Revolutionalized Travel - Case Study Example

AIRPLANE ENGINES Introduction The invention of the airplane has great significance in history, as it revolutionalized travel and commerce, fuelled technological advancement, and formed an important accomplishment of humankind. Airplane engines are designed for reliability and long service lives. There are several factors that impact the energy produced by an airplane engine for flying. Two critical components of airplane engine performance are: the load that the airplane is carrying and the density of the air. Air density decreases when the air becomes warmer; similarly air density lowers with increased humidity in the air because some of the space in a given volume is taken up with water vapour not air molecules. However, the adverse effects of higher humidity is not as high as the problems associated with increased altitude and higher temperatures (Eichenberger: 178-179). Airplane engines are hence continually modified for highest levels of performance, with advances in technology and aviation science. This paper proposes to discuss the history of airplane engines, the development of airplane engines, how the airplane engine works, and its effects on the environment. Discussion History of Airplane Engines At the start of the twentieth century, aircraft engines were simple, low-powered machines that were designed and custom-built for specific aircraft. However, engines started being built in quantity, often by several licensed manufacturers in different countries. The earliest airplane engines were stationary, and were either radial or in-line. The Antoinette series of engines were the most commonly used. These were followed by the rotary engine, the best known of which were the Gnome and Le Rhone. These were succeeded by the in-line Liberty engine which was designed for mass production, and gained monopoly over the aero-engine market. Henceforth, increasingly powerful and more sophisticated stationary in-line engines were developed until the manufacture of the jet engine a couple of decades later. The first successful powered flight in 1903 by the Wright brothers had an engine designed and built by Charlie Taylor, and is a landmark in aviation history. It was lower powered than the 50 horse-powered engine designed earlier in the century by Charles Manley, which could not demonstrate its potential since it was designed for another faulty aircraft. The Wright brothers’ engine had no fuel pump, carburetor or spark plugs, had four in-line cylinders, was water-cooled, generated 12 horsepower, and had weighed 179 pounds without the fuel. Numerous types of engines were subsequently designed and built. By 1911 other engine manufacturers began building rotary engines. The British Rolls-Royce Eagle and its successor, the Falcon: a liquid-cooled V-12 developed in 1915, marked the beginning of a famous line of aviation engines that produced the Merlins and Griffons of World War II.. It was built in several versions that culminated with the 375-horsepower Mark VII of 1917. “It powered the Vimy plane that John Alcock and Arthur Whitten Brown flew across the Atlantic in June 1919” (Rumerman, 2003). Direct air cooling was the natural choice for the designers of the rotary radial engines used extensively in World War I military aircraft. The technology necessary to produce the cylinders was readily available, and the major parts of the engine were constucted from billets and forgings of alloy steel rather than from castings. The materials were very likely one of the low-to-medium carbon steels alloyed with nickel that were popular in that era. The first of the well-known French rotary engines, the 50 horsepower Gnome, had been flown successfully in 1909. Aircraft designers preferred the rotary mechanism since the power-to-weight ratio of the rotaries was generally better than that of other aircraft engines. In response to military needs, larger rotary engines were manufactured in growing quantities in Germany as well as in France and Britain. Some rotary engines were manufactured in the United States under license agreements with the French (Genevro, 2006). These were succeeded by the durable Mercedes engine with six water-cooled cylinders, followed by several others, especially the 400 horse-powered Liberty which was one of the most powerful engines used in the World War I. It was in use for several years. There has been ongoing development in airplane engines with increasing advance in technology and aviation science (Rumerman, 2003). By the mid 1950s, the evolution of the air-cooled cylinder for the large radial engines came to an end, as the gas turbine in the form of either turboprop or turbojet became the dominant powerplant for larger aircraft (Genevro, 2006). The Development of Airplane Engines During the period between the World Wars, unprecedented progress in aircraft design occurred, resulting in radical improvement in aircraft engines. Engine development is a very laborious and minute process of building an engine, running it to destruction, analysing the components that broke, designing a remedy, and repeating the process. Aircraft engines must produce as much power as possible while weighing as little as possible. This is usually expressed in pounds per horsepower (lb/ hp). It is not feasible to make the engine more powerful by making it bigger since this would also make the engine heavier. Metal cannot be reduced to make it lighter, as parts would break and become less durable. Fuel-efficiency of the engine has to be ensured so that less fuel needs to be carried by the airplane. A great deal of the take-off weight of an airplane is dedicated to fuel. Ocean-crossing airliners are possible only because of the superb fuel consumption of advanced engines (McKutcheon, 2006). These remarkable developments were made by systematically improving seven areas of engine design and construction: arrangement, materials, cooling, induction, lubrication, fuels, and operation; and most of these factors are interrelated. In addition to engine improvements, there were also important advances in aircraft and propeller design. One of the greatest engine-related advances was the development of the NACA cowl that reduced the cooling drag of air-cooled radial engines to levels that equalled those of liquid-cooled engines (McKutcheon, 2006). By 1950, aircraft piston engines had reached the peak of development, becoming light, powerful, durable and fuel-efficient. They also reached their utmost development in power and complexity. It was considered impractical