Abstract. If a pile rod gets bowed within its cooling tube it becomes warmer on the side which approaches the tube wall, and thermal expansion tends to warp it in the same direction as the original displacement. This was discussed roughly in N-601, and it was there concluded that the mechanism was not important for an isolated short slug. In connection with current development of continuous jacket (cartridge) assemblies, it seems desirable to look at this question again. In this case it is possible that the effect may be of some concern.

"Analysis of rotating stall of compressor blade rows requires specification of a dynamic lift curve for the airfoil section at or near stall, presumably including the effect of lift hysteresis. Consideration of the Magnus lift of a rotating cylinder suggests performing an unsteady boundary-layer calculation to find the movement of the separation points of an airfoil fixed in a stream of variable incidence. The consideration of the shedding of vorticity into the wake should yield an estimate of lift increment proportional to time rate of change of angle of attack" (p. 881).

Report presenting the results of an experimental investigation of the downwash and longitudinal stability characteristics of a semispan, triangular-wing airplane model with a horizontal tail. Lift, drag, and pitching-moment data re presented for the wing-fuselage combination. Results indicated that the model with the tail on or below the wing-chord plane possessed satisfactory stability characteristics throughout the test range of lift coefficient.

Memorandum presenting an investigation in the 20-foot free-spinning tunnel on a 1/20-scale model to determine the effect of two alternate nose designs on the spin and recovery characterstics of the McDonnel XF3H-1 airplane. The results indicated that, in order to insure satisfactory recovery from any developed spin obtained in the airplane with either of the two alternate nose designs, it may be necessary to use ailerons deflected with the spin in conjunction with rudder reversal, as was the case for the original nose design.

Report presenting time histories of horizontal-tail loads, elevator loads, and deformations on a jet-powered bomber airplane at wind-up turns. Results regarding total tail loads, elevator loads and elevator positions, stabilizer and elevator twist, and fuselage deflection are provided.

Report presenting the suggestion of an engine configuration that is intended to minimize difficulties caused by exhaust products that are expected to adhere to stationary parts but not rotating parts and exploit the high reactivity of fuel. Component efficiencies of the engine are assigned and its performance is compared with that of a single-stage turbine engine. Results regarding the effect of reaction-nozzle-jet angle, effect of turbine-exit axial Mach number, comparison of rotojet and turbojet performance, and performance of fixed-geometry rotojet engine are provided.

"In a round turbulent jet at room temperature, measurement of the shear correlation coefficient as a function of frequency (through band-pass filters) has given a rather direct verification of Kolmogoroff's local-isotropy hypothesis. One-dimensional power spectra of velocity and temperature fluctuations, measured in unheated and heated jets, respectively, have been contrasted. Under the same conditions, the two corresponding transverse correlation functions have been measured and compared" (p. 1).

Report presenting an investigation of the hydrodynamic characteristics of a scale powered dynamic model of a patrol-type seaplane designed by the Glenn L. Martin Company. The seaplane had a high-aspect-ratio wing and a T-tail with an all-movable stabilizer. A comparison was made between two forebody configurations, one with a sharp forebody keel in cross section and the other with the forebody cross section rounded in the vicinity of the keel.

"The nature and formation of smoke and its combustion were investigated. Smoke, which consist of tiny mesomorphous crystals tightly packed into popcorn-ball-like particles that agglomerate to give filaments, was found to contain about 5 percent of the hydrogen originally present in the fuel. Factors affecting smoke formation were studied in both diffusion flames and premixed Bunsen flames. It is suggested that smoking tendency increases with increasing stability of the carbon skeleton of the molecule, as determined by relative bond strength" (p. 657).

From introduction: "The purpose of the present report is to describe briefly certain improvements that have been made in the experimental facilities and to present the results of further measurements on critical masses and spatial neutron flax distributions in Be reflected reactors having square and thin slab geometries."

The monitoring of thermal and resonance neutron flux in a thermal reactor having high flux over periods of time from 1 to 12 months using think Co foils is considered. Special attention is paid to the many correction factors to be applied to the activation data; neutron temperature, effective cadmium cutoff energy, burnout of Co59 and Co60, and decay of Co60. Results on a homogeneity test of 10 mil, 0.08% Co-A1 alloy foils is given.

