Abstract. The diffusion length of thermal neutrons in water as a function of the water temperature has been measured. The results are expressed as a linear relation: L = 2.644 + 0.0061T where L is the diffusion length in centimeters and T is the temperature in degrees centigrade.

Report presenting data tables which summarize neutron cross sections for elements from hydrogen to bismuth. This data was to be available on September 1, 1947. Purpose and acknowledgements are given as well as criteria for omitting measurements and explanation of the material.

Report presenting the performance characteristics of a 20-inch ramjet opeerating with preheated unleaded 62 octane fuel. The results of the investigation indicated an improvement in the combustion efficiency and operating range of the ramjet when using preheated fuel.

Report presenting an investigation in the free-flight tunnel to determine the low-speed, power-off dynamic stability and control characteristics of a model with a 35 degree sweptback wing. The investigation consisted of force and flight tests of the model and calculations of the lateral oscillatory stability with wing-tip fuel tanks off and on.

An investigation has been made in the Langley full-scale tunnel of a 47.5 degree sweptback wing-fuselage combination equipped for boundary-layer control by suction. The wing aspect ratio was 3.5, the taper ratio was 0.5 and the airfoil sections normal to the quarter-chord line were NACA 61(sub 1)-A112. Tests included the plain wing and the wing with various combinations of extensible leading-edge and split flaps.

"A method is presented for determining the effect of time lag in an automatic stabilization system on the lateral oscillatory stability of an airplane. The method is based on an analytical-graphical procedure. The critical time lag of the airplane-autopilot system is readily determined from the frequency-response analysis. The method is applied to a typical present-day airplane equipped with an automatic pilot sensitive to yawing acceleration and geared to the rudder so that rudder control is applied in proportion to the yawing acceleration" (p. 1).

"An analysis of the estimated high-speed flying qualities of the Chance Vought XF7U-1 airplane in the Mach number range from 0.40 to 0.91 has been made, based on tests of an 0.08-scale model of this airplane in the Langley high-speed 7- by 10-foot wind tunnel. The analysis indicates longitudinal control-position instability at transonic speeds, but the accompanying trim changes are not large. Control-position maneuvering stability, however, is present for all speeds. Longitudinal lateral control appear adequate, but the damping of the short-period longitudinal and lateral oscillations at high altitudes is poor and may require artificial damping" (p. 1).

Report presenting testing of half-span models of two wings of different plan form as both all-movable and fixed surfaces in the presence of a half fuselage. All-movable surfaces are being considered for supersonic aircraft as possible angle-of-attack indicators, control surfaces, and all-movable wings. Results regarding the lift characteristics, center of pressure, and drag of the wings are provided.