This report presents the results of a flight investigation to determine the effect on the performance of a turbosupercharged engine of an exhaust-gas-to-air heat exchanger installed between the engine-exhaust collector ring and the turbosupercharger. The background, results, and discussion of the investigation are described.

Report presenting a report illustrated by photographs and vibration records on the failure of the P-47 rudder in the high-speed tunnel at a true speed of 468 miles per hour and a density corresponding to 9000 feet altitude. The fin-rudder unit was tested as being at least representative of the tail design of the P-47 airplane.

Report presenting force tests conducted on a model of a section of the XP-63 horizontal tail surface in the 4- by 6-foot closed-throat vertical wing tunnel. The angle-of-attack range was from the negative to the positive stall for all flap deflections.

Report presenting static tests on four full-scale two-bladed propellers differing only in blade sections at blade angles from 0 to 20 degrees at the three-quarters radius. Two of the propellers were also tested as three-bladed propellers. For all of the propellers tested, the highest value of the static thrust figure of merit occurred at a tip-speed ratio between 0.7 and 0.9; the highest efficiency in flight may be expected in the same range of tip-speed ratios.

Report presenting static tests on two full-scale three-bladed propellers differing only in blade sections at blade angles from 0 to 20 degrees at the three-quarters radius.

From Introduction: "The tests reported herein, conducted during the early part of 1945, were made to determine the inherent charge-air distribution characteristics of the engine-stage supercharger of the double-row radial engine."

Data are presented of the flow conditions in the vicinity of an NACA D sub S -type cowling. Tests were made of a 1/2 scale-nacelle model at inlet-velocity ratios ranging from 0.23 to 1.02 and angles of attack from 6 deg to 10 deg. The velocity and direction of flow in the vertical plane of symmetry of the cowling were determined from orifices and tufts installed on a board aligned with the flow. Diagrams showing velocity ratio contours and lines of constant flow angles are given.

Report presenting an investigation to determine the effect of the location of the diffuser vanes with respect to the supercharger outlets and the effect of flow conditions at the impeller inlet on the air-flow distribution in the outlets of the engine-stage supercharger of an 18-cylinder double-row radial aircraft engine. The effect of flow conditions at the impeller inlet was investigated by distorting the flow at the inlet and noting the effect in the supercharger outlets. Results regarding the diffuser effect and inlet effect are provided.

Tests of four 10-foot propellers were made in the propeller-research tunnel for the Army Air Corps to check flight and static thrust test results made on several propellers embodying Clark Y and modified NACA 16-series sections. These propellers were identical as to diameter and activity factor and very closely identical in thickness ratio and pitch distribution. The blades embodied sections with both single- and double-cambered Clark Y, modified NACA 16-series, and a combination of Clark Y and modified NACA-16 airfoils. Tests covered a range of blade angles from 20 deg. to 70 deg., and were all made at tip speeds below 280 feet per second. Although these tests were not conclusive in themselves, owing to the conditions under which they were made, the results seem to check the flight and static tests as closely as would be expected.

Report presenting tests conducted on a steel cylinder barrel with aluminum fins in order to determine the heat-transfer coefficients of the cylinder and the excellence of the bond between the steel barrel and the aluminum fins. Results regarding the heat-transfer tests and physical tests are provided.

Report presenting an investigation to develop methods and equipment for the measurement of operating stresses in aircraft-engine crankshafts and connecting rods. The results indicate that the measurement of stresses in connecting rods is feasible. Results regarding stresses in the crankshaft and stresses in the master connecting rod are provided.

Report presenting testing of two engine cylinder barrels with aluminum fins. The primary purpose was to determine the heat-transfer coefficients and the excellence of the bonds between the aluminum fins and the aluminum base and between the aluminum base and the steel of the two barrels when manufactured by a large-volume production method.

"Air-consumption data from calibrations of two radial aircraft engines were analyzed to show the relation of engine air consumption to its primary influencing factors: intake-manifold pressure, exhaust back pressure, intake-manifold temperature, and engine speed. The analysis of the test data from these two engines led to the establishment of a relation of variables upon which the design of automatic metering controls can be based. The data obtained from one engine indicate that the air-consumption correlation obtained for this engine is accurate within 2 percent except under certain conditions that are well outside current engine-operation limits" (p. 1).

"The lateral- and directional-stability and -control characteristics of a twin-engine patrol airplane as predicted from the results of wind-tunnel tests of a powered model and as measured in flight are compared in this report. The predictions from wind-tunnel-test data were in good agreement with the flight-test results. The results show that such predicted flying-qualities characteristics are sufficiently accurate to indicate the unsatisfactory lateral- and directional-stability and -control characteristics of airplanes in the preliminary design stage" (p. 1).

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 testing of the flutter characteristics of the SB2U model conducted after the model had been modified to lower its flutter speed. The model was tested to destruction and the flutter speed was measured throughout.

"At the request of the Bureau of Aeronautics, Navy Department, tests were made in the 7- by 10-foot wind tunnel of the 1/8-scale model of the Brewster F2A airplane with full-span slotted flaps. The object of the tests was to determine the power-on static lateral and longitudinal stability of the complete model with a new wing which had a full-span slotted flap and a plain and slot-lip aileron for lateral control" (p. 1).

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.

Report presenting testing of a model of the Curtiss XBTC-2 airplane in the 7- by 10-foot tunnel. This report consists of a preliminary investigation of the lateral stability and control of one particular configuration of the airplane. Results regarding the effect of wing plan form and power at small and large angles of yaw, the effect of upturned wing tips, outboard flap modification, canopy opening, aileron control, and rudder-free characteristics are provided.

Report presenting a full-size single-engine pursuit airplane, with wing tips cut off, tested in the 16-foot wind tunnel. The purpose was to find means for eliminating an extreme rumble which occurred at high speeds when the radiator air-duct-exit openings were small. Results regarding rumble, cooling air, and drag are provided.

Report discussing tests of a model of the XP-55 to determine which modifications would prevent trim at large positive and negative angles of attack. The model was found to not trim at flat attitudes if the large wing tips with an extension of the wing-tip trimmers and a large elevator are installed on the airplane.

Report discussing spin tests performed on a scale model of the Curtiss-Wright XP-55 airplane. A large elevator with increased deflections and large wing tips with extensions were installed to improve the longitudinal-trim characteristics. Information about the spins, attitude after rotation, and recommended technique for spin recovery is provided.

"The data presented in this report are part of a general program to determine the effects of xylidines on the knock-limited performance of currently used aviation fuels" (p. 2).

An investigation was conducted to determine the effect of a coolant solution of 25 percent ethyl alcohol, 25 percent methyl alcohol, and 50 percent water by volume and maximum-economy spark advance on knock-limited performance and fuel economy of a large air-cooled cylinder. The knock-limited performance of the cylinder at engine speeds of 2100 and 2500 rpm was determined for coolant-fuel ratios of 0.0, 0.2, and 0.4. The effect of water-alcohol injection on fuel economy was determined in constant charge-air flow tests. The tests were conducted at a spark advance of 20 deg B.T.C. and maximum-economy spark advance.