A guide to organizing and operating a dairy-herd-improvement association for the purpose of maintaining records used to improve the profitability of herds.

Memorandum presenting a theoretical investigation to determine the reasons for poor airplane response to longitudinal control. Some effects of airplane configuration on the response, primarily for short time periods, were also determined. Results regarding a comparison of three airplanes, the effect of changes on airplane B, and the effect of changes on airplane C are provided.

From Summary: "The general effect of wing sweep on cloud-droplet trajectories about swept wings of high aspect ratio moving at subsonic speeds is discussed. A method of computing droplet trajectories about yawed cylinders and swept wings is presented, and illustrative droplet trajectories are computed. A method of extending two-dimensional calculations of droplet impingement on nonswept wings to swept wings is presented."

Memorandum presenting a direct-connect duct investigation conducted with a one-quarter segment of a 25.5 inch diameter annular combustor which had been previously developed for liquid fuel injection. The combustor was modified by changing the fuel injectors and the liner design for vapor fuel injection. Results regarding accuracy and reproducibility, combustion efficiency, combustor-outlet temperature profiles, and pressure losses are provided.

Report presenting an investigation to determine the effect of blade-section camber on the stall-flutter characteristics of three propellers using a 6000-horsepower propeller dynamometer. Up to a certain blade angle, there was an increase in flutter-speed coefficient with an increase in blade-section design lift coefficient. An increase in thrust was found to lead to an increase in tip Mach number in the flutter region of the propeller blades.

Note presenting a method for the rapid determination of design velocity diagrams of turbine stages within specified aerodynamic limits. The method is presented in both chart and tabular form.

Note presenting porcelain-enamel ground coats, which were prepared and applied under conditions that gave various degrees of adherence between enamel and a low-carbon steel. This study was primarily undertaken to find out additional information on the mechanism of adherence of porcelain-enamel ground coats to iron.

Note presenting results of an investigation of the fatigue strength of several full-scale aircraft wing structures. The 34 fatigue failures which resulted from the tests were of four main types and occurred in three principal localities on the test wings. Results regarding the definition of fatigue failure, load history of specimens, description of fatigue failures, spread in fatigue life, stress concentration factors, rate of crack growth, and effect of fatigue damage on natural frequency and damping are provided.

From Introduction: "This paper presents the basic design method and experimental results of calibration of a nozzle which was constructed to conform to the analytically determined ordinates."

"An approximate method for computing water loads and pressure distributions on lightly loaded elliptical cylinders during oblique water impacts is presented. The method is of special interest for the case of emergency water landings of helicopters. This method makes use of theory developed and checked for landing impacts of seaplanes having bottom cross sections of V and scalloped contours. An illustrative example is given to show typical results obtained from the use of the proposed method of computation" (p. 1).

From Introduction: "The purpose of this report is to treat analytically heat addition heat addition to a divergent stream with initially sonic flow and to employ the results thus obtained in evaluating the effect of delayed combustion on convergent-divergent nozzle performance."

Report presenting an experimental investigation to determine the effect of changes in shape of the rear fuselage of an airplane on ditching behavior. The behavior of the models was recorded with a high-speed camera, the records were analyzed, and the data is presented as curves of speed, attitude, and center-of-gravity height plotted against time.

Report presenting an analysis for optimum controllers of general, linear, time-invariant multiloop systems. General representations of controller characteristics, stable process characteristics, and error relations are used. General solutions are presented for four special cases.

Presents zero-lift drag data of an NACA RM-10 slender body of revolution with and without stabilizing fins attached. The results from several wind tunnels and in flight are compared. The results cover a Reynolds number range from about 1 time 10 to the 6th power to 40 times 10 to the 6th power for the flight models. The Mach numbers covered include 1.5 to 2.4 in the wind tunnels and 0.85 to 2.5 in flight.

"A study of the motion of a personal-owner or liaison airplane through the stall and into the incipient spin has been made by catapulting a dynamic model into still air. The results showed that the model became unstalled in inverted flight after its initial rotation of substantially 180 degrees in roll. Since the rates of rotation were low, it may be inferred that termination of the incipient spin would be most readily obtained by proper control movements at this point" (p. 1).

