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Fuel and Additive Effects on Engine Systems, 2017

Topics include the effects of fuel and additives on deposit formation, intake system cleanliness, friction, wear, corrosion, and elastomer compatibility. Also covered are effects of fuel specification on drivability, on evaporative emissions, and on the relationship between emissions and drive cycle.

Monitoring NO2 Production of a Diesel Oxidation Catalyst

A combination of laboratory reactor measurements and vehicle FTP testing has been combined to demonstrate a method for diagnosing the formation of NO2 from a diesel oxidation catalyst (DOC). Using small cores from a production DOC and simulated diesel exhaust, the laboratory reactor experiments are used to support a model for DOC chemical reaction kinetics. The model we propose shows that the ability to produce NO2 is chemically linked to the ability of the catalyst to oxidize hydrocarbon (HC). For thermally damaged DOCs, loss of the HC oxidation function is simultaneous with loss of the NO2 production function. Since HC oxidation is the source of heat generated in the DOC under regeneration conditions, we conclude that a diagnostic of the DOC exotherm is able to detect the failure of the DOC to produce NO2. Vehicle emissions data from a 6.6 L Duramax HD pick-up with DOC of various levels of thermal degradation is provided to support the diagnostic concept.

Catalyzed Particulate Filter Passive Oxidation Study with ULSD and Biodiesel Blended Fuel

A 2007 Cummins ISL 8.9L direct-injection common rail diesel engine rated at 272 kW (365 hp) was used to load the filter to 2.2 g/L and passively oxidize particulate matter (PM) within a 2007 OEM aftertreatment system consisting of a diesel oxidation catalyst (DOC) and catalyzed particulate filter (CPF). Having a better understanding of the passive NO2 oxidation kinetics of PM within the CPF allows for reducing the frequency of active regenerations (hydrocarbon injection) and the associated fuel penalties. Being able to model the passive oxidation of accumulated PM in the CPF is critical to creating accurate state estimation strategies. The MTU 1-D CPF model will be used to simulate data collected from this study to examine differences in the PM oxidation kinetics when soy methyl ester (SME) biodiesel is used as the source of fuel for the engine.

Tailored Conversion Coatings for Enhanced Adhesion to Metal

The use of silane chemistries tailored to promote the adhesion of performance and appearance coatings to metal substrates are requiring new methodologies for measuring, approving, and implementing on commercial aircraft. Engineering performance, lean manufacturing, environmental and employee safety considerations are driving the commercial aerospace industry to replace long standing conversion coating materials and processes. Tailored silane chemistries such as Boegel are being considered for many of these applications. Silanes work by reacting with metal oxides providing a strong covalent bond, cross linking to form a tough barrier and have an organic functional group tailored to react with the specific resin system in the subsequent coating. Traditionally conversion coatings such as anodize and chromate conversion coating performance is validated based on meeting standalone requirements.
Technical Paper

Duralumin All-Metal Airplane Construction

PSYCHOLOGY of the public, as well as engineering structure and aerodynamics, is involved in commercial aviation. The public has confidence in metal. With quantity production in view, the author and his associates considered costs of production as related to quantity and also costs of maintenance at airports and in the field, and chose metal as the material of construction. Structural members are fashioned from sheet duralumin rather than from tubes and a type of construction was evolved that can be made with the minimum investment in tools, that is cheap to put together and that can be repaired with the smallest amount of equipment and labor. For compression loads, duralumin has a great deal more strength for a given weight than has steel. It cannot be used, however, for compression members in combination with steel in tension members because of the difference in coefficient of expansion.
Technical Paper

Methods of Building Metal Airplane Structures

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

Self-Energizing Brakes

THE theory and characteristics of brakes of the Steeldraulic system are set forth and their application in practice is explained. Self-energizing brakes are said to be desirable because they allow large clearances, low pedal-effort and frictional coefficient and, if properly designed, give a high degree of efficiency with smooth uniform action. To accomplish these results, the controls should deliver equal and accurate actuation to all brakes at all times, be designed to minimize the possibility of becoming inoperative on account of dirt and rust, require no servicing, be noiseless and of good appearance, and remain unaffected by climatic changes. Shoe design should allow very liberal limits and tolerances in wheel, axle and drum assemblies, without causing erratic brake-action or noises. The brake hook-up should follow the simplest line and use the least number of connecting links.
Technical Paper

Alloy Steels and Their Application in the Automotive Industry

AFTER outlining the progress of research in the development of the alloy steels, the author says that alloys of steel containing nickel, chromium, and nickel and chromium, are the most important to the automotive industry, which is especially interested in alloys containing up to 5.0 per cent of nickel and up to approximately 1.5 per cent of chromium, with the carbon content ranging from 0.10 to 0.50 per cent. The additions of these amounts do not materially change the nature of the metallographic constituents, but the elements exert their influence on the physical properties largely by altering the rate of the structural changes. In straight carbon-steel, especially of large sections, it is not possible by quenching to retard the austenite transformation sufficiently to produce as good physical properties as are desired.
Technical Paper

