This report records two samples of Xe-135 that have been isolated with activities sufficient for the measurement of the cross section of Xe by the velocity spectrometer technique.

On June 1, 1948, a fire in the neoprene seal at 100-F Area potentially exposed nine to radioactive. An overnight collection of urine was made from these men and the samples submitted, along with a piece of neoprene seal, to the H.I. Development Laboratory for analysis. It is the purpose of this report to present the results of our investigation as to the type of contamination from the burning neoprene and the amount of contamination found in the urine sample.

A procedure for making Be foils between 10{sup -5} cm. and 10{sup -3} cm. thick, and with diameters up to an inch and a half is described, and methods of mounting these foils are indicated.The problem of making thin Be foils was presented in connection with focusing the proton beam in the Berkeley Linear Accelerator, and although the foils are not now used in the accelerator, they have proved to be quite useful as thin targets, target supports, thin windows, etc. The Be was evaporated in vacuum and deposited on a metal collector plate. The problems encountered were: (1) obtaining reproducible quantities of evaporated Be; (2) stripping of Be from the collector plates; (3) preventing curl of the foils when they were stripped; and (4) mounting the foils.

This summary of the research progress meeting on March 18, 1948 covers the following topics: (1) Proton-proton scattering at 7 Mev; (2) Some animal experiments with 90 Mev neutrons; and (3) Yields of spallation products of antimony.

Historical: This process is based on experimental work done in Jackson Laboratory, Send Works, Blue Products, and East Area. It supersedes the Tentative Chambers Works Process for the Manufacture of Fluorine Using Carbon Anode Units, dated December 2, 1943.

Report of example scenarios and useful equations for determining the production of radioactive isotopes by pile or other radiations.

A theoretical discussion of the formation and steady state kinetic behavior of metal complexes is provided.

From Introduction: "An analysis of an engine having a division of work such that the power of the reciprocating engine is just sufficient to drive the compressor is reported herein. This combination of a reciprocating-type internal-combustion engine that drives its own supercharging compressor and generates gas for further expansion through a turbine will be called a piston-type gas generator in this report."

Memorandum presenting wind-tunnel tests of a semispan model of an unswept wing of aspect ratio 4 and a taper ratio of 0.50, equipped with leading- and trailing-edge flaps. The purpose of the tests was to determine the low-speed aerodynamic characteristics of the wing as affected by the separate or combined deflections of a full-span, constant-chord, leading-edge, plain flap and a partial-plan, constant-chord, trailing-edge flap of either the plain or split type. Results regarding the maximum lift characteristics, pitching-moment characteristics, drag coefficients, lift-drag ratio, and effect of Reynolds number and profile modification are provided.

Report presenting an investigation of a turbojet engine with compressor-inlet total pressure at various values below that of the exhaust pressure to determine engine performance under conditions simulating operation with inlet-duct losses. Results regarding general performance, application to inlet-duct losses, application to airplane boundary-layer control, and application to turbojet-engine thrust control are provided.

Memorandum presenting wind-tunnel tests at high subsonic Mach numbers conducted on a model of a pursuit airplane with a 45 degree sweptback wing. Tests were made to determine the effect of the wing trailing-edge angle, the fuselage contour at the wing-fuselage intersection, and an extension at the leading edge of the wing root.

Memorandum presenting a theoretical analysis of the effect of aerodynamic hysteresis on stalling flutter. The results were applied to a given airfoil and correlation of the experimental and theoretical results was found possible by assuming that the angle of aerodynamic lag varies as the slope of the static-lift curve. It was shown that the phenomenon of stalling flutter can at least in some cases be explained on the basis of an aerodynamic lag or hysteresis effect.

Report presenting theoretical calculations made by means of semirigid-flutter theory to determine the effect of centrifugal force on the critical flutter speed of a uniform cantilever beam. Calculations are made on airfoils with fundamental bending frequencies up to 2000 radian per second. Centrifugal force can under certain conditions reduce the critical flutter speed.

Report presenting an investigation to determine the performance of a Bumblebee 18-inch ram jet with a rake-type flame holder was conducted using kerosene and propylene oxide as fuels. Experiments occurred at a range of pressure altitudes and ram-pressure ratios over the operable range of fuel-air ratios. Use of propylene oxide was found to improve the stability of combustion, increased the operable range of fuel-air ratios, and allowed ignition at high values of combustion-chamber-inlet velocities.

"The problem of oscillating lifting surface of finite span in subsonic compressible flow is reduced to an integral equation. The kernel of the integral equation is approximated by a simpler expression, on the basis of the assumption of sufficiently large aspect ratio. With this approximation the double integral occurring in the formulation of the problem is reduced to two single integrals, one of which is taken over the chord and the other over the span of the lifting surface" (p. 969).

Determinations of the density and coefficient of thermal expansions of postum (Polonium 210) were attempted on 20 curies of polonium as obtained from production foils.

This document contains reproductions of technical papers on some of the recent research results from the NACA Laboratories in the field of aircraft loads. These papers were presented at the NACA Conference on Aircraft Loads held at the Langley Memorial Aeronautical Laboratory, February 18 and 19, 1948. The primary purpose of this conference was to convey these research results to the military services and their airplane contractors and to provide those attending an opportunity for discussion of the results.

From Summary: "An investigation was conducted on a large centrifugal compressor from an experimental turbojet engine to determine the performance of the compressor and to obtain fundamental information on the aerodynamic problems associated with large centrifugal-type compressors. The results of the research conducted on the compressor indicated that the compressor would not meet the desired engine-design air-flow requirements (78 lb/sec) because of an air-flow restriction in the vaned collector (diffuser). Revision of the vaned collector resulted in an increased air-flow capacity over the speed range and showed improved matching of the impeller and diffuser components."

"Flight tests have been made to determine the longitudinal stability and control and stalling characteristics of the P-47.E-30 airplane. The teat results show the airplane to be unstable stick free in any power-on condition even at the most forward center-of-gravity position tested. At the rearward center-of-gravity position tested the airplane also had neutral to negative stick-fixed stability with power on. The characteristics in accelerated flight were acceptable at the forward center-of-gravity position at low and high altitudes except at high speed where the control-force variations with acceleration were high" (p. 1).

This report talks about the aircraft configuration