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Technical Paper

COOLING CAPACITY OF AUTOMOBILE RADIATORS

1923-01-01
230012
Annual Meeting Paper - The heat-dissipating properties of three types of radiator core have been investigated at the Mason Laboratory, Yale University. These include the fin-and-tube, the ribbon and the air-tube groups, so classified according to the flow of the water and the air. The ratio of the cooling surface to the volume is shown to be nearly the same in the fin-and-tube and the air-tube cores, while that of the ribbon core is somewhat greater. A formula is derived for computing the heat-transfer coefficient, which is defined as the number of heat units per hour that will pass from one square foot of surface per degree of temperature-difference between the air and the water and is the key to radiator performance, as by it almost any desired information can be obtained. When the heat-transfer coefficients have been found for a sufficiently wide range of water and air-flows the cooling capacity of a radiator can be computed for any desired condition.
Technical Paper

IMPROVED NICKEL-PLATING METHODS

1924-01-01
240053
A practical method of nickel-plating is outlined and the various processes are described by which the Packard Motor Car Co. has been successful in producing a durable coating of nickel on automobile parts in general, and the radiator shells, the rim plates and the tire-carrier plates, in particular. These are the parts of greatest exposure, and for plating them a new system of moving-cathode tanks was installed. The three problems to which special attention was devoted were rusting, pitting and peeling. No effort was made to secure a coating of any designated depth but reliance was placed solely on the results indicated by a 24-hr. salt-spray test, which was considered to be the equivalent of 2 years' exposure to the usual weather conditions. Peeling was overcome by thoroughly cleaning the parts before plating. New equipment was purchased and laid out in accordance with the system decided upon, namely, copper-plating, buffing and nickel-plating.
Technical Paper

RECENT AEROPLANE-ENGINE DEVELOPMENTS

1916-01-01
160025
The author gives a brief review of developments during the past year in the construction of aeroplanes, particularly as affected by the European War. He takes as an example the Renault twelve-cylinder engine, citing the respects in which the present differs from previous models. Such factors as the changes in cooling systems, method of drive, valve construction and starting devices are considered. The requirements of aeroplane engines, such as constant service, high speeds (of aeroplanes) and stream-line form of engines and radiators, are outlined. Propeller requirements are dealt with at length, curves being given by which the efficiency and diameter of the propeller can be obtained. In conclusion a number of different engine installations are illustrated and compared.
Technical Paper

HIGH OPERATING-TEMPERATURE AND ENGINE AND CAR OPERATION

1926-01-01
260016
This subject is treated in a paper in two parts. Part I, by Alex Taub, deals with laboratory tests to prove by comparative data that the higher average operating-temperatures maintained in the engine by the constant-temperature, or evaporation, system of cooling have negligible detrimental effects. Part II, by L. P. Saunders, gives the results of road-tests of cars operated under the same conditions when fitted with a standard water-cooling radiator-core and with a constant-temperature cross-flow condenser-core. Although contamination of the crankcase oil by heavy ends of the fuel is not prevented by the higher temperature of constant-temperature operation, it is asserted that this higher temperature is effective in striking an acceptable balance in such contamination and results of the tests show that the cylinder-walls are maintained at temperatures sufficiently above the vaporization point of water to reduce the condensation of water vapor to the minimum.
Technical Paper

Efficiency Test for Radiator-Fan-Type Air-Cleaners

1927-01-01
270038
SINCE air-cleaners of the radiator-fan type cannot be tested satisfactorily by the older method, in which a known weight of dust is fed directly into the airstream entering the air-cleaner, a special method was found necessary in which the air-cleaner under test is mounted in its normal position behind a radiator fan that is located inside of an elliptical wind-tunnel within which the fan circulates air. A tractor engine running at constant speed and load drives the fan in the wind-tunnel and draws the air for its carbureter from the wind-tunnel through the air-cleaner under test and an absolute air-cleaner connected in series. A 100-gram charge of a standardized dust is introduced into the wind-tunnel. By averaging the results obtained from repeated tests, using three different collecting-type dry centrifugal air-cleaners, it is found that under normal conditions 15 per cent of the total dust-charge actually reaches the air-cleaner under test in the described apparatus.
Technical Paper

