This report presents the results of flight tests made to determine the lateral control characteristics of short wide ailerons and spoilers, as a consequence of the promise shown in wind-tunnel tests by these devices as means of obtaining lateral control, particularly at angles of attack above the stall. Several forms of spoilers, front-hinge, rear-hinge, plain retractable, and saw-tooth retractable were tested alone and in combination with the ailerons. The tests were made with several different amounts of wing dihedral so that the effect of the yawing moments of the different lateral control combinations, which varied from large negative to large positive values, could be evaluated. In conjunction with the tests, observations were made to throw some light on the feasibility of operating the airplane with two controls instead of the present three.

It is shown that the lift distribution for a biplane with unequal chords may be calculated by the method developed in NACA Technical report no. 458 if corrections are made for the inequality in chord lengths. The method is applied to four cases in which the upper chord was greater than the lower and good agreement is obtained between observed and calculated lift coefficients.

This report presents performance results of air cooled and water-cooled engines. The results obtained were sufficiently promising to warrant further investigation with fuel injection and spark ignition, with the same arrangement of inlet ports and exhaust valves at the bottom of the cylinder and the exhaust gases discharged through two poppet valves in the cylinder head. The displacement of the engine was 118 cubic inches. Optimum performance was obtained with the inlet air directed into the cylinder at an angle of 20 degrees to the radial.

This report presents test results of experiments on the vibration-response characteristics of airplane structures on the ground and in flight. It also gives details regarding the construction and operation of vibration instruments developed by the National Advisory Committee for Aeronautics.

"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).

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.

A comparison is made of the boundary-layer flow computed by the approximate method developed by K. Pohlhausen with the exact solutions which have been published for several special cases. A modification of Pohlhausen's method has been developed which extends the range of application at the expense of some decrease in the accuracy of the approximations.

"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).

This report details the designs of high-speed aircraft from various countries from 1931 on, with special emphasis on the United States and Germany.

This report details the design and construction of the Heinkel 70 mailplane and its comparison with the Lockheed "Orion".

Report issued by the U.S. Bureau of Mines discussing the "occurrence, milling, and metallurgy of manganese in the United States" (p. 1). Different properties and compounds of manganese are also discussed. This report includes a map, tables, illustrations, and photographs.

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.

"The present report gives a method for computing the torsion of boxes with thin shear-resistant or simply tension-resistant walls under any torsional load, support and dimension. The final stress condition is developed from that of a principal system with unconstrained sectional warping corresponding to Bredt's formula and an additional stress condition due to constrained cross-sectional warping. This is computed by means of the deflection condition of the principal system from a statically indeterminate calculation" (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: "The report includes a description of the commonly used types and some others, the underlying principle utilized in the design, and some design data. The inherent errors of the instrument, the methods of making laboratory tests, descriptions of the test apparatus, and data in considerable detail in the performance of commonly used instruments are presented. Standard instruments and, in cases where it appears to be of interest, those used as secondary standards are described."

This report presents the results of a series of negative thrust and torque measurements made with a 4 foot diameter model of a conventional aluminum-alloy propeller. The tests were made in the 20-foot propeller-research tunnel of the National Advisory Committee for Aeronautics. The results show that the negative thrust is considerably affected by the shape and size of the body behind the propeller, that the maximum negative thrust increases with decrease in blade-angle setting, and that the drag of a locked propeller may be greatly reduced by feathering it into the wind.

"The results of an experimental investigation on the boundary-correction factor are presented in this report. The values of the boundary-correction factor from the theory, which at the present time is virtually completed, are given in the report for all conventional types of tunnels. With the isolation of certain disturbing effects, the experimental boundary-correction factor was found to be in satisfactory agreement with the theoretically predicted values, thus verifying the soundness and sufficiency of the theoretical analysis" (p. 79).

"In this report a theoretical solution is developed for the torsion on a round thin-walled tube for which the walls become unstable. The results of this theory are given by a few simple formulas and curves which cover all cases. The differential equations of equilibrium are derived in a simpler form than previously found, it being shown that many items can be neglected" (p. 3).

Circular presenting a description of the first British airplane with a retractable landing gear, which is a small and aerodynamically clean monoplane. A description of the design and flight characteristics is provided.

Report issued by the U.S. Bureau of Mines on the specifications and development of methods used in plain-carbon steel production. Proposed methods and experiment results are presented. This report includes tables, graphs, and photographs.

Circular describing the Dewoitine D.500 pursuit airplane, which is an all-metal cantilever low-wing monoplane. Details of the fuselage, cockpit, control surfaces, weapons, landing gear, fuel tanks, wing, engine, characteristics, performances, drawings, and photographs are provided.

"An investigation was conducted in the N.A.C.A. full-scale wind tunnel to determine the effects of exposed rivet heads on the aerodynamic characteristics of a metal-covered 6 by 36 foot Clark Y airfoil. Lead punching simulating 1/8 inch rivet heads were attached in full-span rows at a pitch of 1 inch at various chord positions. Tests were made at velocities varying from 40 to 120 miles per hour to investigate the scale effect" (p. 1).

Experiments and results are presented in testing needle bearings, especially in comparison with roller bearings. Reduction in coefficient of friction is discussed as well as experimental methods and recording devices.

"The static longitudinal stability of an airplane with locked elevator is usually determined by analysis and model tests. The present report proposes to supply the results of such measurements. The method consisted of recording the dynamic pressure versus elevator displacement at different center-of-gravity positions in unaccelerated flight" (p. 1).