Sustainable Aviation

The link below is to a webpage I build dedicated to my research topic on sustainable aviation.

http://sustainableaviation.weebly.com/

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Going Green in the Blue: Reducing the Environmental Impact of Aviation.

It was a cold December morning in 1903 on the shores of Kitty Hawk, North Carolina. Two brothers, Orville and Wilbur Wright where set to make history; for on this day they would become the first men to successfully fly a powered aircraft. This would set into motion a series of events that would turn aviation into one of mankind’s most important achievements. Little could the Wright brothers know that in just over one hundred years there would be aircraft carrying passengers all over the world with wingspans longer than the distance of their first flight. With all of the advances in aviation technology, one question is on the minds of every airline, government, manufacturer, and engineer. How can aircraft be made sustainable for the future? Well, I believe the answer lies in the examination of four areas in aviation, fuel, engines, structure, and design. By looking in those areas we could find the answer to the “green question.”

The Wright Brother’s “Wright Flyer” used a single piston engine to turn two propellers. Variations of piston engines would continue to evolve, becoming much more powerful. Piston engines would reach the limit of their development during the Second World War when a new type of aircraft engine would be introduced to the skies over Europe. By 1944, two aircraft, the British built Gloster Meteor and the German built Messerschmitt Me-262, would take to the skies powered by a new type of engine, the turbojet. The Me-262 in particular proved the advantages of the turbojet engines when they were sent after American bomber formations that were escorted by one of the most advance piston engine fighters of the war, the North American P-51 Mustang. The Mustang was fast, with a top speed of about 450 miles per hour, but the Me-262 was about 100 miles per hour faster. The Me-262s would come in at full speed and tear through the bomber formations, claiming several bombers and a few of the escort fighters before the fighter pilots or the defensive gunners on the bombers could even react. Fortunately for the allies the Me-262 was a case of too little too late. There were too few of the new jet fighters to make a difference in the outcome of the war and too late because by 1944-45, the manufacturing centers of Nazi Germany had been bombed to oblivion. Because of the constant bombing the manufacturing process were not always the greatest and the Me-262’s engines were unreliable and very fragile, a disadvantage that American and British fighter pilots exploited to some success. The Me-262 did prove that piston engines had reached their limit and that the jet was the way of the future. While most aircraft designers after the war embraced the turbojet for military aircraft, few would look at applying the technology to civilian aircraft. Many believed that the turbojet was economically unfeasible for airline use. That idea would soon change however thanks to one enterprising British airplane manufacturer.

In 1947, the British de Havilland Company changed the world with the first flight of world’s first jet powered commercial airliner. The de Havilland DH.106 Comet was powered by four turbojet engines and had a top speed of around 500 miles per hour, cutting flight times in half versus piston engine airliners. The Comet proved that a jet powered airliner was economically feasible and set off a scramble among other airplane manufacturers to build a jet airliner to compete with it. By the mid-1950s three American companies would debut their own jet airliners, Boeing with its 707 airliner, McDonnell-Douglas with its DC-8, and Convair with its 880 and 990 airliners. All of these aircraft were initially powered by turbojet engines and one major drawback with the early turbojets became apparent, they were too underpowered for a large commercial airliner during takeoff and they were gas guzzlers. In order to alleviate the lack of power drawback during takeoff many of the turbojets had a water injection system that would force water into the engine to fool it into creating more power, but that process would mean very smoky and very, very noisy takeoffs. There had to be a better engine for the job, and one was found. Enter the turbofan.

The turbofan was the first leap in jet engine technology over the turbojet. The main difference between the two engines is that turbofans allow air to bypass the engine core where as in a turbojet; all air that goes into the engine goes through the core. Turbofans could generate more power while using less fuel and were quieter than turbojets. Boeing and McDonnell-Douglas where some of the first aircraft manufacturers to start building commercial aircraft with turbofans installed, both choose the Pratt and Whitney JT3D engines. This not only increased the takeoff performance; it decreased the fuel consumption and as a side effect of that, increased range. Engines like the JT3D and the later JT8D, which powered the Boeing 727 and 737 as well as the McDonnell-Douglas DC-9, are known as a low-bypass ratio turbofans because the ratio of bypass airflow to non-bypass airflow is very small, the next evolution in turbofans would led to the creation of the high-bypass ratio turbofan.

High-bypass ratio turbofans have very large ratio of bypass airflow to non-bypass airflow versus low bypass ratio turbofans. The high-bypass ratio turbofans offer increased power and decreased noise and fuel consumption. The first patent for the high-bypass ratio turbofan was filed by Siegfried H. Decher and Dale H. Rauci on February 26, 1965 (Decher and Rauci, 1965). A few years later, the first aircraft powered by the new high bypass ratio turbofans would take to the skies. These aircraft were the new generation of wide body airliners (that means they have more than six abreast seating which would require more than one aisle in the cabin). These aircraft would include the Boeing 747, McDonnell-Douglas DC-10, Lockheed L1011 TriStar, and the Airbus A300, which was the first aircraft built by European manufacturer Airbus. These aircraft had even more range thanks in part to the new type of engine and where much quieter than their predecessors. High bypass ratio turbofans have been used on almost every aircraft manufactured since the late 1960s. As the years have passed by, the bypass ratios have increased and as a result so have engine diameters; a Boeing 777 engines have the same diameter as the fuselage of a Boeing 737. All of this adds up to increased weight, as you can imagine the engines on a Boeing 777 are very heavy and more weight leads to drag and loss of fuel efficiency. There is also the matter of harmful CO2 (carbon dioxide) and NOx (nitrogen oxide compounds) emissions that aircraft engines produce. In order to address these issues, there is a lot of attention and effort being spent on technologies to reduce the negative impacts of the emissions and weight issue, and one company is heavily invested in finding solutions to these problems.

