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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

Ventilation of Motorcoach and Motor-Truck Bodies

1932-01-01
320016
This report of the S.A.E Subcommittee on Motorcoach and Motor-Truck Ventilation states that, to the motor-vehicle operator, ventilation means the elimination of gas odors from the coach body or truck cab; but to the public it means, no doubt, simply proper interior ventilation. Adequate interior ventilation becomes a necessity because of the stigma against buses which has arisen due to their characteristic odor. The investigation of the Subcommittee over millions of miles of operation indicates that there is no one cause of fumes, and certainly no single cure. In the report, discussion is included relating to the causes of gas fumes, such as fumes due to leaks and to engine condition; exhaust-pipe location; carbureter adjustment; the importance of proper driving; engine maintenance and body ventilation. Ten causes of “gassing” are listed.
Technical Paper

ESSENTIALS OF A SUCCESSFUL CONSTANT-COMPRESSION ENGINE1

1924-01-01
240008
The efficiency of internal-combustion engines increases with the pressure of the charge at the time of ignition. Therefore, a compression at full load just below that of premature ignition is ordinarily maintained. But when such an engine is controlled by throttling, the efficiency drops as the compression is reduced, and as automobile engines use less than one-quarter of their available power the greater part of the time, the fuel consumption is necessarily high for the horsepower output. On account, also, of the rarefaction due to throttling, more power must be developed than is necessary to drive the car; automobile engines in which the fuel is introduced during the induction stroke, would be more efficient, therefore, if the maximum compression were constant during all ranges of load.
Technical Paper

PROPER UTILIZATION OF NATURAL GASOLINE1

1923-01-01
230010
The term “natural gasoline” has been accepted generally by the petroleum industry as applying to the gasoline product extracted by any process from natural gas. Two processes are in use. The older one is the compression process applied to casinghead gas, which is produced from the oil-bearing sands of oil wells and carries vapors from the oil with which it has been in contact. This process of subjecting the relatively rich gas to a high pressure and then cooling it to or below atmospheric pressure, results in the direct condensation of gasoline which is weathered later to remove the “wild” unusable vapors. The later method is the absorption process in which the gas is brought into contact with a heavy oil, originally of no gasoline-content, which absorbs the gasoline. The enriched oil is then heated to distill off the gasoline, and these two operations of absorption and distillation are repeated continuously within a closed system.
Technical Paper

WATER RECOVERY FOR AIRSHIPS

1924-01-01
240058
Describing how the total weight of an airship becomes less as its flight continues and how its elevators can be used to keep the airship's nose pointed downward, thus balancing the excess lift by “dynamic lift,” the author says that 5 hr. is about the limit of flight for which the too great lightness can be overcome in this fashion safely, explains how different the conditions become on long flights and gives details of the means used to counteract this rising tendency. Valving of gas to overcome airship lightness is wasteful and costly, especially when the craft is inflated with helium gas but, if this is not done, some substance must be collected and stored at the same rate as that at which fuel is consumed in the engines and the most practicable method seems to be to recover water from the exhaust gases.
Technical Paper

RECENT COOPERATIVE FUEL-RESEARCH PROGRESS

1925-01-01
250001
This report deals with further progress in the cooperative fuel-research. General factors underlying starting ability are discussed and experiments showing the effect of changes in spark character and of gas leakage are described. The probable mechanism of crankcase-oil dilution is treated, and further experiments with reference to this subject are explained. One experiment deals with operation with oil as a cooling medium to obtain high jacket-temperatures. Other experiments show the effect of change in piston clearance and in the number of piston-rings employed. Factors influencing the rate at which the diluent is eliminated from the diluted oil are shown to be of importance, and methods of examining these factors are stated.
Technical Paper

