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Buckling Tests on Eccentrically Loaded Beam Columns: "Formulas are obtained for computing the buckling load of rods eccentrically loaded at each end, the computation being extended in particular to the inelastic range. The test results are graphically presented on three sets of curves. Two of these, at least for the elastic range, are independent of the material tested. The third set, which is independent of the material, possesses greater clearness and is therefore used for comparing the test results with the theoretical" (p. 1).
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).
Building a Full-Size Glider: The building and flying of a glider is possible for anyone who can use a few basic tools. This report presents some plans and techniques for building your own glider.
Calculating Thrust Distribution and Efficiency of Air Propellers: I am now proposing a method for the preliminary approximate calculation of the thrust distribution and efficiency of air propellers under any operating conditions. Our task becomes the following, namely, to determine the speed relations and the forces developed on a section with a given direction and velocity of the air current, a problem which can be solved with the aid of the momentum theory.
Calculation of Airplane Performances Without the Aid of Polar Diagrams: For good profiles the profile-drag coefficient is almost constant in the whole range which comes into consideration for practical flight. This is manifest in the consideration of the Gottingen airfoil tests and is confirmed by the investigations of the writer (measurements of the profile drag during flight by the Betz method), concerning which a detailed report will soon be published. The following deductions proceed from this fact. The formulas developed on the assumptions of a constant profile-drag coefficient afford an extensive insight into the influences exerted on flight performances by the structure of the airplane.
Calculation of Centrally Loaded Thin-Walled Columns Above the Buckling Limit: "When thin-walled columns formed from flanged sheet, such as used in airplane construction, are subjected to axial load, their behavior at failure varies according to the slenderness ratio. On long columns the axis deflects laterally while the cross section form is maintained; buckling results. The respective breaking load in the elastic range is computed by Euler's formula and for the plastic range by the Engesser- Karman formula. Its magnitude is essentially dependent upon the length" (p. 1).
Calculation of Combining Effects in the Structure of Airplane Wings: A Rational Basis for Estimating the Reduction in the Design Load on Wing Beams Due to the Influence of Ribs and Covering Toward Causing the Beams to Deflect Together: This lecture concerns the combining effects in airplane wings so as to save some of the dead weight. Equations are provided in order to calculate some of the load characteristics and some of the effects to be considered.
The Calculation of Compressible Flows with Local Regions of Supersonic Velocity: This report addresses a method for the approximate calculation of compressible flows about profiles with local regions of supersonic velocity. The flow around a slender profile is treated as an example.
Calculation of Counterrotating Propellers: "A method for calculation of a counterrotating propeller which is similar to Walchner's method for calculation of the single propeller in the free air stream is developed and compared with measurements. Several dimensions which are important for the design are given end simple formulas for the gain in efficiency derived. Finally a survey of the behavior of the propeller for various operating conditions is presented" (p. 1).
The Calculation of Lateral Stability With Free Controls: The discussion of the structural methods for obtaining lateral stability discloses the remarkable influence of the constant fuselage and wing proportions to the yawing moments. For the effectiveness of modifications in vertical tail surfaces and tail length, these quotas - little observed heretofore, in this connection - are decisive. This also applies to the amount of dihedral of the wing with regard to the roll stability of the complete wing already existing without angle of the dihedral.
Calculation of Load Distribution in Stiffened Cylindrical Shells: "Thin-walled shells with strong longitudinal and transverse stiffening (for example, stressed-skin fuselages and wings) may, under certain simplifying assumptions, be treated as static systems with finite redundancies. In this report the underlying basis for this method of treatment of the problem is presented and a computation procedure for stiffened cylindrical shells with curved sheet panels indicated. A detailed discussion of the force distribution due to applied concentrated forces is given, and the discussion illustrated by numerical examples which refer to an experimentally determined circular cylindrical shell" (p. 1).
Calculation of Potential Flow Past Airship Bodies in Yaw: An outline of Von Karman's method of computing the potential flow of airships in yaw by means of partially constant dipolar superposition on the axis of the body is followed by several considerations for beginning and end of the superposition. Then this method is improved by postulating a continuous, in part linearly variable dipolar superposition on the axis. The second main part of the report brings the calculation of the potential flow by means of sources and sinks, arranged on the surface of the airship body.
