UNT Libraries Government Documents Department - 19 Matching Results

Search Results

Aerodynamic heating and the deflection of drops by an obstacle in an air stream in relation to aircraft icing

Description: From Summary: "Two topics of interest to persons attempting to apply the heat method of preventing ice formation on aircraft are considered. Surfaces moving through air at high speed are shown, both theoretically and experimentally, to be subject to important aerodynamic heating effects that will materially reduce the heat required to prevent ice. Numerical calculations of the path of water drops in an air stream around a circular cylinder are given. From these calculations, information is obtained on the percentage of the swept area cleared of drops."
Date: October 1940
Creator: Kantrowitz, Arthur

Blueberries.

Description: Discusses aspects of blueberry production in the United States from planting through harvesting and marketing, and examines different types of blueberries.
Date: October 1940
Creator: Darrow, George M. (George McMillan), 1889-

The cause of welding cracks in aircraft steels

Description: The discussion in this article refers to gas welding of thin-walled parts of up to about 3 mm thickness. It was proven that by restricting the sulphur, carbon, and phosphorous content, and by electric-furnace production of the steel, it was possible in a short time to remove this defect. Weld hardness - i.e., martensite formation and hardness of the overheated zone - has no connection with the tendency to weld-crack development. Si, Cr, Mo, or V content has no appreciable effect, while increased manganese content tends to reduce the crack susceptibility.
Date: October 1, 1940
Creator: Muller, J

Corrections on the thermometer reading in an air stream

Description: A method is described for checking a correction formula, based partly on theoretical considerations, for adiabatic compression and friction in flight tests and determining the value of the constant. It is necessary to apply a threefold correction to each thermometer reading. They are a correction for adiabatic compression, friction and for time lag.
Date: October 1, 1940
Creator: Van Der Maas, H J & Wynia, S

Full-Scale Tests of Several Propellers Equipped with Spinners, Cuffs, Airfoil and Round Shanks, and NACA 16-Series Sections, Special Report

Description: Wind-tunnel tests of several propeller, cuff, and spinner combinations were conducted in the 20 foot propeller-research tunnel. Three propellers, which ranged in diameter from 8.4 to 11.25 feet, were tested at the front end of a streamline body incorporating spinners of two diameters. The tests covered a blade angle range from 20 deg to 65 deg. The effect of spinner diameter and propeller cuffs on the characteristics of one propeller was determined. Test were also conducted using a propeller which incorporated aerodynamically good shank sections and using one which incorporated the NACA 16 series sections for the outer 20 percent of the blades. Compressibility effects were not measured, owing to the low testing speeds. The results indicated that a conventional propeller was slightly more efficient when tested in conjunction with a 28 inch diameter spinner than with a 23 inch spinner, and that cuffs increased the efficiency as well as the power absorption characteristics. A propeller having good aerodynamic shanks was found to be definitely superior from the efficiency standpoint to a conventional round-shank propeller with or without cuffs; this propeller would probably be considered structurally impracticable, however. The propeller incorporating the NACA 16 series sections at the tims were found to have a slightly higher efficiency than a conventional propeller; the take-off characteristics appeared to be equally good. The effects noted above probably would be accentuated at helical speeds at which compressibility effects would enter.
Date: October 1940
Creator: Biermann, David; Hartman, Edwin P. & Pepper, Edward

Internal-flow systems for aircraft

Description: An investigation has been made to determine efficient arrangements for an internal-flow system of an aircraft when such a system operates by itself or in combination with other flow systems. The investigation included a theoretical treatment of a problem and tests in the NACA 5-foot vertical wind tunnel of inlet and outlet openings in a flat plate and in a wing. When an internal-flow system tends to decrease the final velocity of it's wake, the results showed that it should be arranged in series with the propulsive system; the inlet opening should be located at a forward stagnation point; and the outlet opening should be so shaped and located as to recover the kinetic energy of the jet without increasing the drag of other portions of the aircraft. When an internal-flow system tends to increase the final velocity new b's wake, as does a propeller, location of the inlet opening in the boundary layer or in the wake of the wing or in the fuselage may be desirable.
Date: October 1, 1940
Creator: Rogallo, F M

Investigations of the parasites of Popillia japonica and related scarabaeidae in the Far East from 1929 to 1933, inclusive.

