"The cavitation in nozzles on airfoils of various shape and on a sphere are experimentally investigated. The limits of cavitation and the extension of the zone of the bubbles in different stages of cavitation are photographically established. The pressure in the bubble area is constant and very low, jumping to high values at the end of the area. The analogy with the gas compression shock is adduced and discussed" (p. 1).

Some of the problems considered in this report include: thermodynamics of surface friction, application of thick wing sections, special applications of controllable propellers, and gas turbines for aircraft.

Aerodynamic force tests of an NACA 23018 airfoil with a Gwinn flap having a chord 25 percent of the overall chord and of an NACA 23015 airfoil with a plain flap having a 25-percent chord were conducted to determine the relative merits of the Gwinn and the plain flaps. The tests indicated that, based on speed-range ratios, the plain flap was more effective than the Gwinn flap. At small flap deflections, the plain flap had lower drag coefficients at lift-coefficient values less than 0.70. For lift coefficients greater than 0.70, however, the Gwinn flap at all downward flap deflections had the lower drag coefficients.

Pressure-distribution tests of an NACA 0009 airfoil with an 80-percent-chord plain flap and three plain tabs, having chord of 10, 20, and 30 percent of the flap chord, were made. Section data suitable for application to the design of horizontal and vertical tail surfaces were obtained. Resultant-pressure diagrams for the airfoil with the flap and the 20-percent-chord tab are presented. Plots are also given of increments of normal-force and hinge-moment coefficients for the airfoil, the flap, and the three tabs. A comparison of some characteristic slopes for the 30-, the 50-, and the 80-percent-chord flaps, tested in the general investigation of plain flaps for control surfaces, is included. Section aerodynamic and load data have been made available for a wide range of flap and a tab chords to be used on an NACA 0009 airfoil or on other conventional sections.

From Summary: "Pressure-distribution tests of an NACA 0009 airfoil with a 30-percent-chord plain flap and three plain tabs, having chords 10, 20, and 30 percent of the flap chord, were made. The purpose of these tests was to continue an investigation to supply structural and aerodynamic section data that may be applied to the design of horizontal and vertical tail surfaces. The results are presented as diagrams of resultant pressures and of resultant-pressure increments for the airfoil with the flap and the 20-percent-chord tab. Increments of normal-force and hinge-moment coefficients for the airfoil, the flap, and the three tabs are also given. At all unstalled flap and tab deflections, the experimental distributions agree well with those calculated by an analytical method. The agreement is poor, however, then the stalled or the unstalled condition of the flap or tab deflected alone was changed to an unstalled or stalled condition by the simultaneous deflection of both the flap and the tab."

Note presenting an investigation of three centrifugal impellers, the same except for angular blade curvature, to determine the effect of the distribution of blade loading on impeller performance. Results regarding impeller efficiency, energy addition and pressure ratio, flow characteristics, and operating range are provided.

"An analytical investigation is made of the effect of shear lag on the bending vibration of wings that are designed essentially as shallow box beams, and a procedure is outlined for incorporating this effect in the determination of bending modes and frequencies. Numerical examples show that shear-lag action in a box beam can have a large influence on its vibration characteristics. The calculations indicate that even though only a small shear-lag action may be observed in a simple static deflection test of the beam, reductions in the second and higher-mode frequencies may be relatively large" (p. 1).

Technical report. The object of the research is to determine the procedure and equipment for the preparation of U233 on a semi-works scale. The general proposed procedure is that thorium carbonate in aluminum cans will be irradiated with pile neutrons. The Pa233 resulting from neutron absorption the Th232 and the decay of Th233 will be extraction from 99% of the thorium and the natural U in thorium by MnO2 precipitations. The Pa233 will then be allowed to decay to U233 which in turn will be isolated from the remaining Th and partially decayed Pa233 by ether extraction.

Abstract. to estimate the oxygen picked up by thorium in casting a rapid method of running the acid insoluble content was developed. the quickest procedure consists of reacting with mixed acids, fuming with perchloric and filtration to separate the "free" thorium from the "combined". The precipitate is ignited and weighed as thorium dioxide.

A report on high voltage pulse transformer designs at the University of California Radiation Laboratory.

Report presenting the results of testing in the transonic range of four flutter airfoils attached to a freely falling body. Failures of the airfoils were metered and recorded in order to determine the Mach numbers and altitudes of failure.

