Apparatus, field layout, miscellaneous testing, and the method of analysis of a 100-ton test at Trinity.

Abstract: The velocity of sound at the time of 100-ton shot at Trinity was measured to be 1116.1 ft/sec. Values of blast pressure computed from the excess velocity are given, but are not considered as reliable.

Report presenting an investigation of the characteristics of partial-span spoilers located at 0.75 of the chord on an NACA 66-series tapered wing, especially at high speeds. The effect of small spoiler projections was found to increase with an increase in speed until the critical Mach number was exceeded.

Abstract. Methods for determination of both uranium and nickel in solutions of these metals are described. Alloys can be dissolved in nitric acid treated with citric acid to complex the uranium, and the nickel precipitated as nicked dimethylglyoxime. The uranium is reduced and titrated with standard ceric sulfate. These methods are for the determination of macro amounts of uranium and nickel with errors on the order of 0.1%.

Report presenting a series of tests to determine the bearing yield and ultimate strengths of samples of 1/4- and 2-inch-thick plate of aluminum alloy 24S-T and to establish nominal ratios of bearing-to-tensile properties for the commercial range of plate thicknesses. Results regarding individual bearing testing, ratios of average bearing to tensile properties, and ratios of bearing yield strength to tensile yield strength are provided.

From Summary: "A theoretical investigation was made of the behavior of a cantilever beam in rotational motion about a transverse axis through the root determining the stresses, the deflections, and the accelerations that occur in the beam as a result of the arrest of motion. The equations for bending and shear stress reveal that, at a given percentage of the distance from root to tip and at a given trip velocity, the bending stresses for a particular mode are independent of the length of the beam and the shear stresses vary inversely with the length. When examined with respect to a given angular velocity instead of a given tip velocity, the equations reveal that the bending stress is proportional to the length of the beam whereas the shear stress is independent of the length."

From Summary: "Column and plate compressive strengths of 17S-T aluminum-alloy sheet were determined both within and beyond the elastic range from tests of thin-strip columns and from local-instability tests of formed Z- and channel-section columns. These tests are part of an extensive research investigation to provide data on the structural strengths of various aircraft materials. Results are presented in the form of curves and charts that may be used in the design and analysis of aircraft structures."

"Column and plate compressive strengths of 24S-T aluminum-alloy sheet were determined both within and beyond the elastic range from tests of thin-strip columns and from local-instability tests of formed Z-end channel-section columns. These tests are the first of a series in an extensive research investigation to provide data on the structural strength of various aircraft materials. The results, which are presented in the form of curves and charts that may be used in the design and analysis of aircraft structures, supersede preliminary results published previously" (p. 1).

Two-dimensional data were obtained in Mach range of from 0.40 to 0.94 and Reynolds Number range of (3.4 - 4.2) X 10 Degrees. Results indicate that thickness ratio is dominating shape parameter at high Mach numbers and that aerodynamic advantages are attainable by using thinnest possible sections. Effects of jet boundaries, Reynolds Number, and Data presented are free from jet-boundary and humidity effects.

Technical report on the studies that have been made on the composition and thermal decomposition of uranyl peroxide. The conditions of precipitation and drying have been found to have no appreciable effect on the composition of the compound, but do affect the physical appearance of the precipitate and the rate of thermal decomposition. The UO4 + 2H2O appears to be thermodynamically unstable with respect to UO3 at 25 degrees C and atmospheric pressure, although the rate of conversion is extremely slow. The UO4 + 2H2O is completely converted to UO3 on standing at 150 degrees C and atmospheric pressure for two weeks. Partially decomposed uranyl peroxide samples contain extra oxygen which is released on immersing the sample in water.

"Typical thrust and torque coefficients and increments, due to the propeller, in the ratio of the dynamic pressure at the tail to the free-stream dynamic pressure are presented for 10 full-scale airplanes. Calculations indicate that an error of about 2 percent mean aerodynamic chord appears possible in determining the neutral point from wind-tunnel tests or a model in the gliding condition if the propeller is operated at zero thrust rather than at the values of thrust coefficient indicated by the flight tests" (p. 1).