Because of how jet engines operate, by mixing air and fuel and burning it, one of the byproducts is harmful emissions, mainly CO2, NOx, and SOx (sulfur oxide compounds). Aviation emissions account for only about 2% of the total greenhouse gas emissions, but this is expected to grow to 3% by 2050 (Parker, 2009).   There are new policies that include how to better manage air traffic that can reduce emissions, but one of the most looked at ways of reducing emissions is using technology. Since the 1960s there has been a 70% reduction in CO2 and a 50% reduction in NOx emissions, most of this was out the airlines’ cost saving desires but a lot of it was also to stricter ICAO (International Civil Aviation Organization) regulations since the 1980s (Parker, 2009). One of the companies taking a big step in emission reduction is British engine manufacturer Rolls-Royce in response to Advisory Council for Aeronautical Research in Europe (ACARE) Vision 2020 agenda which strives for a 50% reduction in CO2 emissions though airframe, engine, and air traffic management improvements (Parker, 2009). This represents a challenge since one of the hardest things to do is bring technology to market; this requires an extensive research and development budget. Rolls-Royce spends roughly two thirds of an £800 million per year R&D budget on technologies for reducing environmental impact (Parker, 2009). However, simply throwing money at a problem will not make it go away, you need to have a plan set up for it that not only monitors what will be going on today, but also in a few years and a few decades down the line. Rolls-Royce has done that with their Vision 5, Vision 10, and Vision 20 programs. These look at technology that is already available, what will be available within the decade and technologies that are only theoretical or in very early stages of development, respectively (Parker, 2009). Vision 5 has already given the world two new technologies in recent years; the hollow, swept back titanium fan blades that are used on the Rolls-Royce Trent 900 engines for the Airbus A380 and the electric Environmental Control and Anti-Ice systems in the Trent 1000 engines that power Boeing’s 787 Dreamliner, both help reduce emissions in both aircraft (Parker, 2009). All of this research as brought up numerous ways to reduce emissions; while some are better than others they all have their merits.

One method of reducing emissions is by increasing bypass ratios in jet engines, however you can only increase the ratio so much before the weight and drag created by the engine offset the fuel and emissions savings. One solution is by using open rotor design on mainly short haul aircraft such as the Boeing 737 and Airbus A320. There are issues with certification, maintenance, and integration as the exposed fan blades need a bit more room than a traditional engine. Increasing temperature and engine combustion pressure is another option, however this is limited by the materials that make up the engine and there is also the undesirable consequence of increasing NOx emissions. There is research going into making engine components out of a single nickel alloy crystals, which are stronger than traditional alloys because they lack grain boundaries which are weak points in the material which would allow higher pressures and temperatures in the engine (Parker, 2009). There is however another school of thought that wants to move away from fossil fuel burning engines and towards electric based propulsion.

The idea of using electric engines has merit. The electric engines would overcome the physical limitations of traditional jet engines in regards to gains in efficiency by using varying speed control by the fact that all of the components are connected to the same drive shaft and that the low pressure, or intake fan, cannot exceed the speed of sound during normal, non-takeoff, operations. An electric engine would use an multiple generators linked to a turbo shaft, with the fan for propeller connected electronically to the generators though an “electrical gearbox” which would allow the faster rotational speeds and less stages necessary, all of this would reduce weight and increase efficiency (Luongo, et al., 2009). It would also enable more control flexibility, kind of like a transmission in a car. The electric engines are a popular contender for the concept of “distributed propulsion” which would use multiple small engines integrated in an aircraft’s structure. While engine technology is one of the main ways to improve aviation sustainability it is not the only way. One of the ways is by looking at what enables jet engines to operate, their fuel.

Since powered flight was first achieved airplanes have needed one thing to be able to fly, fuel. The early piston engine aircraft used very heavily refined, high octane fuels to produce power. When jet engines were first considered for commercial aviation many people believed the idea to be economically unfeasible because they assumed that jet fuel would need to be more refined than the fuel used in piston engines. What they did not realize was that jet fuel was no more than kerosene. Kerosene is a very basic, inexpensive, and easily produced fuel and because it burns with a lot of energy, made an idea fuel for a jet engine. In aviation this kerosene based fuel is called Jet A. While Jet A is a good fuel because of how energetically it burns, it is still a fossil fuel and like all fossil fuels produces pollution, mainly CO2, NOx, SOx, and unburnt hydrocarbons (e.g. smoke). All of these are harmful to the environment both locally and globally. There needs to be a fuel source that has both the energy potential of kerosene and is a cost effective solution or else it will be harder to convince manufactures and operators alike to use it.

