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 De Havilland Express Air Liner, which is a four-engine two-bay biplane of clean and well-streamlined form. Details of the cabin, controls, fuselage, tail, wings, engines, cockpit, characteristics, performance, drawings, and photographs are provided.

Circular describing the Comper Streak single-seat low-wing cantilever monoplane. Details of the fuselage, construction, wing, stabilizer, engine, landing gear, characteristics, drawings, and photographs are provided.

Circular describing the Avia 51 commercial airplane, which is a Czechoslovakian cantilever high-wing monoplane with a fairly orthodox design. Details of the performance, construction, wing, ailerons, fuselage, landing gear, engines, characteristics, drawings, and photographs are provided.

Circular presenting a description of the Short Scylla, which is a 39-passenger landplane with four Bristol Jupiter XF BM engines. A description of the characteristics, blueprints, and photographs of the aircraft are provided.

Circular describing the Fokker F.XX, which is a three-engine high-wing cantilever monoplane with retractable landing gear and tail wheel. Details of the wing, fuselage, cockpit, cabin, covering and cowling, control surfaces, landing gear, power plant, fuel and oil systems, characteristics, drawings, and photographs are provided.

Results of an investigation wherein the change of the normal force coefficient with Reynolds Number was obtained statically for a 15.5-centimeter hemispherical cup.

Circular describing the Avro 642, which is a mixed construction high-wing cantilever monoplane. Details of the engines, controls, interior, wings, cockpit, ailerons, landing gear, characteristics, performance, drawings, and photographs are provided.

Circular describing the Avro Commodore, which is a cabin biplane of metal construction that is designed for comfort rather than performance. Details regarding the fuselage, wings, landing gear, controls, characteristics, drawings, and photographs are provided.

Circular describing the De Havilland Comet, which is a long-range airplane that has been designed for the England-Australia race and was constructed using a stressed-skin construction. Details of the fuselage, landing gear, design, drawings, and photographs are provided.

Circular presenting a description of the Bernard 82, which is a scaled-up version of the 80 G.R.; they have similar designs but the 82 has greater span and wing area, deeper chord, higher fuselage, and a thicker wing for the bombs. A description of some flight tests and characteristics is also provided.

A description of the Hamburg tank and carriage is provided as well as a layout of the control station and generator room.

"The aerodynamic forces on an oscillating airfoil or airfoil-aileron combination of three independent degrees of freedom were determined. The problem resolves itself into the solution of certain definite integrals, which were identified as Bessel functions of the first and second kind, and of zero and first order. The theory, based on potential flow and the Kutta condition, is fundamentally equivalent to the conventional wing section theory relating to the steady case" (p. 291).

"The results of a complete tank test of a model of a flying-boat hull of unconventional form, having a deep pointed step, are presented in this note. The advantage of the pointed-step type over the usual forms of flying-boat hulls with respect to resistance at high speeds is pointed out. A take-off example using the data from these tests is worked out, and the results are compared with those of an example in which the test data for a hull of the type in general use in the United States are applied to a flying boat having the same design specifications. A definite saving in take-off run is shown by the pointed-step type" (p. 1).

"In this report are presented the results of wind-tunnel tests of retractable spoilers on the upper surface of a Clark Y wing, which have been made as part of an investigation of lateral control devices being conducted by the National Advisory Committee for Aeronautics. Spoilers with chords up to 15.0 percent of the wing chord were tested in several locations on a plain rectangular wing and in two locations on the same wing equipped with a 20.0 percent chord split flap down 60 degrees. Charts are given for four representative angles of attack from which values of rolling- and yawing-moment coefficients may be obtained for spoilers up to 15.0 percent chord located on the upper surface of a Clark Y wing" (p. 1).

"Drag tests were conducted in the N.A.C.A. full-scale wind tunnel on full-scale models of two Army Air Corps type A-6 landing lamps mounted on an 8 by 48 foot airfoil. Drag measurements were made with the lamps in the leading edge and attached to the lower surface at the 5 and 10 percent chord positions. The drag of the lamps when faired into the airfoil was also measured. The results show that at 100 miles per hour and at the angle of minimum drag of the airfoil the unaired lamps in the leading edge produced an increase in drag of 5.5 pounds and that the unaired lamps on the lower surface at either position increased the airfoil drag 22.5 pounds" (p. 1).

