This report discusses several types of construction that permit a reduction in the length of the blower.
Date: January 1947
Creator: Eckert, B.
Partner: UNT Libraries Government Documents Department

Systematic model researches on the stability limits of the DVL series of float designs

Description: "To determine the trim range in which a seaplane can take off without porpoising, stability tests were made of a Plexiglas model, composed of float, wing, and tailplane, which corresponded to a full-size research airplane. The model and full-size stability limits are in good agreement. After all structural parts pertaining to the air frame were removed gradually, the aerodynamic forces replaced by weight forces, and the moment of inertia and position of the center of gravity changed, no marked change of limits of the stable zone was noticeable" (p. 1).
Date: December 1949
Creator: Sottorf, W.
Partner: UNT Libraries Government Documents Department

Analysis of Experimental Investigations of the Planing Process of the Surface of Water

Description: Pressure distribution and spray measurements were carried out on rectangular flat and V-bottom planing surfaces. Lift, resistance, and center of pressure data are analyzed and it is shown how these values may be computed for the pure planing procees of a flat or V-bottom suface of arbitrary beam, load and speed, the method being illustrated with the aid of an example.
Date: March 1944
Creator: Sottorf, W.
Partner: UNT Libraries Government Documents Department

Landing Procedure in Model Ditching Tests of Bf 109

Description: The purpose of the model tests is to clarify the motions in the alighting on water of a land plane. After discussion of the model laws, the test method and test procedure are described. The deceleration-time-diagrams of the landing of a model of the Bf 109 show a high deceleration peek of greater than 20g which can be lowered to 4 to 6g by radiator cowling and brake skid.
Date: December 1949
Creator: Sottorf, W.
Partner: UNT Libraries Government Documents Department

Experiments with planing surfaces

Description: A previous report discusses the experimental program of a systematic exploration of all questions connected with the planing problem as well as the first fundamental results of the investigation of a flat planing surface. The present report is limited to the conversion of the model test data to full scale.
Date: March 1934
Creator: Sottorf, W.
Partner: UNT Libraries Government Documents Department

Experiments with planing surfaces

Description: Experiments with planing surfaces are fundamental, hydrodynamic researches for the purpose of obtaining the most favorable forms for planing boats, flying boats, and seaplane floats, with respect to water resistance and seaworthiness.
Date: March 1932
Creator: Sottorf, W.
Partner: UNT Libraries Government Documents Department

The design of floats

Description: Following a summary of the multiplicity of domestic and foreign floats and a brief enumeration of the requirements of floats, the essential form parameters and their effect on the qualities of floats are detailed. On this basis a standard float design is developed which in model families with varying length/beam ratio and angle of dead rise is analyzed by an experimental method which permits its best utilization on any airplane.
Date: April 1938
Creator: Sottorf, W.
Partner: UNT Libraries Government Documents Department

New method of extrapolation of the resistance of a model planing boat to full size

Description: "The previously employed method of extrapolating the total resistance to full size with lambda(exp 3) (model scale) and thereby foregoing a separate appraisal of the frictional resistance, was permissible for large models and floats of normal size. But faced with the ever increasing size of aircraft a reexamination of the problem of extrapolation to full size is called for. A method is described by means of which, on the basis of an analysis of tests on planing surfaces, the variation of the wetted surface over the take-off range is analytically obtained. The friction coefficients are read from Prandtl's curve for turbulent boundary layer with laminar approach. With these two values a correction for friction is obtainable" (p. 1).
Date: March 1942
Creator: Sottorf, W.
Partner: UNT Libraries Government Documents Department

Scale effect of model in seaplane-float investigations

Description: For the purpose of solving all the problems involved, an investigation was made with flat, rectangular planing surfaces. The investigation of a flat, rectangular planing surface, which can be considered as the portion of a flat float bottom lying in front of the step, has the advantage that the frictional resistance can be determined directly from the test results. Normal and tangential forces act on the lower side of the planing surface towed through still water, while the upper side and the lateral edges are under constant atmospheric pressure.
Date: April 1933
Creator: Sottorf, W.
Partner: UNT Libraries Government Documents Department

Seaplanes floats and hulls. Part 1

Description: This part of the report presents characteristics and graphic representations of water resistance. The laws of similarity are discussed as well as the theory of model tests. The test procedures and model tests of other countries are also discussed.
Date: August 1927
Creator: Herrmann, H.
Partner: UNT Libraries Government Documents Department

Relative economy of different methods of airplane construction

Description: "A comparison of the relative economy of airplane construction shows that monoplanes are cheaper than biplanes; that all-metal construction is much more expensive than mixed construction; that multi-engine airplanes are more expensive than single-engine types of the same carrying capacity and speed;that the cost of airplanes is materially reduced by increasing their size without increasing the number of engines. The greatest economy usually coincides with the best aerodynamic and static conditions and the cost is always increased by safety requirements" (p. 1).
Date: April 1931
Creator: Herrmann, H.
Partner: UNT Libraries Government Documents Department

Analysis of flight and wind-tunnel tests on Udet airplanes with reference to spinning characteristics

Description: This report presents an analysis of results of wind-tunnel tests conducted at the D.V.L. Values were determined for the effectiveness of all the controls at various angles of attack. The autorotation was studied by subjecting the rotating model to an air blast.
Date: March 1929
Creator: Herrmann, H.
Partner: UNT Libraries Government Documents Department

Tank tests of twin seaplane floats

Description: The following report contains the most essential data for the hydrodynamic portion of the twin-float problem. The following points were successfully investigated: 1) difference between stationary and nonstationary flow; 2) effect of the shape of the step; 3) effect of distance between floats; 4) effect of nose-heavy and tail-heavy moments; 5) effect of the shape of floats; 6) maneuverability.
Date: October 1928
Creator: Herrmann, H.; Kempf, G. & Kloess, H.
Partner: UNT Libraries Government Documents Department