Fuel-Mixture Distribution

1929-01-01
290018
AFTER outlining the effects of improper distribution of fuel mixture in an internal-combustion engine and stating how the distribution of a gas is governed, the author discusses motor-fuel condensation and states that, since preheating the air is objectionable and hot-spots do not supply sufficient heat to vaporize the fuel completely, the induction system must distribute wet mixtures; and the partial or complete solution of this problem ordinarily is the result of experimenting with different designs for any particular engine. Regarding the manifold action with wet fuel-mixtures, it is stated that the phenomena occurring in manifolds which distribute such mixtures are complicated and unstable but some insight into them can be obtained by studying the action in a two-cylinder engine. Analysis shows that the even distribution of wet mixtures is extremely difficult.
Technical Paper

Combustion Control by Cylinder-Head Design

1929-01-01
290016
DETONATION and shock, the two principal barriers to increased compression, are subject to a degree of control which can readily make possible the use of compression ratios in the neighborhood of 6-1 on commercial fuel without objectionable effects and without sacrifice of output. Since detonation depends primarily upon the temperature attained by the residual unburned gas, it can be controlled by combustion-chamber design which intensifies the heat transfer from the unburned gas to the walls. The shock tendency, which originates in the pressure-time characteristic of combustion, can be controlled only by deliberate incorporation of the desirable anti-shock characteristic in the chamber design by a method of calculation which is explained in detail.
Technical Paper

Interpretation of the Indicator Card

1929-01-01
290013
TRUE thermodynamic interpretation of the indicator card must be based upon the properties of the actual medium working in the engine and must take into account the actual nature of the heat liberation. The temperature-energy diagram for the working combustible mixture and for the resultant combustion products provides for this interpretation a foundation that is universally applicable to engines using a given type of fuel. This diagram automatically includes the effect of variation in specific heat with temperature, because the entire energy content of a gas at any temperature is the energy required to raise it, at constant volume, from absolute zero to that temperature. The work done during the actual changes of state, as determined from the indicator card, can readily be represented on the same diagram, and the heat interchanges involved can be determined quantitatively by comparison with the adiabatic criterion.
Technical Paper

Vapor-Pressure Data on Motor Gasolines

1929-01-01
290026
THE REPORT deals specifically with that part of the Bureau of Standards' program involving vapor-pressure measurements. A description is given of a method and apparatus for the removal of dissolved gases from dried gasolines, without appreciably affecting the propane content and without otherwise changing their composition. Vapor-pressure measurements with a small bubble of vapor present have been made on 10 motor gasolines over a considerable temperature range. Log p, 1/T plots of these data were found to be linear in the case of all the fuels within 1 to 2 mm. on the average, p representing the pressure and T the absolute temperature. The normal bubble-points (p = 760 mm.) of the 10 gasolines were shown to be equal to the 10-per cent A.S.T.M. temperatures, corrected for loss, within the accuracy of determining the latter.
Technical Paper

Developments in Lighter-than-Air Craft

1929-01-01
290053
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.
Technical Paper

BURNING KEROSENE IN TRACTOR ENGINES

1917-01-01
170031
The author states as his object a review of what has been done and what must be done to make tractors successful in operating on low-grade fuels, especially kerosene. He takes up in order the four principal methods in common use of applying heat to vaporize kerosene, pointing out the advantages and disadvantages of each method and of its modifications. The author then cites various experiments with different types of carbureters in burning kerosene, drawing at length upon his own experience in this connection. He cites difficulties with gas distribution, manifold condensation, pistons and spark-plugs and points out that carbureter design is inseparable from considerations of tractor engine and manifold design. That better progress has not been made in the past in developing kerosene-burning tractor engines is stated to be largely owing to the fact that there has not been sufficient cooperation between engine and carbureter manufacturers.
Technical Paper