to use cylinders larger than around 200 cubic inches, producing more than 200 horsepower, or more than 28 cylinders. From around 1945, development of piston engines gave way to jet engines (McKutcheon, 2006). How the Airplane Engine Works The type of gas turbine engine used in airliners is called as a turbofan engine or a jet engine. It works in the following way: first air is drawn into the front of the engine by a large rotating fan. Some of the air passes into a compressor where it is compressed before passing into a combustion chamber. Then aviation fuel is ignited in the combustion chamber. The fuel and air mixture burn intensively producing hot gases at high temperature and pressure. These gases expand rushing towards the back of the engine. As the gases stream backwards, the engine and the craft it is attached to, is forced forwards. The thrust occurs inside the engine, pushing the aircraft forwards. Before emerging from the engine, the gases pass through a turbine, making it spin rapidly. The revolving turbine turns an axle which which drives the compressor and the intake fan. Some of the air taken in at the front of the engine is sent straight to the rear of the engine to keep it cool and reduce the noise (Lafferty: 14). Airplanes generally use air cooled engines for two reasons: they are lighter in weight than liquid-cooled engines because they do not have radiators, water pumps, associated plumbing and the weight of the liquid coolant. Secondly, the absence of the above-mentioned components is an advantage, as causes for failure are decreased. With advancement in the sciences of engine design and metallurgy, there has been an increase in the development of liquid-cooled airplane engines. Liquid-cooled engines are more efficient than air-cooled ones, and the rising price of fuel is compelling aviation manufacturers to improve efficiency. “These newer liquid-cooled engines are designed to run for an extended period of time even after all the coolant has leaked out, which would match their safety to that of an air-cooled engine” (Eichenberger: 103). The airplane engine has two complete and separate ignition systems that supply power to the spark plugs in the cylinders. There are two spark plugs in each cylinder and each is powered by a different ignition system. Reliability and safety are enhanced by ensuring that each of the two magnetos powers one of the separate systems, with the electrical energy necessary to provide power to the spark plugs. This electrical system supplies the power to start the functioning of the engine (Eichenberger: 104). Impact of Airplane Engine on the Environment Environmental impact from air traffic can be divided into air pollution, water pollution and noise problems. Airplane engines can contribute to air pollution through aircraft operations, aircraft taxiing to and from runways, re-fuelling of aircrafts, and emissions from engine test areas. The extent of air emissions from airplane engines is dependent on total emissions during a landing and take-off cycle (LTO). It includes all aircraft operations from ground level to 900 metres altitude. The duration of an LTO cycle varies from 15 minutes to 30 minutes, depending on the type of airplane and the airport. The main LTO pollutants are: carbon monoxide, nitrogen oxides, hydrocarbons, benzene, ethylene, polyaromatic hydrocarbons and soot. A large proportion of the total emissions occur at high altitudes, at cruising level. Further, fuel losses can occur during several steps in fuel handling processes, and take place due to pressure variations in fuel containers as well as if overfilling is done during refuelling activities (Ryding: 117). Water pollution takes place due to de-icing of aircraft and runways, pollution from fire-fighting equipment practices, and oil and fuel spills. The most widely used aircraft de-icing agent is a solution of glycol and water. For de-icing runways, urea in a granulated form is commonly used. Other salt compounds are also frequently used. Fire-fighting agents often contain detergents, with additions of phosphorus and other chemicals (Ryding: 118). Excessive noise is of significant concern especially to those living close to airports. Two different ways are used to describe air traffic noise: the equivalent level which is the average value during a certain period of time, and the maximum level which occurs at specific times. Noise at maximum levels can cause serious disturbance and inconvenience (Ryding: 118). . Conclusion This paper has highlighted the airplane engine, and discussed its history, development, how the airplane engine works and the ways in which the it affects the environment. The continued growth of the airplane industry presents tremendous opportunities on the one hand, and environmental challenges on the other. The future aero engines will need to be more reliable, have lower operating costs and significantly lower environmental impact than those currently in service. The Efficient and Environmentally Friendly Aero Engine (EEFAE) technology platform tests advanced technologies in turbines, engine control system, compressor, combustor and other components of the engine (Wells et al: 163), thus “reducing fuel consumption and greenhouse gas emissions, improve reliability, reduce life cycle cost and accelerate the introduction of these improved technologies into service” (Dossier: 151). Works Cited Dossier, Aviation and the Environment. Europe’s aero engine community targets major environmental improvements. Air and Space Europe, 2.3 (2000): 51. Eichenberger, Jerry A. Your pilot’s license. The United Kingdom: McGraw-Hill Professional. 2003. Genevro, George. Aircraft engine history: from the past. Pilotfriend Aero Engines. 2006. Available at: http://www.pilotfriend.com/aero_engines/aero_aircooled.htm Lafferty, Peter. How things work. London: The Octopus Publishing Group. 1992. McKutcheon, Kimble, D. A brief overview of aircraft engine development. 2006. Available at: http://www.pilotfriend.com/aero_engines/aero_eng_dvmt.htm Rumerman, Judy. Early Aircraft Engines. U.S. Centennial of Flight Commission. 2003. Available at: http://www.centennialofflight.gov/essay/Aerospace/earlyengines/Aero4.htm Ryding, Sven-Olof. Environmental management handbook: the holistic approach – from problems to strategies. England: IOS Press. 1994. Wells, Guy, Morgan, Steve, Masse, Bruno, Scheugenpflug, Hermann. Aircraft Technologies: EEFAE – Efficient and Environmentally Friendly Aero Engine - technology platform. Air and Space Europe, 3.3/4 (2001): 163-165. Read More