One group of fuels that is being looked into is synthesized fuels which include biodiesel, syngas, and hydrotreated oils. The advantage in using a synthesized fuel is that it is known as a “drop-in” fuel meaning it would avoid a costly and time consuming redesign of aircraft engines. That would make it easier to deploy worldwide since it could be put to use in existing aircraft.
Biodiesel, also known as fatty acid ester or FAE, produced from the transesterification of bio-oils into bio diesels using either methyl (FAME) or ethyl (FAEE) (Blakely, et. al, 2011). Another fuel type is called syngas which is a mixture of hydrogen and carbon monoxide which is derived from coal, gas, or biomass. It is created using the Fischer-Tropsch process which creates chains of carbon that form chains of alkanes, this then becomes synthetic crude which can be refined into synthetic kerosene (Blakely, et. al, 2011). Fuels created from hydrotreated oils are another option for an aviation fuel source. Hydrotreated oils are created from the hydroprocessing of vegetable oils which removes undesirable materials such as oxygen, sulfur, and any metals in the oil and breaks it down in to smaller carbon chain lengths which is necessary for a fuel (Blakely, et. al, 2011). There are many benefits to using synthetic fuels in aviation. For one, they can use current engine technology, their chemical compositions can be precisely controlled, and they do offer reductions in emissions, for example Syngas offers up to a 20% reduction in carbon emissions while only loosing 5% in specific energy output (Boretti, Dorrington, 2013). While these fuels do offer a reduction in emissions, they are not emission free. For that we need to look at a simple element, which also happens to be the most abundant in the universe.

The use of hydrogen in aviation is not a new idea; German Zeppelins which were large ridged airships used hydrogen as a means to stay airborne. The most famous Zeppelin is the Hindenburg which flew transatlantic flights in the mid-1930s. The Hindenburg was destroyed by a fire when landing in New Jersey. That accident is the reason why hydrogen is not used as a ballast gas in airships anymore. But now there is another potential use for hydrogen in aviation and it is not for ballast, but instead as a fuel source. There are many advantages to using hydrogen in aircraft. It is lighter than kerosene, far more abundant, renewable, and would produce zero emissions. It would also enable aircraft to have smaller wings which would reduce takeoff weight by 30% and operating costs by 3% because the wing size would not be restricted to storing fuel (Verstraete, 2006). However there are complications to using hydrogen as a fuel. For one the production of hydrogen would need a lot of electricity not only for the electrolysis of water but to also run the plant that would be producing it. It is estimated at with a plant running at 80% efficiency would require 105 megawatts of electricity and 28 cubic meters per hour of desalted water to create 50,000 kilograms of hydrogen per day, and to liquefy all of that hydrogen it would take an additional 25,555 kilowatts of electricity (Khandelwal, et. al., 2013). Another issue would be that the most feasible way to store hydrogen is as a liquid which at atmospheric pressure means temperatures as low as 20.4 kelvin (or about -252.75°C) (Khandelwal, et. al., 2013). Another issue is that hydrogen atoms are much smaller than kerosene molecules, which means that traditional storage methods will not work as the hydrogen will find a way to escape. This means that new types of fuel tanks as well as new types of engines would need to be developed. That would mean that these hydrogen powered aircraft would be more complicated as well as more expensive to build and maintain. These caveats would mean that it could be decades before hydrogen powered airplanes take to the skies. While both engines and fuels are good places to turn to in order to improve the environmental impact of aviation. One of the more interesting ways that this could be done is with an aircraft’s structure and design.

The very first aircraft had wooden skeletons with fabric skin. It was lightweight which was necessary for the low powered engines of the era. That changed in the 1920s with the introduction of more powerful engines which facilitated the use of metals, such as aluminum, which replaced wood and fabric as the preferred material for aircraft and it has not changed since then. However, there are new aircraft being introduce that move away from aluminum as the primary material and onto carbon fiber and composite materials. The first commercial jet aircraft to use composite materials in their construction was Airbus’s A320 family of aircraft. The composite materials reduced the weight of the aircraft which in turn reduced the operating costs, this has made the A320 family one of the most popular short-to-medium ranged aircraft in the world.   New aircraft such as the Boeing 787 Dreamliner and the Airbus A350 use carbon fiber and composites in their construction. Carbon fiber is lighter and stronger than aluminum which makes the aircraft more durable all the while reducing their operating costs and fuel burn. While the use of carbon in aircraft has mainly been on the outside there are some interesting applications for it underneath the skin of the aircraft.

Carbon nanotubes (CNTs), as their name suggests, are small tubes of carbon atoms arranged into a cylindrical shape (tubular). They were first discovered in 1991 and have been the subject of a lot of research into potential applications, including aerospace (Gohardani et al., 2014). They are very small and lightweight but are incredibly strong. Since lightweight and strong are two very important properties in aviation their use in aviation could have some major benefits in regards to reducing the climatological impact of aviation. One potential use of CNTs in aircraft would be in their airframes. There was a study conducted in which a simulation was created where CNTs replaced aluminum as the primary airframe material on a Boeing 747, 757, Airbus A320, and an Embraer ERJ145. The replacement resulted in a 14.1% reduction in weight, 13.2% increase in range, and a 9.8% decrease in fuel consumption (Gohardani, et al., 2014). CNTs could also be used to replace the copper wiring used in aircraft. For example, a Boeing 747 has 135 miles of copper wires which adds up to a weight of 4000 lbs, but replacing the copper wire with CNTs would result in a weight reduction of 69% (Gohardani, et al., 2014). While using lighter materials in construction is a step in the right direction, it is not the only way. One of the most important aspects of an aircraft is how it’s designed. There are a lot of ideas on what a more ecofriendly aircraft would look like. Some look similar to today’s aircraft while others looked like they were ripped from the pages of a science fiction novel.

