Refine Your Search

Topic

Author

Affiliation

Search Results

Technical Paper

Methods of Building Metal Airplane Structures

1928-01-01
280029
USEFUL load-carrying capacity is a measure of the comparative value of two airplanes of the same size, having identical powerplants, speed, rate of climb and other flying characteristics. It seems to be feasible to combine in the same airplane both the greatest ability to carry useful load and the least cost of construction. Blanked and pressed metal work offers substantial advantage to the extent that parts, particularly sub-assemblies, can be made directly by machine in complete units ready to set in the final assembly. The author shows and describes the methods followed by his organization in forming the members, building the frames and assembling the units of metal aircraft. Trusses are blanked and the web members pressed to ¾-circle form. Dies for long members are variable in length by being made in pieces that can be removed or inserted as desired. Flanged-tube sections are employed for truss chords.
Technical Paper

Shock- Absorber Characteristics

1928-01-01
280019
AN effort is made to determine the essentials of an ideal shock-absorber and to describe the types that approach or depart from this ideal. Mathematical analysis is not used, but judgment is based on the experience of the author with various types. The requirements of a satisfactory shock-absorber are defined and the methods used by the author in culling out certain shock-absorbers that fail to meet these requirements are outlined. By means of a machine based on the principle, of a steam-engine indicator, the energy required to move a shock-absorber throughout its cycle at varying speeds is measured and charts are obtained. When these charts are compared with a characteristic shape of diagram of a shock-absorber found from repeated trials on the road to give the most satisfactory riding, the merits or shortcomings of any other shock-absorber can be deduced from the difference in shape.
Technical Paper

Service Aviation, Aeronautical Engineering and Commercial Aviation

1927-01-01
270068
INFLUENCE that the research and development work done in aeronautics by the naval and military services has had in the advancement of design and construction of airplanes and aircraft engines suitable for commercial operations is pointed out and exemplified by citing a few instances of direct adaptability of military types of airplane to commercial uses. Nearly all of this work would have been done much later or not at all if the airplane had been purely a commercial vehicle, but the constructor for purely commercial purposes and the commercial operator have had the benefit of it. Major fundamentals, such as speed, safety, reliability and economy, are the same in both types of aviation; divergencies between the requirements for the two kinds of service begin to appear in materiel, personnel, or methods of operation only at a somewhat advanced stage of evolution.
Technical Paper

Aircraft Propellers

1929-01-01
290059
NEARLY all the aircraft propellers used by both the Army and the Navy are of the detachable-blade type. The Navy has found it necessary to make its own designs and to furnish the propeller manufacturers with finished detail drawings. The author lists the sources from which data can be obtained and shows a chart from which can be found a diameter and setting of a pair of detachable blades that will give reasonably good performance for nearly any horsepower, revolutions per minute and airspeed commonly used with the direct-drive type of propeller. Discrepancies between model tests and wind-tunnel tests are cited, and the author then considers the subject theoretically. Substitute propellers are next considered, and also the strength of propellers.
Technical Paper

Gearing of Aircraft Propellers

1929-01-01
290062
FOLLOWING a brief outline of the development of aircraft propellers and a statement of the most important fundamentals of propeller design, the authors discuss the problem of propellers for use on geared-down engines, this being the installation of reduction gearing between the crankshaft of the engine and the propeller hub when the increase of airplane-performance characteristics more than offsets the added complication of the installation. The advantages and the disadvantages of using reduction gearing are considered. Concerning the installation of reduction gears, the authors state that the decision whether to use gears or not must result from a compromise between the gains and the losses involved and the amount of net gain depends largely upon the particular engine and airplane combination and its designed performance.
Technical Paper

Service Characteristics of Light Alloys

1929-01-01
290064
ALUMINUM and magnesium, being the lightest commercial metals and therefore the most suitable for aircraft construction, are discussed in their pure and alloyed states. Physical properties of the pure metals and their alloys are given and the effects of adding small quantities of alloying elements are shown. Heat-treating as a means of increasing the strength per unit weight of the alloys is discussed at length, together with the effects of natural aging and artificial aging at elevated temperatures and of quenching in hot and in cold water after heat-treating. The several types of corrosion are considered and resistance to corrosion of the metals and their various alloys are discussed. Protection afforded to aluminum alloy by a surface coating of pure aluminum is described, and other methods are mentioned.
Technical Paper

