Report presenting a study of the aerodynamic factors upon which the ability to perform the maneuver depends in an attempt to obtain a better understanding of the conditions involved and, if possible, to evolve criterions that may be used during design.

From Summary: "The analysis of results of wind-tunnel stability and control tests of powered airplane models in terms of the flying qualities of full-scale airplanes is advocated. In order to indicate the topics upon which comments are considered desirable in the report of a wind-tunnel stability and control investigation and to demonstrate the nature of the suggested analysis, the present NACA flying-qualities requirements are discussed in relation to wind-tunnel tests. General procedures for the estimation of flying qualities from wind-tunnel tests are outlined."

From Summary: "This report suggests a method whereby information on the strength under repeated stresses of aircraft materials or structural parts can be used in conjunction with information on service loadings as a means of comparing alternative designs."

Report presenting equations for calculating the stick-force characteristics obtained with a spring-tab type of elevator control. The main problems encountered in the design of the satisfactory elevator spring tab are to provide stick forces in the desired range, to maintain the force per g sufficiently constant throughout the speed range, to avoid undesirable "feel" of the control in ground handling, and to prevent flutter.

"Column and plate compressive strengths of extruded R303-T aluminum alloy were determined both within and beyond the elastic range form tests of thin-strip columns and local-instability tests of H-, Z-, and channel-section columns. These tests are part of an extensive research investigation to provide data on the structural strength of various aircraft materials. The results are presented in the form of curves and charts that are suitable for use in the design and analysis of aircraft structures" (p. 1).

Report presenting comparisons of measured and calculated loads on the wing and horizontal tail in pull-up maneuvers for six airplanes over a range of weights. Good agreement was obtained between calculated and measured loads under certain circumstances, but the agreement in some cases was only fair, which may be attributed to poor quantitative knowledge of the aerodynamic parameters or to violation of the assumptions on which the method is based.

"An analysis is made to simplify pressure-drop calculations for nonadiabatic and adiabatic friction flow of air in smooth cylindrical tubes when the density changes due to heat transfer and pressure drop are appreciable. Solutions of the equation of motion are obtained by the use of Reynolds' analogy between heat transfer and skin friction. Charts of the solutions are presented for making pressure-drop calculations" (p. 1).

Report presenting a theory regarding engine-cooling variables from a previous report, which was used as a basis for the development of a semi-empirical equation to correlate exhaust-valve temperature with engine conditions. Results regarding the determination of constants, influences of operating variables on mean effective gas temperatures, thermal-resistance factor, and accuracy of correlating equation are provided.

Report presenting the basic methods of theoretically calculating the critical stress for plates with elastically restrained edges. Design charts for various types of sections and columns and critical stress for flat plates and curved sheets are provided.

Report presenting tests conducted with two liquid-cooled cylinders in order to isolate the effects of the various engine and coolant variables on cylinder temperatures and to obtain engine-cooling data required for a fundamental study of the heat-transfer processes in liquid-cooled engines. Cylinder temperatures were obtained for a large range of engine speeds, manifold pressures, carburetor-air temperatures, fuel-air ratios, spark advances, coolant-flow rates, average coolant temperatures, and coolant pressures with water and AN-E-2 ethylene glycol and other ethylene glycol-water mixtures as coolants.

Report presenting tests of curved panels of four different thicknesses and with radius-thickness ratios varying from about 150 to infinity. Results are also included from some previous testing.

"An investigation of cowlings for long-nose radial engines was made on the Curtiss XP-42 fighter in the NACA full-scale wind tunnel. The unsatisfactory aerodynamic characteristics of all the cowlings with scoop inlets tested led to the development of the annular high-velocity inlet cowlings. Tests showed that ratio of cooling-air velocity at cowling inlet to stream velocity should not be less than 0.5 for this type of cowling and that critical compressibility speed can be extended to more than 500 mph at 20,000 ft altitude" (p. 1).