From Summary: "An analysis of the nose-inlet shapes developed in previous investigations to represent the optimum from the standpoint of critical speed has shown that marked similarity exists between the nondimensional profiles of inlets which have widely different proportions and critical speeds. With the nondimensional similarity of such profiles established, the large differences in the critical speeds of these nose inlets must be a function of their proportions. An investigation was undertaken in the Langley 8-foot high-speed tunnel to establish the effects of nose-inlet proportions on critical Mach number to develop a rational method for the design of high-critical-speed nose inlets to meet desired requirements."

Report presenting results of a full-scale horizontal tail surface made to determine the effect of elevator-profile modifications and trailing-edge strips on the elevator hinge-moment characteristics for elevators having fixed plan plan form and constant balance. Results regarding the basic data with the metal elevator, effect of trailing-edge angle, effect of nose shape, and effects of trailing-edge strips are provided.

Report presenting an investigation of a full-scale horizontal tail surface to determine the elevator-fabric deflection at high speeds and the aerodynamic effects of the fabric deflection. Two fabric-covered elevators differing only in rib spacing and a solid wooden elevator were tested. Results regarding fabric deflection and aerodynamic characteristics are provided.

Efficiency tests have been conducted on a single-stage impulse engine having an 11-inch pitch-line diameter wheel with inserted buckets and a fabricated nozzle diaphragm. The tests were made to determine the effect of inlet pressure, Inlet temperature, speed, and pressure ratio on the turbine efficiency. An analysis is presented that relates the effect of inlet pressure and temperature to the Reynolds number of the flow. The agreement between the analysis and the experimental data indicates that the changes in turbine efficiency with Inlet pressure and temperature may be principally a Reynolds number effect.

Report discussing the effect of internal coolants on the knock-limited performance of a liquid-cooled multicylinder aircraft engine. Both water and water-ethanol mixtures were tested at several carburetor-air temperatures. Fuel-nozzle injection of the coolant was found to be more effective than injection through intake-manifold spray jets.

Report discussing the results of power-off wind tunnel tests of a twin-engine cargo airplane equipped with wheel skis. Stability characteristics are described for two flap positions and three ski positions. The effect of fairing the main skis in the retracted position on the drag coefficient is also described.

Report presenting an investigation to determine the effect of varying the carburetor throttle settings on the flow characteristics at the outlet of the supercharger inlet elbow. Air flow tests were made at several carburetor throttle settings ranging from open to closed. Results regarding distortion and turbulence are provided.

Report presenting the results of a theoretical and experimental investigation of wall interference for an airfoil spanning a closed-throat circular wind tunnel.

Report presenting an investigation of the use of ethylene dibromide to leaded fuel in order to prevent lead deposits within the cylinder. It is meant to react with lead to form volatile compounds that will be scavenged with exhaust gases. Results regarding the lead deposits, knock-limited effective pressures, performance, and temperatures are provided.

Report presenting tests of a powered model of the Boeing XPBB-1 flying boat in order to observe the effects of trim and powered propellers, of lengths of forebody and afterbody, and of various spray strips on the low-speed spray characteristics. The effects of powering the propellers were to lower the trim and to pick up spray that would not strike the propeller disks when the propellers were windmilling. Results regarding the effects of trim and powered propellers, effect of length of forebody and afterbody, effect of angle of dead rise, and effect of various spray strips are provided.

Report comparing the drag of an airplane with a conventional body with that of an airplane carrying cargo in a detachable airfoil-shaped body. Information about the performance, longitudinal stability, and control characteristics of a lifting-body cargo airplane is also provided and compared with a conventional cargo airplane.

Report presenting a concept of a simplified vortex system of a rotor wake in order to obtain a formula for the normal component of induced velocity along the fore-and-aft diameter of the rotor disk of a helicopter rotors.

Report presenting flight tests with a P-47D airplane to determine the flow characteristics on a section of the upper surface of the wing. The behavior of the wool tufts used to measure these characteristics was determined from motion pictures. The results indicated that the flow remained smooth over the test panel until the critical Mach number was exceeded by 0.08 at lift coefficient 0.10 and by 0.05 at a lift coefficient of 0.50.