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 Decade: 1920-1929
 Collection: Technical Report Archive and Image Library
Effect of aerofoil aspect ratio on the slope of the lift curve

Effect of aerofoil aspect ratio on the slope of the lift curve

Date: January 1, 1922
Creator: Diehl, Walter S
Description: On of the most important characteristics of an airfoil is the rate of change of lift with angle of attack, (sup dC)L/d alpha. This factor determines the effectiveness of a tail plane in securing static longitudinal stability. The application of the Gottingen formulas given here for calculating the variation of (sup Dc)L/d alpha with aspect ratio should be of interest to many aeronautical engineers. For the convenience of the engineer, a set of curves calculated by the method set forth here are given in graphical form. Also, the observed values of (sup dC)L/d alpha for the same airfoil at various aspect ratios follow the calculated curves closely.
Contributing Partner: UNT Libraries Government Documents Department
Impact tests for woods

Impact tests for woods

Date: February 1, 1922
Creator: unknown
Description: Although it is well known that the strength of wood depends greatly upon the time the wood is under the load, little consideration has been given to this fact in testing materials for airplanes. Here, results are given of impact tests on clear, straight grained spruce. Transverse tests were conducted for comparison. Both Izod and Charpy impact tests were conducted. Results are given primarily in tabular and graphical form.
Contributing Partner: UNT Libraries Government Documents Department
Downwash of airplane winds

Downwash of airplane winds

Date: January 1, 1923
Creator: Munk, Max & Cario, Gunther
Description: The data for the calculation of the air forces acting on the elevators, obtained from previous model experiments are not immediately applicable in practice, as the angle at which the control surfaces meet the air stream is, in general, still unknown. The air stream, when it reaches the elevator has already been deflected by the wings and although the velocity imparted to the air current by the wings is of negligible amount compared with the speed of flight, the air behind the wings has been deflected downwards, so that the elevators work in an airstream which is inclined in a downward direction. The angle at which the air stream meets the elevator surface is, therefore, different from, and, with the usual arrangement of elevators, less than the angle made by the elevator surfaces with the line of flight.
Contributing Partner: UNT Libraries Government Documents Department
Recent European developments in helicopters

Recent European developments in helicopters

Date: April 1, 1921
Creator: unknown
Description: Descriptions are given of two captured helicopters, one driven by electric power, the other by a gasoline engine. An account is given of flight tests of the gasoline powered vehicle. After 15 successful flight tests, the gasoline powered vehicle crashed due to the insufficient thrust. Also discussed here are the applications of helicopters for military observations, for meteorological work, and for carrying radio antennas.
Contributing Partner: UNT Libraries Government Documents Department
Further information on the laws of fluid resistance

Further information on the laws of fluid resistance

Date: December 1, 1922
Creator: Wieselsberger, C
Description: None
Contributing Partner: UNT Libraries Government Documents Department
A preliminary study of airplane performance

A preliminary study of airplane performance

Date: November 1, 1922
Creator: Norton, F H & Brown, W G
Description: Flight tests were carried out at the Langley Field laboratory of the NACA, on several airplanes for the purpose of determining their relative performance with the same engine and the same propeller. The method used consisted in flying each airplane on a level course and measuring the airspeed for the whole range of engine revolutions. In general the results show that a small change in the wing section or the wing area has but a slight effect upon the performance, but changes in those parts which cause the structural resistance have a very important effect.
Contributing Partner: UNT Libraries Government Documents Department
Notes on aerodynamic forces II : curvilinear motion

Notes on aerodynamic forces II : curvilinear motion

Date: July 1, 1922
Creator: Munk, Max M
Description: The laws of curvilinear motion are established and the transverse forces on elongated airship hulls along a curved path are investigated.
Contributing Partner: UNT Libraries Government Documents Department
The determination of the angles of attack of zero lift and of zero moment, based on Munk's integrals

The determination of the angles of attack of zero lift and of zero moment, based on Munk's integrals

Date: January 1, 1923
Creator: Munk, Max M
Description: The integration is accomplished by the use of the mean camber of the section at particularly selected points. Simple graphical constructions of the zero directions are derived from the results.
Contributing Partner: UNT Libraries Government Documents Department
Notes on aerodynamic forces 1 : rectilinear motion

Notes on aerodynamic forces 1 : rectilinear motion

Date: July 1, 1922
Creator: Munk, Max M
Description: The study of the motion of perfect fluids is of paramount importance for the understanding of the chief phenomena occurring in the air surrounding an aircraft, and for the numerical determination of their effects. The author recently successfully employed some simple methods for the investigation of the flow of a perfect fluid that have never been mentioned in connection with aeronautical problems. These methods appeal particularly to the engineer who is untrained in performing laborious mathematical computations, as they do away with these and allow one to obtain many interesting results by the mere application of some general and well-known principles of mechanics. Discussed here are the kinetic energy of moving fluids, the momentum of a body in a perfect fluid, two dimensional flow, three dimensional flow, and the distribution of the transverse forces of very elongated surfaces of revolution.
Contributing Partner: UNT Libraries Government Documents Department
The use of multiplied pressures for automatic altitude adjustments

The use of multiplied pressures for automatic altitude adjustments

Date: January 1, 1922
Creator: Sparrow, Stanwood S
Description: The efficient performance of an airplane requires that certain adjustments be made as the density of the air through which the airplane passes changes. The safety of the over-dimensioned aircraft engine depends upon careful manipulation of spark advance and throttle opening and a proper control of a variable pitch propeller, if the maximum performance of the supercharged engine is to be obtained. It is evident that there is a real need for satisfactory devices to make such adjustments automatically. Discussed here is a method of automatic compensation which deserves consideration in the design of such devices. Existing schemes for automatic compensation all depend upon some contrivance which functions primarily because of changes in atmospheric pressure. In these devices a leak in the supposedly tight chamber means utter failure. The elimination of this source of danger is one of the aims of the method of altitude compensation described here. The change suggested is to make the source of operation the difference between atmospheric pressure and some multiple of atmospheric pressure instead of the difference between the atmospheric pressure and that of the gas confined in a tight chamber. The design of a device based on this method of altitude compensation is ...
Contributing Partner: UNT Libraries Government Documents Department