Technical report covering classified work of the Critical Experiments Program in the Physics Division for the period December 20, 1950 to March 20, 1951. Report outlines investigations of properties of critical assemblies composed of uranium and various reflectors and moderators, preliminary measurements of the effective energy for fission in the assembly. [From Introduction and Summary]

Report presenting an investigation to determine the suitability of alloy 73J as a turbojet turbine-blade alloy and the effect of grain size on engine operating life. Blades made of alloy 73J were run in a full-scale J33-9 turbojet engine under cyclic conditions. Results regarding the macroexamination of blades, engine life, engine life against stress-rupture life, blade failures, blade elongation, metallographic results, and blade dimensions and the possible effects of overdimensions are provided.

Report presenting an investigation in a 16-inch-diameter simulated afterburner using gaseous hydrogen fuel. Results regarding combustion efficiency, afterburner pressure losses, spontaneous ignition, and a heat-balance check are provided.

The present paper summarizes and correlates broadly some of the research results applicable to fin-stabilized ammunition. The discussion and correlation are intended to be comprehensive, rather than detailed, in order to show general trends over the Mach number range up to 7.0. Some discussion of wings, bodies, and wing-body interference is presented, and a list of 179 papers containing further information is included. The present paper is intended to serve more as a bibliography and source of reference material than as a direct source of design information.

Memorandum presenting an investigation of a number of short turbojet combustor configurations for hydrogen fuel in a quarter-annulus duct. The best combustor liner consisted of an annular primary zone and a secondary zone composed of T-shaped channels sloping from the primary zone to the combustor wall.

Report that is part of a program to investigate the aerodynamic characteristics in pitch, yaw, and steady roll of various model configurations with variations in the wing geometric parameters. The paper presents the aerodynamic characteristics in pitch of wing-fuselage combinations with wings of aspect ratio 4, taper ratio of 0.6, and sweep angles varying from 3.6 degrees to 60 degrees. Results regarding lift characteristics, pitching-moment characteristics, drag characteristics, and lift-drag ratios are provided.

"An investigation was conducted to determine the effectiveness of suction applied through a porous area at the leading edge of the flap, on a 35 degree sweptback wing. Several chordwise extents and positions of area suction were tested for the suction flap deflected 55 degrees and 70 degrees. The results indicated that large increases in flap lift increment can be made by applying suction with very small flow quantities to an area near the leading edge of a flap" (p. 1).

Memorandum presenting an investigation of the problem of air-cooled turbine rotor-blade weight reduction for aircraft gas turbines as part of the NACA turbine-cooling research program. A bulb-root-type blade-base design was achieved which utilized forming and brazing techniques in its manufacture and was combined with an axial-flow turbojet engine aerodynamic profile. Results regarding the sheet-metal bulb-root-type air-cooled base designs, air-cooled pinned-type base design, and some weight reduction considerations are provided.

Report presenting the results of a wind-tunnel investigation of the torsional damping characteristics of a constant-chord control surface. The results indicated that the damping coefficient at supersonic speeds was near zero with a tendency toward instability at low supersonic Mach numbers. Results regarding theory, damping moments, and restoring moments are provided.

From Summary: "The 15-stage experimental axial-flow compressor was investigated at 78.5 percent of design speed, which falls in the region of the surge-limit line discontinuity. In this region indications of multiple characteristic curves of compressor operation had been found. On the basis of previous stage-matching analyses, these multiple performance characteristics appear to be the result of multiple-valued stage performance characteristics."

The 300A and loop were operated for 2862 hr with thorium oxide slurry at 1500 psi and 280ºC to determine the effects vane inlet and exit geometries on impeller wear, the wear rate of aluminum oxide bearings in this size pump, and the operating characteristics of the loop. The thoris, a 1600*C-fired oxide, had a mean particle size of approximately 2 u. Average circulating slurry concentration was approximately 450 grams of thorium per kilogram of water and average flow rate was approximately 300 gpm.