If the end game is a more ecofriendly aircraft then design is an area that really needs to be paid attention to. There have been some interesting designs for aircraft that have come out in the past few years. For example, the Boeing 787, in addition to using lightweight materials in construction, also utilizes very long, glider-like wings. In fact the 787 is one of the few aircraft where its wingspan is greater than the length of the plane. The long wings create more lift when means less power is required to get airborne and stay that way. Boeing is also in the process of testing a new type of aircraft called a blended wing body. The X-48 as it is known has no obvious fuselage, it is known as a “flying wing” and that design reduces the drag on the aircraft while also increasing lift, so far the only prototype is a remote controlled model but the potential use for the aircraft design, however it is not just boing that is taking an active role in designing for the future.

In 2010, NASA (The National Aeronautics and Space Administration) launched a design program to see what the aircraft of the future would look like. Some of the stipulations of the program where a 71 decibel reduction in noise, 75% reduction in nitrogen oxide emissions, a 70% reduction in fuel burn, and the ability to use more airports in larger cities to reduce congestion and delays (congestion and delays increase fuel use and pollution thanks to aircraft stuck waiting on the ground and in holding patterns in the air, think of it like a traffic jam on a highway with hundreds of idling cars) (Banke, 2008). The result of the research program was designs submitted by four groups, General Electric, Massachusetts Institute of Technology, Northrop Grumman, and Boeing. General Electric designed a 20 passenger aircraft that could reduce congestion at major airports by using smaller regional airports, with its oval-shaped fuselage which smoothes the airflow over the surfaces which reduces drag and lowers fuel burn. MIT’s entry is the most interesting one because of its shape, called the “double bubble.” They essential put to fuselages together lengthwise and mounting the engines on the back of the fuselage. MITs design actually increases the bypass ratio of the engines without making the engine larger, instead the made the jet exhaust larger. Northrop Grumman’s design which is called SLECT or Silent Efficient Low Emissions Commercial Transport is designed for spreading out air traffic over a larger area by using smaller airports and combined with ceramic composites, high bypass ratio turbofans, nanotechnology, and shape memory alloys allow this aircraft to meet the goals of the competition. Finally we have Boeing’s Subsonic Ultra Green Aircraft Research, or SUGAR. This aircraft concept utilizes a high mounted wing with two hybrid electric engines mounted on the wings. The long straight wings increase lift while the hybrid engines reduce the amount of fuel that is needed to be burned. These aircraft show what the future may hold for aviation and that using design to reduce the impact on our climate is a very feasible plan.

It is a feasible idea to create more sustainable aircraft; people need to be up to the challenge for that to occur. While it will not be an easy task by any stretch of the imagination, the benefits will be enormous. Reducing emissions would improve the air quality around airports and the moving away from our depleting supply of fossil fuels and towards renewable fuels would be of economic benefit was well as an environmental victory. I believe that these changes will happen, it may take several years and even several decades, but it will happen, and I hope to be a apart of the solution.

Sources

Decher, S. H., Rauch, D. H. (July 2, 1968). High bypass ratio turbofan. Retrieved from http://www.google.com/patents/US3390527

Banke, J. (May 17, 2010). Beauty of Future Airplanes is More than Skin Deep. Retrieved from http://www.nasa.gov/topics/aeronautics/features/future_airplanes.html#.VDM_GRbEjGc

Gohardani, O., Elola, M. C., Elizetxea, C. (2014). Potential and prospective implementation of carbon nanotubes on next generation aircraft and space vehicles: A review of current and expected applications in aerospace sciences. Progress in Aerospace Sciences, 70, 42-68. Retrieved from http://www.sciencedirect.com.argo.library.okstate.edu/science/article/pii/S0376042114000530

Gohardani, A. S. (2013). A Synergistic Glance at the Prospects of Distributed Propulsion Technology and the Electric Aircraft Concept for Future Unmanned Air Vehicles and Commercial/Military Aviation. Progress in Aerospace Sciences, 57, 25-70. Retrieved from http://www.sciencedirect.com

Khandelwal, B., Karakurt, A., Sekaran, P. R., Sethi, V., & Singh, R. (2013). Hydrogen Powered Aircraft: The Future of Air Transport. Progress in Aerospace Sciences, 60, 45-59. Retrieved from http://www.sciencedirect.com

Verstraete, D. (2013). Long Range Transport Aircraft Using Hydrogen Fuel. International Journal of Hydrogen Energy, 38, 14824-14831. Retrieved from http://www.sciencedirect.com

Boretti, A., & Dorrington, G. (2013). Are Synthetic Liquid Hydrocarbon Fuels the Future of More Sustainable Aviation in Australia? International Journal of Hydrogen Energy, 38, 14832-14836. Retrieved from http://www.sciencedirect.com

Blakely, S., Rye, L., & Wilson, C. W. (2011). Aviation Gas Turbine Alternative Fuels: A Review. Proceedings of the Combustion Institute, 33, 2863-2885. Retrieved from http://www.sciencedirect.com

Luongo, C.A., Masson, P.J., Nam, T., Mavris, D., Kim, H.D., Brown, G.V., Waters, M., & Hall, D. (2009). Next Generation More-Electric Aircraft: A Potential Application for HTS Superconductors. IEEE: Transaction on Applied Superconductivity, 19, 1055-1068.

