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A Theoretical Investigation of the Drag of Generalized Aircraft Configurations in Supersonic Flow
"It seems possible that, in supersonic flight, unconventional arrangements of wings and bodies may offer advantages in the form of drag reduction. It is the purpose of this report to consider the methods for determining the pressure drag for such unconventional configurations, and to consider a few of the possibilities for drag reduction in highly idealized aircraft. The idealized aircraft are defined by distributions of lift and volume in three-dimensional space, and Hayes' method of drag evaluation, which is well adapted to such problems, is the fundamental tool employed" (p. 1).
Date:
January 1957
Creator:
Graham, E. W.; Lagerstrom, P. A.; Licher, R. M. & Beane, B. J.
System:
The UNT Digital Library
Turbulence in the Wake of a Thin Airfoil at Low Speeds
From Summary: "Experiments have been made to determine the nature of turbulence in the wake of a two-dimensional airfoil at low speeds. The experiments were motivated by the need for data which can be used for analysis of the tail-buffeting problem in aircraft design. Turbulent intensity and power spectra of the velocity fluctuations were measured at a Reynolds number of 1.6 x 10(exp 5) for several angles of attack. Total-head measurements were also obtained in an attempt to relate steady and fluctuating wake properties."
Date:
January 1957
Creator:
Campbell, George S.
System:
The UNT Digital Library
Theory of Two-Dimensional Potential Flow About Arbitrary Wing Sections
"Three general theories treating the potential flow about an arbitrary wing section are discussed in this report. The first theory treats the method of conformal transformation as laid down by Theodorsen and Garrick; the second is a generalization of Birnbaum's theory for moderately thick airfoils; the third is a general investigation of the complex velocity function with particular reference to the relations first discussed by F. Weinig. The relative merits of the different methods in question are illustrated on a worked-out example and will be published in a subsequent issue of this periodical" (p. 1).
Date:
January 1939
Creator:
Gebelein, H.
System:
The UNT Digital Library
Wrinkling of Reinforced Plates Subjected to Shear Stresses
An analysis is made here of the problem of long plates with transverse stiffeners subject to shear. A typical example would be a long Wagner beam. The shear stress is calculated at which the web wrinkles and shear stress becomes a maximum. The equation is solved for both a condition of free support and rigidity of support on the edges.
Date:
January 1931
Creator:
Seydel, Edgar
System:
The UNT Digital Library
Wrinkling Phenomena of Thin Flat Plates Subjected to Shear Stresses
This report covers a series of tests on thin flat elastic strips restrained at two parallel edges and subjected to shear by conversely directed stresses. Theoretical treatments, particularly those of Lilly, Southwell and Skan, and Timoshenko are briefly outlined. The problem to be solved by these tests was to find out whether, and to what extent the conditions and assumptions upon which the calculations are based are complied with in the tests.
Date:
January 1931
Creator:
Bollenrath, F.
System:
The UNT Digital Library
Stresses Produced in Airplane Wings by Gusts
Accurate prediction of gust stress being out of the question because of the multiplicity of the free air movements, the exploration of gust stress is restricted to static method which must be based upon: 1) stress measurements in free flight; 2) check of design specifications of approved type airplanes. With these empirical data the stress must be compared which can be computed for a gust of known intensity and structure. This "maximum gust" then must be so defined as to cover the whole ambit of empiricism and thus serve as prediction for new airplane designs.
Date:
January 1932
Creator:
Küssner, Hans Georg
System:
The UNT Digital Library
Stresses in Reinforcing Rings Due to Axial Forces in Cylindrical and Conical Stressed Skins
"At the ends of a monocoque fuselage concentrated axial forces in the skin must generally be taken up. Such axial forces must also be taken up in the case of other members where axial forces from the neighboring stressed skin construction must be considered. In order to take up these axial forces two bulkheads or reinforcing frames may be arranged at the positions where the forces are applied" (p. 1).
Date:
January 1938
Creator:
Drescher, K. & Gropler, H.
System:
The UNT Digital Library
The Buckling of Curved Tension-Field Girders
"The present paper reports on experiments made to determine the buckling load under shear of circular curved tension-field webs. The buckling load of the webs may be expressed with reference to the buckling load of the stiffeners. It is found that within the explored range the buckling load is approximately twice as great as that of the identically stiffened flat wall of equal web depth" (p. 1).
Date:
January 1938
Creator:
Limpert, G.
System:
The UNT Digital Library
On the Theory of Hydrofoils and Planing Surfaces
The present article describes the application of the results of airfoil theory to hydrofoils and planing surfaces with consideration of the boundary conditions of the free upper surface.
Date:
January 1938
Creator:
Weinig, F.
System:
The UNT Digital Library
Investigations of Compression Shocks and Boundary Layers in Gases Moving at High Speed
The mutual influences of compression shocks and friction boundary layers were investigated by means of high speed wind tunnels.Schlieren optics provided a clear picture of the flow phenomena and were used for determining the location of the compression shocks, measurement of shock angles, and also for Mach angles. Pressure measurement and humidity measurements were also taken into consideration.Results along with a mathematical model are described.
Date:
January 1947
Creator:
Ackeret, J.; Feldmann, F. & Rott, N.
