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A Method for Estimating Heat Requirements for Ice Prevention Gas Heated Hollow Propeller Blades
Report presenting a method for determining the temperature and flow of heated gas necessary for ice prevention of hollow propeller blades in flight and icing conditions. A variety of conditions are taken into consideration and suggested simplifications and short methods are provided in order to not overcomplicate the design modifications.
Date:
December 1947
Creator:
Gray, V. H. & Campbell, R. G.
System:
The UNT Digital Library
An Investigation Utilizing an Electrical Analogue of Cyclic Deicing of a Hollow Steel Propeller with an External Blade Shoe
"A study has been made of the heat requirement for the cyclic de-icing of hollow steel propellers fitted with external blade heating shoes. Solutions to the equations for the heat flow in cyclic heating of propellers were obtained, using an electrical analogy. The study showed how the energy requirement for propeller de-icing with existing blade shoes could be decreased, and illustrated the effect of blade-shoe design on the energy requirement. It was demonstrated, for example, that by increasing the heating intensity and decreasing the heating period from those currently used the energy requirement could be decreased in the order of 60 percent" (p. 1).
Date:
December 1952
Creator:
Neel, Carr B., Jr.
System:
The UNT Digital Library
Effect of Type of Porous Surface and Suction Velocity Distribution on the Characteristics of a 10.5 Percent-Thick Airfoil With Area Suction
Note presenting an investigation at low speed of the two-dimensional characteristics of a 10.51-percent-thick symmetric airfoil with area suction for boundary-layer control near the leading edge. The lift and suction-flow characteristics were determined with different porous surfaces consisting of perforated plates and sintered steel for various suction velocity distributions obtained by varying the permeability arrangement.
Date:
December 1953
Creator:
Dannenberg, Robert E. & Weiberg, James A.
System:
The UNT Digital Library
Experimental Droplet Impingement on Four Bodies of Revolution
An experiment was conducted to obtain the rate and area of cloud droplet impingement on four bodies of revolution was conducted in the icing tunnel with a dye-tracer technique. The study included several forebody shapes of different fineness ratios over a range of angles of attack and rotational speeds. Results regarding velocity distribution, local impingement characteristics, and correlation of impingement characteristics are provided.
Date:
December 1957
Creator:
Lewis, James P. & Ruggeri, Robert S.
System:
The UNT Digital Library
The Calculation of the Heat Required for Wing Thermal Ice Prevention in Specified Icing Conditions
Note presenting a verification of previously derived equations for calculating the rate of heat transfer from airfoils in icing conditions, which have come about as a result of an investigation of the meteorological conditions conducive to the formation of ice on aircraft and a study of the process of airfoil thermal ice prevention. The results indicated that knowledge of these components has increased to a point where the design of heated wings on a fundamental, wet-air basis can now be undertaken with reasonable certainty.
Date:
December 1947
Creator:
Neel, Carr B., Jr.; Bergrun, Norman R.; Jukoff, David & Schlaff, Bernard A.
System:
The UNT Digital Library
General Correlation of Temperature Profiles Downstream of a Heated Air Jet Directed at Various Angles to Air Stream
An experimental investigation was conducted to determine the temperature profiles downstream of heated air jets directed at angles of 90 deg, 60 deg, 45 deg, and 30 deg to an air stream. The profiles were determined at two positions downstream of the jet as a function of jet diameter, jet density, jet velocity, free-stream density, free-stream velocity, jet total temperature, orifice flow coefficient, and jet angle. A method is presented which yields a good approximation of the temperature profile in terms of the flow and geometric conditions.
Date:
December 1952
Creator:
Ruggeri, Robert S.
System:
The UNT Digital Library
Statistical Explanation of Spontaneous Freezing of Water Droplets
Note presenting a statistical theory based on the presence of small crystallization nuclei suspended in water developed to explain experimental results showing that, on average, small droplets can be supercooled to lower temperatures than large ones. The average behavior of supercooled droplets is reproduced on the basis of probability theory with an assumed distribution of crystallization nuclei with respect to the temperatures at which the nuclei cause freezing.
