Data complied regarding wells and other water resources, including water quality analysis, measurements, and other relevant information.

Report presents the results of a photographic study of the combustion in a spark-ignition engine using both Schlieren and flame photographs taken at high rates of speed. Although shock waves are present after knock occurs, there was no evidence of any type of sonic or supersonic compression waves existing in the combustion gases prior to the occurrence of knock. Artificially induced shock waves in the engine did not in themselves cause knock.

This paper is a critical analysis of the methods of determination of the tendency to detonation. No attempt has been made to describe in detail the different fuels and the different methods proposed.

Report presenting a study of eight wings and three tails covering a wide range of aerodynamic characteristics in 24 wing-tail combinations. Observations were made of the steady spin for four control settings and of recoveries for five control manipulations. The effect of wing shape, tail arrangement, control settings, relationships between spin characteristics, and comparison with results for basic loading are provided.

The purpose here is to consider the mechanical characteristics of reinforced phenol-formaldehyde resin as related to its use as structural material for aircraft. Data and graphs that have appeared in the literature are reproduced to illustrate the comparative behavior of plastics and materials commonly used in aircraft construction. Materials are characterized as to density, static strength, modulus of elasticity, resistance to long-time loading, strength under repeated impact, energy absorption, corrosion resistance, and ease of fabrication.

"An investigation was made in the N.A.C.A. 7 by 10 foot wind tunnel of the distribution of air pressure over one chord section of a Clark Y-H airfoil with a split flap. The results obtained are given in the form of diagrams showing the chordwise distribution of pressure on both airfoil and flap as plots of calculated aerodynamic coefficients for both airfoil and flap" (p. 1).

"The N.A.C.A. has developed a simple pressure-level meter for the measurement of sound-pressure levels above 70 db. The instrument employs a carbon microphone but has no amplification. The source of power is five flashlight batteries. Measurements may be made up to the threshold of feeling with an accuracy of plus or minus 2 db; band analysis of complex spectra may be made if desired" (p. 1).

Report presenting testing of rectangular Clark-Y biplane cellules with zero and -0.25 stagger, the gap equal to the chord, and 0 degrees decalage were tested on the NACA spinning balance in the 5-foot vertical tunnel.

"This report presents the results of a combined theoretical and experimental investigation conducted at the Georgia School of Technology on the static thrust of the lifting air screw of the type used in modern autogiros and helicopters. The theoretical part of this study is based on Glauert's analysis but certain modifications are made that further clarify and simplify the problem. Of these changes the elimination of the solidity as an independent parameter is the most important" (p. 1).

"An investigation was undertaken to determine the character and importance of the transition phase between the ground run and steady climb in the takeoff of an airplane and the effects of various factors on this phase and on the airborne part of the takeoff as a whole. The information was obtained from a series of step-by-step integrations, which defined the motion of the airplane during the transition and which were based on data derived from actual takeoff tests of a Verville AT airplane. Both normal and zoom takeoffs under several loading and takeoff speed conditions were considered" (p. 1).

Report presents the results of tests made of a Clark y airfoil with a Clark y Fowler flap and of an NACA 23012 airfoil with NACA Fowler flaps. Some of the tests were made in the 7 by 10-foot wind tunnel and others in the 5-foot vertical wind tunnel. The pressures were measured on the upper and lower surfaces at one chord section both on the main airfoils and on the flaps for several angles of attack with the flaps located at the maximum-lift settings.

Data complied regarding wells and other water resources, including water quality analysis, measurements, and other relevant information.

"The method of Poggi is employed for the determination of the effects of compressibility upon the flow past an obstacle. A general expression for the velocity increment due to compressibility is obtained. The general result holds whatever the shape of the obstacle; but, in order to obtain the complete solution, it is necessary to know a certain Fourier expansion of the square of the velocity of flow past the obstacle. An application is made to the case flow of a symmetrical Joukowski profile with a sharp trailing edge, fixed in a stream of an arbitrary angle of attack and with the circulation determined by the Kutta condition" (p. 197).