Calculation of Pressure Distribution on Airship Hulls: These calculations were based on the shape of the ZR III, with the following simplifications: cars, fins, and rudders removed; all cross sections replaced by equivalent circular cross sections. Under these assumptions the pressure distribution was calculated for the following cases: symmetrical case, or flow parallel to the axis; unsymmetrical case, or flow at an angle to the axis. In both cases the simple potential flow first forms the basis for the determination of the pressure distribution.
Calculation of Tapered Monoplane Wings: The tapered wing shape increases the lift in the middle of the wing and thus reduces the bending moment of the lifting forces in the plane of symmetry. Since this portion of the wing is the thickest, the stresses of the wing material are reduced and desirable space is provided for stowing the loads in the wing. This statically excellent form of construction, however, has aerodynamic disadvantages which must be carefully weighed, if failures are to be avoided. This treatise is devoted to the consideration of these problems.
Calculation of the Bending Stresses in Helicopter Rotor Blades: A comparatively rapid method is presented for determining theoretically the bending stresses of helicopter rotor blades in forward flight. The method is based on the analysis of the properties of a vibrating beam, and its uniqueness lies in the simple solution of the differential equation which governs the motion of the bent blades.
Calculation of the hull and of the car-suspension systems of airships: Differential and integral curves are presented and well as numerous calculations relating to hulls. Some of the calculations include those relating to hulls, those relating to the invariability of the shape of the hulls, and those relating to the suspension of the hull.
Calculation of the Induced Efficiency of Heavily Loaded Propellers Having Infinite Number of Blades: Report presenting an approximate method of computing the induced efficiency of heavily loaded propellers in suitable form for extension to finite number of blades and a comparison of results obtained using the method with the data of the Betz-Helmbold theory for heavily loaded propellers.
Calculation of the Lateral-Dynamic Stability of Aircraft: "Graphs and formulas are given with the aid of which all the aerodynamic coefficients required for computing the lateral dynamic stability can be determined. A number of numerical examples are given for obtaining the stability derivatives and solving the characteristic-stability equation. Approximate formulas are derived with the aid of which rapid preliminary computations may be made and the stability coefficients corrected for certain modifications of the airplane" (p. 1).
Calculation of the Pressure Distribution on Bodies of Revolution in the Subsonic Flow of a Gas Part 1 - Axially Symmetrical Flow: "The present report concerns a method of computing the velocity and pressure distributions on bodies of revolution in axially symmetrical flow in the subsonic range. The differential equation for the velocity potential Phi of a compressible fluid motion is linearized tn the conventional manner, and then put in the form Delta(Phi) = 0 by affine transformation. The quantity Phi represents the velocity potential of a fictitious incompressible flow, for which a constant superposition of sources by sections is secured by a method patterned after von Karman which must comply with the boundary condition delta(phi)/delta(n) = 0 at the originally specified contour" (p. 1).
Calculation of the Pressures on Aircraft Engine Bearings: For aircraft engines the three principal operating conditions are idling speed, cruising speed, and diving with the engine stopped. In what follows, we will discuss a method which affords a good idea of the course of pressure for the above mentioned operating conditions. The pressures produced in the driving gear are of three kinds; namely, the pressure due to gases, the pressure due to the inertia of the rotating masses, and the pressure due to the inertia of the reciprocating masses.
Calculation of the Shape of a Two-Dimensional Supersonic Nozzle in Closed Form: "The idea is advanced of making a supersonic nozzle by producing one, two, or three successive turns of the whole flow; with the result that the wall contour can be calculated exactly by means of the Prandtl-Meyer "Lost Solution" (p. 1).
Calculation of Tubular Radiators of the Automobile Type: "We propose to show how to calculate the cooling capacity of all radiators through which the air flows in separate streamlets, whether enclosed in actual tubes or not and whatever cross-sectional shape the tubes may have. The first part will give the fundamental principles for calculating velocity of air in the tubes and the heat exchange by radiation, conduction and convection, and show, by examples, the agreement of the calculation with experiments. In the second part, the effect of the dimensions and conditions of operation on the heat exchange will be systematically investigated" (p. 1).
Calculation of Turbulent Expansion Processes: "On the basis of certain formulas recently established by L. Prandtl for the turbulent interchange of momentum in stationary flows, various cases of "free turbulence" - that is, of flows without boundary walls - are treated in the present report. Prandtl puts the apparent shearing stress introduced by the turbulent momentum interchange. This present report deals first with the mixing of an air stream of uniform velocity with the adjacent still air, than with the expansion or diffusion of an air jet in the surrounding air space" (p. 1).