E. Green (2009) The potential for reducing the impact of aviation on climate, Technology Analysis & Strategic Management, 21:1, 39-59, DOI: 10.1080/09537320802557269

Ric Parker (2009) From blue skies to green skies: engine technology to reduce the climate-change impacts of aviation, Technology Analysis & Strategic Management, 21:1, 61-78, DOI: 10.1080/09537320802557301

Reflections: Experiences from Essay Two

Here I am in this post essay two era, spending a lazy weekend at my parents’ house with a plate of homemade tacos, a bottle of 7-Up, and a white pit bull trying to silently beg for some of my tacos. I am thinking of all that I did for essay two in regards to finding articles and dealing with the extreme annoyance that comes from finding out that the library database articles cannot be access from saved URLs. A few minor hurtles aside, the process was relatively painless in regards to my research process and I will make essay four just that much easier.

One the most important things that I learned while finding articles is that while Google is a valuable resource, there are times where my patience with it has been tried. These frustrations, however offset are also those glorious moments when you find a really good source, my web browser’s bookmarks folder is full of them.  The topic of my research is; what can be done to make aircraft more sustainable?  I found many sources that have dealt with the technological aspect of it, mainly propulsion, design, construction materials, and fuel sources.  My main reason for choosing this topic based upon the reading we did at the beginning of the semester called Waste Not, Want Not, which was about our excessively wasteful lifestyles.  I then did my essay one topic on how we could recycle aircraft materials in aircraft graveyards. Both of these led me into the direction of writing a paper about green tech in aviation.

My research process was mainly a reverse pyramid method, starting broad and then narrowing it down. I first searched very general topics about sustainability and aerospace as well as synonyms for those words such as aviation, environment, efficiency, and green. Those terms and their various combinations returned a fair amount on their own. I then decided that it was time to start becoming more specific in my research. I tried using terms like propulsion, design, fuel, and materials and was able to pull a few more articles from the database search engines. I then tried to search for specific aircraft such as the Boeing 787 Dreamliner but that was met with more mixed results versus my previous attempts.

One day our entire class met up in the computer lab one day to search for articles in the databases. I went through about five different databases on the Oklahoma State University Library website with my favorites becoming Science Direct, ProQuest, and Academic Search Premier. That day I was able to get about fourteen to fifteen articles but unfortunately for me I would not be able to use them all due. Some of the articles I had to put in a request for a full text version from the library and on some of the Science Direct articles the library did not have the full text versions. My articles varied in length from a roughly five pages to over forty pages, so figuring out how to summarize them became my next mountain to climb.

The day I typed essay two was probably one of the longest days of my life. Putting the essay together took over five hours, all of which was spent in a stuffy library reading room. I am just going to go on a tangent and say that they need a much better air conditioning system in that room; it must have been about eighty degrees in there. On top of that, it was a cool day so I was wearing jeans and that only compounded the discomfort. Anyway back to the topic at hand. The worst part about putting all of the sources into the annotated bibliography for me anyway was how mind numbingly repetitive the whole process was since I was using the same template for all of them. By the time of creating essay two, I had eleven sources, and I had to put them all in the paper. Most of my articles varied from eight to forty pages long, the short ones were easy to summarize, and the long ones took a bit more reading and effort on my part to get them done. I did start to get a little worried about my topics because it seemed that they were all too similar but to my relief each one that talked about similar subject matter approached it differently.

With essay two now done, all I need to do is figure out how I am going to organize all of the information into essay four. I should not be too difficult since the hardest part of a research paper is the research itself. I will figure out how to make a good paper out of all of my hard research, especially since I will likely be taking on the ecofriendly challenge when I graduate college in a few years.

How Can Aviation Be Made More Sustainable?: The Annotated Bibliography

Decher, S. H., Rauch, D. H. (July 2, 1968). High bypass ratio turbofan. Retrieved from http://www.google.com/patents/US3390527

“Patent US3390527: High Bypass Ratio Turbofan,” a patent submitted to the United States Patent Office, is intended for researchers and engineers. The article is organized with the main idea at the beginning before it delves into the supporting science in later paragraphs. Siegfried Decher and Dale Rauch argue that their design solves performance issues at subsonic flights and increases overall efficiency. In support of this argument, they point out that their design does not require guide vanes, which are at risk of icing and that high bypass ratios offer better fuel economy. Decher’s and Rauch’s claim that their design solves performance issues at subsonic flights and increases overall efficiency is convincing in that high bypass ratios allow more air to enter the engine and with air entering the engine turning the turbine fans will allow the use of less fuel; however, However they had to solve a loss of efficiency with the larger fan disks at high speeds since the tips would break the sound barrier. Whereas prior to encountering this source, I believed that high bypass ratios didn’t offer many advantages over low bypass ratio turbofans and that their size negated many of those advantages, I now think this was an important development in the history of aviation. This article will be useful for introducing the most common type of aircraft engine because it’s one of the components that is receiving the most attention.

Banke, J. (May 17, 2010). Beauty of Future Airplanes is More than Skin Deep. Retrieved from http://www.nasa.gov/topics/aeronautics/features/future_airplanes.html#.VDM_GRbEjGc

“Beauty of Future Airplanes is More than Skin Deep,” a scholarly journal article, academic book chapter, is intended for engineers and scientifically minded people. The article is organized with a general overview of modern aviation and then it mentions as NASA competition. Jim Banke argues that the future of aviation does not rest in some science fiction inspired design, but in the technologies that reside underneath the skin of the aircraft. In support of this objective, he points out that in a 2010 NASA research competition, many firms and groups submitted designs that seemed old fashioned but that contained many new technologies and ideas. For example, shape memory alloys, ceramic for fiber composite skins, fiber optic cables, self-healing skin, hybrid electric engines, and double fuselages. Jim Banke’s claim that the future of aviation does not rest on some space age design but rater what goes on the inside is convincing in that some of the best ideas are the tried and true ones and that its more about how it is built, how it is powered, and what it is made out of; however, one problem with some of these designs is that many rely on technology that is either theoretical or in a highly experimental phase. Whereas prior to encountering this source, I believed that it would take a radical design to achieve sustainability, I now think that the tech that goes on the inside as well the type of propulsion is what will make the biggest difference. This article will be useful for introducing a unique point of view and providing factual information because some of the best new technologies come from NASA competitions.