Date:
December 1950
Creator:
Levine, Joseph
System:
The UNT Digital Library
Experimental Droplet Impingement on Several Two-Dimensional Airfoils with Thickness Ratios of 6 to 16 Percent
"The rate and area of cloud droplet impingement on several two-dimensional swept and unswept airfoils were obtained experimentally in the NACA Lewis icing tunnel with a dye-tracer technique. Airfoil thickness ratios of 6 to 16 percent; angles of attack from 0 deg to 12 deg, and chord sizes from 13 to 96 inches were included in the study. The data were obtained at 152 knots and are extended to other conditions by dimensionless impingement parameters" (p. 1).
Date:
December 1956
Creator:
Gelder, Thomas F.; Smyers, William H., Jr. & von Glahn, Uwe
System:
The UNT Digital Library
Progress Made in the Construction of Giant Airplanes in Germany During the War
The construction of giant airplanes was begun in Germany in August, 1914. The tables annexed here show that a large number of airplanes weighing up to 15.5 tons were constructed and tested in Germany during the War, and it is certain that no other country turned out airplanes of this weight nor in such large numbers. An examination of the tables shows that by the end of the War all the manufacturers had arrived at a well-defined type, namely an airplane of about 12 tons with four engines of 260 horsepower each. The aircraft listed here are discussed with regard to useful weight and aerodynamic qualities.
Date:
December 1920
Creator:
Baumann, A.
System:
The UNT Digital Library
Design of Recording Wind Tunnel Balances
Given here is a description of the design of a scientific recording wind tunnel balance. It was decided that the most satisfactory arrangement would be a rigid ring completely surrounding the tunnel or wind stream, so that the model could be supported from it by wires or any arrangement of spindles. The forces and moments acting on this ring can then be recorded by suitable weighing apparatus. The methods available for recording forces on the arms are explained. The proposed type of balance will support the model rigidly in a variety of ways, will make a complete test without attention, and will plot the results so that all computations are avoided.
Date:
December 1920
Creator:
Norton, F. H.
System:
The UNT Digital Library
Ground Influence on Aerofoils
The question of ground influence on airplanes has recently attracted some attention in view of the claims made by certain designers that the landing speed of their airplanes is much decreased by an increase in lift coefficient due to the proximity of the ground in landing. The results of wind tunnel tests indicate that ground effect is not entirely beneficial. It decreases the landing speed and cushions the landing shock somewhat. However, it does so at the expense of an increased length of preliminary skimming over the ground.
Date:
December 1921
Creator:
Raymond, Arthur E.
System:
The UNT Digital Library
High thermal efficiency in airplane service
Described here is a method by which high average fuel economy has been achieved in aircraft engines. Details are given of the design of certain foreign engines that employ an unusual type of fuel-air ratio control in which the change in power produced by a mixture change is due almost entirely to the change in the power producing ability of the unit weight of the mixture. The safety and performance features of this type of control are explained.
Date:
December 1920
Creator:
Sparrow, S. W.
System:
The UNT Digital Library
The Steadiness Factor in Engine Sets
Technical notes discussing the steadiness factor in engines and the calculations that can be used to arrive at it. Factors affecting the steadiness factor are detailed, including the mass of parts, torque, engine rotation, and power.
Date:
December 1920
Creator:
Margoulis, W.
System:
The UNT Digital Library
A Variable Speed Fan Dynamometer
Fan brakes used as absorption dynamometers in testing internal combustion engines have the disadvantage that a given fan will run only at one speed when the engine is delivering full power. In order to be able to vary the speed at which a given power will be absorbed, English manufacturers have for some time been using a cylindrical housing around the fan with one or two variable openings in the periphery. Here, results are given of tests conducted to determine how great a range of speed can be obtained from such a device.
Date:
December 1920
Creator:
Wood, Karl D.
System:
The UNT Digital Library
Mutual Influence of Wings and Propeller
Report presenting an experiment consisting of an aerofoil and propeller in order to discover the mutual influence between the two components and variations in moment due to the propeller influence.
Date:
December 1921
Creator:
Prandtl, L.
