Circular presenting a description of the De Havilland Dragon Moth, or D.H. 84, which is the first twin-engine airplane built by this particular company. Details of the design, components, flight characteristics, performance, drawings, and photographs are provided.

Circular presenting a description of the A.W. XVI, which is a single-bay staggered biplane of metal construction with a clean external design. A description of the tail unit, control system, cockpit, fuselage, characteristics, performance, drawings, and photographs are provided.

Note discussing the lift of a finite wing including the calculations and constants for each step of the lift. This information is compared against the lift of an infinite wing. From Summary: "Unsteady lift function for wings of finite aspect ratio have been calculated by approximate methods involving corrections of the aerodynamic inertia and of the angle of the infinite wing. The starting lift of the finite wing is found to be only slightly less than that of the infinite wing; whereas the final lift may be considerably less. The calculations indicate that the distribution of lift near the start is similar to the final distribution."

Circular presenting a description of the Hanriot H 431, which was designed to meet the requirements of the French War Ministry for general purpose airplanes. Details are provided for the design, flying qualities, and improvements over other aircraft designs.

Report presenting an experiment regarding tank and float venting conditions that exist on diving airplanes undergoing rapid changes in altitude. The results indicated that large pressure differences build up between the outside and inside of tanks and floats on diving airplanes unless the correct size of venting tube is used.

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.

This report provides a summary of the important steps to be taken in combating airplane fires. Some considerations and ways of preventing fires from developing are provided.

We first undertook experiments with air, devoted principally to the investigation of the disturbances due to the differences in the nature of the flow to the nozzle. The difficulty of measuring the air, however, caused us to experiment with water. Due to the possibility of measuring the capacity of the container, this method was much more accurate than measuring with Pitot tobes.

It was learned that the law of resistance for high R values does not follow the simple powers, and that the powers, which can be obtained approximately for the velocity distribution, gradually change. Since, moreover, very important investigations have recently been made on the resistance of plates at very high R values, it seemed of interest to apply the above line of reasoning to the new general law of resistance. For this purpose, the resistance and velocity distribution along the plate must always be equal to the values of the pipe flow at the corresponding Reynolds number.

In the present study it is proposed to provide an equipment permitting the study of the propagation of the region of reaction in mixtures of air and carbureted gases enclosed within a cylinder. Ignition is produced at the end of compression by an electric spark. With this apparatus it is proposed to determine: 1) the influence of the richness of the explosive mixture on the rate of flame propagation; 2) the influence of the degree of volumetric compression on one of the hydrocarbons; 3) the influence of the variation of initial temperature of the mixture before compression; 4) the influence of tetraethyl-lead on the propagation - notably on the formation of the explosive wave.

The nature of turbulent flow through pipes and around obstacles is analyzed and illustrated by photographs of turbulence on screens and straighteners. It is shown that the reversal of flow and of the resistance law on spheres is not explainable by Prandtl's turbulence in the boundary layer. The investigation of the analogous phenomena on the cylinder yields a reversal of the total field of flow.

"Measurement of perpendicular impacts of a landing gear with different shock-absorbing struts against the drum testing stand. Tests were made with pneumatic shock absorbers having various degrees of damping, liquid shock absorbers, steel-spring shock absorbers and rigid struts. Falling tests and rolling tests. Maximum impact and gradual reduction of the impacts in number and time in the falling tests. Maximum impact and number of weaker impacts in rolling tests" (p. 1).

Memorandum presenting a description of the Dornier seaplane Do X. Details of the general description, materials, details of the main wing and upper wing, details of the hull and of the wing stubs, tail surfaces and control lines, power plant, and launching car and floating dock are provided.

"Flight tests were made to determine the profile-drag coefficients of a portion of the original wing surface of an all-metal airplane and of a portion of the wing made aerodynamically smooth and more nearly fair than the original section. The wing section was approximately the NACA 2414.5. The tests were carried out over a range of airplane speeds giving a maximum Reynolds number of 15,000,000. Tests were also carried out to locate the point of transition from laminar to turbulent boundary layer and to determine the velocity distribution along the upper surface of the wing" (p. 483).

"Factors derived from wing theory are presented. By means of these factors, the angle of zero lift, the lift-curve slope, the pitching moment, the aerodynamic-center position, and the induced drag of tapered wings with partial-span flaps may be calculated. The factors are given for wings of aspect ratios 6 and 10 , of taper ratios from 0.25 to 1.00, and with flaps of various length. An example is presented of the method of application of the factors. Fair agreement with experimental results is shown for two wings of different taper ratio having plain flaps of various spacing" (p. 1).

Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel of a large-chord NACA 23012 airfoil with several arrangements of venetian-blind flaps to determine the aerodynamic section characteristics as affected by the over-all flap chord, the chords of the slats used to form the flap, the slat spacing, the number of slats and the position of the flap with respect to the wing. Complete section data are given in the form of graphs for all the combinations tested.

From Summary: "Section characteristics for use in wing design are presented for the NACA 23012 airfoil with plain and split flaps of 20 percent wing chord at a value of the effective Reynolds number of about 8,000,000. The flap deflections covered a range from 60 degrees upward to 75 degrees downward for the plain flap and from neutral to 90 degrees downward for the split flap. The split flap was aerodynamically superior to the plain flap in producing high maximum lift coefficients and in having lower profile-drag coefficients at high lift coefficients."

"Static thrust and power measurements were made of six full-scale propellers. The propellers were mounted in front of a liquid-cooled-engine nacelle and were tested at 15 different blade angles in the range from -7 1/2 degrees to 35 degrees at 0.75r. The test rig was located outdoors and the tests were made under conditions of approximately zero wind velocity" (p. 85).

Report presents the results of an investigation of full-scale nose-slot cowlings conducted in the NACA 20-foot wind tunnel to furnish information on the pressure drop available for cooling. Engine conductances from 0 to 0.12 and exit-slot conductances from 0 to 0.30 were covered. Two basic nose shapes were tested to determine the effect of the radius of curvature of the nose contour; the nose shape with the smaller radius of curvature gave the higher pressure drop across the engine. The best axial location of the slot for low-speed operation was found to be in the region of maximum negative pressure for the basic shape for the particular operating condition. The effect of the pressure operating condition on the available cooling pressure is shown.

Circular presenting a description of the Kay 331 gyroplane, which is an all-metal single-seater with a Pobjoy R engine. A description of the propeller, control, fuselage, tail, flight characteristics, specifications, drawings, and photographs are provided.

Circular presenting a description of the Weymann-Lepère W.E.L. 10. Some of the characteristics described include the principles of the construction, aerodynamics, descriptions of the components, flight characteristics, and photographs and blueprints.

Circular presenting a description of the Focke-Wulf F 19a "Ente" aircraft, which includes the unique design feature of the horizontal control surfaces being placed at the forward end of the fuselage while the wing is farther aft. Details of the design, aerodynamic characteristics, wings, controls, landing gear, power plant, fuel tanks, characteristics, drawings, and photographs are provided.

Report presenting a description of the Dornier Do K commercial airplane. Details of the construction, design, wing, fuselage, tail, and landing gear are provided.

Report presents the results of an investigation made in the NACA 7 by 10-foot wind tunnel to determine the aerodynamic properties of tapered wings having partial-span flaps for high lift and ordinary ailerons for lateral control. Each of two Clark-y wings, tapered 5:1 and 5:3, was equipped with partial-span split flaps of two lengths and with ordinary ailerons extending from the outboard ends of the flap to the wing tips. Measurements of wing forces and moments and of aileron hinge moments were made for the two conditions of flaps neutral and deflected.