From Summary: "The experimental and calculated aerodynamic characteristics of 22 tapered wings are compared, using tests made in the variable-density wind tunnel. The wings had aspect ratios from 6 to 12 and taper ratios from 1:6:1 and 5:1. The compared characteristics are the pitching moment, the aerodynamic-center position, the lift-curve slope, the maximum lift coefficient, and the curves of drag. The method of obtaining the calculated values is based on the use of wing theory and experimentally determined airfoil section data. In general, the experimental and calculated characteristics are in sufficiently good agreement that the method may be applied to many problems of airplane design."

From Summary: "Engine test results are presented for simulated altitude conditions. A displaced-piston combustion chamber on a 5- by 7-inch single cylinder compression-ignition engine operating at 2,000 r.p.m. was used. Inlet air temperature equivalent to standard altitudes up to 14,000 feet were obtained. Comparison between performance at altitude of the unsupercharged compression-ignition engine compared favorably with the carburetor engine."

Report presents the results of a survey of problems encountered in applying general test data to the design of flying-boat hulls. It is shown how basic design features may be readily determined from special plots of test data. A study of the effect of the size of a flying boat on the probable limits to be covered by the general test data is included and recommendations for special tests and new methods of presenting test data for direct use in design are given.

Circular presenting a description of the Fairey "Battle", which is the first stressed-skin aircraft they have constructed and is also an all-metal low-wing cantilever monoplane. Details of the fuselage, wings, skin, design, flaps, landing gear, characteristics, performance, drawings, and photographs are provided.

"Data are presented to show the extent to which the maximum lift coefficient and consequently the minimum speed of an airplane, determined by flight tests, may vary with test conditions. The data show that cl-max may vary as much as 14 percent, depending on the altitude and wing loading at which the tests were made, the position or motion of the propeller, and the rate at which the angle of attack is changing when the maximum lift coefficient is obtained. The variation of the maximum lift coefficient with these factors, which are under the control of the test engineer, shows the need of standardizing the test procedure. A further variation is shown with wing conditions as affected by weathering and vibration, factors that cannot be completely controlled" (p. 1).

"Measurements were made of the maximum push, pull, and tangential forces that could be applied to airplane wheel-type controls for a wide range of fore-and-aft positions of the wheel. The measurements were conducted with several sizes of wheels and several heights of the center of the wheel above the seat. Various one and two-hand grips with pilots both secure and free were studied for each of the two pilots used in the investigation" (p. 1).

"Wind tunnel and flight tests were made to determine the performance characteristics of two designs of commercially available venturi tubes used in airplanes to operate air-driven gyroscopic instruments. Data obtained at sea level may be used to make approximate predictions of performance at higher altitudes. There is some indication that this may also be done for single venturi tubes" (p. 1).

The pressure drop across finned cylinders in a jacket for a range of air speeds from approximately 13 to 230 miles per hour has been investigated. Tests were made to determine the effect on the pressure drop of changes in fin space, fin width, jacket entrance and exit areas, skirt-approach radius, and the use of fillets and a separator plate at the rear of the cylinder. The pressure drop across the cylinder increased as the fin space decreased, the increase being very rapid at fin spaces smaller than approximately 0.20 inch. Fin width had little effect on the pressure drop for the range of widths tested. The pressure drop across the cylinder was nearly halved by increasing the skirt-approach radius from 3/4 inch to 1-1/4 inches, but fillets and a separator plate at the rear of the cylinder had little effect on the pressure drop. The pressure drop across a cylinder with tapered fins was greater than that for a cylinder having rectangular fins with the same effective fin spacing.

This report gives a brief review of the properties that have been attained with the synthetic materials with which we are at present familiar. Results of investigations are presented as well as possibilities for construction applications. Endurance strength and bonding tests are also presented.

Report presenting a consideration of the general problem of stalling as affecting the safety of airplanes. The increased difficulties associated with modern efficient wings, particularly highly tapered wings and high-life devices, are discussed and means are considered for avoiding these difficulties.

In the present paper we shall consider a figure of revolution, so that the formulas applicable to the more simple cases as, for example, a wing or flat plate will follow from our equations as corollaries. For checking the results of our theory, we made use of the data derived from the tests of Freeman on a 1/40-scale model of the airship "Akron" conducted in the large NACA wind tunnel. In the first part we shall derive the fundamental equation for a body of revolution according to the Karman theory in its original form, and in the second part we shall give all the comparisons of the results of tests with the modified theory.