Modern Naval Aircraft

1927-01-01
270072
MORE and more is being demanded of Navy airplanes beyond the requirements of commercial planes. Catapulting and deck landings are required of some planes and corrosion must be guarded against. Bombers and fighting planes each have their special requirements, and planes must be able to land safely on either land or water. The most important developments in aerodynamics now going on are to restrict the travel of the center of pressure of the wings as the angle of attack changes; but widespread adoption of slotted wings and other results of experimental development may be expected. Metal is being used more than formerly in structural work but there are as yet no all-metal service-types in the Navy. Chrome-molybdenum steel is replacing mild carbon-steel in the tubular frames of fuselages, and there is a tendency to seek substitutes for welded joints. Duralumin is slowly replacing steel where welding is not required, but its adoption is retarded because of corrosion.
Technical Paper

Modern Light Alloys and Their Application to Aircraft-Engine Design

1929-01-01
290063
A NUMBER of the more important commercial alloys having aluminum as their base are discussed by the author, who points out their main physical characteristics and outlines methods which can be used in their fabrication, indicating in a general way which alloys are best suited to various aircraft-engine requirements. Tables are given showing chemical compositions and physical properties, including a table of physical properties of various casting alloys at elevated temperatures. Special-purpose alloys are commented upon, and also a new aluminum alloy for pistons which is beginning to find commercial application and possesses properties particularly desirable in aircraft engines. Recent developments in magnesium alloys and their application to aircraft-engine design are specified, tables of physical properties are given, and comments are made on the characteristics of the material as compared with aluminum alloys.
Technical Paper

Airplane Lighting Requirements

1929-01-01
290067
INCREASE in the amount of night flying with the advent of airplanes into the commercial field makes more acute the need for proper lighting facilities, not only of airports and airways, but of the airplanes themselves. As only about one-half of the regularly used airways in this Country are lighted for night flying, and few airports are equipped with lighting facilities for night landings, it is necessary for airplanes to be provided with lighting equipment for flying and for emergency landing at night. Besides the high-intensity lighting needed for following unlighted airways and for landing, airplanes need navigation lights and illumination for the instruments and the cabin. Immediate study and direction should be given to the problems of meeting each of these requirements most effectively and economically before it becomes too difficult to standardize methods and equipment.
Technical Paper

Recent Developments in Aircraft Ignition-Systems

1927-01-01
270063
THE fundamental electrical and mechanical requirements of ignition equipment for aircraft engines are outlined and the special requirements peculiar to this service and that apply, in general, equally to military and commercial aircraft, are described. Brief descriptions are given of various new types of both magneto and battery ignition and the developments in each are pointed out. Characteristics of an ideal ignition system are enumerated as a basis for further development. Among the general requirements reliability is given place of first importance, followed by light weight, compactness, low cost and adaptability of a single model to engines of different types. The chief design-requirements are speed, ruggedness, simple mounting, light rotating-parts, resistance to vibration, ample lubrication, protection against moisture, and fire-proof ventilation. Each of these subjects is dealt with specifically.
Technical Paper

High-Speed Oil-Engines

1930-01-01
300013
THIS paper, which was presented at meetings of the Buffalo and Pennsylvania Sections, begins with a statement of the advantages sought in adapting the Diesel cycle and developing oil engines to operate at high rotative speeds. Oil engines are classified according to their means for injecting and burning the fuel, and disadvantages attributed to the various systems are listed. Then follow descriptions of a number of engines of the different classes, selected according to the contribution their designs have made to the art. Particular attention is given to provisions for metering the fuel and for supercharging, which latter is said to have the same object as increasing the speed. Discussion* at the Buffalo meeting was on general problems of lubrication and fuel, on other methods for securing power from fuel oil, and on economic comparison of gasoline and oil engines.
Technical Paper

Bending Moments in the Master Rod of a Radial Aircraft Engine

1932-01-01
320069
HEREIN are presented the results of an investigation of the bending moments in the master rod of a radial aircraft engine by a graphical method, and a simple formula derived therefrom for approximating this moment in similar engines. The bending stress in the master rod comes from turning moments about the crankpin axis caused by the action of the articulated rods due to gas-pressure and inertia forces and also by the inertia forces in the master rod itself. Charts are presented that show the magnitude and fluctuation of these turning moments. Accurate computation of these moments involves much tedious work. A method of approximating them with sufficient accuracy for engineering purposes is given for the case of a nine-cylinder radial aircraft engine. The method is applicable also to non-radial engines and to radial engines having other than nine cylinders, but in these cases investigation of the turning moments due to the gas loads in certain cylinders seems advisable.
Technical Paper

Judging Super-Balloon Tires

1932-01-01
320065
CAR engineers are haunted again by the ghost of very low-pressure tires, which they had hoped several years ago was laid. These tires are one of the elements of airplanes that they hoped not to have to adopt. As was the case with the balloon tire of 10 years ago, the super-balloon was offered by tire companies in answer to a demand of car owners for a replacement tire that would give a softer ride. The question now disturbing car engineers is whether super-balloons must be offered as regular or optional equipment on new cars. They have an eye and sales appeal but doubts exist regarding their safety in event of blow-out, their susceptibility to puncture, their relative mileage life, their effect on steering and the like. Mr. Lemon discusses these points and the engineering changes that will be necessary in the chassis if super-balloons are to become regular equipment.
Technical Paper