Note presenting tests in a wind tunnel to determine the control forces and air loads acting on split flaps. Clark Y wing models were used with two different sizes of full-span split flaps, one with a medium chord and one with a narrow chord. The results indicated that at angles of attack and flap deflections for maximum lift, the lift loads on the split flaps were only 5 percent and 9 percent of the total lift for the narrow and medium-chord flaps respectively.

From Summary: "Data obtained at the N.A.C.A. tank from tests on the models of three flying-boat hulls - N.A.C.A. models 11-A, 16, and 22 - are used to demonstrate the effect of trim angle on water resistance. A specific example is taken, and data from Model 11-A are used to show that the trim angle giving the minimum water resistance will give minimum total air-plus-water resistance. Total-resistance curves for best trimmed angles and other angles are compared for the same example."

Three tapered airfoils based on the N.A.C.A. 2200, the N.A.C.A.-M6, and the Clark Y sections were tested in the variable-density wind tunnel at a Reynolds Number of approximately 3,100,000. The models, which were of aspect ratio 6, had constant core center sections and rounded tips, and tapered in thickness from 18 percent at the roots to 9 percent at the tips. The aerodynamic characteristics are given by the usual dimensionless coefficients plotted for both positive and negative angles of attack and by effective profile-drag coefficients plotted against lift coefficients.

An investigation to determine the rate of descent, the horizontal velocity, and the attitude at contact of an autogiro in landings was made by the National Advisory Committee for Aeronautics at the request of the Bureau of Air Commerce, Department of Commerce. The investigation covered various types of landings. The results of the investigation disclosed that the maximum rate of descent at contact with the ground (10.6 feet per second) was less than the minimum rate of descent attainable in a steady glide (15.8 feet per second); that the rates of descent at contact were of the same order of magnitude as those experienced by conventional airplanes in landings; that flared landings resulted in very low horizontal velocities at contact. Also that unexpectedly high lift and drag force coefficients were developed in the latter stages of the flared landings.

"Four planing surfaces, all having beams of 16 inches and lengths of 60 inches but varying in dead rise by 10 degrees increments from 0 degrees to 30 degrees, were tested in the N.A.C.A. tank. The results cover a wide range of speed, loads, and trim angles, and are applicable to a variety of problems encountered in the design of seaplanes. The data are analyzed to determine the characteristics of each surface at the trim angle giving minimum resistance for all the speed and loads tested. A planing coefficient intended to facilitate the application of the results to design work is developed and curves of resistance, wetted length, and center of pressure are plotted against this coefficient" (p. 1).

"The results of take-off calculations are given for an application of simple trailing-edge flaps to two hypothetical flying boats, one having medium wing and power loading and consequently considerable excess of thrust over total resistance during the take-off run, the other having high wing and power loading and a very low excess thrust. For these seaplanes the effect of downward flap settings was: (1) to increase the total resistance below the stalling speed, (2) to decrease the get-away speed, (3) to improve the take-off performance of the seaplane having considerable excess thrust, and (4) to hinder the take-off of the seaplane having low excess thrust" (p. 1).

"This note presents a study of the pitching moments and the stability characteristics of monoplanes. Expressions for the pitching-moment coefficient and the Diehl stability coefficient for the monoplane are developed, suitable for the use of airplane designers. The effective difference between the high-wing and low-wing types is portrayed and discussed. Comparisons between experimental and computed values are made. Charts for use in the solution of numerical values of the pitching-moment and stability coefficients are presented" (p. 1).

Note presenting the findings of a committee established to consider the general question of hazards to aircraft due to electrical phenomena and make recommendations as to what should be done to insure the least hazard. The two primary hazards focused on were electrostatic attraction to the earth and high-frequency discharges.