Gohardani, O., Elola, M. C., Elizetxea, C. (2014). Potential and prospective implementation of carbon nanotubes on next generation aircraft and space vehicles: A review of current and expected applications in aerospace sciences. Progress in Aerospace Sciences, 70, 42-68. Retrieved from http://www.sciencedirect.com.argo.library.okstate.edu/science/article/pii/S0376042114000530

“Potential and Prospective Implementation of Carbon Nanotubes on Next Generation Aircraft and Space Vehicles: A Review of Current and Expected Applications in Aerospace Sciences,” a scholarly journal article, is intended for engineers and scientists. The article is organized with a introduction to carbon nanotubes, followed by their potential use in aerospace, followed by recent developments, challenges. Omid Gohardani, Maialen Elola, Cristina Elizetxea argue that the potential implementations carbon nanotubes have been predicted to have a large impact on future aircraft and space vehicles. In support of this argument, they point out that certain properties of carbon nanotubes that make them ideal for the aerospace industry. For example, carbon nanotubes have several distinct features, which include superior mechanical, thermal and electrical properties. Gohardani’s, Elola’s, and Elizetxea’s claim that carbon nanotubes have been predicted to have a large impact on future aircraft and space vehicles is convincing in that carbon based items are durable and lightweight; however, they can be tricky to manufacture in a large scale. Whereas prior to encountering this source, I believed that carbon nanotubes would be of little use to the aerospace industry, I now think they could open up a whole new realm of possibilities for aviation. This article will be useful for introducing a new technology that would help answer my research topic in regards to aircraft design because the main goal of this article is to point out the sustainability benefits of carbon nanotubes as well as the efficiency benefits that go along with it.

Gohardani, A. S. (2013). A Synergistic Glance at the Prospects of Distributed Propulsion Technology and the Electric Aircraft Concept for Future Unmanned Air Vehicles and Commercial/Military Aviation. Progress in Aerospace Sciences, 57, 25-70. Retrieved from http://www.sciencedirect.com

“A Synergistic Glance at the Prospects of Distributed Propulsion Technology and the Electric Aircraft Concept for Future Unmanned Air Vehicles and Commercial/Military Aviation,” a scholarly journal article, is intended for engineers. The article is organized by talking about the historical use of distributed components in aviation, and then goes on into the research portion. Amir S. Gohardani argues that distributed propulsion technologies and all electric engines are one of the ways that we could power future aircraft in order to meet noise and environmental requirements. In support of this argument, he/she points out the historical use of distributed wings, fuselages, landing wheels, flow control, and propulsion technology. For example, he points to research that was done just before World War I about the advantages of triplanes vs. biplanes. Gohardani’s claim that distributed propulsion is the future of aviation power plants is convincing in that distributed propulsion was used on the Convair B-36 bomber which had six propeller engines and four jet engines in order to power the massive aircraft; however, distributed propulsion is very complicated and in many cases leads to delays in deployment, such as with the Rockwell B-1 Lancer bomber. Whereas prior to encountering this source, I believed that there was only one way to power aircraft, I now think distributed propulsion can be used in future aircraft. This article will be useful for introducing a unique point of view because this author is one of the few that has looked into this less researched idea.

Khandelwal, B., Karakurt, A., Sekaran, P. R., Sethi, V., & Singh, R. (2013). Hydrogen Powered Aircraft: The Future of Air Transport. Progress in Aerospace Sciences, 60, 45-59. Retrieved from http://www.sciencedirect.com

“Hydrogen Powered Aircraft: The Future of Air Transport,” a scholarly journal article, is intended for engineers. The article is organized by talking about historical use of hydrogen in aviation, then talking about the production of hydrogen, the technology of how to use it, and then the safety of it. Bhupendra Khandelwal, Adam Karakurt, Paulas Sekaran, Vishal Sethi, and Riti Singh argue that hydrogen is the most like aviation fuel of the future. In support of this argument, they point out that hydrogen has zero emissions and is the most abundant element in the universe. For example, they talked about how during the last fuel crisis, hydrogen was studied very intently as a fuel source. Their claim that hydrogen is the fuel of the future is convincing in that liquid hydrogen is easy to produce at a given rate since its main source is water; however, combustion of hydrogen still releases nitrogen oxide compounds which are harmful, but it release very little and coupled with the lack of carbon dioxide emissions means that it is almost pollutant free. Whereas prior to encountering this source, I believed hydrogen would be too difficult to use as a fuel source, I now think hydrogen should be looked at as a major fuel source very intently. This article will be useful for providing factual information, because fuel sources are always a major talking point when it comes to sustainability.

