Propulsion Selection for 85kft Remotely Piloted Atmospheric Science Aircraft

This paper describes how a 3 stage turbocharged gasoline engine was selected to power NASA's atmospheric science unmanned aircraft now under development. The airplane, whose purpose is to fly sampling instruments through targeted regions of the upper atmosphere at the exact location and time (season, time of day) where the most interesting chemistry is taking place, must have a round trip range exceeding 1000 km, carry a payload of about 500 lb to altitudes exceeding 80 kft over the site, and be able to remain above that altitude for at least 30 minutes before returning to base. This is a subsonic aircraft (the aerodynamic heating and shock associated with supersonic flight could easily destroy the chemical species that are being sampled) and it must be constructed so it will operate out of small airfields at primitive remote sites worldwide, under varying climate and weather conditions. Finally it must be low cost, since less than $50 M is available for its development. These requirements put severe constraints on the aircraft design (for example, wing loading in the vicinity of 10 psf) and have in turn limited the propulsion choices to already-existing hardware, or limited adaptations of existing hardware. The only candidate that could emerge under these circumstances was a propeller driven aircraft powered by spark ignited (SI) gasoline engines, whose intake pressurization is accomplished by multiple stages of turbo-charging and intercooling. Fortunately the turbocharged SI powerplant, owing to its rich automotive heritage and earlier intensive aero powerplant development during WWII, enjoys in addition to its potentially low development costs some subtle physical advantages (arising from its near-stochiometric combustion) that may make it smaller and lighter than either a turbine engine or a diesel for these altitudes. Just as fortunately, the NASA/industry team developing this aircraft includes the same people who built multi-stage turbocharged SI powerplants for unmanned military spyplanes in the early 1980's. Now adapting hardware developed for reconaissance at 65-70 kft to the interests of atmospheric science at 80-90 kft, their efforts should yield an aero powerplant that pushes the altitude limits of subsonic air breathing propulsion

Volume 35 - Issue 2 - November, 1925

https://scholar.rose-hulman.edu/technic/1317/thumbnail.jp

The Lumberjack, January 07, 1966

The student newspaper of Humboldt State University.https://digitalcommons.humboldt.edu/studentnewspaper/2810/thumbnail.jp

The potential use of bio-ultracarbofluids in a standard diesel engine

The replacement of diesel fuel by ultra-carbofluids was perceived to offer the potential to decrease the emissions of environmental pollutants such as carbon dioxide, carbon monoxide, hydrocarbons (HC's) and smoke. Such ultracarbofluids consist of a suspension of coal in fuel oil and water generally in the ratio of 5: 3: 2 plus a small amount of stabilising additive. The literature relating to the economies of coal and fuel oil production, and the production and properties of charcoal and vegetable oils has been critically reviewed. The potential use of charcoal and vegetable oils as replacements for coal and fuel oil are discussed. An experimental investigation was undertaken using novel bio-ultracarbofluid formulations. These differed from an ultracarbofluid by having bio-renewable charcoal and vegetable oil in place of coal and fuel oil. Tests were made with a Lister-Petter 600cc 2-cylinder, 4-stroke diesel engine fitted with a Heenan-Froude DPX 1 water brake dynamometer to measure brake power output, and Mexa-321E and Mexa-211E analysers to measure exhaust pollutants. Measurements were made of engine brake power output, carbon dioxide, carbon monoxide, hydrocarbons and smoke emissions over the speed range 1000 to 3000 rpm at 200 rpm intervals. The results were compared with those obtained with a standard diesel reference fuel. All the bio-ultracarbofluid formulations produced lower brake power outputs (i.e. 5.6% to 20.7% less brake power) but substantially improved exhaust emissions of CO2, CO, HC's and smoke. The major factor in the formulation was found to be the type and amount of charcoal; charcoal with a high volatile content (27.2%) and present at 30% by mass yielded the best results, i.e. only slightly lower brake power output and significantly lower exhaust pollutants

Interactions between charge conditioning, knock and spark-ignition engine architecture