Methods of Obtaining Greater Power from a Given Engine

1929-01-01
290011
DEMAND for increased car-performance forces manufacturers to provide more powerful engines. It is desirable to obtain the increased power without designing a new engine, particularly in the case of large-scale manufacturers. The author lists possible means of doing this as making increases in the speed, the volumetric efficiency, the compression ratio, the thermal efficiency and the mechanical efficiency; and explores each of these methods in the light of latest developments in engine design. Among the concrete suggestions are greatly increased valve-lift, hydraulic valve-gears, multiple car-bureters, injection of vaporized fuel into cold air, cutting out the fan at high speed, and the use of superchargers. Higher compression generally involves changes in cylinder-head design, which are covered in some detail. Subjects covered in the discussion include lubrication, roller-chain camshaft drives, form of combustion-chamber, availability of engine power, and two-cycle engines.
Technical Paper

Atmospheric Humidity and Engine Performance

1929-01-01
290033
SO-CALLED correction factors to compensate for variations in atmospheric temperature and pressure have been in practical use in connection with engine testing; but the influence of the varying amount of aqueous vapor present in the atmosphere has not had sufficient consideration. The author submits brief test-data indicative of the effect of humidity on some factors of engine performance and of the feasibility of using rational power-correction factors. By assigning due importance to the effect of humidity, he believes that a more satisfactory analysis of car and of engine performance can be obtained. Using a single-cylinder engine operated at full throttle and 1000 r.p.m. under stabilized conditions, tests were made observing maximum power, air-flow, fuel-flow, detonation and spark-advance requirements over a wide range of relative humidity for an air-intake temperature of 100 deg. fahr. Curves made from the data obtained are given and discussed.
Technical Paper

SOME ASPECTS OF AIRCRAFT-ENGINE DEVELOPMENT

1925-01-01
250066
Infallible performance and economical operation are the bases of successful commercial flying. Airplanes, having passed through the experimental and demonstration periods, must now prove their usefulness. Heretofore, because of military requirements, designers have fostered the use of power rather than refinement of design to obtain performance, but commercial operation demands efficiency, and in each of the four essentials, namely, dependability, size, total powerplant weight and cost, opportunity for decided improvement still exists. The requirements and limiting factors of each of these essentials are discussed in turn and the conclusion is drawn that a relation exists between the amount of thrust delivered to the air and the weight put into an airplane for its propulsion. To obtain the best over-all performance, if these terms are considered as a fraction, the numerator should have the maximum and the denominator the minimum value.
Technical Paper

DEVELOPMENT AND DESIGN OF HYDRAULIC-BRAKE UNITS1

1925-01-01
250045
The principles of hydraulics have long been known and the use of a liquid for transmitting power has proved safe and reliable in many applications, notably in the operation of passenger elevators. Hence it was natural to make use of these principles in a device for controlling an automobile under traffic conditions that demand an efficient and dependable braking mechanism. The ideal of equalized braking-effort is sought but variation in the coefficient of friction between brake-bands and brake-drums and between tires and road introduces complications, so we must be content for the present with the nearest possible approach to equalized pressure at the brake-bands. In the hydraulic system, pressure is transmitted equally throughout the liquid and to the levers that actuate the brake-bands. These levers are also designed to transmit the pressure equally to the brake-bands on all four wheels.
Technical Paper

PREVENTION OF SHIMMY BY HYDRAULIC STEERING-CONTROL

1925-01-01
250048
Experiments with hydraulic steering-control with the object of preventing or reducing shimmying and tramping were made by the author, who asserts that the elimination of backlash by doing away with mechanical joints and by holding the front wheels as rigid as the rear wheels has been amply proved by the results to be a long step in the right direction. With a Marmon car fitted with an hydraulic steering-system and driven over the roughest roads it was impossible to discern any front-wheel wabble as the car approached and passed the observer.
Technical Paper

DYNAMOMETER TEST OF BRAKE-DRUM HEAT IN DUAL WHEELS

1926-01-01
260051
Premature failures in the summer of 1925 of inner-dual motorcoach tires and tubes on 20-in. wheels in which the brake-drum was directly under and close to the rim caused the rubber companies to undertake development work on tire beads, flaps and tubes; but no solution of the problem was to be found by a change of the rubber compound. The need for definite information regarding actual tire temperatures developed in road service led to extensive joint tests in Florida early in 1926 by a tire and a wheel company. In these tests a brake-drum temperature was maintained as nearly as possible constant at 475 deg. fahr. above atmospheric temperature by successively accelerating the car and applying the brake. When it was judged that this temperature had been reached, stops were made to take thermocouple readings of the temperature.
Technical Paper