Service Characteristics of Light Alloys

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

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

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

Prevention of Corrosion in Duralumin Airplane Structures

AT first believed immune, aluminum alloys have been found extremely susceptible to both surface corrosion and intercrystalline corrosion. The latter goes on under paint that has been applied to imperfectly cleaned surfaces, and shows only as blisters. Because of this, it has become commonplace to break with the fingers the ribs and the trailing edges of duralumin lower wings and tail-surfaces. Contact of duralumin with brass or steel hastens corrosion, and protective paint coverings are dissolved by dope where fabric surfaces meet metal parts. All-duralumin structures are not considered suitable for sea-going aircraft unless all joints and seams are of water-tight construction, not only in hulls but in other members of the structure. Corrosion over the land is much less severe. Few manufacturers seem awake to the importance of corrosion. The fight to avoid it should begin with avoiding seams that are difficult to protect and hollow members that cannot be sealed hermetically.
Technical Paper


Mr. Woolson points out that designers are continually trying to make 1 lb. do the work of 2 lb. but are prone to underestimate the important possibilities of alloyed cast iron in automotive engineering. Recent improvements in methods of handling molten metal for casting lends these methods to the obtaining of uniformity of castings and physical properties. Some readily obtainable properties of electric-furnace iron are strength approximately double that of ordinary cast iron, increased wear resistance, reduced growth characteristics, heat resistance and corrosion resistance.
Technical Paper

The Gum Stability of Gasolines

AN investigation of the accelerated oxidation method for predicting the gum stability of gasolines was made to determine the effects of oxygen pressure and of temperature on the observed induction periods. The data obtained on the effect of pressure indicated that there was a definite relation between the induction period at any pressure and the induction period at an air pressure of 1 atmosphere. The data obtained on the effect of temperature showed that the induction periods of different gasolines changed to a different extent with temperature, so that gasolines with the same induction period at any one temperature might have very different periods of stability at storage temperatures. Since temperature has a marked effect on the observed induction period and since the gasoline is at a lower temperature than that of the bath for a considerable period of time at the beginning of the experiment, a correction factor was applied to obtain true induction periods at the bath temperature.
Technical Paper

Magnesium Alloys in Aircraft-Engine Construction

ACHIEVEMENTS of the last ten years in increasing the power-weight ratio of aircraft engines are stated and contributing factors are analyzed. Aluminum alloys have replaced cast iron and steel for certain parts, not entirely because of their lower weight but because of a combination of properties which better fit them for the task. Similar considerations must govern the replacement of aluminum-base alloys by those of magnesium. The most promising immediate field for the magnesium alloys is said to lie in applications wherein strength and lightness are the main considerations and high-temperature properties are of secondary importance. Properties of magnesium castings and forgings are compared with those of castings and forgings of the aluminum alloys. Features of design are discussed which should receive special attention when changing a part from aluminum to magnesium. Machining practices for magnesium are covered in some detail.
Technical Paper


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


Corrosion in gasoline engines is generally believed to be due to sulphuric acid formed by the combination of sulphur carried in low-grade fuels and oils with water that enters or is generated in the engine. Much of this trouble occurs in winter and may be traced directly to the action of water that condenses on the inside of the cylinders and crankcase when a cold engine is started. The water destroys the oil-film and comes into direct contact with metal of the pistons, cylinders and other parts, causing them to rust. If this occurs and the lubricating system does not supply more oil to the surfaces immediately upon the restarting of the engine, scored cylinders and pistons are likely to result, or, if the engine is stopped before it is warmed up, condensation and rusting will be rapid and will result in excessive wear.
Technical Paper


HE lubricating possibilities of silicones are summarized by the authors as follows: 1. Silicone fluids offer possible solutions to lubrication problems involving heat stability, oxidation resistance, nonvolatility, and low change of viscosity with change in temperature. 2. Different types of silicone fluids vary in their lubricating ability and in their behavior toward various rubbing metal surfaces. Some silicone fluids approach petroleum oils in ability to reduce wear. 3. Silicone greases, because of their oxidation resistance and low volatility, should find application in the operation of ball bearings under severe conditions and in permanently lubricated ball bearings where long service life is essential.
Technical Paper


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

Instrumentation for Valve-Burning Studies

A NEW technique is described utilizing a dynamic micrometer to observe valve motion during actual operation under simulated highway conditions. Using this instrumentation, studies were conducted on the effect on valve life due to dynamic sticking resulting from additive concentration, valve motion, and valve flexure. The test data indicate that exhaust-valve burning in passenger-car engines appears to be due principally to valve-face corrosion.