Calculation of Wing Spars: A simplified formula for calculating wing spars is presented.
Calculation of Wing Spars: The author presents a comparison and combination of the numerical and geometrical determinations of the maximum M, when calculating the maximum bay moment.
Calculation of Wing Spars: The author presents a comparison and combination of the numerical and geometrical determinations of the maximum M, when calculating the maximum bay moment.
Calculation of Wing Spars of Variable Cross-Section and Linear Load: "The calculation of wing spars of constant cross-section and load has been thoroughly treated by a large number of authors. Such is not the case,however, regarding the calculation of wing spars whose section and linear load diminish toward the ends, as in wings of trapezoidal contour and decreasing section" (p. 1).
Calculations and Experimental Investigations on the Feed-Power Requirement of Airplanes With Boundary-Layer Control: "Calculations and test results are given about the feed-power requirement of airplanes with boundary-layer control. Curves and formulas for the rough estimate of pressure-loss and feed-power requirement are set up for the investigated arrangements which differ structurally and aerodynamically. According to these results the feed power for three different designs is calculated at the end of the report" (p. 1).
Calibration and Measurement in Turbulence Research by the Hot-Wire Method: "The problem of turbulence in aerodynamics is at present being attacked both theoretically and experimentally. In view of the fact however that purely theoretical considerations have not thus far led to satisfactory results the experimental treatment of the problem is of great importance. Among the different measuring procedures the hot wire methods are so far recognized as the most suitable for investigating the turbulence structure" (p. 1).
Calibration Tunnel for High Speed: "For the investigation of measuring instruments at higher speeds up to a Mach number 0.7 a tunnel with closed test section was built in 1942 which was as simple and cheap as possible. The blower was a radial blower with straight sheet vanes of 800-millimeter diameter the tips of which were bent backward a little. The blower sucks the air through a honeycomb of diameter 1.2 meter with wide meshes" (p. 1).
Cantilever Wings for Modern Aircraft: Some Aspects of Cantilever Wing Construction with Special Reference to Weight and Torsional Stiffness: In the foregoing remarks I have made an attempt to touch on some of the structural problems met with in cantilever wings, and dealt rather fully with a certain type of single-spar construction. The experimental test wing was a first attempt to demonstrate the principles of this departure from orthodox methods. The result was a wing both torsionally stiff and of light weight - lighter than a corresponding biplane construction.
Carburetion in Aviation Engines: This report tries to solve the problem of supplying the engine cylinders with a mixture of fuel and air in the right ratio to obtain the greatest power from the engine with the least consumption of fuel.
The Cathode Oscillograph for the Study of Low, Medium, and High Frequencies: The object of this work has been to construct an apparatus for obtaining oscillogram of voltages and currents which are variable with respect to time and of the frequency which is constantly met in radio.
The Cause of Welding Cracks in Aircraft Steels: The discussion in this article refers to gas welding of thin-walled parts of up to about 3 mm thickness. It was proven that by restricting the sulphur, carbon, and phosphorous content, and by electric-furnace production of the steel, it was possible in a short time to remove this defect. Weld hardness - i.e., martensite formation and hardness of the overheated zone - has no connection with the tendency to weld-crack development. Si, Cr, Mo, or V content has no appreciable effect, while increased manganese content tends to reduce the crack susceptibility.
Causes of Failure of Airship Sheds: Different causes of airship shed collapse are discussed, with suction and human carelessness being the prime causes.
The Cells of Giant Airplanes: This report presents a discussion of the Rohrbach type of giant airplane. The problems considered are structural drag, wing loading and divided power plants.
Central Aerohydrodynamic Institute of Moscow, Russia: The staff and construction of the Institute are described as well as a variety of experiments and researches being conducted there. The six sections of the laboratory are described, including the Section for Theoretical Researches, Section for Aerodynamic Researches, Windmill Section, Section for Engine-Propeller Groups, Section for Material Testing, and Section for Instrument Making. Special attention is given to the various wind tunnels and testing facilities present.
The Cetene Scale and the Induction Period Preceding the Spontaneous Ignition of Diesel Fuels in Bombs: In the present report a comparison is made between the scale obtained with mixtures of cetane and l-methyl naphthalene in a bomb, and that obtained with the same fuels in a Waukesha engine. The tests were conducted in a metal bomb heated by a Nichrome spiral. The fuel was injected into the bomb from a Bosch jet by means of a specially constructed plunger pump. The instant injection and the pressure curve in the bomb were registered by a beam of light which was reflected from a mirror connected to the needle of the jet and to a membrane indicator.