Verstraete, D. (2013). Long Range Transport Aircraft Using Hydrogen Fuel. International Journal of Hydrogen Energy, 38, 14824-14831. Retrieved from http://www.sciencedirect.com

“Long Range Transport Aircraft Using Hydrogen Fuel,” a scholarly journal article, is intended for engineers. The article is organized into comparisons between kerosene fuelled aircraft and hydrogen fuelled aircraft. Dries Verstraete argues that hydrogen is a candidate for an environmentally friendly fuel for future aviation. In support of this argument, he/she points out that hydrogen can lead to major energy usage reductions for transport aircraft. For example, hydrogen can reduce the energy usage of a long range aircraft by 11%. Verstraete’s claim that hydrogen is the fuel of the future is convincing in that in that not only does he do the comparison between current fuels and hydrogen using future technology, he does it using current technology as well; however, hydrogen powered aircraft may need larger fuselages and that reduces aerodynamic efficacy and the baseline fuel costs would be slightly higher. Whereas prior to encountering this source, I believed hydrogen would be far too difficult to work with, I now think that the use of hydrogen as a fuel source to be entirely feasible. This article will be useful for providing factual information because of his direct comparisons with current fuels used in aircraft.

Boretti, A., & Dorrington, G. (2013). Are Synthetic Liquid Hydrocarbon Fuels the Future of More Sustainable Aviation in Australia? International Journal of Hydrogen Energy, 38, 14832-14836. Retrieved from http://www.sciencedirect.com

“Are Synthetic Hydrocarbon Fuels the Future of More Sustainable Aviation in Australia?” a scholarly journal article, is intended for engineers and chemists. The article is organized by the different methods and sources that need to be used in order to synthesize hydrocarbon fuels. Alberto Boretti and Graham Dorrington argue that the idea of synthesizing fuels was born out of the need for a more sustainable fuel source that can be used in the aviation sector without the need to redesign engines and other components significantly. In support of this argument, they point out that there are several process and sources that can be used to create a sustainable synthetic fuel. For example, The Fischer-Tropsch process that combines monoxide and hydrogen at high pressure into hydrocarbons. Boretti and Dorrington’s claim that synthetic hydrocarbons is a possible fuel source is convincing in that we already know how to do it; however, there is a 5% reduction in energy output, but this is countered with a 20% reduction in carbon emissions. Whereas prior to encountering this source, I believed that synthetic fuel production would be far too difficult to achieve, I now think this could be a reliable stop-gap fuel that we could utilize before we find a better alternative fuel. This article will be useful for introducing a unique point of view and providing factual information because they explain the different process that can be used to create these fuels.

Blakely, S., Rye, L., & Wilson, C. W. (2011). Aviation Gas Turbine Alternative Fuels: A Review. Proceedings of the Combustion Institute, 33, 2863-2885. Retrieved from http://www.sciencedirect.com

“Aviation Gas Turbine Alternative Fuels: A Review,” a scholarly journal article, is intended for engineers and chemists. The article is organized with a section about current kerosene fuels and then it delves into the different production process and fuel types. Simon Blakey, Lucas Rye, Christopher Wilson argue that there are many ways to produce alternative fuels but which process produces a truly clean fuel or has the potential to be one. In pursuit of this objective, they point out that there are specific standards that must be met in order for the aviation sector to be able to use the fuel. For example, one of the requirements is that it must have good burning characteristics and must be able to be relit at high altitudes. Blakey, Rye, and Wilson’s claim that there are several ways to produce fuels but only a few of them will produce fuel that is clean is convincing in that we have process that are currently available that can produce these fuels; however, the fuel has to be same all over the world, unlike the automotive industry. Whereas prior to encountering this source, I believed that synthetic fuels where just as dirty as fossil fuel based fuels, I now think there are some green options in this line of research. This article will be useful for introducing a unique point of view and providing factual information because the authors compared several methods directly to each other and then compared those to the current fuel used in aviation.

Luongo, C.A., Masson, P.J., Nam, T., Mavris, D., Kim, H.D., Brown, G.V., Waters, M., & Hall, D. (2009). Next Generation More-Electric Aircraft: A Potential Application for HTS Superconductors. IEEE: Transaction on Applied Superconductivity, 19, 1055-1068.

“Next Generation More-Electric Aircraft: A Potential Application for HTS Superconductors,” a scholarly journal article, is intended for engineers. The article is organized with a section talking about modern high bypass turbofans and then it talks about electric aeroengines and using superconductors in aviation. Cesar Luongo, Philippe Masson, Taewoo Nam, Dimitri Mavris, Hyun Kim, Gerald Brown, Mark Waters, and David Hall argue that with in rapid growth in the aviation sector, a more fuel efficient and less environmentally damaging means of power, one such way is with electric motors. In support of this argument, they point out that several draw backs of current high bypass ratio turbofan engines. For example, the tips of the fan blades should not exceed the speed of sound, except during takeoff. Luongo, Masson, Nam, Mavris, Kim, Brown, Waters, and Hall’s claim that electric engines are the power plants of future aircraft is convincing in that there are many factors that favor electric engines, including lower engine weight; however, electric superconductors require a cryocooling system which while are just simple plug and play systems, by current standards they are too heavy for use in aircraft. Whereas prior to encountering this source, I believed electric engines would be limited to small (less than ten passengers) aircraft, I now think that there is potential for use in larger aircraft. This article will be useful for \introducing a unique point of view and providing factual information because it is a novel approach to solving a common problem with modern aviation.

