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The Mechanical Properties of Wood of Different Moisture Content Within -200 Degrees to +200 Degrees C Temperature Range
Systematic experiments were undertaken with special reference to the effect of gross specific weight (specific weight inclusive of pores) and the moisture content of wood. It was found that the modules of elasticity of wood at room temperature and frozen at -8 degrees is practically the same. The effect of moisture on the compression strength of frozen wood was explored as well as the flexural and impact strength of frozen wood and frozen laminated wood.
Date:
September 1941
Creator:
Kollmann, Franz
System:
The UNT Digital Library
A Discussion of the Several Types of Two-Stroke-Cycle Engines
This report discusses different types of two-stroke engines as well as the three most important design factors: volume of scavenge and charge delivery, scavenging process (scavenging result), and result of charge. Some of the types of engines discussed include: single cylinder with crank-chamber scavenge pump and auxiliary suction piston linked to working connecting rod; and two cylinder engines with a rotary scavenge pump arrangement. Three and four cylinder engines are also discussed in various designs.
Date:
September 1935
Creator:
Venediger, Herbert J.
System:
The UNT Digital Library
Contribution to the Mutual Interference of Wing and Propeller
"The change of induced wing drag due to the field of flow of the propeller was analyzed quantitatively. The field of flow of the propeller is represented by a uniform distribution of sinks over the propeller disk area, whose strength is determined by the increase in speed in the slipstream. The superposition of this sink flow on the basic flow reproduces the actual field of flow outside of the slipstream with close approximation" (p. 1).
Date:
September 1934
Creator:
Wieselsberger, C.
System:
The UNT Digital Library
Stipa Monoplane With Venturi Fuselage
This report presents a detailed examination of the factors that went into the design of the Stipa monoplane. The model tested in the wind tunnel was made dissymmetrical externally, in order to produce a lift even at an angle of attack of 0 degrees with respect to the longitudinal axis of the tube.
Date:
September 1934
Creator:
Stipa, Luigi
System:
The UNT Digital Library
An airfoil spanning an open jet
From Summary: "The first part of the report treats of the theory involved. The second part describes the experiments performed for the purpose of proving the theory."
Date:
September 1933
Creator:
Stüper, J.
System:
The UNT Digital Library
Guide Vanes for Deflecting Fluid Currents With Small Loss of Energy
The transverse momentum of the deflected air stream to be absorbed is divided between the intermediate and outside walls, so that the pressure increase on each wall is much smaller and the danger of separation is diminished. The formation of secondary vortices is also diminished. By taking as the basis profiles with high c(sub a), such as have proved practically favorable, it is not possible to find a satisfactory form of grid simply on the assumption that the flow is potential.
Date:
September 1933
Creator:
Kröber, G.
System:
The UNT Digital Library
Results of Extended Tests of the Focke-Wulf F 19a "Ente," a Tail-First Airplane
These investigations consisted chiefly of measurements of the take-off distance under various starting conditions and with the c.g. in different positions; of the climbing speed as a function of the impact pressure and location of the c.g.; of the longitudinal stability and fore-and-aft controllability and of the determination of the elevator forces and characteristics of the elevator control.
Date:
September 1933
Creator:
Hübner, Walter
System:
The UNT Digital Library
The Principles of Turbulent Heat Transfer
"The literature on turbulent heat transfer has in the course of years attained a considerable volume. Since this very complicated problem has not as yet found a complete solution, further studies in this field may be expected. The heat engineer must therefore accommodate himself to a constantly increasing number of theories and formulas. Since the theories generally start from hypothetical assumptions, and since they contain true and false assertions, verified knowledge and pure suppositions often being intermingled in a manner difficult to tell them apart, the specialist had difficulty in forming a correct evaluation of the individual studies" (p. 1).
Date:
September 1957
Creator:
Reichardt, H.
System:
The UNT Digital Library
The Influence of the Jet of a Propulsion Unit on Nearby Wings
"The present investigation was intended to ascertain how far a tail unit is subject to disturbance by the jet of a propulsion unit. The parameters upon which this disturbing influence depends, and the values it reaches, had to be determined" (p. 1).
Date:
September 1946
Creator:
Falk, H.
System:
The UNT Digital Library
Determination of the Maximum Control Forces and Attainable Quickness in the Operation of Airplane Controls
"This report is intended to furnish bases for load assumptions in the designing of airplane controls. The maximum control forces and quickness of operation are determined. The maximum forces for a strong pilot with normal arrangement of the controls is taken as 1.25 times the mean value obtained from tests with twelve persons. Tests with a number of persons were expected to show the maximum forces that a man of average strength can exert on the control stick in operating the elevator and ailerons and also on the rudder bar" (p. 1).
Date:
September 1930
Creator:
Hertel, Heinrich
System:
The UNT Digital Library
Further Flight Tests on the Effectiveness of Handley Page Automatic Control Slots
Investigation of damping in roll within range of maximum lift with the Albatross L 75, with and without Handley Page automatic control slots, revealed the following: Without control slots, any attempt to go beyond a certain angle of attack near c(sub a max) in glide and climb, is followed by sudden sideslip. The conduct of the airplane throughout the motions in roll, moreover, confirmed that all attempts to higher angles of attack are accompanied by sudden loss of damping in roll.
