"For several kinds of wire gauze the difference in static, dynamic and total or absolute pressure in front of and behind the gauze were determined for comparison with the pressure drop caused by an airplane radiator, such gauze being used on airplane models to represent the radiator" (p. 1).

Memorandum describing the results of the Royal Aero Club light airplane competition and some of the history surrounding the event. A list of the planes that participated and an analysis of the performance of the various aircraft are provided.

This report gives the results of a recent series of experiments performed on a wing designed for a cantilever monoplane. Both wings were trapezial in their ground plan, with their tips rounded elliptically. These wing sections combine all known devices for increasing the lift, namely, the slot, the increased camber and angle of attack by means of an aileron running the whole length of the span.

Two series of experiments were tried, in order to determine the ignition point at any desired pressure, the first series at constant and the second at varying pressure. The results differ greatly and indicate that testing under pressure, in the investigation of liquid fuels, can be done best in the laboratory and that the determination of the ignition points in an open vessel furnishes no certain indication of the behavior of the fuel in the engine.

Memorandum presenting the experimental results of tests to confirm the contribution to the study of normal burning in gaseous carbureted mixtures.

First, the Weissinger method, as it applies to a rectangular wing,is discussed. By building on this framework it is shown how to treat the lift problem for any thin wing of arbitrary plan form. The result of using this method may be arrived at by examination of the general equations applying to lifting surfaces.

"The present report deals with the development of a thermometer for recording stagnation temperature in compressible mediums in turbulent flow within 1 to 2 percent error of the adiabatic temperature in the stagnation point, depending upon the speed. This was achieved by placing the junction of a thermocouple near the stagnation point of an aerodynamically beneficial body, special care being taken to assure an uninterrupted supply of fresh compressed air on the junction together with the use of metals of low thermal conductivity, thus keeping heat-transfer and heat-dissipation losses to a minimum. In other experiments the use of the plate thermometer was proved unsuitable for practical measurements by reason of its profound influence in the reading by the Reynolds number and by the direction of flow" (p. 1).

This report presents the results of testing on a glider designed and built by the College Aviation Group. The design and construction were based on the following principles: 1) the glider will be made to descend as slowly as possible; 2) rigidity and resistance were arranged to meet the conditions of varied loads; 3) construction is as simple as possible; 4) and great ease in assembling and dismounting have been sought.

The author expresses his views that engine performance would be affected only at very low temperatures is presented in this report.

From Summary: "The resistance coefficients of commercial types of round wire grids were examined for the purpose of obtaining the necessary data on supercharger test stands for throttling the inducted air to a pressure corresponding to a desired air density. The measurements of the coefficients ranged up to Reynolds numbers of 1000. In the arrangement of two grids in tandem, which was necessary in order to obtain high resistance coefficients with the solidity, that is, mesh density of grid, was found to be accompanied by a further relationship with the mutual spacing of the individual grids."

From Summary: "The stipulation of best thrust distribution is applied to the annular elements of the screw propeller with infinitely many blades in frictionless, incompressible flow and an ideal jet propulsion system derived possessing hyperbolic angular velocity distribution along the blade radius and combining the advantage of uniform thrust distribution over the section with minimum slipstream and rotation losses. This system is then compared with a propeller possessing the same angular velocity at all blade elements and the best possible thrust distribution secured by means of an induced efficiency varying uniformly over the radius. Lastly, the case of the lightly loaded propeller also is discussed."

Predicated on the assumption of certain normal conditions for engine and propeller, simple expressions for the static and dynamic stresses of propeller blade roots are evolved. They, in combination with the fatigue strength diagram of the employed material, afford for each engine power one certain operating point by which the state of stress serving as a basis for the design of the root is defined. Different stress cases must be analyzed, depending on the vibration tendency of engine and use of propeller. The solution affords an insight into the possible introduction of different size classes of propeller.

These two reports are surveys on the progress and present state of development of dive-control flaps for gliders and airplanes. The second article describes how on the basis of wind tunnel and free-flight tests, the drag increase on brake flaps of the type DFS, can be predicted. Pressure records confirm a two-dimensional load distribution along the brake-flap surface.

