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Viewing 19831 to 19860 of 190617
1934-01-01
Technical Paper
340086
E. S. Hall
1934-01-01
Technical Paper
340081
Eastman N. Jacobs
THIS paper, which has been awarded the Wright Brothers Medal for 1933, considers first the air forces acting on airfoil sections, their origin, and the nature of the differences between the air forces acting on an ideal airfoil section and on an actual one. These differences, which are due primarily to the action of viscosity, are considered in detail because they distinguish the desirable from the undesirable sections. The effects of viscosity are discussed in relation to the air-flow about the section as affected by a variation of the dynamic scale or Reynolds Number of the flow. Separation of the flow from the airfoil surface, which produces the most marked deviations from the ideal flow, is discussed in detail, considering the effects of varying the Reynolds Number and the initial turbulence of the air. Finally, the paper considers the variation of the aerodynamic properties of sections with changes in the section shape.
1934-01-01
Technical Paper
340075
L. V. Newton
OPERATING, or so-called variable charges, are considered in this paper, and comments are offered on the subject of fixed charges. Because economies effected since about 1929 have brought fleet-operation costs to a very low level, the difficult problem of how they can be further reduced and yet maintain the same quality of service is facing all fleet operators; but it is not insurmountable. Through adequate study of each item of operating expense, and with proper treatment of each item of cost, Mr. Newton believes that reductions will be effected. Itemizing the charges, Mr. Newton says that gasoline purchase is primarily the buying of heat units. Gasoline should not deteriorate in storage, must be clean, have low sulphur content and should not vapor lock. Using a higher antiknock gasoline than necessary increases fuel cost. Correct and effective lubrication lengthens vehicle life and reduces repair costs; as few different grades as will assure good lubrication should be used. Mr.
1934-01-01
Technical Paper
340065
MERRILL C. HORINE
1934-01-01
Technical Paper
340061
E. P. Lott
1934-01-01
Technical Paper
340062
G. E. Clinton
1934-01-01
Technical Paper
340057
Henry S. Debbink
1934-01-01
Technical Paper
340096
R. F. Gagg, E. V. Farrar
THE rapidly increasing use of aircraft engines fitted with superchargers for improving the power output at high altitudes has focused attention on means for predicting their performance in advance of actual flight tests in an airplane. A considerable amount of engine testing has been performed in several well-equipped laboratories in the past. These results have been carefully compared to determine the degree of similarity of the performance of these engines, and to form conclusions from which the performance of other engines may be predicted. Since the gear-driven centrifugal supercharger has demonstrated its superiority for use at moderate altitudes over other types on the grounds of simplicity, capacity, weight and space requirements, the data considered are almost entirely concerned with this type. It is shown, however, that naturally aspirated engines have quite similar characteristics.
1934-01-01
Technical Paper
340093
L. M. K. Boelter, D. D. Davis, W. L. Fons, D. O. Rusk
HEADLAMP construction is presented in summarized form, twelve needful factors being stated by the authors. Accelerated mechanical tests, which are designed to give within a few days results of what may be expected to take place after several years of road service, are conducted in the Headlight Laboratory of the University of California. These are described and illustrated under the headings: Vibration, durability, moisture, dust and electrical insulation, and the results are stated. A few correlation tests are commented upon. Headlamp vibration is treated at length, together with an analysis of headlamp vibration-characteristics, and a differentiation is made between vibration due to the engine and that due to roadway shocks.
1933-01-01
Technical Paper
330053
JOHN M. ORR
SYNOPSIS Careful predetermination of work requirements and operating conditions will insure the best possible choice of new vehicles. Proper coordination of the vehicle to be used with the work to be done is necessary to obtain lowest costs of operation and maximum vehicle service. The simplest type of vehicle is preferable, if applicable, in all cases. Chassis equipped with special bodies and equipment should apply only where the additional costs and restricted flexibility of application to other uses can be offset by operating advantages over standard vehicles. Vehicle investment, operating costs, and the life tenure of fleet vehicles, justify detailed examination of all facts that can influence selection. Precedent should be ignored and specifications for new vehicle requirements developed from fundamental requirements. This plan is an aid correct vehicle application and greater user satisfaction.
1933-01-01
Technical Paper
330063
J. B. Fisher, L. L. Bower
1933-01-01
Technical Paper
330005
F. W. Caldwell, F. M. Thomas
Summary THE primary purpose of this paper is to discuss some of the most pressing problems involved in choosing the propeller that is most suitable for use on a particular airplane. Propeller design is not dealt with, the discussion being limited to the selection of metal propellers of established design. Questions of noise, efficiency and diameter limitation are merely mentioned, and the emphasis is placed upon the choosing of propellers which will transmit the most engine power for the most needed condition of airplane performance; maximum and cruising speeds at altitude, or take-off and climb. Airplane performance enters only inasmuch as it is used to illustrate a case of power absorption. The proper choice of a propeller is becoming increasingly difficult to determine because of the current design trends of both airplanes and engines.