"General relationships for the lead susceptibilities of paraffins, cycloparaffins, and olefins are presented. Methods are described by which the lead response may be estimated for these hydrocarbon classes, whether the lead response is indicated by octane number, critical compression ratio, or indicated mean effective pressure as limited by knock" (p. 1).

An investigation is being conducted to determine the altitude performance characteristics of the British Nene II engine and its components. The present paper presents the preliminary results obtained using a standard jet nozzle. The test results presented are for conditions simulating altitudes from sea level to 60,000 feet and ram pressure ratios from 1.0 to 2.3. These ram pressure ratios correspond to flight Mach numbers between zero and 1.16 assuming a 100 percent ram recovery.

"A solution based upon small-deflection theory is presented for the critical shear stress of curved rectangular panels with simply supported edges. Computed curves which cover a wide range of panel dimensions are presented; these curves are found to be in good agreement with test results. Estimated curves are also given for panels with clamped edges" (p. 1).

Report presenting the aerodynamic characteristics of 19 isolated tail surfaces, which have been determined by wind tunnel tests. Testing was also made of rectangular airfoils of various aspect ratios with and without double end plates of various shapes. The analysis indicated that the slope of the lift curve could be predicted within 10 percent for all models by use of lifting-surface-theory equations.

Report presenting testing in the high-speed wind tunnel to determine the drag characteristics of several types of radial-engine nacelle on a low-drag airfoil. The drag coefficients of nacelles incorporating cowling-nose shapes shown by previous tests to be efficient and afterbodies of adequate length were about the same magnitude as commonly obtained for comparable installations on conventional wings. Results regarding the reduction of data, effect of nacelles on lift, and pressures at wing-nacelle juncture are provided.

Test of a ducted body with Internal flow were made in the 8-foot high-speed wind tunnel for the purpose of studying the effects on external drag and an critical speed of the addition of efficient inlet and outlet openings to a basic streamline shape. Drag tests of a 13.6- inch-diameter streamline body of fineness ratio 6.14 were made at Mach numbers ranging from 0.20 to 0.75. The model was centrally mounted on a 9-percent-thick airfoil and was designed to have an efficient airfoil-body juncture and a high critical speed.

Report discusses the results of testing to determine the maximum rates of control stick (elevator) motion and corresponding maximum stick forces that could be exerted based on experiments with several pilots. The main topics explored were the comparison of the maximum rates of push and pull, maximum rates of push and pull when a mental restriction was placed on the pilot, and maximum rates at which the pilot though he would apply the elevator control forces versus the actual application of forces. Information about experimental procedures and the rig the testing occurred on is included.

Report presenting a flight investigation made to determine the effectiveness of dive-recovery flaps installed on the XP-51 airplane as a safety device for recovery from contemplated terminal-velocity dives. The flap installation is described and results are presented of measurements obtained during stick-free pull-ups and pull-outs made by deflecting the dive-recovery flaps to two selected values of flap angle .

Abstract: The procedures recommended for analysis in Department 190 Laboratories, in the Limits Control Laboratory, and in the Analytical Development Laboratories, of all process materials from the HCP cycle are presented in a stepwise manner. A description of the characteristics of each sample type along with a brief description of factors involved in the Analytical Quality Control program is included.

Report presenting an investigation to develop an instrument for the determination of rain densities in this range in flight. The major requirements for the instrument are ease of operation, minimum weight and bulk, rapid response, and simplicity of installation.

Report presenting tests to determine the damping in roll and aileron rolling effectiveness of three wings with different degrees of sweepback. The results showed that the values of damping in roll decreased with increasing sweepback. The rolling effectiveness of the aileron of the sweptback wing was found to be predicted with fair accuracy from static aileron-rolling-moment tests and wing-damping tests.

Porpoising characteristics were observed on V-body fitted with tail surfaces for different combinations of load, speed, moment of inertia, location of pivot, elevator setting, and tail area. A critical trim was found which was unaltered by elevator setting or tail area. Critical trim was lowered by moving pivot either forward or down or increasing radius or gyration. Increase in mass and moment of inertia increased amplitude of oscillations. Complete results are tabulated and shown graphically.

Report presents and discusses the improvements in hydrodynamic and aerodynamic performance of a seaplane with a retractable planing flap instead of a conventional main step. A type of flap that could be used is described and tested for hydrodynamic stability. Results regarding the trim limits of stability, limiting positions of the center of gravity, and skipping are provided.