SOLVING THE GASOLINE PROBLEM

1917-01-01
170047
The author first compares mineral oils with certain other liquids in order to point out clearly certain of their characteristics. He then shows the economic benefits that would result from making more of the crude available for use as fuels. He discusses such topics as cracking methods in use, advantages of dry gas, initial flame propagation, gas producers, hot mixtures, wet mixtures and difficulties of correcting existing engines. He concludes by proposing as a solution of the gasoline problem the more general use of superheated homogeneous fixed dry gases made in vaporizing devices independent of engine cylinders, and outlines means for attaining this end. Performance data covering the use of mixtures of kerosene and gasoline on several cars are included in a table, and several charts throughout the paper illustrate many of the topics discussed.
Technical Paper

METROPOLITAN SECTION PAPERS TREATMENT OF HYDROCARBON FUELS

1917-01-01
170046
The author states that the objects of the paper are to define and trace the development of the various processes of carburetion, and to offer such suggestions along these lines as may assist the investigator in developing motorboats, automobiles and self-contained unit motor cars for railway purposes. The surface carburetor is mentioned chiefly as of historic interest. In considering the jet carbureter the author discusses the proportion of gas desired, the effect of the varying inertia of the air and the liquid gasoline and the breaking up of the combustible needed. Following sections review the devices for using kerosene, such as gasoline jet carbureters to which heat is applied, devices of the fixed gas type, the introduction of combustible directly into the cylinder, forcing combustible directly upon a hot surface in the cylinder and devices which raise the combustible to the boiling point.
Technical Paper

HEAT RECOVERY - Applied to Heating and Anti-Icing of Aircraft

1946-01-01
460247
THIS paper discusses the use of heat recovered from engine exhaust for heating airplane cabins and flight decks, as well as for anti-icing of aerodynamic surfaces and propellers. The author shows that some of the objections to the use of exhaust gas are more apparent than real and that increased comfort, safety, and utility of transport airplanes will be achieved by using recent developments.
Technical Paper

Utilization of Exhaust Gas of Aircraft Engines

1946-01-01
460259
THIS paper-relates to the recovery of energy from the exhaust gas of aircraft reciprocating engines by means of the exhaust jet, the steady-flow turbine, and the blowdown turbine. The performance of a reciprocating engine compounded with these energy-recovery devices is discussed in detail. The operating conditions for maximum performance are presented, and the effects of engine cooling and knock limit on these conditions are considered. A comparison is made of the overall weight of the engine plus fuel for the various exhaust energy-recovery systems at several operating conditions and durations.
Technical Paper

NEW Synthetic LUBRICANTS

1946-01-01
460215
DESCRIBED here are the detailed characteristics of two series of synthetic lubricants, one essentially insoluble and the other soluble in water at room temperature. These lubricants are synthesized from natural or other hydrocarbon gases as raw materials. Results of laboratory and field tests indicate that the lubricants can be successfully used in internal-combustion engines. In fact, the authors report that one of them has already been used extensively in aircraft engines by the Army Air Forces and the Air Transport Command.
Technical Paper

CYLINDER WEAR MEASURED WITH A MICROSCOPE

1947-01-01
470232
AN instrument for the accurate measurement of cylinder wear is described by the authors. The instrument consists of a diamond indenting tool, an indentation locator, and a microscope. To determine wear, the length of an indentation is observed with the microscope before and after periods of operation. Wear, which is reflected by changes in the depth of the indentation, is calculated from changes in the length of the indentation. Using this instrument in their experiments, the authors found that most cylinder wear is due to corrosion and occurs during warmup, when cylinder temperatures are low. It appears that corrosive gases condense on cool cylinder walls and attack the surface. Then the corroded film and lubricating oil are wiped away by the piston, leaving the walls ready for further corrosion.
Technical Paper

Weld Repair of Aircraft Quality Magnesium Castings

1957-01-01
570009
GENERAL techniques used in the weld repair of magnesium aircraft castings by both gas and arc welding methods are described here. Coverage is given to equipment, methods of surface preparation, preheating, welding procedure, post-heat-treatment. Some typical arc weld repair jobs are described and illustrated. Included also are descriptions of weld defects encountered because of poor welding technique. Typical mechanical property data are shown.
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