This report describes a specific apparatus used to monitor the intensity of gamma radiation. The report includes a diagram of the apparatus.

From introduction: "Report based chiefly on the field work prosecuted during 1905, 1906, 1907, and 1909. It is primarily a characterization of the several major distribution areas or life zones."

Smoke was used to visualize outer-wall secondary flows in a low-speed turbine utilizing rotor tip air discharge and suction. Photographs as well as visual observations of the effect of tip air discharge and suction were made by independently varying the direction and quantity of the tip air discharge and suction, and varying tip clearance, and main-stream air speed. In addition, the cross-sectional area of the hollow blade discharge opening was varied for the case of tip air discharge.

Performance data are presented for a transonic axial-flow compressor rotor designed to operate at a tip speed of 1300 ft/sec with maximum relative tip Mach number of 1.37. The compressor had an inlet diameter of 16 inches, a hub-tip diameter ratio of 0.5 and design specific weight flow of 31.1 (lb/sec/(sq ft frontal area). Experimental values of relative total-pressure-loss coefficient were considerably higher than the assumed values. This disparity, hub choking, and application of the simple radial-equilibrium concept are discussed.

Report presenting two low-solidity configurations tested to provide data on the effects of solidity on overall and blade-element performance. Results regarding weight flow, pressure ratio, and efficiency, stall characteristics, rotor-inlet conditions, total-pressure ratio, work coefficient, and efficiency are provided.

Report documenting the progress of the Army Gas-Cooled Reactor Systems Program to develop a mobile, low-power, nuclear power plant for Military field operation.

Scientific paper issued by the Bureau of Standards over studies conducted on radio fading. As stated in the abstract, "the series of measurements on fading were devoted to studies of fading effects during the sunset period, effects during the solar eclipse of January 24, the fading variations throughout a 24-hour day, and the effects of high transmitting power on fading" (p. 419). This paper includes tables, maps, illustrations, and photographs.

Report presenting force tests of a 0.10-scale model of the Douglas A4D-1 airplane in the 8-foot transonic pressure tunnel to investigate the static longitudinal characteristics of wing and fuselage modifications and the static lateral characteristics of the basic model. Tests were conducted over a range of Mach numbers and angles of attack.

A theoretical investigation has been made to determine the effect on the lateral stability of the Douglas D-58-II airplane of an autopilot sensitive to yawing velocity. The effects of inclination of the gyro spin axis to the flight path and of tire lag in the autopilot were also determined. The flight conditions investigated included landing at sea level, approach condition at 12,000 feet, and cruising at 50,000 feet at Mach numbers of 0.80 and 1.2. The results of the investigation indicated that the lateral stability characteristics of the D-558-II airplane for the flight condition discussed should satisfy the Air Force - Navy period-damping criterion when the proposed autopilot is installed. Airplane motions in sideslip subsequent to a disturbance in sideslip are presented for several representative flight conditions in which a time lag in the autopilot of 0.10 second was assumed.

"A theory of primary failure of straight centrally loaded columns is presented. It is assumed that the column cross section and the load are constant throughout the length. Primary failure is defined as any type of failure in which the cross sections are translated, rotated, or translated and rotated but not distorted in their own planes" (p. 141).

The relation of hydrogen and methane to carbon monoxide in the exhaust gases from internal-combustion engines operating on standard-grade aviation gasoline, fighting-grade aviation gasoline, hydrogenated safety fuel, laboratory diesel fuel, and auto diesel fuel was determined by analysis of the exhaust gases. Two liquid-cooled single-cylinder spark-ignition, one 9-cylinder radial air-cooled spark-ignition, and two liquid-cooled single-cylinder compression-ignition engines were used.

Report presents an equation that connects all the major qualities of a fabric, from which the fabric may be rigidly designed with respect to maximum ultimate economy.

A flight test was made a t high subsonic, transonic, and supersonic speeds and at high Reynolds numbers to determine the zero-lift drag of a 1/14-scale model of the Northrop MX-775B pilotless aircraft with small small body. The triangular wing of the model had 67.5 deg leading-edge sweep and 15 deg. trailing-edge sweep, The wing airfoil sections were modified NACA 0004 sections. The drag coefficient based on total wing area was 0.0107 at Mach number 1.60. At transonic speeds the maximum drag coefficient was 0.0125. The force-break Mach number was 0,98.