System:
The UNT Digital Library
Effects of Varying the Relative Vertical Position of Wing and Fuselage
"The object of this series of experiments was to determine the influence of the relative vertical position of wing and fuselage on the efficiency of the wing. Since the longitudinal position of the wing can be varied but slightly with reference to the center of gravity in a normal airplane, it was kept constant in the experiments to be described and only the vertical position of the wing with reference to the fuselage was varied" (p. 1).
Date:
December 1921
Creator:
Prandtl, L.
System:
The UNT Digital Library
Instrument for measuring engine clearance volumes
With the advent of the V type engine, a new method to measure the clearance volume in cylinders was needed. It was suggested that this measurement could be made by a process which consisted essentially of simultaneously changing both a known and unknown volume of gas by a known amount and then calculating the magnitude of the unknown from the resulting difference in pressure between the two. An instrument based on this design is described.
Date:
December 1920
Creator:
Sparrow, S. W.
System:
The UNT Digital Library
Experiments With Fabrics for Covering Airplane Wings, to Determine Effect of Method of Installation
Note presenting some information on the effect of changes in the loading and in the disposition of the supporting framework on the covering fabric. The magnitude of the air forces to be taken into account and the corresponding factors of safety to be expected will be covered in a future report. Tables regarding some of these fabric characteristics are provided.
Date:
December 1923
Creator:
Pröll, A.
System:
The UNT Digital Library
Reduction in Efficiency of Propellers Due to Slipstream
"In the slipstream behind a propeller there is a considerable amount of kinetic energy which has been imparted to it by the engine without producing any corresponding propeller thrust. The increased absorption of power reduces the propeller efficiency. Attention has been previously directed to this question by Bendemann and Madelung and other writers. Their contribution serves to verify a simple method of calculating the reduction in the propeller efficiency due to the slip stream" (p. 1).
Date:
December 1923
Creator:
Munk, Max M.
System:
The UNT Digital Library
Compressive Strength of Tapered Airplane Struts
Note presenting methods for ascertaining the value of n in Euler's simplified formula, which can be used for the compressive strength of tapered airplane struts, by estimating from curves and by calculation.
Date:
December 1923
Creator:
Lewe, Viktor
System:
The UNT Digital Library
Further Information on the Laws of Fluid Resistance
Note presenting experiments with cylinders of different shapes and some of the strange phenomena that manifested in connection with the cylinder.
Date:
December 1922
Creator:
Wieselsberger, C.
System:
The UNT Digital Library
The Nichols Wing Cutting Equipment
Described here is wing cutting equipment for the economical production of metal wings for wind tunnel models. The machine will make any size of constant-section wing or strut up to one-sixth inch chord by 36-inch span and up to a thickness of one and one-quarter inches. It cuts a smooth, true model that is accurate to within two-thousandths of an inch on any ordinate. The holding jaws are so designed as to leave the model free of chip marks, and the only hand finishing necessary after the cutting is a rub with amunite to remove burrs. The actual change on ordinate in this finishing rub is less than .0002 inches.
Date:
December 1923
Creator:
Ford, James B.
System:
The UNT Digital Library
A Mechanical Device for Illustrating Airplane Stability
An instrument is described which will illustrate completely in a qualitative sense the longitudinal stability characteristics of an airplane. The instrument is primarily of use for the lecture room, but it is hoped that ultimately it will be possible to obtain quantitative results from it.
Date:
December 1921
Creator:
Norton, F. E.
System:
The UNT Digital Library
Introduction to the Problem of Rocket-Powered Aircraft Performance
An introduction to the problem of determining the fundamental limitations on the performance possibilities of rocket-powered aircraft is presented. Previous material on the subject is reviewed and given in condensed form along with supplementary analyses. Some of the problems discussed are: 1) limiting velocity of a rocket projectile; 2) limiting velocity of a rocket jet; 3) jet efficiency; 4) nozzle characteristics; 5) maximum attainable altitudes; 6) ranges. Formulas are presented relating the performance of a rocket-powered aircraft to basic weight and nozzle dimensional parameters. The use of these formulas is illustrated by their application to the special case of a nonlifting rocket projectile.
Date:
December 1947
Creator:
Ivey, H. Reese; Bowen, Edward N., Jr. & Oborny, Lester F.
System:
The UNT Digital Library