Volume provides a summary of the progress of each agricultural experiment station. Also includes statistics, discussions of foreign investigations, and selected studies.

Report discussing an investigation to determine the free-jet performance characteristics of the XRJ43-MA-3 20B3 ram-jet engine at a Mach number of 2.70 at several angles of attack, inlet temperatures, and fuel-air ratios. Information about the inlet supercritical mass-flow ratio, diffuser-outlet Mach number contours, and effect of angle of attack and inlet temperature on engine performance is provided.

From Summary: "Trajectories of water droplets about an ellipsoid of revolution with a fineness ratio of 10 (10 percent thick) in flight through a droplet field were computed with the aid of a differential analyzer. Analyses of these trajectories indicate that the local concentration of liquid water at various points about an ellipsoid varies considerably and under some conditions may be several times the free-stream concentration. Curves of the local concentration factor as a function of spatial position were obtained and are presented in terms of dimensionless parameters that describe flight and atmospheric conditions."

Report presenting the results of oscillation tests to measure the dynamic-rotary stability derivatives of an airplane model at high subsonic speeds. Measurements taken included the damping in pitch, damping in yaw, damping in roll, and the yawing moment due to rolling velocity.

Memorandum presenting a review of some of the analytical and experimental studies of the use of liquid hydrogen as a jet-engine fuel and which show the possible extension of aircraft performance that will follow adequate research and development effort on the problem of its use.

A graphical method is described by which the enthalpy, entropy, and compressibility factor for the equilibrium mixture of atoms and diatomic molecules for pure gaseous elements may be obtained and shown for any dissociating element for which the necessary data exist. Results are given for hydrogen, oxygen, and nitrogen. The effect of dissociation on the heat capacity is discussed briefly.

Note presenting extensive data relating properties of wrought N-155 alloy under static, combined static and dynamic, and completed reversed dynamic stress conditions. Time periods for fracture ranged from 50 to 500 hours at room temperatrue, 1000, 1200, 1350, and 1500 degrees Fahrenheit. Results regarding the rupture and fatigue strengths, fatigue strengths based on cycles to failure, influence of superimposed fatigue loads on creep, influence on superimposed fatigue stress on elongation in the rupture test, stress-strain characteristics under fatigue loading, damping effects, influence of cyclic speed on fatigue properties, influence of notches on fatigue, surface finish, and limitations of findings are provided.

Report presenting the description and characteristics of two small temperature recorders suitable for flight use. One recorder is an electro-mechanical followup, self-balancing potentiometer type and one obtains self-balance by using an electronic feedback amplifier.

Report presenting an approximate method for the calculation of the compressible laminar boundary layer with heat transfer and arbitrary pressure gradient, based on Thwaites' correlation concept. The method results from the application of Stewartson's transformation to Prandtl's equations, which yields a nonlinear set of two first-order differential equations. Calculations of an example show that the method is reliable when compared with the perturbation method over the same range of Mach number, pressure gradient, and heat transfer.

Note presenting the problem of the effect of yaw on the turbulent boundary layer and skin friction of infinite cylinders, which is reviewed and compared with the case of laminar flow. The conclusion indicates that present understanding of the mechanism of turbulent shear does not permit exhaustion of two-dimensional data even to this elementary case of three-dimensional flow. Results regarding pressure distributions, two-dimensionality and flow direction, velocity profiles, virtual origin, virtual origin for yawed plates, boundary-layer growth, and the results obtained by Young and Booth are provided.

Note presenting a study of the strength of the tendency for segregation to the gain boundaries of substitutional solute atoms which differ substantially in size from those of the solvent in single-phase high-purity aluminum through observations on the intergranular corrosion in 20 percent hydrochloric acid.

Note presenting a hot-wire anemometer used to study turbojet-engine compressor rotating stall and surge. The system was capable of measuring flow over a frequency range of zero to 500 cycles per second. A description of the anemometer and a description of the dynamic characteristics, static characteristics, and operation and performance are provided.

Report presenting the results of an analytical and experimental investigation of the steady-state and dynamic characteristics of three types of throttle-controlled fuel systems. The three systems tested are a throttle with regulated upstream pressure, a throttle plus bypass differential-pressure regulator, and a throttle plus reducing-valve differential-pressure regulator with regulated supply pressure. Results regarding the effect of output pressure on the controlled flow, response of output flow to step changes in throttle area, and response of output flow to a sinusoidal variation in throttle area are provided.