Next Decade's Aero Engines Will Be Advanced But Not Radical

1933-01-01
330049
WIDER use of air-cooled engines in aircraft, considerable reduction in engine volume, and improved fuel consumption are predicted by Mr. Fedden in tracing the course of the next ten to fifteen years in aircraft development. Pointing out that in accordance with Prandtl's theories, startling innovations in aerodynamics are not to be looked for, and that improvement of aircraft will probably follow the line of improvements in detail, the author considers the effect on future aircraft-engine design of such detailed improvements. Piston-connecting rod-crankshaft linkage will survive, he believes. Higher compression ratios will rule, and radical innovations in engines will probably be tried first on automobiles.
Technical Paper

Engineering Aspects of the Modern Autogiro

1932-01-01
320055
HEREIN is presented for the first time a technical analysis of many of the fundamental engineering features of the development of the Autogiro by the engineering departments of the parent American company and its licensees. Intensive study is still being given to both the aerodynamic and the structural improvement of the rotor and also to other component elements. Attention is given in the paper to many of the developments that have contributed to the present engineering status of the machine in this Country. Phases of the subject discussed and analyzed are the aerodynamic relationships existing in the three or four widely different combinations of rotor and fixed wing and the longitudinal balance and stability of these several types of Autogiro to determine the extent of displacement of the center of gravity that is possible without impairing the behavior of the machine in slow forward speed or nearly vertical descent, while still maintaining longitudinal stability at high speed.
Technical Paper

Aerial Navigation-Methods and Equipment

1932-01-01
320042
HEREIN the author describes methods and shows instruments, tables, scales and curves used for air navigation. The ground-speed-and-drift meter devised by him and used with such remarkable success in the round-the-world flight with Wiley Post in less than nine days, on which the author was navigator, is illustrated and described. Much has been accomplished in the last few years in providing methods and equipment for quickly and accurately determining the position and laying the correct course of aircraft, but considerable improvement remains to be made in instruments, particularly sextants. No one method of navigation can be used under all conditions; a combination of four is necessary to achieve the best results.
Technical Paper

Controllable and Automatic Aircraft Propellers

1932-01-01
320036
THE DEMAND for a successful controllable or automatic propeller is greater today than ever. Such a propeller will enable commercial aircraft to take off safely with greater loads, and it may enable multi-engine airplanes that cannot now maintain altitude with one engine dead to do so with a safe margin of power. For military aircraft it means increased rate of climb and increased speed at altitude, especially with supercharged engines. To obviate confusion in nomenclature, the authors give definitions of adjustable, controllable and automatic propellers. Distinction is drawn between the needs of different classes of airplane for different types of changeable-pitch propellers. Many propellers falling within the several classes have been designed but few are in use. Cost, weight and complication are obstacles to their commercial success. Several problems still confront the designer in this field, the chief one being that of obtaining material that is sufficiently light and strong.
Technical Paper

Requirements for Large Air-Cooled Engines

1930-01-01
300035
SOME fuels marketed as aviation gasoline cause temperatures in large air-cooled cylinders 300 degrees higher than in normal operation. Piston trouble has frequently been found to result from detonation caused by such fuels. Pyrometers have not been common in the past, but now they are available at reasonable cost for instrument-board installation. Many oil companies lack adequate apparatus for determining knock values. The Pratt & Whitney Aircraft Co. maintains a limited testing-service to determine experimentally the suitability for aircraft engines of fuels that are submitted. The author urges the recognition of a high standard for undoped aviation gasoline which shall be available throughout the Country. The addition of 2 cc. per gal. of tetraethyl lead to such a fuel will make possible a change from 5:1 to 6:1 in the compression ratio of large engines, with a corresponding increase in brake mean effective pressure from 130 to 135 lb. per sq. in.
Technical Paper

Aircraft-Engine Installation

1930-01-01
300037
THE PAPER urges united cooperation instead of the present division of responsibility between the engine designer and the airplane designer in the installation of aircraft engines. The tubular rings upon which engines are commonly mounted are usually supported by structural members that are welded to the ring and attached to the fuselage at the four longitudinals. Inaccuracy is common in these structures, and many of them lack sufficient stiffness. Gravity gasoline-feed is recommended for its simplicity, provided the pressure head required by the carbureter can be secured, but the author reports having seen an installation in which the engine would operate so long as the airplane had its tail on the ground, yet the engine would die as soon as the tail was raised during a take-off. The use of gasoline-resisting rubber-hose with metal liners and the avoidance of sharp bends are recommended for the gasoline connections.
X