Circular presenting a description of the British Klemm "Eagle", which is a low-wing commercial cantilever monoplane. Details of the components, flying qualities, design characteristics, weights and loadings, drawings, and photographs are provided.

Circular describing the Armstrong Whitworth XV "Atalanta" airplane, which is a commercial multiplace cantilever monoplane. Details of the wings, landing gear, fuselage, control surfaces, structural design, wing, engine, characteristics, drawings, and photographs are provided.

Circular presenting a description of the Blériot 137, which is a metal modification of the Bléirot 127. A description of the crew, the equipment, firing tests of the guns, and flight characteristics are provided.

Report presenting a description of the Dyle and Bacalan D.B. 80 airplane, which can be used for delivering mail. Details of the wing, fuselage, tail, landing gear, fuel tanks, and flying qualities are provided.

Circular presenting the Valetta, which is a twin-float seaplane and flying boat with a power plant comprised of three Bristol "Jupiter" XI F geared engines. A description of the design, characteristics, performance, blueprints, and photographs are provided.

Circular presenting a description of the Breguet 390 T, which is a three-engine all-metal transport sesquiplane with the same structural principles as the Breguet military airplane. This aircraft design replaces a girder fuselage with an orthodox rectangular fuselage with accommodations for ten passengers and baggage. Details of the design, components, flying qualities, drawings, and photographs are provided.

Circular presenting a description of the Wibault 220 R.N. 3 airplane. A description of the design, fuselage, engines, flight characteristics, blueprints, and photographs are provided.

In order to clarify the viscosity effect some experiments were made in the Gottigen low-pressure tunnel with the Bruhn double-throat Venturi tube. This type of tunnel makes it possible to vary the pressure and thereby the density within wide limits and consequently, to examine the viscosity effect. This, however, did not impair the results because pressure and temperature were determined at different periods.

Circular describing the Spartan "Cruiser", which is a six-seat low-wing cantilever commercial monoplane with three engines. Details of the construction, fuselage, wing, tail unit, power plant, fuel system, lubrication system, landing gear, controls, cabin arrangement, characteristics, performance, drawings, and photographs are provided.

Circular presenting a description of the Breda 32, which is a commercial airplane with three engines and an all-metal construction. Details regarding the design, components, flight qualities, drawings, and photographs are provided.

This report presents a review of German light airplane construction. Some of the topics discussed include: engines, fuselages, wings, landing gear, and other mechanical parts.

A simplified aerodynamic theory of the cyclogiro rotating wing is presented herein. In addition, examples have been calculated showing the effect on the rotor characteristics of varying the design parameters of the rotor. A performance prediction, on the basis of the theory here developed, is appended, showing the performance to be expected of a machine employing this system of sustentation. The aerodynamic principles of the cyclogiro are sound; hovering flight, vertical climb, and a reasonable forward speed may be obtained with a normal expenditure of power. Auto rotation in a gliding descent is available in the event of a power-plant failure.

From Summary: "The various possible means of preventing ice adhesion on airplane surfaces are critically reviewed. Results are presented of tests of the adhesives forces between ice and various solid and liquid forces. It is concluded that the de-icing of airplane wings by heat from engine exhaust shows sufficient promise to warrant full-scale tests. For propellers, at least, and possibly for certain small areas such as windshields, radio masts, etc. the use of de-icing or adhesion-preventing liquids will provide the best means of protection."

"Charts are presented for the coefficients in formulas for the critical compressive stress at which cross-sectional distortion begins in a thin-wall member with either a channel section or a Z-section with identical flanges. The energy method of Timoshenko was used in the theoretical calculations required for the construction of the charts. The deflection equations were carefully selected to give good accuracy. The calculation of the critical compressive stress at stresses beyond the elastic range is briefly discussed. In order to demonstrate the use of the formulas and the charts in engineering calculations, two illustrative problems are included" (p. 1).