System:
The UNT Digital Library
Possibilities of Reducing the Length of Axial Superchargers for Aircraft Motors
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.
System:
The UNT Digital Library
The Gyroplane: Its Principles and Its Possibilities
This report begins by indicating several simple principles concerning the velocity distribution over the blades of a lifting propeller of diameter D, revolving at n revolutions per second, and animated by a horizontal movement of translation at speed V. The calculation, compared with the test data, has shown that the aerodynamic action of the air on the blades depends almost only on the velocity components in a plane at right angles to the blade span. A history of gyroplane and gyrocopter development is presented as well as the advantages in using both types of craft.
Date:
January 1937
Creator:
Breguet, Louis
System:
The UNT Digital Library
Knocking in an Internal-Combustion Engine
The question remains open of the relation between the phenomena of knocking in the engine and the explosion wave. The solution of this problem is the object of this paper. The tests were conducted on an aircraft engine with a pyrex glass window in the cylinder head. Photographs were then taken of various combinations of fuels and conditions.
Date:
January 1940
Creator:
Sokolik, A. & Voinov, A.
System:
The UNT Digital Library
Constant-Pressure Blowers
"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" (p. 1).
Date:
January 1940
Creator:
Sörensen, E.
System:
The UNT Digital Library
Effect of Wing Loading, Aspect Ratio, and Span Loading of Flight Performances
"An investigation is made of the possible improvements in maximum, cruising, and climbing speeds attainable through increase in the wing loading. The decrease in wing area was considered for the two cases of constant aspect ratio and constant span loading. For a definite flight condition, an investigation is made to determine what loss in flight performance must be sustained if, for given reasons, certain wing loadings are not to be exceeded. With the aid of these general investigations, the trend with respect to wing loading is indicated and the requirements to be imposed on the landing aids are discussed" (p. 1).
Date:
January 1940
Creator:
Göthert, B.
System:
The UNT Digital Library
Flow in Smooth Straight Pipes at Velocities Above and Below Sound Velocity
"To investigate the laws of flow of compressible fluids in pipes, tests were carried out with air flowing at velocities below and above that of sound in straight smooth pipes. Air was chosen as the flow medium. In order that the effect of compressibility may be brought out most effectively, the velocity should lie between 100 and 500 m/s (200 and 1,000 mph); that is, be of the order of magnitude of the velocity of sound in air. The behavior of the compression shock in a smooth cylindrical pipe was also investigated" (p. 1).
Date:
January 1938
Creator:
Frössel, W.
System:
The UNT Digital Library
Torsion and buckling of open sections
Following an abstract of the well-known theory of torsion in compression, the writers give directions for the practical calculation of the values of C(sub BT) (resistance to flexure and torsion) and i(sub SP(exp 2)), which determine the torsion. The second part treats the experiments in support of the theory of torsion of plain and flanged angle sections.
Date:
January 1936
Creator:
Wagner, H. & Pretschner, W.
System:
The UNT Digital Library
Analysis of the Three Lowest Bending Frequencies of a Rotating Propeller
From Summary: "The present report is a survey of the existing data for computing the bending frequency and a check on the dependability of the calculating methods."
Date:
January 1936
Creator:
Liebers, F.
System:
The UNT Digital Library
Behm Acoustic Sounder for Aircraft
The Behm acoustic sounder for aircraft enables the barometric determination for the altitude by night or fog and therefore promises to prove of great importance in safeguarding air traffic.
Date:
January 1926
Creator:
unknown
System:
The UNT Digital Library
Testing a Windmill Airplane ("Autogiro")
In order to clear up the matter ( In the Spanish report it was stated that the reference surface for the calculation of the coefficients c(sub a) and c(sub w) was the area of all four wings, instead of a single wing), the model of a windwill airplane was tested in the Gottingen wind tunnel.
Date:
January 1927
Creator:
Seiferth, R.
System:
The UNT Digital Library
Stall-Proof Airplanes
Report investigating some characteristics of aircraft stall, including the following: Is the danger of stalling necessarily inherent in the airplane in its present form and structure, or can it be diminished or eliminated by suitable means? Do we possess such means or devices and how must they operate?
Date:
January 1927
Creator:
Lachmann, G.
System:
The UNT Digital Library
Tensile Strength of Welded Steel Tubes: First Series of Experiments
The purpose of the experiments was to determine the difference in the strength of steel tubes welded by different methods, as compared with one another and also with unwelded, unannealed tubes, including; moreover, a comparison of the results obtained by experienced and inexperienced welders.
Date:
January 1928
Creator:
Rechtlich, A.
System:
The UNT Digital Library
Crank Case Scavenging of a Two-Stroke-Cycle Engine
"Experiments with a two-stroke-cycle, crank case scavenging engine. Effect of systematic variation of the height of the scavenge and exhaust ports on the scavenging, as determined by gas analysis. The best results were obtained under conditions differing from the usual ones" (p. 1).
Date:
January 1928
Creator:
Holm, Otto
System:
The UNT Digital Library
Stressed Coverings in Naval and Aeronautic Construction
We propose to make a study of the difficulties in using stressed coverings and their appropriate solutions. Fatigue and buckling are also discussed.
Date:
January 1928
Creator:
Kahn, L. L.
System:
The UNT Digital Library