Description: Describes the results of scientific research of parasites of the Japanese beetle at various stages of the beetle life cycle. The studies were carried out from 1929 to 1933 in Japan, Chosen (Korea), India, and Taiwan.
Date: October 1940
Creator: Gardner, T. R. (Theodore Roosevelt), b. 1899. & Parker, L. B. (Lawrence Bemis), 1901-

Lettuce growing.

Description: A guide to lettuce growing, including soil preparation, planting, cultivation, control of insect pests; also discusses the lettuce market.
Date: October 1940
Creator: Beattie, W. R. (William Renwick), b. 1870

Mathematical analysis of aircraft intercooler design

Description: A mathematical analysis has been made to show the method of obtaining the dimensions of the intercooler that will use the least total power for a given set of design conditions. The results of this analysis have been used in a sample calculation and, on the basis of this calculation, a new inter cooler arrangement is suggested. Because the length of the two air passages of the new arrangement is short in comparison with the third dimension, the height of the intercooler, this intercooler arrangement has unusual dimensions. These dimensions give the proposed intercooler arrangement an advantage over one of usual dimensions because less total power will be consumed by the intercooler, the weight and volume of the intercooler will be smaller, and the pressure drop of both the engine air and the cooling air in passing through the intercooler will be lower.
Date: October 1, 1940
Creator: Joyner, Upshur T

Measured moments of inertia of 32 airplanes

Description: A compilation of the experimentally determined moments of inertia of 32 airplanes is presented. The measurements were obtained at the laboratories of the naca by means of a pendulum method. The airplanes tested are representative of several types of aircraft of gross weight less than 10,000 pounds. The results are presented in coefficient as well as in dimensional form. An elementary analysis of the data disclosed the possibility of grouping the results according to wing type of the airplane, as low-wing monoplanes, parasol and high-wing monoplanes, and biplanes. The data are shown to provide a convenient means of rapidly estimating the moments of inertia of other airplanes. A three view drawing of each of the 32 airplanes is included.
Date: October 1, 1940
Creator: Gracey, William

Notes on the stalling of vertical tail surfaces and on fin design

Description: A discussion is given of the important aspects of the stalling of vertical tail surfaces. The type of instability encountered is described and the possibilities of inadvertent occurrence are noted. The influence of directional flight tests on the behavior of a airplane when the tail stall takes place is discussed. In this connection, flight tests of a twin-engine airplane in which the vertical fin area was increased are cited. The reasons for inadequate directional stability in certain modern designs are accounted for and the properties and applications of dorsal fins are discussed. In addition, the chief factors regulating the requirements for conventional area are given, in which connection simplified criterion for directional stability is presented. It may be concluded that the stalling of vertical tail surfaces is not in itself a dangerous condition. Provided sufficient directional stability exists at large angles of sideslip, the tail stall may occur with modern airplanes, as with those of the past, without the knowledge or concern to the pilot.
Date: October 1, 1940
Creator: Thompson, F L & Gilruth, R R

Packing apples in boxes.

Description: Discusses the practicality of packing apples in boxes for shipment, the construction of packing houses, and methods of wrapping. Includes diagrams of apple packs.
Date: October 1940
Creator: Pailthorp, Raymond R., 1889- & Kinsey, Frank S. (Frank Stewart), 1881-

Resonance vibrations in intake and exhaust pipes of in-line engines III : the inlet process of a four-stroke-cycle engine

Description: Using a previously developed method, the boundary process of four-stroke-cycle engines are set up. The results deviate considerably from those obtained under the assumption that the velocity fluctuation is proportional to the cylinder piston motion. The deviation is less at the position of resonance frequencies. By the method developed, the effect of the resonance vibrations on the volumetric efficiency can be demonstrated.
Date: October 1, 1940
Creator: Lutz, O