The icing hazard can, in most cases, be avoided by correct execution of the flights according to meteorological viewpoints and by meteorologically correct navigation (horizontal and, above all, vertical). The zones of icing hazard are usually narrowly confined. Their location can be ascertained with, in most cases, sufficient accuracy before take-off.

A general description of the small DVL wind tunnel is provided, with emphasis on air conduction, blower and velocity regulation, velocity measurement, and balance and model suspension.

From Summary: "The purpose of this report is to make the complicated processes on the direct-lift propeller amenable to analysis and observation. This is accomplished by placing the physical phenomena, starting with the most elementary process, in the foreground, while limiting the mathematical treatment to the most essential in view of the fundamental defects of the theorems. Comparison with model experiments supplements and corroborates the theoretical results."

The viewpoints are discussed, according to which the scavenging of two-stroke-cycle engines can be evaluated, and the relations between scavenging pressure and the quantity of the scavenging medium required, as also between the scavenging pressure and the revolution speed, are developed. It is further shown that the power increase is limited by the scavenging process, so that further researches are desirable for qualitative improvement. These results lead to several conclusions regarding the propulsion of motor vehicles by the two-stroke-cycle engines.

"This report presents a survey of previous theoretical and experimental investigations on wing flutter covering thirteen cases of flutter observed on airplanes. The direct cause of flutter is, in the majority of cases, attributable to (mass-) unbalanced ailerons. Under the conservative assumption that the flutter with the phase angle most favorable for excitation occurs only in two degrees of freedom, the lowest critical speed can be estimated from the data obtained on the oscillation bench" (p. 1).

The present report is a comparison of the experimentally defined temperature and heat output of cooling fins in the air stream with theory. The agreement is close on the basis of a mean coefficient of heat transfer with respect to the total surface. A relationship is established between the mean coefficient of heat transfer, the dimensions of the fin arrangement, and the air velocity.

The performance of a glider is determined by means of the velocity polar, which represents the connection between horizontal and sinking speed. The mean sinking speed for a given speed range can be determined on the basis of the velocity polar. These data form the basis for the most propitious design of a performance-type glider with a view to long-distance flight.

"A survey of the possibilities of gliding in convection currents reveals that heretofore only the most simple kind of ascending convection currents, that is, the "thermic" of insolation, has been utilized to any extent. With the increasing experience in gliding, the utilization of the peculiar nature of the "wind thermic" and increased glider speed promises further advances. Evening, ocean, and height "thermic" are still in the exploration stage, and therefore not amenable to survey in their effects" (p. 1).

"The static stresses of airplane parts, the magnitude of which can be determined with the aid of static load assumptions, are mostly superposed by dynamic stresses, the magnitude of which has been but little explored. The object of the present investigation is to show how the strength of airplane parts can best be tested with respect to dynamic stresses with and without superposed static loading, and to what extent the dynamic strength of the parts depends on their structural design. Experimental apparatus and evaluation methods were developed and tried for the execution of vibration-strength tests with entire structural parts both with and without superposed static loading" (p. 1).

This report describes a device for arbitrary enlargement of the gliding angle of airplanes, especially of such with flat gliding angle and difficult landing characteristics. The D.V.L. gliding angle control (design, Hubner) permits a local interruption of the lift distribution along the span and consequently an increased induced drag. The mechanism comprises two wing rudders operated by lever from the pilot's cockpit. Said rudders are fitted on the top side of the wing near the leading edge. The displacement of these rudders results in a separation of the air flow on the top side of the wing.

The quantity of air which the disk area described by propeller blades travels through, is accelerated rearward conformably to the momentum of the forces acting on the propeller. The accelerated air mass forms behind the propeller the so-called slipstream, in which among others, the mean velocity of advance is increased. If the propeller axis slopes toward the relative flight direction, the slipstream direction likewise changes, i.e., it sets up a downwash behind the propeller.