Report presenting a method of organizing design calculations for the cooling systems of aircraft power-plant installations for use by representatives of airplane and engine companies invited to participate in the NACA power-plant installation section.

Flow across tube banks was investigated by surveys of total dynamic and static pressure by visualization of the flow through the use of titanium tetrachloride smoke, by thermocouple surveys of heated tubes, and by hot-wire surveys of both heated and unheated tubes. It was found that turbulence increased as the depth of the bank increased and that the broad wake behind each tube affected flow over the succeeding tubes.

Report presenting a brief, nontechnical discussion of condensation trails for flying personnel. World maps showing trail-forming zones at different altitudes and seasons are presented. Means for suppression trails are given.

Report presenting an ice detector that can serve as a basis for a rate-of-icing indicator. The instrument consists of a wire screen and a pitot tube mounted behind the screen with both enclosed in a cylindrical shell. Observed data and some possibilities for future development are provided.

Report presenting testing of cooling blowers for air-cooled engine installations and an exploration of the methods used in the blower design and operating characteristics of the blowers over a range of flight speeds and altitudes. The results indicate that the blowers operate as a more efficient type of propeller cuff and in many cases provide considerably more pressure boost than using a cuff.

Report presenting testing of a Pratt & Whitney R-1830-43 engine mounted in a B-24D nacelle in the full-scale wind tunnel in order to investigation the potential improvements of fuel economy. Suggestions for improving the cruising power and cruising range by operating at specified fuel-air ratios are provided.

Report presenting two series of diagonal-tension beams with double uprights tested to destruction while strain measurements were being made at a large number of points. On the basis of a revised formula, more than 100 tests made by five manufacturers were analyzed.

Report presenting a technique of testing wind tunnel powered models developed as a result of experience gained in the investigation of the static longitudinal and lateral staiblity and control characteristics of several powered models in the 7- by 10-foot wind tunnel. A discussion of the conditions to be investigated, methods of presenting and interpreting the data, and a suggested operating technique are given.

Report presenting an analytical study of the influence of full-span slotted and Fowler flaps on the requirements for horizontal tail surfaces. The elevator deflection required to land at three-point attitude, elevator deflection required to stall the airplane at altitude, and permissible center-of-gravity range have been calculated for a fighter-type airplane.

Report presenting a study of the performance of bombers powered by four 2000-horsepower engines supercharged to 25,000 feet. A series of charts is provided with the coordinates of power loading and wing loading in order to simplify the selection of the best airplane for a given purpose.

Report presenting a study of the performance of bombers powered by one, two, four, and six 2000-horsepower engines supercharged to 25,000 feet. The performances are computed and are based on drag coefficients equal to the best obtained on modern airplanes and on weight estimates obtained from modern Army Air Forces airplanes. A chart is provided with the coordinates of power loading and wing loading noted so that all performances can be compared.

Report presenting a study of the performance of bombers powered by two, four, and six 3000-horsepower engines supercharged to 35,000 feet. The performances are computed and are based on drag coefficients equal to the best obtained on modern airplanes and on weight estimates obtained from modern Army Air Forces airplanes. A chart is provided with the coordinates of power loading and wing loading noted so that all performances can be compared.

Report presenting an investigation of means to increase the range of several airplanes to 6000 miles, including the B-17E, B-24D, B-26C, and B-25A. Tank-wing trailers and tank gliders were found to be the most practical ways of increasing range and calculations are provided for determining the proper loading and dimensions.

Report presenting flight-test data contributing to the development of the present SBD-1 flying qualities based on the interest expressed in the methods used to obtain control-force characteristics on the Douglas Model SBD-1 by minor relocation of control-surface hinge line in combination with modifications in the aerodynamic balance nose shape. Results regarding the stalling characteristics, lateral-directional stability and control, longitudinal stability and control, and design recommendations are provided.

Report presenting an investigation of the flying qualities of a Hawker Hurricane airplane. Thirteen flights and approximately 17 hours of flying time were required to complete the tests, which included extensive measurements of stability, controllability, and stalling characteristics. The results were similar to the flying qualities of other previously studied pursuit airplanes.

Report presenting testing of combinations of an NACA 23012 tapered wing and a circular fuselage with a wedge-shaped rear to determine the effect of wing-fuselage interference on the lateral-stability characteristics. The model configurations represented a high-wing, a mid-wing, and a low-wing monoplane. Results regarding the lateral stability at small and large angles of yaw are provided.

Report presenting testing in the two-dimensional tunnel of four models submitted by the Glenn L. Martin Company as intermediate sections of the wing of the XB-33 airplane. Each airfoil model had different types of flaps or no flaps at all. Results regarding the lift and drag data, lift coefficients, effect of flap positions, aileron effects, drag coefficients, and hinge-moment coefficients are provided.

Three airfoils were tested with an intersecting flat plate normal to the span as a preliminary study of interference effects on airfoils. Small interference effects were noted on the first two airfoils, while larger effects were noted on the NACA 66,2-422 section, which had previously been shown to be unconservative with respect to separation. Airfoils known to be conservative should be used for inboard sections subject to nacelle and fuselage interference.

Report presenting measurements of drag, lift, and aileron hinge moments on a 100-inch-chord model with various modifications to the trailing edge of the 0.20c Frise type aileron. The purpose of the data is to show qualitatively the effects of comparatively small modifications to the trailing edge of an aileron.

Bulletin presenting a study of several airfoils, including a conventional NACA 23021 and some low-drag airfoils for which the thickness had been increased, as smooth airfoils and after the application of a standard roughness. The results show some of the airfoils to be critical to separation resulting from such flow disturbances.

From Summary: "An investigation was carried out in the NACA low-turbulence tunnel to develop low-drag airfoil sections suitable for admitting air at the leading edge. A thickness distribution having the desired type of pressure distribution was found from tests of a flexible model. Other airfoil shapes were derived from this original shape by varying the thickness, the camper, the leading-edge radius, and the size of the leading-edge opening. Data are presented giving the characteristics of the airfoil shapes in the range of lift coefficients for high-speed and cruising flight."

Report presenting tests in the 7- by 10-foot wind tunnel of the scale model of the Brewster F2A airplane equipped with full-span slotted flaps and a new horizontal tail. The primary objective was to determine the power-on static longitudinal stability and control characteristics of the model with the new horizontal tail.

Report presenting calculations to determine the effects of spring and gravity moments in the control system on the longitudinal-stability characteristics of the Brewster XSBA-1 airplane, and the computed results have been verified by flight tests.

Report presenting flight tests conducted to measure the lateral-control characteristics of an airplane, equipped with a lateral-control system, in which as the flaps are lowered the ailerons droop and a gradual transition of lateral control from ailerons to spoilers takes place. The variation of maximum rolling velocity with lateral stick movement as obtained in abrupt rudder-locked rolls was satisfactorily smooth except when control was by spoiler alone.