Photogeologic map of the Orange Cliffs-10 quadrangle, Wayne and Garfield counties, Utah

"In an effort to prolong the life of certain equipment, an investigation has been made of the applicability of several high temperature ceramic coatings prepared by the National Bureau of Standards Laboratories."

A report about the mechanical properties of dilute uranium alloys which might be crucial to developing high strength alloys for possible use as fuel.

From Introduction: "The purpose of the paper is to discuss the assumptions and the reasoning by which the calculations described in the Engineering Manual were derived from the data in [1]. The relevant curves from [1] are given in Appendix A and the technical charts from the Engineering Manual are given in appendix B."

From introductory paragraph: "This report concerns the hydrolysis of rare-earth dicarbides, sesquicarbides, solid solutions of carbon in rare-earth metals as well as rare-earth carbon alloys of varying compositions. Many of the carbide samples used in this study were those which had been studied by Gschneider (9)(7) and had been preserved in evacuated, sealed tubes. Some additional preparations of the sesquicarbides were made especially for these studies. The hydrolytic reactions were carried out in water and hydrochloric acid solutions of varying concentrations. Assay of the gaseous products was by mass spectrometry and gas chromatography. Both instruments were carefully calibrated with pure hydrocarbons and hydrogen and mixture thereof."

Report documenting two in-pile loop experiments conducted at the Battelle Research Reactor-Gas Cooled Reactor (BRR-GCR). These experiments test heat transfer calculations and the behavior of the fuel element under severe thermal-cycling conditions.

From Summary: "An investigation was conducted in a 16-inch-diameter simulated afterburner using gaseous hydrogen fuel. No flameholder was used with a multipoint fuel injector. The burner length was varied from 9.5 to 38 inches. The afterburner-inlet conditions were: temperature of 1200 degrees or 1500 degrees F, pressure of 14 to 44 inches mercury absolute, and velocity of 300 to The measured combination efficiency ranged from 85 to 98 percent over an equivalence-ratio range of 0.2 to 1.0. The cold-flow pressure-drop coefficient was 1.0 for the system. Spontaneous ignition was always possible at temperatures above 1200 degrees F but was not possible at temperatures above 1200 degrees F but was not possible below 1100 degrees F for all pressures and velocities tested."

Satisfactory combustion efficiencies and outlet radial-temperature distributions at low total-pressure loss were obtained in an experimental, quarter-annulus combustor with hydrogen fuel at total pressures as low as 5.7 inches of mercury absolute. The combustor was 25 percent shorter than previous models for liquid hydrocarbon fuels. Similar performance was obtained from this combustor design operated with hydrogen in a full-scale engine.

Memorandum presenting a procedure for reducing the interference pressure drag of the root and tips of sweptback wings. Experimental and theoretical pressure-drag values over a range of Mach numbers for configurations designed by the method were compared with the values of two similar configurations designed by the transonic and supersonic area-rule methods. Results regarding total drag, pressure drag, and drag comparison are provided.

From Introduction: "The present report is concerned with the characteristics of a body in the two-dimensional flow field of a circular-arc wing of rectangular plan form."

Report presenting wind-tunnel testing to evaluate the effects of wing fences and a tail on the longitudinal characteristics of a highly swept wing in combination with a fuselage. The model, which had a cambered and twisted wing with a leading-edge sweepback of 63 degrees and an aspect ratio of 3.5, was tested with fences of various shapes and swept and unswept horizontal tails. Results regarding exploratory tests, final-configuration tests, static longitudinal stability factors, and maximum lift-drag ratios are provided.

"Presented in this report is a summary of local and net angle-of-attack wing-panel loads measured in flight on six airplanes. In addition, a comparison of these loads measured in flight with calculations based on simple theory is presented" (p. 1).

Report presenting a study and evaluation of interception attacks made by an experienced pilot flying a Grumman F9F-3 airplane on a nonmaneuvering target. The runs were made under visual conditions at subsonic speeds and an altitude of 30,000 feet. Results regarding interceptor control characteristics, tracking characteristics, effect of interceptor turning capabilities, data significant to design of interceptor control systems, and evaluations applied to the automatic control apparatus.