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Evolution of the Helicopter

Description: Report presenting an investigation of problems related to helicopters. Also included are the history of the evolution of the helicopter and a series of propeller experiments.
Date: March 1923
Creator: Balaban, Karl
Partner: UNT Libraries Government Documents Department

Calculation of wing spars

Description: The author presents a comparison and combination of the numerical and geometrical determinations of the maximum M, when calculating the maximum bay moment.
Date: August 1921
Creator: Müller-Breslau, H.
Partner: UNT Libraries Government Documents Department

Recent experiments at the Gottingen Aerodynamic Institute

Description: This report presents the results of various experiments carried out at the Gottingen Aerodynamic Institute. These include: experiments with Joukowski wing profiles; experiments on an airplane model with a built-in motor and functioning propeller; and the rotating cylinder (Magnus Effect).
Date: July 1925
Creator: Ackeret, J.
Partner: UNT Libraries Government Documents Department

Air forces on airfoils moving faster than sound

Description: We are undertaking the task of computing the air forces on a slightly cambered airfoil in the absence of friction and with an infinite aspect ratio. We also assume in advance that the leading edge is very sharp and that its tangent lies in the direction of motion.
Date: June 1925
Creator: Ackeret, J.
Partner: UNT Libraries Government Documents Department

Approximation method for determining the static stability of a monoplane glider

Description: The calculations in this paper afford an approximate solution of the static stability. A derivation of the formulas for moment coefficient of a wing, moment coefficient of elevator, and the total moment of the combined wing and elevator and the moment coefficient with reference to the center of gravity are provided.
Date: November 1927
Creator: Lippisch, A.
Partner: UNT Libraries Government Documents Department

Technical report of the 1928 Rhon soaring-flight contest

Description: Report presenting some information on the gliders that participated in the 1928 Rhön soaring flight contest. Almost all of the gliders represented an improvement over gliders used in the previous years. A great increase in the skill of the glider pilots is also noted.
Date: May 1929
Creator: Lippisch, A.
Partner: UNT Libraries Government Documents Department

Computative examination of bending strength of girders originally curved and subjected to longitudinal compression

Description: This report examines the stipulation contained in the 1918 BLV, that a girder subjected to longitudinal compression under the influence of half of the specified breaking load, along with Euler bending safety with an initial deflection of 1/200 of the length of the girder can, at most, be subjected to half the stipulated breaking strength.
Date: October 1922
Creator: Hoff, Wilhelm
Partner: UNT Libraries Government Documents Department

Calculation of wing spars

Description: The author presents a comparison and combination of the numerical and geometrical determinations of the maximum M, when calculating the maximum bay moment.
Date: August 1921
Creator: Müller-Breslau, H.
Partner: UNT Libraries Government Documents Department

Influence of struts and stays on the speed of an airplane

Description: Report presenting an experiment in the Rechlin airdrome in the fall of 1918 to determine the influence of struts and stays on the speed of an airplane. Results indicated that only a slight increase in horizontal speed was shown in a stayless airplane, but it had considerably greater climbing speed.
Date: October 1921
Creator: Heidelberg, V.
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

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

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

The Flight of an Autogiro at High Speed

Description: This report presents a method for computing the flight performance of an autogiro at high speed, the velocity component along the blades being accounted for by calculation of the profile drag and the equation for zero torque.
Date: December 1933
Creator: Bennett, J. A. J.
Partner: UNT Libraries Government Documents Department

Preliminary Calculation of Cylinder Dimensions for Aircraft Engines

Description: It is extremely important in building aircraft engines to determine the requisite cylinder dimensions as accurately as possible, in order that the weight required for a given power shall not be excessive. This report presents a calculation method that depends on the air requirement of the fuel.
Date: September 1921
Creator: Schwager, Otto
Partner: UNT Libraries Government Documents Department

Measurements of Rudder Moments on an Airplane During Flight

Description: Tests indicated that: 1) C airplanes with two struts are extremely susceptible to aileron maneuvers, slight alterations of the aileron sufficing to compensate great unequalized moments; 2) great unequalized moments can be produced or neutralized by the unequalized alternation of the angle of attack below the outer and inner struts. Adjustment below the outer strut is the more effective of the two. 3) When a load of bombs is suspended beyond the center of the airplane, below the wings, the bombs need not be dropped simultaneously. 4) The propeller wash of a wide open engine has considerable influence on the position and operation of the elevator. The elevator is more susceptible in flight with the engine running than in gliding flight. 5) Adjustable tail planes are not advisable for D airplanes, nor for the C type, but they are, on the other hand, to be recommended for large size and giant airplanes in which the center of gravity changes during flight. 6) The aileron values obtained by wind tunnel measurements are about 10 percent too low, though otherwise applicable. For the elevator, the results of such measurements should be taken as mean values between flight with the engine running and gliding flight.
Date: January 1921
Creator: v. Heidelberg, Ing.
Partner: UNT Libraries Government Documents Department

Investigation of the Variations in the Velocity of the Air Flow About a Wing Profile

Description: Memorandum presenting an investigation to determine the variations in the velocity of the air when it was obliged to flow about a wing profile. Special interest was paid to the determination of velocity as compared with that of the undisturbed flow and of the velocity drop in successive planes perpendicular to the flow direction at increasing distances from the wing profile.
Date: July 1930
Creator: Repenthin, Walter
Partner: UNT Libraries Government Documents Department

Airplane Stability in Taxying

Description: The stability analysis of an airplane while rolling is much more simplified to the extent that it can be obtained for numerical data which can be put to practical use in the design of landing gear dimensions. Every landing gear type attains to a critical ground friction coefficient that decides the beginning of instability, i.e., nosing over. This study has, in addition, a certain interest for the use of wheel brakes.
Date: September 1932
Creator: Anderlik, E.
Partner: UNT Libraries Government Documents Department

Future Problems of Soaring Flight: Report of 1932 Rhon Soaring Contest

Description: Memorandum presenting two reports. One is a description of the 1932 Rhön Soaring Contest and some of the problems encountered by the aircraft in the contest. The other is a description of films of cloud formations that were presented at the same contest.
Date: May 1933
Creator: Georgii, Walter & Eisenlohr, Roland
Partner: UNT Libraries Government Documents Department

Experiments With Slotted Wings

Description: Note presenting an investigation of various aspects of slotted wings, including some theoretical and experimental results and characteristics of certain slotted wings currently in production.
Date: November 1921
Creator: Lachmann, G.
Partner: UNT Libraries Government Documents Department

The Effect of the Nature of Surfaces on Resistance as Tested on Struts

Description: The chief concern was to measure the variations of resistance brought about by the nature of the surface of the struts. The struts were spanned with aviation linen, and then covered with one coat of varnish. The top surface was not perfectly smooth after this treatment, being slightly rough owing to the threads and raised fibers of the fabric. The results of the measurements of the surfaces are shown by the dotted lines of the curves plotted in several figures.
Date: February 1921
Creator: Wieselsberger, Ing. G.
Partner: UNT Libraries Government Documents Department

Distant-Compass

Description: Report presenting a description of fluid compasses that are being used in aircraft, including why magnetic compasses are not usable. Details of the distant compass are provided, which is an improved form of the compass that has a practical application in seaplanes.
Date: June 1921
Creator: Friedensburg, Walter & Miner, D. M.
Partner: UNT Libraries Government Documents Department