"Surface waviness and rib stitching have been investigated as part of a series of tests to determine the effects on wing drag of common surface irregularities. The tests were made in the N.A.C.A. 8-foot high-speed wind tunnel at Reynolds Numbers up to 17,000,000. The results of the tests showed that the waviness common to airplane wings will cause no serious increase in drag unless the waviness exists on the forward part of the wing, where it may cause premature transition or premature compressibility effects" (p. 1).

Note presenting testing of twenty-two models of flying-boat hulls for the purpose of determining the effects on water resistance and spray of 13 variations in the transverse section of the bottom of the forebody and of three variations in the form of the afterbody. Generally, the effect of chine flare on the resistance was small, although the resistance of force with chine flare was generally less than the resistance of the form without chine flare.

"Rules and methods for insuring safe structural strength of racing airplanes used in the major air meets in this country have recently been considered. Acceleration records made in racing airplanes during actual air races were therefore considered desirable, and the NACA undertook the measurement of acceleration of loads on airplanes during all conditions of flight. Accelerations were measured on four airplanes at the Miami All-American Races in January 1934 and January 1935" (p. 1).

The results of a general tank test model 11-C, a conventional pointed afterbody type of flying-boat hull, are given in tables and curves. These results are compared with the results of tests on model 11-A, from which model 11-C was derived, and it is found that the resistance of model 11-C is somewhat greater. The effect of changing the plan form of the step on model 11-C is shown from the results of tests made with three swallow-tail and three pointed steps formed by altering the original step of the model. These results show only minor differences from the results obtained with the original model.

"Preliminary fatigue tests on two aluminum-alloy wing-beam specimens subjected to reversed axial loading are described. The motion used consists in incorporating one or two reciprocating motors in a resonance system of which the specimen is the spring element. A description is given of the reciprocating motors, and of the method of assembling and adjusting the vibrating system" (p. 1).

An investigation was made to determine the aerodynamic properties of rectangular and tapered NACA 23012 wings with plain ailerons and a full-span split flap, the flap retracting ahead of the ailerons. Measurements were made of lift and drag and of pitching, rolling, yawing, and hinge moments for all conditions of full-span flaps neutral and deflected at different chord locations. The results of the tests showed that a 0.20c(sub w) full span split flap located at approximately the 0.75c(sub w) point gave higher lift coefficients than had previously been obtained with a conventional 0.20c(sub w) partial-span split flap of a length to permit satisfactory control with plain ailerons. Still higher lifts were obtained if the full-span flap, when deflected, was moved back to the aileron axis. Moving the flap back to the aileron, in general, improved the aileron characteristics over those with the flap retracted. The most promising arrangement of full-span split flap and plain aileron combination tested, both for high lift and lateral control, was the rectangular wing with 0.20c(sub w) deflected 60 degrees at the 0.90c(sub w) location with 0.10c(sub w) semispan ailerons.

"The results of flight tests of four nose-slot cowling designs with several variations in each design are presented. The tests were made in the process of developing the nose-slot cowling. The results demonstrate that a nose-slot cowling may be successfully applied to an airplane and that it utilizes the increased slipstream velocity of low-speed operation to produce increased cooling pressure across the engine" (p. 1).

"A monocoque box specimen of aluminum alloy was subjected to end compression and the strains in the stringers were measured up to loads at which permanent set became noticeable. The stringer strains at low loads agreed closely with those computed from the assumption of uniform stress distribution. Buckling of the 0.026-inch sheet between stringers and of the 0.075-inch shear web took place at stresses in accord with theoretical values" (p. 1).

Tests of nine symmetrical airfoils, having different leading-edge radii, were made in the variable density wind tunnel. Three symmetrical NACA airfoils having maximum thickness-to-chord ratio of 0.06, 0.012, and 0.018 were used as basic (or normal) sections; and for each of these thicknesses one thinner and one blunter nose section were developed. Although the slope of the lift curve varies with thickness, these tests show that for any given thickness the slope is independent of nose radius.

This note presents the results of flight pressure-distribution tests on the right upper wing panel of a Douglas M-3 airplane equipped with a modified elliptical tip having a slight amount of washout. The results are given in tables and curves in such form that the load distribution for any normal force coefficient within the usual range encountered in flight may be determined.