Report presenting the application of transient theory to the rational determination of dynamic loads on airplane structures during initial landing impact. Simplified procedures are described by which the distribution of the maximum attainable value of the dynamic stresses in the structure may be obtained.

Report presenting data pertaining to forces and moments developed by V-bottom planing surfaces of different angles of dead rise in order to compute the effect of dead rise on the lower trim limit of stability on a seaplane. Increase of angle of dead rise in the range of 10 degrees to 30 degrees causes an important increase in the lower limit of stability.

Report presenting an investigation made on a supercharged CFR engine to determine a method for estimating lead susceptibilities of pure or blended paraffinic fuels. As a result of these studies, a chart consisting of a series of straight lines passing through the origin was developed to represent the lead susceptibilities of pure and blended paraffinic fuels in terms of knock-limited indicated mean effective pressures and octane numbers.

Report presenting an investigation of the effect of changes in the length-beam ratio of flying-boat hulls on resistance and spray. A family of three models of hulls of different length-beam ratios was used and, in order to maintain comparable hull sizes, the plan-form areas of the hulls were made approximately equal by keeping equal products of length and beam. Results regarding resistance, spray, and take-off performance are provided.

Report presenting an investigation to determine the effect of acid on the strength and aging properties of various types of resin bonds for plywood. The pH values of the birch plywoods, flexural and impact strengths before and after aging of birch plywoods bonded with urea-formaldehyde resins and phenolic resins, and delamination properties of birch plywoods bonded with each type of resin are provided.

"Data from wind-tunnel measurements of elevator hinge-moment coefficients at high angles of attack are utilized in estimating elevator stick forces in spins. The analysis indicates that elevator forces on several current airplanes will be so high that the pilot will be unable to push the stick to the neutral position. Large nose balances involve danger of the elevator locking in the full-up position" (p. 1).

Report presenting an investigation of the relation between the knock limit and the blend composition of aviation fuels when tested under supercharged conditions in an air-cooled aircraft-engine cylinder. Results regarding the blending characteristics of two gasolines, paraffinic fuels, olefinic fuel, naphthenic fuel, aromatic fuels, when xylidines are present in the fuel components, and fuel components containing unequal concentrations of tetraethyl lead are provided.

"In Mach range of 0.25 - 0.69, boundary-layer measurements were made on upper wing surface at 25% semi-span, pressure-distribution measurements made on upper surface at 63% semi-span, and wake surveys made at 63% semi-span. The minimum profile-drag coefficient of 0.0062 was indicated for smooth section at 63% semi-span. Critical mach number was exceeded by 0.04, but no compressibility shocks appeared. In slipstream, boundary layer transition occurred as far back as 20% chord on upper surface at low lift coefficients" (p. 1).

Report presenting the use of the Ackeret iteration process to obtain higher approximations than that of Prandtl and Glauert for the flow of a compressible fluid past a circular arc profile. The procedure is to expand the velocity potential in a power series of the camber coefficient.

Report presenting an investigation of the icing and de-icing characteristics of a Pratt & Whitney R-1830 engine induction system. The current report covers a program to determine the most effective rate and method of injection of de-icing fluid to remove a heavy ice formation from the induction system. Results regarding the flow rates, recovery times, de-icing portions of the runs, and ice formation characteristics are provided.

Report presenting an investigation of the effect of direction of propeller rotation on the dynamic lateral stability characteristics of a twin-engine airplane model equipped with single vertical tails of three different sizes. The effects of flap deflection and amount of power were also studied. The most satisfactory lateral-stability characteristics of the model in flight were encountered for the model with large vertical-tail areas.

Report presenting an investigation of underslung cooling-air ducts in various locations on a model of a typical single-engine tractor airplane in the full-scale tunnel. The report contains the results of tests of two forward underslung ducts. Results regarding pressure recoveries at the radiator, pressures behind the radiator, drag and duct efficiency, and critical speeds are provided.