Report presenting an investigation of the pressure limits of flame propagation for isooctane, ammonia, and mixtures of the two in air at a range of temperatures. A hot-wire ignition source was used and testing occurred in a 2-inch-diameter flame tube that was closed at both ends. For all mixtures studied, the rich limit rose considerably and the lean limit decreased slightly when temperature was raised.

From Introduction: "In rounded-approach nozzles with discharge coefficients close to unity, the frictional effects are concentrated in the boundary layer. A method of obtaining an analytical relation among the discharge coefficient, Reynolds number, and the nozzle geometry by utilization of elementary boundary-layer theory is presented herein."

The generalized shock-expansion method is applied to obtain solutions to the flow field about pointed bodies of revolution at high supersonic airspeeds and small angles of attack. Simple explicit expressions are obtained for the surface Mach numbers and surface pressures in the special case of slender bodies. In the case of inclined cones, algebraic solutions are obtained defining the entire flow field. Experimental pressure-distribution data for cones and ogives at Mach numbers from 3 to 5 are included. (author).

Report presenting an investigation to determine the hydrodynamic tares and interference effects on lift, drag, and pitching moment for an NACA 66(sub 1)-012 airfoil-section surface-piercing strut operating with an aspect-ratio-0.25 modified-flat-plat rectangular lifting surface. The interference effects of the struct on lift were negligible at all depths for drag and at all but very shallow depths for lift and pitching moment.

Report presenting a two-dimensional wind-tunnel investigation of the effectiveness of area suction near the trailing edge for increasing the lift of an NACA 65(sub 1)-012 airfoil modified to incorporate a porous, round trailing edge. The modified section had a thickness-chord ratio of 0.16 and a thin, small chord vane on the round trailing edge. Results regarding the model with vane, model without vane, model with faired vane, control surface, and comparison with similar lift-control devices are provided.

Note presenting flight tests on a twin-engine transport airplane to determine the effects of fuselage-nacelle interference on the circumferential distribution of the rise in total pressure at one radial station behind the propellers. The effects of the flow interference on the operation of a simple propeller-thrust indicator are investigated. Results regarding the effect of airspeed at full power, effect of wing flaps in approach condition, effect of power in cruise condition, effect of angle of yaw in the cruise condition, effect of engine cowl flaps in the approach condition, and thrustmeter-tube locations are provided.

Report presenting measurements of shock-strut internal pressures, telescoping velocity, and strut stroke made during drop tests of a small oleo-pneumatic landing gear to determine the characteristics of the orifice and to show the relationships between internal strut pressures and the overall loads developed by the strut. Results regarding the selection of pressure taps, evaluation of landing-gear loads from internal-pressure measurements, orifice coefficients, and evaluation of landing-gear loads from orifice coefficients are provided.

Note presenting an analysis of the normal accelerations and operating conditions encountered by two different airmail helicopters and a military pilot-training helicopter. The results indicate that maneuvers are usually responsible for the relatively large accelerations encountered, whereas gusts contribute primarily to the large number of smaller accelerations and the corresponding increase in the amount of time spent in the accelerated state. Results regarding operating conditions, gust and maneuver loads, take-off and climb, en route, landing approach, landing loads, operating variables, and acceleration frequency of occurrence are provided.

Report presenting a statistical study of the values of wing-lift factor at the instant of ground contact for four transport airplanes. Frequency-distribution curves and probability curves were fitted to the samples of data obtained from each of the transport airplanes.

Note presenting an investigation to obtain an indication as to the desired magnitudes of the pilot's stick forces and stick displacements in relation to the tracking performance.The tests have been performed on a ground simulator with one degree of freedom, pitch. The results of the tests for a well-damped airplane show that, as the required stick displacements were reduced, the accuracy of the subjects in performing the tracking task improved.

Report presenting the slender-body approximation of linearized compressible flow as applied to the problem of a delta wing in which flow separation occurs at the leading edges. Leading-edge separation was found to produce an increase in lift over that given by the Jones slender-wing theory and that lift does not linearly increase with angle of attack.