AUTOMOBILE EXPERIENCES IN THE GREAT WAR

1916-01-01
160032
The author outlines the constructions that have performed cially that four-cylinder engines carried under a hood are the most satisfactory. The defects revealed by war service are given in considerable detail, the author finding that all of the trucks used had developed some weak point. Radiators and springs are specified as a general source of trouble. The author outlines a number of operating troubles developed under the existing conditions of operation and gives examples of the way these have been remedied. Considerable attention is paid to the methods of operating trucks away from made roads. The methods of fitting chains to the wheels, and the use of caterpillar attachments are described. Dimensions are given for bodies and a number of suggestions made as to their proper construction.
Technical Paper

REFINEMENTS IN TRUCK DESIGN

1916-01-01
160031
The author describes a number of detailed developments that took place during the working out of a line of worm-driven trucks. The details of front axle and steering parts are dealt with at length, the reasons for the final constructions being clearly explained and the constructions themselves well illustrated. Details concerning difficulty with the Hotchkiss type of drive on heavy trucks, troubles with drive-shafts and lubrication of the worm wheel are all covered thoroughly; spring-shackle construction and lubrication, radiator and hood mounting come in for detailed attention and the question of governors is interestingly covered. Brief reference is made to the influence of unsprung weight, the differences between truck and pleasure car practice in this respect being pointed out.
Technical Paper

LESSONS OF THE WAR IN TRUCK DESIGN

1917-01-01
170027
The title of this paper fully indicates its scope. The author presents an intimate picture of conditions prevailing at the war front which affect the operation and maintenance of war trucks, and these two factors in turn indicate the trend that design should take. The training of the mechanical transport personnel of the Army is also gone into at some length. The English and American trucks used earlier in the war consisted of about nineteen different makes and forty-two totally different models, resulting in a very serious problem of providing spare parts and maintenance in general. In the British Army transportation comes under an Army Service Corps officer called the Director of Transport and Supplies. At the outbreak of the war these officers had had little mechanical experience, horses being employed principally. In the French Army motor vehicles were used to a greater extent before the war, under the artillery command.
Technical Paper

LABORATORY TESTING IN THE AUTOMOTIVE INDUSTRY

1917-01-01
170043
This paper emphasizes the importance of using standardized testing equipment in order that mental calculations may be avoided in interpreting the reports of other engineers. The situation and environments of the engine-testing plant, cooperation among the men conducting tests, standardized methods of conducting tests, value of venturi meters and testing of accessories are among the subjects discussed in the first part of the paper. The subject of the testing of engine cooling systems is treated at some length, the importance of obtaining operating conditions being emphasized. The paper concludes with two sections covering spark-plug testing and tests for preignition.
Technical Paper

AUTOMOBILE ENGINE COOLING

1917-01-01
170041
This paper deals only with water-cooled engines, the cooling system being considered as made up of four main units-the water jacket, the circulating system, the radiator and the fan. Water-jacket problems are first considered, followed by a comparison of pump and gravity (thermosyphon) systems of circulation. The next section is devoted to radiator requirements. The balance of the paper relates to the fan. Five curves show graphically the correlations of the various factors of cooling, power consumed, air velocity and volume, engine speed, fan speed, air and water temperatures and the element of time, the results applying to different types and sizes of fans. These curves are of service in the selection of fans for radiator cooling purposes. The classification of fans, fan power consumption and speed, fan belts and pulleys, disadvantages of high fan speed, types of fan bearings, and applications of fans are the subjects next taken up.
Technical Paper

ENGINE SHAPE AS AFFECTING AIRPLANE OPERATION

1920-01-01
200025
The annual report covering transportation by the largest British air-transport company laid particular emphasis upon the greater value of the faster machines in its service. Granted that efficient loads can be carried, the expense, trouble and danger of the airplane are justified only when a load is carried at far greater speed than by any other means. A reasonable conclusion seems to be that we can judge the progress made in aviation largely by the increased speed attainable. It is interesting and possibly very valuable therefore to inquire into the relations of power and resistance as applied to small racing machines with aircraft engines that are available.
Technical Paper

DESIGN FACTORS FOR AIRPLANE RADIATORS

1920-01-01
200026
The paper defines properties that describe the performance of a radiator; states the effects on these properties of external conditions such as flying speed, atmospheric conditions and position of the radiator on the airplane; enumerates the effects of various features of design of the radiator core; and compares methods that have been proposed for controlling the cooling capacity at altitudes. Empirical equations and constants are given, wherever warranted by the information available.
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