Report presenting measurements of a Consolidated B-24D airplane of accelerations at various points on the wing during landing impacts. landings were made with the wheels initially stationary but free to rotate, with the brakes set before contact, and with the main wheels rotating prior to contact.

Bulletin presenting an analysis of the vertical-tail loads to be expected as a result of abrupt aileron action in accelerated flight, as in rolls from turns or pull-outs, for example. Critical tail loads may occur in rolling pull-out maneuvers, particularly on airplanes with good ailerons and low directional stability.

From Introduction: "Flight tests with electricity heated propeller-blade shoes reported in references 1 and 2 have establish the practicability of protecting propeller blades from ice formations by thermal-electric means."

From Introduction: "The purpose of this report is to show that it is practical to apply a least-squares method to the correlation of engine-cooling data."

Improvements, however, have been attained which permit a shortening of the structure without any impairment of the efficiency. The axial supercharger has a better efficiency and a simpler design than the radial supercharger. The relatively narrow range in which it operates satisfactorily should not be a very disturbing factor for practical flight problems. The length of this type of supercharger may be reduced considerably if some impairment in the efficiency is permitted.

Report discussing some calculations made for the effects of water in cooling the inlet air of aircraft-engine cylinders. From Summary: "The estimates indicate that the cooling effect of the water on the inlet air can be more extensive than the cooling now obtained with the intercoolers or aftercoolers in the air-induction system. In connection with water recovery from the exhaust gas, the estimates indicate that sufficient water can be recovered from 50 percent of the exhaust gas to provide an inducted water-fuel ratio of 0.5."

"Charts are presented for the calculation of the critical compressive stress - the stress at which local instability occurs - for idealized web- and T-stiffened panels, and examples of the use of the charts are given" (p. 1).

Report presenting charts showing the rotor profile drag-lift ratio for a helicopter rotor operating in forward flight and having hinged rectangular untwisted blades. The charts are given for a range of power input covering glides, level flight, and moderate rates of climb. A drag curve was used for preparing the charts, and the curve is compared with experimental curves for typical airfoils.

Report presenting an investigation of the possibility of using internal cooling instead of fuel enrichment to suppress knock and to estimate the fuel savings that will result. Data from four different sources was examined and an analysis of the fuel consumption was conducted. Four different types of coolants were explored.

"The number of partial contact surfaces of a brush-ring contact is measured by means of a statistical method. The particular brush is fitted with wicks - that is, insulated and cemented cylinders of brush material, terminating in the brush surface. The number of partial contact surfaces can be computed from the length of the rest periods in which such wicks remain without current" (p. 1).

Report presenting tests made with a dynamic model of the Army B-26 airplane to determine its behavior when landed on water. Results regarding the general behavior, effect of flaps, effect of landing attitude and speed, tests with undamaged model, tests with simulated damage, tests with propellers, vertical decelerations, and effect of weight are provided.

"In many studies, especially of nonstationary flight motion, it is necessary to determine the angular velocities at which the airplane rotates about its various axes. The three-component recorder is designed to serve this purpose. If the angular velocity for one flight attitude is known, other important quantities can be derived from its time rate of change, such as the angular acceleration by differentiations, or - by integration - the angles of position of the airplane - that is, the angles formed by the airplane axes with the axis direction presented at the instant of the beginning of the motion that is to be investigated" (p. 1).

Note presenting compressive testing made on twenty-one 24S-T aluminum-alloy sheet-stringer panels 12 inches in length and 16 inches in developed width, reinforced by four Z stringers spaced 4 inches apart. Results regarding strains, buckling, and failure are provided.

Rough conventional, smooth conventional, and laminar-flow or low-drag sections were tested. The items covered are rotor thrust for fixed power in hovering, range and endurance at cruising speed, and power required at high-forward speed. Calculations indicated that a smooth conventional section gives marked performance gains. Smaller gains are obtainable by using a low-drag section. At high speeds or loads the low-drag section is inferior to the smooth conventional section.

Report presenting an analysis of the effect of power on the variation of stick-fixed neutral point with lift coefficient for several single-engine monoplanes. Testing occurred with the power off and with rated, climbing, or wave-off power and with flaps neutral and deflected. Results for these different conditions are provided.

"In connection with studies of airfoils applicable to large high-speed aircraft, the effects of roughness on three 22-percent-thick airfoils were investigated. The tests were made over a range of Reynolds number from about 6 to 26 x 10(exp 6) for the airfoils smooth and with roughness strips applied to the surfaces. The results indicated that for the roughened models the scale effect was generally favorable" (p. 1).

"An electronic circuit for instantaneously indicating angular velocity and acceleration, both positive and negative, of rotating masses is described; readings are taken on electrical indicating meters. The indicator is described in terms of general application. A circuit diagram, calibration curves, and a mathematical analysis of the differentiation circuit are included" (p. 1).

Report presenting an investigation of the suitability of methyl tert-butyl ether as a component of aviation fuel from considerations of knock-limited performance tests and laboratory inspection tests. Data were obtained from testing on the 17.6 engine under supercharged conditions with fuel blends containing 10 and 20 percent methyl tert-butyl ether. Results regarding small-scale-engine data, full-scale-engine data, and inspection data are provided.

Report presenting the results of a wind-tunnel investigation of propellers operating at negative thrust. Negative-thrust characteristics of two- and four-blade single propellers and four- and eight-blade dual propellers were determined. The results indicate that the constant-speed reversed-pitch propellers posses aerodynamic characteristics that should make them excellent aerodynamic brakes.

"Hardy's statement that the frictional force is largely adhesion, and to a lesser extent, deformation energy is proved by a simple experiment. The actual contact surface of sliding contacts and hence the friction per unit of contact surface was determined in several cases. It was found for contacts in normal atmosphere to be about one-third t-one-half as high as the macroscopic tearing strength of the softest contact link, while contacts annealed in vacuum and then tested, disclosed frictional forces which are greater than the macroscopic strength" (p. 1).

"A brief summary of the contents of this paper is presented here. In part I the differential equations of the problem of a gas flow in two dimensions is derived and the particular integrals by which the problem on jets is solved are given. Use is made of the same independent variables as Molenbroek used, but it is found to be more suitable to consider other functions. The stream function and velocity potential corresponding to the problem are given in the form of series" (p. 1).

Report presenting an investigation of the suitability of 27 aromatic amines for overwater storage of their gasoline blends. The program is also meant to determine the antiknock effectiveness and low-temperature solubility in gasoline.

Report presenting data on the thermal performance and the static pressure drop characteristics of two finned-type exhaust gas and air heat exchangers. One heater was constructed of copper and stainless steel while the other was constructed from aluminum alloy. The measured thermal outputs and static pressure drops are compared with predicted magnitudes.

Report divided into two sections. One discusses a correction that must be applied to a heat meter when it is used at temperatures other than temperatures at which it was calibrated. The other section contains the results of an application of the two methods of correcting the heat-transfer rates for contact and heat-meter resistance to experimental data.