From Summary: "A pursuit type airplane encountered severe diving moments in high-speed dives which make recovery difficult. For the purpose of investigating these diving moments and finding means for their reduction, a 1/6 scale model of the airplane was tested in the 16-foot high-speed wind tunnel at Ames Aeronautical Laboratory. The test results indicate that up to a Mach number of at least 0.75, the limit of the tests, the dive-recovery difficulties can be alleviated and the longitudinal maneuverability improved by the substitution of a long symmetrical fuselage for the standard fuselage."

Report presenting an investigation of the performance of a two-stage turbosupercharger with mixed-flow impellers. Two complete superchargers were tested; both were the same except for modified vanes in the interstage passage and a slightly different first-stage diffuser shape. The modified supercharger performed slightly better than the original, but both showed good characteristics over a range of operating conditions.

Report presenting a control-motion study in flight that is part of series covering a range of types and sizes of modern airplanes. This particular one involves the PBM-3 flying boat, which is equipped with a control mechanism typical of the cable-type systems in large transport, cargo, or bomber airplanes as well as those employed in flying boats. The elasticity of the elevator control system of the PBM-3 was such to limit the obtainable acceleration to about 3g for center-of-gravity positions in the usual operating range; that is, 26 to 30 percent mean aerodynamic chord, and for the range of airspeeds covered by the tests.

Report presenting an investigation conducted in the full-scale tunnel to determine methods of improving the cooling of the B-24D engine installation. The B-24D is a four-engine high-wing monoplane having a span of 110 feet, a wing area of 1048 square feet, and a gross weight of 56,000 pounds.

Report presenting results of high-speed and climb tests of an NACA C cowling on the XP-42 airplane. Results regarding maximum speed, pressures and temperatures, ground cooling, and effects of cuffs are provided.

Report presenting the flight tests of beveled trailing-edge ailerons on the North American XP-51 airplane which were extended to determine the aileron characteristics in high-speed dives. Standard recording instruments were used to determine airspeed, aileron position, stick force, and rate of roll. The results show that the beveled trailing-edge form of aerodynamic balance had no abnormal or unusual characteristics in high-speed flight.

Report presenting an examination of the effects of variations in efficiency parameters, including engine economy, aerodynamic efficiency, and structural efficiency, on airplane performance. Efficiency parameters were found to be extremely ineffective in adjusting the airplane performance to its tactical mission as compared to primary parameters like altitude, power, gross weight, and wing area.

Report presenting an investigation of the Supermarine Spitfire airplane equipped with exhaust stacks designed according to the jet-propulsion exhaust-stack system developed by the NACA. An increase in the high speed of the airplane of 6 mph was obtained as compared with the airplane equipped with the Rolls Royce exhaust system. Results regarding performance and exhaust-flame visibility are provided.

Report presenting testing of a scale model of a twin-engine pursuit airplane in order to investigate the possibility of high-speed diving difficulties and to find remedies for them. Most of the data were obtained in force tests, although some pressure-distribution measurements, elevator hinge moments, and wake surveys were also made. The tests showed that the airplane will experience serious diving moments above lift coefficients of 0.5 at a Mach number of 0.65, and 0.1 at a Mach number of 0.725.

Tests were made in 8-ft high-speed wind tunnel to determine the drag reduction possible by eliminating the barrel jacket of a protruding 50-caliber aircraft gun. It was found that the drag of a standard aircraft gun protruding into the air stream at right angles to the flow can be reduced by 23% by discarding the barrel jacket. At 300 mph and sea-level conditions, this amounts to a decrease in drag of from 83 to 64 pounds. A rough surface finish on the barrel was found to have no adverse effects on the drag of the barrel, the drag being actually less at high Mach Numbers.

Report presenting testing in the full-scale tunnel to provide data for estimating the longitudinal stability and control characteristics of the Curtis XP-55 airplane. Testing included lift, drag, pitching-moment, hinge-moment, and elevator pressure measurements for various combinations of angle of attack, elevator deflection, and elevator tab settings. The results of the force tests and some correlation of the results of the force tests and the pressure measurements are presented in the report.

Report presenting tests of representative models of flying boat hulls to determine the resistance at low speeds. Results regarding the effect of load coefficients, resistance coefficients, and towing and drifting calculations are provided.

Supplement using data from a previous report to show the cargo that can be carried at various ranges, pounds of cargo that can be carried per pound of fuel, and other graphs to simplify the problem of determining which cargo can be carried at any range. The assumptions, parameters, and equations from the original report are carried over in the supplement.

Report presenting an investigation of the effect of spray strips on the low-speed spray characteristics on a model of the Consolidated PB2Y-3 flying boat. The main purpose of the investigation was to determine what form the strips should be fitted to give the most practicable answer to the problem of controlling the spray at heavy loads.

Report presenting tests in the full-scale tunnel to determine the longitudinal- and lateral-stability and control characteristics of a scale model of the XP-69 airplane. The data include measurements of the forces and moments on the model at various angles of attack and angles of yaw. The effects of elevator, rudder, and aileron deflection on control-surface effectiveness and on hinge moments were determined.

Report presenting testing in the two-dimensional low-turbulence pressure tunnel and the two-dimensional low-turbulence tunnel of two models made by the Consolidated Aircraft Corporation, one of the outboard section and one of the inboard section.

Report presenting the results of flight investigations showing that a beveled trailing-edge aileron gives as low or a lower profile drag than a contour aileron. Section profile drag and lift coefficients with two different types of ailerons were obtained at 3 different Reynolds numbers.

Report presenting power-off wind tunnel tests of a scale model of a twin-engine cargo airplane equipped with amphibious floats. Longitudinal and lateral stability and control characteristics were investigated for three flap positions.

Report presenting stability, maximum lift, and high-speed tests of an observation airplane fitted with Maxwell leading-edge slots. The static and dynamic longitudinal and lateral stability was generally satisfactory and not affected much by the slots.

Report presenting testing of the flutter characteristics of the SB2U-2 airplane. The secondary purpose of the test, which ended up being the primary purpose, was to study the behavior of the airplane just below the flutter speed. Results regarding flutter amplitude, frequencies, and energy-absorbing qualities are provided.

Report presenting an investigation of the effect of wing loading, power loading, and aspect ratio on the performance of pursuit airplanes. The study is based on data combined from specifications, wind-tunnel, and flight tests of various airplanes and presented in graphs.

Report presenting tests on a scale model of a four-engine cargo airplane, which was tested in the high-speed wind tunnel. The high-speed characteristics of the airplane, particularly the longitudinal stability and control in dives were investigated. Test results indicated that no important changes in longitudinal stability or controllability occurred until the speed exceeded the predicted maximum level-flight speed by more than 38 percent.

"Tests of a tailless pursuit airplane model at the Ames Aeronautical Laboratory have shown that in conditions corresponding to level flight at a Mach number less than 0.7 and at an altitude under 35,000 feet, no serious compressibility effects occurred and that no sudden adverse diving moments were encountered up to a Mach number of 0.74, the maximum speed of the tests. However, there were indications that the elevons might lose their effectiveness for longitudinal control during a pull-out from a steep dive" (p. 1).

Report presenting a flight investigation of the flying qualities and stalling characteristics of a North American XP-51 airplane. The short-period longitudinal oscillation disappeared within one cycle in all conditions tested. Requirements for satisfactory stalling characteristics were met in all respects except for stall warning.