1933-01-01
Technical Paper
330021
1932-01-01
Technical Paper
320062
Luther Harris
VIEWS of the maintenance chiefs of all major air-transport lines, based upon their experiences in this field and as transmitted by them through the Maintenance Committee of the Aeronautical Chamber of Commerce of America, Inc., are embodied in the paper. Representing as it does the collective experience of the best minds in the field, the paper is particularly significant and worthy of the consideration of manufacturers, engineers and others directly concerned with the problems presented. As to fuselage and wing coverings, it is stated that fabric has a definite advantage when considering weight and emergency repairs. Airplanes covered with fabric can be restored to service quickly in cases where, with the same damage, replacement of other forms of covering would cause the plane to be laid up in the shop at a time when it is most needed. With the new improved finishes, fabric is said to be as satisfactory as any covering available.
1932-01-01
Technical Paper
320060
C. E. Frudden
MAGNITUDE of the Mississippi River flood-control work and the huge quantities of earth that must be moved in the building of levees in the South require tractors of the largest commercial sizes and varied dirt-moving machines and wagons to perform the work expeditiously and economically. The author describes briefly the types of tractor and tractor-operated equipment used by the contractors as he observed them at work on two visits to the South. How several hundred tractors are regularly used for hauling crawler-track dump wagons, pulling blade graders and elevating graders, pushing bulldozers and supplementing tower machines and drag-lines is described, and the author pictures vividly the severity of the work, which requires continuous operation for 20 to 22 hr. per day, seven days per week, and the crude provisions for and methods of maintenance, as a consequence of which the machine casualties are heavy.
1932-01-01
Technical Paper
320003
Clyde R. Paton
EXPERIMENTAL work done to ascertain the influence of frame and body structures upon front-end stability of the automobile is described by the author and definite means of preventing the phenomena of wheel wabble, shimmy and vibratory movements of the radiator, head-lamps and fenders are set forth. Early investigation showed that the problem involved not only the unsprung portions of the car but also the structural arrangement of the frame and the body. Chassis-dynamometer tests revealed a nodal point of zero torsional vibration approximately at a plane through the front seat but varying with different cars and body types, the forward portion of the chassis vibrating torsionally about the longitudinal axis in opposite phase to the rear portion. Experiments rather conclusively proved that damping is needed in the frame and body.
1932-01-01
Technical Paper
320017
H. M. Williams, J. W. Carl
SALES potential of refrigerator trucks seems to be several hundred new units annually, according to the authors. Motor-truck transportation of meat, milk, ice cream, fruits and farm produce demands refrigeration, as does delivery-truck transportation of butter, cheese, yeast and dough. Large trucks are needed for the former class and smaller ones for the latter, but the refrigeration problems are fundamentally the same. Desirable body-construction is outlined and the different refrigerating systems are analyzed with regard to quantity of refrigeration needed, type of insulation and insulating material available. Mechanical systems are discussed under electric, power take-off and separate gasoline-engine drives for the compressor. The most desirable location for a refrigerating unit on a truck also is considered.
1932-01-01
Technical Paper
320013
Frank T. Courtney
AIR transport is an essentially expensive business and operators must study economy at least as much as do other commercial companies to make their business self-supporting. A commercial-transport airplane must have an even higher degree of efficiency than that of a large military plane and must be in continuous operation so far as possible. Very high speed may prove to be an expensive luxury; it should be investigated with great care as well as with the present enthusiasm of its sponsors. Speed is not paramount, but profitable load-carrying is. A cheap plane that is inefficient and an efficient plane that is more expensive than it need be are both uneconomical. Air-transport testing consists not merely in the elimination of defects but in the examination of all the characteristics of the plane to effect the maximum improvement that the design will stand and to discover other characteristics for future development or elimination.
1932-01-01
Technical Paper
320024
Roy W. Brown
METHODS are outlined for measuring the characteristics of tires that affect riding-qualities, and typical curves showing rate of deflection and contact area versus tire size are presented. Coordination of service performance with simple laboratory tests is illustrated. Means of securing the inter-effect of tires and springs are outlined and curves of typical axle-body frequency versus tire size are shown. Use of the solenoid accelerometer in conjunction with equipment for interpretation of physical effect of accelerations is suggested for service tests. Secondary riding-quality factors such as tire traction, horsepower and rim diameter are discussed and numerous others mentioned. The influence of tread design and other factors of tire design is indicated.
1932-01-01
Technical Paper
320018
F. I. Hardy
1932-01-01
Technical Paper
320070
George A. Green
COMPARATIVE tests were made, both on the block and in the same motorcoach chassis, of a 525-cu.-in. gasoline and a 495-cu.-in. Diesel engine. The block tests are reported fully in charts, including curves for torque and power against piston displacement and engine weight. Corrected curves are given on the basis of equal piston displacement and for the Diesel engine throttled enough so that it would not smoke. Road tests included fuel consumption, acceleration, hill climbing and top speed, which are also recorded in charts. Other sections of the paper deal with costs of manufacture and maintenance and present and prospective conditions as to supply and cost of Diesel fuel. Stress is laid on the facts that automotive Diesel engines require a much higher grade of fuel than do the larger and slower Diesel units and that more gasoline than fuel oil can be obtained from a given amount of crude.
