Report presenting a flight investigation made of boundary-layer and profile-drag characteristics of smooth wing sections of a P-47D airplane. Measurements were made at three stations on the wing: boundary-layer measurements, pressure-distribution measurements, and wake surveys. The results indicated that a minimum profile-drag coefficient of 0.0062 for the smooth section at 63 percent semispan was obtained.

Report presenting pressure distribution tests of six NACA 16-series propeller sections with 1-foot chords in the 8-foot high-speed tunnel to determine the compressibility effects on peak section pitching-moment coefficients. Data is presented as curves of peak section pitching-moment coefficient against Mach number, thickness ratio, and camber. The peak pitching-moment coefficients were found to occur in the regions of positive and negative stall.

Report presenting pressure-distribution measurements obtained from the horizontal tail surfaces of the Curtiss P-40K airplane during low-speed pull-ups to abrupt stall in which tail buffeting was experienced. The chordwise load distributions during buffeting are similar to those experienced during angle-of-attack changes. The location of the stall and frequency of stall disturbances are also described.

Report presenting an investigation in the 19-foot pressure tunnel of two-tapered wings with NACA 230-series airfoil sections, straight leading edges, and constant-chord center sections. Lift, drag, and pitching-moment coefficients were determined for the plain wing and for each flap arrangement for a range of Reynolds numbers. The results indicated that the wing with the square center section has greater maximum lift coefficients and increments of maximum lift due to flap deflections than the wing with the rectangular center section.

Report discusses an investigation to determine the aerodynamic section characteristics of an NACA 23021 airfoil with a double slotted flap with a chord 32 percent of the airfoil chord with the flaps at various positions. The maximum section lift coefficient, profile-drag coefficient, flap positioning, and effects of deflecting or removing the lower lip are described.

Report presenting an investigation in the 7- by 10-foot wind tunnel of an NACA 23012 airfoil with an 18.05-percent-chord Maxwell leading-edge slat and with a slotted and a split flap. The main purpose of the investigation was to determine the optimum slot gap of the Maxwell slat for, and the aerodynamic section characteristics of, the airfoil with several deflections of both types of flap.

Report discussing the use of variable-ratio geared tabs with an experimental elevator to improve stick-force characteristics in turning flight. The stick forces with the tabs were found to be satisfactory for a variety of center-of-gravity ranges. The ability of pilots to use the controls is also described.

Report presenting an investigation in the 7- by 10-foot tunnel of various modifications to the trailing edge of a 0.155-chord plain aileron on a semispan model of the tapered wing of a fighter airplane. The stick forces and rates of roll were estimated for a fighter airplane with the plain and modified ailerons.

"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).

Description is given of flight tests conducted on gun fairings, designed to correct the detrimental effects of the projecting and submerged wing guns on an F4F-3 fighter. It was found that the installation of unfaired guns on a clean wing resulted in a premature stall that increased the stalling speed in the carrier-approach and landing conditions of flight by suitably fairing the guns, it was possible to reduce the stalling speeds to values approaching very nearly the clean-wing values.

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 a report regarding the basic factors of heat transfer applied specifically to aircraft heating and to guide the experimenter in planning experiments to obtain further data.

Report presenting tests conducted in the 8-foot high-speed wind tunnel of a scale model pursuit-type fuselage with practicable internal duct arrangement designed to meet all of the air requirements of a 1000-horsepower radial engine submerged at the maximum section. The results showed that the required internal flow can be obtained with negligible ducting losses provided that basic principles are observed in designing the air passages.

Report presenting an analysis to compare longitudinal stability and control characteristics obtained with a conventional fixed-stabilizer, an adjustable-stabilizer, and an all-movable horizontal tail. The tail-area requirements, control forces required in the critical landing condition, static margin, control-force gradients in a dive recovery, and elevator-free stability are investigated.

Report presenting the properties of some exhaust gases and air that are pertinent to airplane heat transfer calculations, including air, hydrogen, nitrogen, oxygen, carbon dioxide, and carbon monoxide. A bibliography related to gas properties is also provided.

Report presenting a study of two double tube cylindrical heat exchangers, in which hot exhaust gases pass through the annular space and ventilating air passes through the center tube, to determine heat transfer performance and pressure drop. Tests were performed in order to establish a simple, accurate method of predicting the performance of the double tube heat exchanger, to compare the performance of the straight and dimpled tubes, and to determine the pressure drop across the units.

Report presenting a study of two double tube, cylindrical, longitudinally finned heat exchangers in which hot exhaust gases pass through the annular space and ventilating air passes through the center tube in order to determine heat transfer and pressure drop performance.

Correlation is established between aerodynamic characteristics of control surfaces in two-dimensional and three-dimensional flow. Slope of lift curve was affected little by overhang and balance-nose shape, but increased by sealing flap-nose gap. Effectiveness of balancing tab was same for sealed plain flap and unsealed overhang flap. Changes in hinge-moment coefficient were diminished by sealing gap. Values measured by three-dimensional flow disagreed with two-dimensional flow values until aspect ratio corrections were made.

Report discussing an investigation of the aerodynamic effects of horn balances with various plan forms and of guards on a horizontal tail surface. Rounding the adjacent horn and stabilizer edges causes negligible changes to aerodynamic effects except for the area moment of the horn. A solid horn guard mounted on the end of the stabilizer was found to increase the rate of change of lift with angle of attack and elevator deflection.

Report presenting tests of the NACA 65(sub 3)-018 airfoil section with boundary-layer control by suction in the two-dimensional low-turbulence and two-dimensional low-turbulence pressure tunnels. Results regarding the lift characteristics, flow coefficient, maximum lift, amount of air removed by boundary-layer control, pressure distributions, and boundary layer shape are provided.

Report presenting the results of an investigation made in the two-dimensional low-turbulence pressure tunnel of surface irregularities on a low-drag airfoil section. The primary objective was to determine the effects of riveted and piano-hinge-type skin joints and of an aileron slot of the drag characteristics. Any type of surface irregularities at the front spar were found to cause substantial increase in drag.

Report presenting an investigation of the effects of propellers and of vibration on the extent of laminar flow on the NACA 27-212 airfoil by testing the airfoil in conjunction with a tractor and a pusher propeller and with a mechanical vibrator. The results show that neither the pusher propeller nor vibration with amplitudes up to 0.094 inch and with a frequency of 1650 cycles per minute had any consequential effect on the extent of laminar flow but that the tractor propeller had a very pronounced effect.

Report presenting flight tests to determine whether a towed body that was designed to meet certain specifications met the stability specification, which required that angular deviations in flight should be less than 1 degree. The requirement was met in flight in smooth air, but not in rough air, where the rolling motions were considerably larger.

Report presenting problems relating to the stability and control of tailless airplanes in consideration of contemporary experience and practice. Some observations in regards to small and large airplanes are provided.