Change of 180 Degrees in the Direction of a Uniform Current of Air: In the construction of aerodynamic tunnels, it is a very important matter to obtain a uniform current of air in the sections where measurements are to be made. The straight type ordinarily used for attaining a uniform current and generally recommended for use, has great defects. If we desire to avoid these defects, it is well to give the canals of the tunnel such a form that the current, after the change of direction of its asymptotes, approximates a uniform and rectilinear movement. But for this, the condition must be met that at no place does the flow exceed the maximum velocity assumed, equal to the velocity in the straight parts of the canal.
The Characteristics Method Applied to Stationary Two-Dimensional and Rotationally Symmetrical Gas Flows: "By means of characteristics theory, formulas for the numerical treatment of stationary compressible supersonic flows for the two-dimensional and rotationally symmetrical cases have been obtained from their differential equations" (p. 1).
Charts for Checking the Stability of Compression Members in Trusses: "The present report contains a set of charts developed for computing the fixity effect on a compression member in a truss through its adjacent members, the amount of fixity being considered variable with the particular total truss load. The use of the charts is illustrated on two- and three-bay systems, as well as on a triangular truss" (p. 1).
Charts for Checking the Stability of Plane Systems of Rods: "Charts are presented for checking the stability of plane systems of rods, the use of the charts being illustrated by examples. It is also indicated how best to combine the individual members to form stable structures" (p. 1).
Chief Characteristics and Advantages of Tailless Airplanes: This study will be concerned with the critical examination of two main questions, mainly, susceptibility of centering and more generally, the conditions of static stability, longitudinal equilibrium, and the question of dynamic stability, or at least the damping of longitudinal vibrations about a position of equilibrium that may result from a small variation in the angle of attack.
The Choice of Air Routes: The author lists rules for the development and planning of air routes. He uses as examples India and Texas, as well as discussing the need for more landing fields.
Choice of Profile for the Wings of an Airplane Part 1: "The choice of the profile for the wings of an airplane is a problem which should be solved by a scientific method based on data obtained by systematic experimentation. The problem, in its present form, may be stated as follows: "To find a profile which has certain required aerodynamic characteristics and which encloses the spars, whose number, dimensions and separating distance are likewise determined by structural considerations." At present, the static test, corresponding to the case of accelerated flight at limited speed, requires the knowledge of the moment of the aerodynamic resultant at the angle of zero lift, and the possibility of controlling the magnitude of the corresponding absolute coefficient within more or less extensive limits" (p. 1).
Choice of Profile for the Wings of an Airplane Part 2: This report gives a general method for drawing airplane profiles. This method is useful, but it leads to a somewhat laborious drawing which becomes quite complicated when we take a transformation function having terms of a high degree.
Chordwise Load Distribution of a Simple Rectangular Wing: The chordwise distribution theory was taken over from the theory of the infinite wing. Since in this work a series expansion in b/t was used, the computation converges only for large aspect ratios. In this paper a useful approximate solution will be found also for wings with large chord - i.e., small aspect ratio.
A Class of de Laval Nozzles: "A study is made herein of the irrotational adiabatic motion of a gas in the transition from subsonic to supersonic velocities. A shape of the de Laval nozzle is given, which transforms a homogeneous plane-parallel flow at large subsonic velocity into a supersonic flow without any shockwaves beyond the transition line from the subsonic to the supersonic regions of flow. The method of solution is based on integration near the transition line of the gas equations of motion in the form investigated by S. A. Christianovich" (p. 1).
Clerget 100 Hp Heavy-Oil Engine: A complete technical description of the Clerget heavy-oil engine is presented along with the general characteristics. The general characteristics are: 9 cylinders, bore 120 mm, stroke 130 mm, four-stroke cycle engine, rated power limited to 100 hp at 1800 rpm; weight 228 kg; propeller with direct drive and air cooling. Moving parts, engine block, and lubrication are all presented.
Climbing Efficiency of Aircraft: The object of this report was to indicate that we frequently only make use of 50 percent of the maximum brake horsepower of the engine in taking off the ground, that this loss is not inevitable, and that the effort to get engines of low weight per horsepower by boosting revolutions is of very little use to bombers and commercial airplanes.

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