Report presenting an investigation of the flutter of a small one-blade wooden propeller with a Clark Y section. The highest flutter speeds were found in the vicinity of the angle of zero aerodynamic moment, with flutter speed increasing in this region with decreasing pressure.

Report presenting a survey of two-dimensional data on trim changes near maximum lift resulting from deflection of various types of leading-edge and trialing-edge high lift devices. Results regarding pitching-moment coefficients, pitching-moment increments, and maximum lift coefficients are provided.

Report issued by the Bureau of Mines over motor-fuels sold during the summer of 1949. The properties of the fuels sampled are presented. This report includes tables, and graphs.

"A flight test of the Aero jet Engineering Corporation's 7KS-6000 T-27 Jato rocket motor was conducted at the Langley Pilotless Aircraft Research Station at Wallops Island, Va, to determine the flight performance characteristics of the motor. The flight test imposed an absolute longitudinal acceleration of 9.8 g upon the rocket motor at 2.8 seconds after launching. The total impulse developed by the motor was 43,400 pound-seconds, and the thrusting time was 7.58 seconds" (p. 1).

Report presenting a theoretical solution for the buckling of Alclad plates on the basis of plasticity theory. Both the differential equation of equilibrium of the buckled plate and energy expression are provided. Results regarding the buckling of long simply supported plates under longitudinal compression and under shear and for a plate column are provided.

A simplified lifting-surface theory that includes effects of compressibility and spanwise variation of section lift-curve slope is used to provide charts with which antisymmetric loading due to arbitrary antisymmetric angle of attack can be found for wings having symmetric plan forms with a constant spanwise sweep angle of the quarter-chord line. Consideration is given to the flexible wing in roll. Aerodynamic characteristics due to rolling, deflected ailerons, and sideslip of wings with dihedral are considered. Solutions are presented for straight-tapered wings for a range of swept plan forms.

Report discussing the progress made on a research project for the preparation of ductile zirconium during November 1949.

From introduction: During 1948, the Isotope Research and Production Division undertook to obtain small quantities of nearly pure mercury isotopes by electromagnetic isotope separation. The possible use of a mercury isotope of even-numbered mass to establish an international standard of length required an isotopic purity greater than 99 per cent. It, became apparent that this degree of separation could only be achieved by preventing random diffusion of un-ionized mercury which otherwise would contaminate the isotope collectors.

Report presenting a simplified method for obtaining free-flight measurements of damping in roll through the use of rocket-powered models. Initial configurations have been tested for a range of Mach numbers. Results regarding the rolling velocity with two different airfoil sections and damping-in-roll coefficient are provided.

Report presenting the pressure-recovery characteristics of a model with two scoops situated on the aft position of a long forebody and connected through diffusors to a common settling chamber at a range of Mach numbers. The effects of interaction between the flow in the two air-induction systems and of varying the mass flow through the boundary-layer scoops were studied. Results at several different angles of attack are provided.

Memorandum presenting a calculation of the amount of possible correction for coordinated turns with limited bank angle and level sideslips for a large transport airplane, the C-54D. The results indicate that for all instances from the end of the runway, coordinated turns are the more effective maneuver.

Report presenting a low-speed wind-tunnel investigation to determine the characteristics of deflectable wing-tip ailerons on an untapered 45 degree sweptback semispan wing. Ailerons with triangular and parallelogram plan forms with a maximum chord of 0.625 wing chord and a flat-plat profile were investigated. The aerodynamic characteristics in pitch and lateral control characteristics are included.

An investigation of a 1/18-scale dynamically similar model of the North American B-45 airplane was made to observe the ditching behavior and determine the proper landing technique to be used in an emergency water landing. Various conditions of damage were simulated to determine the behavior which probably would occur in a full-scale ditching. The behavior of the model was determined from high-speed motion-picture records, time-history acceleration records, and visual observations. It was concluded that the airplane should be ditched at the maximum nose-high attitude with the landing flaps full down for minimum landing speed. During the ditching, the nose-wheel and bomb-bay doors probably will be torn away and the rear of the fuselage flooded. A violent dive will very likely occur. Longitudinal decelerations of approximately 5g and vertical accelerations of approximately -6g (including gravity) will be experienced near the pilots' compartment. Ditching braces installed in the bomb bay will tend to improve the behavior slightly but will be torn away along with the bomb-bay doors. A hydroflap installed ahead of the nose-wheel doors will eliminate the dive and failure of the nose-wheel doors, and substantially reduce the motions and accelerations.

Report issued by the Bureau of Mines on the manganese deposits in Tooele County, Utah. The physical features, geology, and descriptions of the deposit samples are listed. This report includes tables, and illustrations.

Report discussing the U.S. Geological Survey's investigation of radioactive element samples found in the Candle Creek area on the Seward Peninsula of Alaska.

Report issued by the Bureau of Mines regarding studies conducted on zinc-lead mines in Clark County, Nevada. Physical qualities of the mine, equipment used, and methods of sampling are presented. This report includes tables, and maps.

"The following report is meant to serve a two fold purpose. First, it is the quarterly report of the homogeneous reactor project for the Technical Division of Oak Ridge National Laboratory. Secondly, it is a description and general feasibility discussion of a 200-1000 K.W. pilot model, homogeneous reactor."

Memorandum presenting a method for varying the mass flow of supersonic inlets with a circular cross section and a central body. The method consists of changing the size of the entering stream tube by means of an inflatable boot on the surface of the central body.

A report regarding pegmatites of the Errington-Theil mine, Elko County, Nevada.

Memorandum presenting wind-tunnel tests of a semispan model of a hypothetical supersonic airplane to determine the static longitudinal stability and control characteristics of the airplane throughout the range of subsonic Mach numbers up to 0.95. The model had a long slender fuselage and a wing and horizontal tail of aspect ratio 4 and taper ratio 0.5. Results regarding the force and moment characteristics, wing wake and effective downwash at the horizontal tail, effects of compressibility, and longitudinal characterisitcs with the flaps deflected are provided.

Report presenting testing of a cambered and twisted wing with constant-chord elevons with a slender fuselage to determine the longitudinal and lateral control from the elevons for a range of Mach numbers. Results regarding lift, drag, pitching-moment, and rolling-moment characteristics for various elevon deflections are provided.

Report discussing an experiment to reinvestigate the spontaneous fission of 48 (Pu-238) in an effort to determine a more accurate value for the spontaneous fission constant that was found in a previous experiment.

In order to obtain insight into the flow conditions on tail surfaces on airplanes during spins, pressure-distribution measurements were performed on a rotating model of the design BFW-M31. For the time being, the tests were made for only one angle of attack (alpha = 60 degrees) and various angles of yaw and rudder angles. The results of these measurements are given; the construction of the model, and the test arrangement used are described. Measurements to be performed later and alterations planned in the test arrangement are pointed out.

"An investigation was made to evaluate the hydrodynamic qualities of a 0.425-scale model of the Navy XP5M-1 hull, which was installed on a modified Navy J4F-2 amphibian. Longitudinal and directional stability during take-off and landing, low-speed maneuverability, spray characteristics, and take-off performance were investigated. The behavior of the airplane in moderately rough water was also observed. The opinions of three pilots have been correlated with the data" (p. 1).