From Summary: "The results of tests of a slender body of revolution designated the NACA rm-10 have been compiled from various NACA test facilities. Zero-lift drag data are presented for a Reynolds number range from about 1 x 10(6) to 40 x 10(6) from several wind tunnels and from about 12 x 10(6) to 140 x 10(6) from free-flight tests. The Mach numbers covered include 1.5 to 2.4 for the wind-tunnel data and 0.85 to 2.5 for the flight results. The wind tunnel models were tested with and without 60 degree sweptback stabilizing fins and the flight models were tested with stabilizing fins."

An investigation of secondary-flow loss patterns originating in three sets of turbine nozzle blade passages was conducted by means of flow-visualization studies and detailed flow measurements. For all cases, high loss values were measured in the fluid downstream of the corners formed by the suction surfaces of the blades and the shrouds, and these losses were accompanied by discharge-angle deviations from design values. Despite the size of the loss regions and angle gradients, over-all mass-average blade efficiencies were of the order of 0.99 and 0.98 and, therefore, are not a good index of blade performance.

An analysis has been made of available experimental data to show the effects of most variables that are predominant in determining base pressure at supersonic speeds. Two dimensional bases and bases of bodies of revolution, restricted to turbulent boundary layers, are covered.

A systematic research program is being carried out in the Langley high-speed 7- by 10-foot tunnel to determine the aerodynamic characteristics of various arrangements of the component parts of research-type airplane models, including some complete model configurations. Data are being obtained on characteristics in pitch, sideslip, and during steady roll at Mach numbers from 0.40 to about 0.95. This paper presents results which show the effect of taper ratio on the aerodynamic characteristics in sideslip of wing-fuselage combinations having wings with a sweep of 45 degrees at the quarter-chord line, an aspect ratio of 4, and a NACA 65A006 airfoil section.

"The results of free-flight drag tests of 40-millimeter shells conducted by the National Advisory Committee for Aeronautics for the Ballistic Research Laboratories, Ordnance Department, U. S. Army, are presented. A drag reduction at supersonic speeds of approximately 20 percent of the projectile's drag was obtained by combustion in the wake of the projectile in flight" (p. 1).

"An investigation was made of the trim and dynamic response characteristics of the free-floating horizontal tail of a 1/7-scale model of the complete tail of the Grumman XF10F-1 airplane in the Langley 8-foot transonic tunnel at Mach numbers up to 1.13. The complete tail was mounted in the tunnel on a 3 degree conical support body. Various configurations were investigated. A loss in damping of the horizontal tail at transonic speeds was shown by both tunnel and flight tests" (p. 1).

"A free-flight 0.12-scale rocket-boosted model of the North American MX-770 (X-10) missile has been tested in flight by the Pilotless Aircraft Research Division of the Langley Aeronautical Laboratory. Drag, longitudinal stability, and duct performance data were obtained at Mach numbers from 0.8 to 1.7 covering a Reynolds number range of about 9 x 10(exp 6) to 24 x 10(exp 6) based on wing mean aerodynamic chord. The lift-curve slope, static stability, and damping-in-pitch derivatives showed similar variations with Mach number, the parameters increasing from subsonic values in the transonic region and decreasing in the supersonic region" (p. 1).

"The term creep of metals is applied to the phenomenon in which, at temperatures beyond a certain limit, the metal subjected to a load slowly undergoes deformation with time. Very slow deformations for a prolonged period are cumulative and lead either to inadmissible changes in the dimensions of a structural part or to its failure. The theory of creep constitutes part of the mechanics of dense media and the mechanical formulation of the problem may be given as the following: a body is subjected to the action of a given system of forces, or initial displacements are prescribed on its surface" (p. 1).

The performance of a 13-stage development compressor for the J40-WE-24 engine has been determined at equivalent speeds from 30 to 112 percent of design. The design total-pressure ratio of 6.0 and the design weight flow of 164 pounds per second were not attained, An analysis was conducted to determine the reasons for the poor performance at the design and over-design speed. The analysis indicated that most of the difficulty could be attributed to the fact that the first stage was overcompromised to favor part-speed performance,.