There are currently many factors motivating car manufacturers to reduce the tailpipe CO2 emissions from their products. One of the major routes to achieving reduced CO2 emissions in spark-ignition 4-stroke engines is to ‘downsize’ the swept volume which, among other advantages, reduces the proportion of fuel energy expended on pumping losses. The full-load performance deficit caused by reducing the swept volume of the engine is normally recovered by pressure charging. One of the limits to pressure charging is combustion knock, which is the unintended autoignition of the last portion of gas to burn in the combustion chamber after combustion has been initiated. This thesis presents results from investigations into a number of methods for suppressing knock, including (1) tests where the density of the intake air is closely controlled and the effect of charge air temperature is isolated, (2) where the latent heat of vaporization of a fuel is used to reduce the outlet temperature of a supercharger, and (3) where the engine architecture is configured to minimize exhaust gas residual carryover to the benefit of stronger knock resistance. Extensive comparison of this resulting engine architecture is made with published data on other strategies to reduce the effect of the knock limit on engine performance and efficiency. Several such strategies, including cooled EGR, were then investigated to see how much further engine efficiency (in terms of brake specific fuel consumption) could be improved if they are adopted on an engine architecture which has already been configured with best knock limit performance in mind. Within the limits tested, it was found that if the charge air density is fixed then the relationship between knock-limited spark advance and air temperature is linear. This methodology has not been found in the literature and is believed to be unique, with important ramifications for the design of future spark-ignition engine charging systems. It was also found that through a combination of an optimized direct-injection combustion system, an exhaust manifold integrated into the cylinder head, and a 3-cylinder configuration, an engine with extremely high full-load thermal efficiency can be created. This is because these characteristics are all synergistic. Against the baseline of such an engine, other technologies such as excess air operation and the use of cooled EGR are shown to offer little improvement. When operating a pressure-charged engine on alcohol fuel, it was found that there exists a maximum proportion of fuel that can be introduced before the supercharger beyond which there is no benefit to charge temperature reduction by introducing more. Strategies for reducing the amount of time when such a system operates were developed in order to minimize difficulties in applying such a strategy to a practical road vehicle. Finally, a new strategy for beneficially employing the latent heat of vaporization of the fuel in engines employing cooled EGR by injecting a proportion of the fuel charge directly into the EGR gas is proposed. This novel approach arose from the findings of the research into pre-supercharger fuel introduction and cooled EGR

Philadelphia Journal of Osteopathy

Articles in this issue include: President O.J. Snyder\u27s Address. Graduating Exercises Philadelphia College of Osteopathy Commencement Exercises Some Nerve Functions Osteopathic Action and Reaction. Physiological Kinesthesia Atmospheric Electric States in Relation to the Nervous System, and the Physiology of Fear in Disease, with Neuropathic Suggestions The Sex Functionhttps://digitalcommons.pcom.edu/phila_j_osteopathy/1016/thumbnail.jp

Colding, Ørsted, and the Meanings of Force

THE DANISH PHYSICIST and engineer Ludvig August Colding (1815-1888) is known to historians of nineteenth-century physics as the author of one of several formulations, during the 1840s, of the concept that eventually gained currency as the principle of the conservation of energy. Thanks largely to the work of Per Dahl, the substance of Colding's work and a rough idea of the route he followed has been known for several decades.1 In brief, Colding sought experimental corroboration, in terms of the frictional heat produced via the expenditure of a measured amount of mechanical work, of a rough notion of the general imperishability of the forces of nature that he derived from an originally metaphysical conviction concerning the imperishability of the human spirit regarded as a species of force. Nor has the importance gone unnoticed of (Holding's relationship to Hans Christian Ørsted (1777-1851), to whom Colding was attached for many years as student and protégé Ørsted had disclosed the interactive relationship between electricity and magnetism in 1820 and was a highly visible proponent of the notion of the unity of nature, as showcased in particular in the collection of essays he entitled The spirit in nature? Yet some of the important details in this overall picture remain unclear. The quality of Colding's metaphysical beliefs has not been explored in appropriate depth, nor has the significance been established of his brief reference to the role played in the development of his ideas by the antimateri alistic pronouncements of zoologist and physiologist Daniel Frederik Eschricht (1798-1863).3 Nor have we been adequately enlightened as to the significance of what he referred to as d'Alembert's principle of lost forces, or to the status of such a principle in the mechanics of the period.4 And his relationship to Ørsted is problematic. Although there would appear to be some important con nection between Colding's and Ørsted's general views on nature and its forces, and Ørsted occasionally asserted some kind of unity among the forces of nature, he failed signally to appreciate the significance of Colding's work when it was given him to evaluate.5 The solution to this apparent paradox will be sought through an understanding of Ørsted's changing conception of force and its relationship to the "activities" of heat, light, electricity, magnetism, and chemical activity.6 Without paying proper attention to language, historians have tended to read back into Ørsted's usages meanings of "force" that came to it in large part as a result of the work of Colding and his generation.

A Guide for Introducing Power Mechanics into the Yakima Public Junior High Schools

In a power dependent society such as ours, it is important that the knowledge of mechanical power and its utilization be offered to the student through the industrial arts curriculum. There are no existing courses in power mechanics in the Yakima Public Junior High Schools, and this is the problem the writer attempts to solve. Therefore, the purpose of this study is to propose a guide containing sufficient information for the inauguration of a basic power mechanics course into the school system

Mechanical equipment in Antarctica and the relation of laboratory research to field performance

Imperial Users onl