Report presenting airspeed and altitude data for nonscheduled cargo operations of a Douglas DC-4 airplane between Seattle, Washington and Alaska during February and March of 1947 to determine the probability of reaching or exceeding given values of airspeed and Mach number. The total probability of exceeding a placard never-exceed speed of 266 mph depends primarily on exceeding the speed in descent. The probability was found to be about once in 100 hours of descent or once in 1000 hours of general flying time.

Memorandum presenting an analysis of selected experimental pressure-distribution data at transonic speeds for the purpose of deriving an empirical method which may be used for estimating the trailing-edge loads and bending moments at the design stage. The trailing-edge normal-force and bending-moment coefficients calculated by the derived method follow the general trend of the experimental data and appear to be a guide where specifically applicable chordwise pressure-distribution data at transonic speeds are not available.

Report presenting an investigation of a model of the Kingfisher XAUM-2 flying torpedo to determine the pressure recoveries within the jet engine nacelle and to determine the effects of several changes in model configuration on the aerodynamic characteristics of the model. The effectiveness of elevons and tabs as control devices was also investigated.

Report presenting a method for the preparation and purification of the intermetallic molybdenum desilicide was developed and its properties were determined. Chemical properties were found to be highly inert, unattacked by boiling hydrochloric acid, sulfuric acid, or aqueous sodium hydroxide, slightly attacked by nitric acid, and dissolved by molten sodium hydroxide. Other mechanical properties of the material were also provided.

From Introduction: "This paper presents the results of the investigation of the wing-alone and wing-fuelage configurations employing a wing with the quarter-chord line swept back 60^o, aspect ratio 4, taper ratio 0.6, and an NACA 65A006 airfoil section parallel to the free stream."

Report presenting a two-dimensional wind-tunnel investigation of a 6-percent-thick symmetrical circular-arc airfoil with leading-edge and trailing-edge high-lift devices. The purpose of the investigation was to determine the effects on maximum section lift coefficient of different leading-edge slats and drooped-nose flaps when used in combination with a plain trailing-edge flap. Results regarding slat configuration, drooped-nose-flap configurations, and a comparison of slat and drooped-nose-flap configurations are provided.

An investigation has been made in the Langley stability tunnel to determine the low-speed static stability and control characteristics of a model of the Bell MX-776. The results of the investigation indicated that the basic model configuration was longitudinally stable in the angle-of-attack range from about -16 deg. to 16 deg. but that the stability was a minimum near O deg angle of attack. The data indicated an aerodynamic-center position about 0.64 body diameters behind the center of gravity at low angles of attack. Reduction in the size of the front horizontal fins increased the longitudinal stability. With 20 percent of the span of the normal front horizontal fins cut off the aerodynamic center was about 1.04 body diameters behind the center of gravity, and with front horizontal fins having the same area as the front vertical fins, the aerodynamic center was 2.26 body diameters behind the center of gravity (at low angles of attack).

Report discussing an investigation of two full-scale NACA propellers at a range of blade angles and at speeds of up to 500 miles per hour. The results are compared to previous investigations of five NACA propellers to evaluate the effects of blade-section thickness ratios on propeller characteristics.

Report presenting the results of an experimental investigation of the downwash and wake characteristics behind a triangular plan-form wing in a supersonic stream. Measurements were made of the variation of downwash angle with angle of attack at several positions within the induced flow field. Results regarding the spanwise variation of the induced stream angle, rate of change of downwash at zero lift, variation of downwash with angle of attack, and wake are provided.

"The inlet guide vanes for the supersonic compressor of the XJ55-FF-1 engine were studied as a separate component in order to determine the performance prior to installation in the compressor test rig. Turning angles approached design values, and increased approximately to through the inlet Mach number range from 0.30 to choke. A sharp break in turning angle was experienced when the choke condition was reached" (p. 1).

From Summary: "The performance of the turbine component of a J33 turbojet engine was determined over a range of turbine speeds from 8000 to 11,500 rpm.Turbine-inlet temperature was varied from the minimum required to drive the compressor to a maximum of approximately 2000 degrees R at each of several intermediate turbine speeds. Data are presented that show the horsepower developed by the turbine per pound of gas flow."

Testing was performed at Mach number 1.53 with a wing-fuselage combination with a wing with 63 degrees leading-edge sweep, an aspect ratio of 3.46, and a taper ratio of 0.25. The wing had an NACA 64A005 thickness distribution parallel to the plane of symmetry and was cambered and twisted. Results regarding the comparison of lift, drag, and pitching-moment characteristics of WF-63c and WF-63, effects of sweep, and effects of Reynolds number are provided.

"Pressure-distribution data of the NACA 64(sub 1)-012 and 64(sub 1)A012 airfoils have been analyzed to determine the effects of increasing the trailing-edge angle from 9 to 14 degrees. The primary effect of increasing the trailing-edge angle was to decrease the loading over the rear portion of the airfoil under lifting conditions. The differences in trailing-edge load increased with Mach number and lift coefficient" (p. 1).

Report presenting the results of a preliminary experimental flutter investigation of widely different unswept cantilever wings at Mach number 1.3. Wings with a variety of mass-density parameters, center-of-gravity positions, and elastic-axis positions were tested.