1931-01-01
Technical Paper
310046
T. L. Preble
SEVERAL major problems that confront the man who has charge of a fleet of automotive vehicles are analyzed by the author, who states that they deserve closer scrutiny and more intensive study. Their solution lies in evolution, which requires time, and their continued discussion by the Society is imperative. They are problems not only of the transportation executive but of the entire industry. Centralized control of a company's equipment is discussed, its advantages are enumerated, the ideal organization and procedure are outlined, the difficulties to be anticipated are listed and a procedure for installing such a system is proposed. The author recognizes that, where the automotive activities of a gigantic company are spread over a wide territory, application of an ideal system of centralized control is very difficult. Consideration is given to the relationships between the transportation executive and the motor-vehicle manufacturer.
1931-01-01
Technical Paper
310048
Brainerd Taylor
CONSIDERATION of motor-transport maintenance in military operations requires a general conception of the national military organization for war. This the author outlines, describing the theater of war, its subdivisions, the zone of the interior, communications and combat zones, and the general character-commercial or military-of motor transportation in each zone. The Quartermaster General's responsibility, and the need for centralizing control of motor transport under his direction as provided in the National Defense Act, is indicated. Maintenance personnel, tool and shop equipment, supplies and various functions are divided into five groups called “echelons,” a military term used to designate the groupings of troops, supplies, functions and military command from front to rear of an army.
1931-01-01
Technical Paper
310041
Oscar W. Schey
CLASSIFYING the superchargers used for present aircraft and automobile service as Roots, centrifugal and vane types, the author states that the vane type for this service is a more recent development than the other two and describes each type. He states further that the ideal type should satisfy many requirements closely related with those of a well-designed engine-such as being light, compact and reliable-and that the practice of supercharging has increased considerably during the last few years. The comparative performance of superchargers is treated at some length, and engine-performance data are presented. The power developed by an engine equipped with geared-centrifugal, turbo-centrifugal and Roots superchargers is illustrated by curves, control methods are compared, net engine-power is computed, and flight-test data on comparative performance are analyzed.
1931-01-01
Technical Paper
310002
Othmar K. Marti
STUDY of aerodynamics was first made in connection with airships and airplanes, asserts the author, and streamlined forms were developed as a result of wind-tunnel tests made by Paul Jaray in Austria and Germany before the World War and supported by mathematical studies. The findings were applied to improvement of the shape of Zeppelin airships, and later the streamline principles were incorporated in automobile designs. The author presents the results of wind-tunnel tests of streamlined automobile models in this Country which showed reduction by almost one-half in the wind resistance at speeds of 40 and 50 m.p.h., as compared with the conventional American sedan model. Results are also given of road tests of a standard Chrysler car and a Jaray-Chrysler car, using the same chassis model and each seating five passengers. The streamlined car is shown to coast farther, accelerate faster and consume much less fuel than the conventional sedan model.
1929-01-01
Technical Paper
290052
JUAN DE LA CIERVA
ESSENTIALLY the Autogiro consists of a fuselage that is propelled more or less horizontally through the air by an ordinary engine and propeller combination and wings that possess at least one degree of freedom with respect to the fuselage and turn around a central axis of rotation that is approximately perpendicular to the longitudinal axis of the fuselage, being articulated to a central hub and free to flap within rather wide limits. The present machines also have two small low monoplane fixed wings, that act mainly as supports for the ailerons, a fixed tail, elevator, fin and rudder. Among the advantages claimed for the Autogiro are perfect stability, great flexibility, great adaptability, safety and the possibility of landing and taking off in a restricted area. The author claims that it is superior to the airplane for almost every purpose and is particularly adapted to civil aviation uses such as passenger transport, night mail service and especially for private flight.
1929-01-01
Technical Paper
290053
KARL ARNSTEIN
NOTABLE developments in 1928 that have greatly increased interest in lighter-than-air craft were the transatlantic flight of the Graf Zeppelin as an experiment in commercial transoceanic air-service, the ordering by the United States Navy Department of the construction in this Country of two rigid airships larger than any yet built or under construction, the development and construction of two British airships for long-distance passenger and mail transportation, the starting of erection of the world's largest airship factory and dock at Akron, Ohio, and the construction and operation in this Country of a number of non-rigid airships to be used for commercial purposes. Each of these developments is dealt with in order. General dimensions, major characteristics, and unique features of the Graf Zeppelin, the new Navy airships, and the projected large transoceanic commercial airships are given.
1929-01-01
Technical Paper
290037
C. FAYETTE TAYLOR
SUPPLEMENTING the results of an investigation at the Massachusetts Institute of Technology on supercharging a single-cylinder automobile engine which were presented at the 1928 Annual Meeting, this paper reports a study that was made to determine whether the mechanical action of a high-speed centrifugal supercharger improves engine performance by increasing the degree of atomization and vaporization of the fuel in the inlet manifold. While changes in the degree of fuel atomization and vaporization might be measured directly by sampling the gases as they pass to each cylinder, an indirect evaluation of these changes by measuring their effect on engine performance was considered more practicable. Tests were made on a six-cylinder automobile engine connected to an electric cradle-dynamometer.
Viewing 19831 to 19860 of 190617