Date:
September 1932
Creator:
Pleines, Wilhelm
System:
The UNT Digital Library
The Controls at Low Hinge Moments
A very stable airplane remains very maneuverable when the hinge moments of the controls remain inferior to those obtained with the conventional forms and when the wing lift at high angles has been improved. From this point of view, elevators balanced by recoil of the hinge, and slotted wings present some interesting features. The results of testing with several different types of wings and tail surfaces are provided.
Date:
September 1932
Creator:
Pris, M.
System:
The UNT Digital Library
The aerodynamic safety of airplanes
This report presents several hypotheses regarding airplane safety, mainly concerning the nondimensional coefficient of air, speed, acceleration, and wing area on aerodynamic considerations of safety.
Date:
September 1932
Creator:
Kahn, Louis
System:
The UNT Digital Library
Propeller Tip Flutter
The present report is limited to a case of tip flutter recognized by experience as being important. It is the case where outside interferences force vibrations upon the propeller. Such interferences may be set up by the engine, or they may be the result of an unsymmetrical field of flow.
Date:
September 1932
Creator:
Liebers, Fritz
System:
The UNT Digital Library
Airplane Stability in Taxying
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.
System:
The UNT Digital Library
The development, design and construction of gliders and sailplanes
This report explains and details the history of glider design and construction through the impetus of the Rhon Sailplane contests. Some of the topics considered include: whether the longitudinal stability (dynamic and static) is sufficient in the tailless typo and a consideration that the structural weight of sweptback wings would be greater than that of a corresponding normal wing.
Date:
September 1931
Creator:
Lippisch, A.
System:
The UNT Digital Library
Limits of Single-Stage Compression in Centrifugal Superchargers for Aircraft
The limits of the single-stage compression in superchargers at the present state of development are determined by five factors. 1) by the rotor material; 2) by the formation of the flow; 3) by the manufacture of double shrouded rotors; 4) by the bearing problem; 5) by the drive method.
Date:
September 1940
Creator:
Kollmann, K.
System:
The UNT Digital Library
Pressure and Temperature Measurement in Supercharger Investigations
"With the further development of the supercharger, requirements with regard to measuring accuracy increase while at the same time the conditions under which the measurements must be carried out become more difficult. The present paper is a contribution toward the improvement and refinement of the measuring methods. For pressure measurements some suggestions are made with regard to design and location of the measuring stations" (p. 1).
Date:
September 1940
Creator:
Franz, A.
System:
The UNT Digital Library
Standards for Discharge Measurement With Standardized Nozzles and Orifices
The following standards give the standardized forms for two throttling devices, standard nozzles and standard orifices, and enable them to be used in circular pipes without calibration. The definition of the standards are applicable in principle to the calibration and use of nonstandardized throttling devices, such as the venturi tube. The standards are valid, likewise, as a basis for discharge measurements in the German acceptance standards.
Date:
September 1940
Creator:
unknown
System:
The UNT Digital Library
Variation in Velocity Profile with Change in Surface Roughness of Boundary
"The present report deals with the variation of a turbulent velocity profile in flow from rough to smooth wall and vice versa. Expressions obtained for the shear-stress distribution with respect to the distance from the point of junction of the different roughnesses and from the wall distance, are utilized to ascertain the developing velocity distributions. Under simplified assumptions, the use of these formulas renders possible the integration of the motion equations for the shear stress. This calculation is carried out and compared with the experiments" (p. 1).
Date:
September 1940
Creator:
Jacobs, W.
System:
The UNT Digital Library
Buckling Tests With a Spar-Rib Grill
"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" (p. 1).
Date:
September 1940
Creator:
Weinhold, Josef
System:
The UNT Digital Library
Behavior of Fast Moving Flow of Compressible Gas in Cylindrical Pipe in Presence of Cooling
For compressible flow with friction in a cylindrical pipe the momentum, continuity, and heat-transfer equations are examined to determine whether an increase in Mach number ("thermal" Laval nozzle) is obtainable through heat conduction from the gas through the pipe walls. The analysis is based on the assumption that the wall temperature is negligibly small in comparison with the stagnation temperature of the gas. The analysis leads to a negative result. When the gas cooling is increased by also considering radiation to the wall, a limited region at high temperatures is obtained where Mach number increases were theoretically possible. Obtaining this condition practically is considered impossible.
Date:
September 1951
Creator:
Varshavsky, G. A.
System:
The UNT Digital Library
Isentropic Phase Changes in Dissociating Gases and the Method of Sound Dispersion for the Investigation of Homogeneous Gas Reactions With Very High Speed
The analytical results of Part I are also applied to sound dispersion by friction and heat conduction, An irreversible change of momentum, energy, and type of particle corresponding to friction, heat conduction, and diffusion effects can appear both in the direction of the sound field and traverse to it. Longitudinal damping, the coupling of longitudinal damping and that due to chemical and physical changes, and coupling of diffusion and compositional changes are treated for a plane sound wave of infinite extent.
Date:
September 1950
Creator:
Damköehler, Gerhard
System:
The UNT Digital Library
Isentropic Phase Changes in Dissociating Gases and the Method of Sound Dispersion for the Investigation of Homogeneous Gas Reactions With Very High Speed
Memorandum presenting a treatment of the problem of the differential isentropic changes of state in dissociating gases.
Date:
September 1950
Creator:
Damköehler, Gerhard
System:
The UNT Digital Library