E. Green (2009) The potential for reducing the impact of aviation on climate, Technology Analysis & Strategic Management, 21:1, 39-59, DOI: 10.1080/09537320802557269

“The Potential for Reducing the Impact of Aviation on Climate,” a scholarly journal article, is intended for engineers. The article is organized by the various methods that one could use to achieve a reduction in environmental damage. J. E. Green argues that while the ability to reduce carbon dioxide and nitrogen oxide compounds is bounded by the laws of physics, there are ways to be able to reduce the overall climate impact of aviation. In pursuit of this objective, he points out that range and empty weight are some of the biggest way to reduce fuel burn. For example, he mentions replacing metal alloys in aircraft with carbon-fiber-reinforced plastics and other lightweight materials, such as what has been done to the Boeing 787 and Airbus A350. Green’s claim that there are many ways that environmental impact and be improved in aviation is convincing in that he mentions the many different ways, such as weight to can be used to improve climate impact; however, he does mention that many methods are limited by the laws of physics and thermodynamics. Whereas prior to encountering this source, I believed it would be easy to improve standards of environmental impact, I now think that improving climate impact will take years of research and a lot of determination. This article will be useful for providing factual information because Green delves into the physics that may limit our ability to reduce impact.

Ric Parker (2009) From blue skies to green skies: engine technology to reduce the climate-change impacts of aviation, Technology Analysis & Strategic Management, 21:1, 61-78, DOI: 10.1080/09537320802557301

“From Blue Skies to Green Skies: Engine Technology to Reduce the Climate Change Impacts of Aviation,” a scholarly journal article, is intended for engineers. The article is organized with the impacts of current technologies on climate and then talks about different methods on how to improve various types of efficiency. Rick Parker argues that there are several methods to improve efficiency and climate impacts of aviation and the each have tier pros and cons. In support of this argument, he points out that the various technologies and references a Technology Strategy made by British jet engine manufacturer Rolls-Royce. For example, he talks about the Environmentally Friendly Engine program that is led by Rolls-Royce. Parker’s claim that there are many ways to improve the climate impact of aviation is convincing in that he not only mentions the technology but he also mentions how a company is planning on introducing these technologies; however, these technologies have to conform to strict and often conflicting standards. Whereas prior to encountering this source, I believed that there was only a handful of ways that could bring about an improvement in climate impacts, I now think that we are only limited by our own ambitions. This article will be useful for introducing a unique point of view and providing factual information because it’s not just a scientist or engineer coming up with these ideas, there is also a corporation wanting to attempt them too.

Wasting Away

On a cold and blustery December morning in 1903, two brothers from Ohio, Orville and Wilbur Wright, would make history by becoming the first humans to successfully build and fly a powered flying machine. Little did they know that their achievement would affect mankind in so many ways. Now let us fast forward one hundred and ten years, and you will see how far we have come in aviation. Every year big aerospace firms such as Boeing in the United States and Europe’s Airbus produce hundreds of planes for both military and civilian operators to add to the thousands already in service around the world. However, all of these aircraft have limited lifespans and eventually they will become obsolete as newer and better aircraft are put on the market. Most of these airplanes will be sent to aircraft storage yards, also known as “aircraft boneyards.” Some of these planes will be cannibalized for parts such as wiring and electronics, but the vast majority will be left to stand as monuments to a bygone era. The boom in the aerospace sector, fueled by new advances in green technology, and the emerging commercial space travel market has put strain on our limited resources. One question gets asked more often than ever; how can aerospace companies reuse the materials left in aircraft boneyards for the construction of new aircraft? Before we take a look at what the aerospace industry is doing, we must first gain a little background information on humanity’s waste problem, and take a look at another industry that is striving to reduce waste.

In the last few decades, businesses have made almost all products disposable. Everything from cans to cars can be more or less thrown away, but all of this waste has to go somewhere. Many places have recycling programs, but sometimes the sheer volume of waste can be impressive and worrisome, even a small town of less than a thousand people can throw out copious amounts of recyclable materials. As stated by Bill McKibbin (2009) in his article Waste Not, Want Not:

Saturday morning, 9 to 12, a steady stream of people show up to sort out their plastics, their corrugated cardboard, their glass, their Styrofoam peanuts, their paper, their cans. It’s quite satisfying. But it’s also kind of disturbing, this waste stream. (p. 363)

Waste is not just limited to the garbage we throw out. There is also pollution generated from power plants and factories that perform critical functions, but are using outdated equipment. We cut down so many trees to make flyers, credit card mail offers, and that four foot long receipt you get from CVS for buying some gum and a soda. We even waste what some people struggle to get, food. Americans throw out fourteen percent of the food they buy (p. 365). The problem is that this kind of lifestyle is ingrained into our society. So much so, that there is an entire industry devoted to waste disposal. In the past few years, there has been a movement to try to reuse items we would normally throw out. It is going to take some time to change our wasteful ways, but it all starts with small steps. There is one industry that has welcomed the idea of producing less waste and increasing efficiency, the architecture and construction industry. One such product of this movement is located on the very campus I attend, Oklahoma State University.

Oklahoma State University (OSU) was founded as a land grand university in 1890. In its one hundred and twenty-four year history the university has gone through several changes from new buildings, to new programs, and majors being added. In 2004, the university began to create a new plan for campus development that, by 2006, had evolved into the Master Plan 2025 called “Achieving Greatness: Celebrating Tradition, Enhancing Identity and Place” (p. 361). One of the designs of this plan, was the new North Classroom Building which opened to students in January of 2009. The building cost $15 million and is touted as one of the “greenest” buildings on the OSU campus (p. 361). One interesting thing about North Classroom Building is that it is able to be a “green” building while still matching the Georgian architecture styling’s of the other buildings on campus. The chimneys and attic dormers allow for extra ventilation while the windows, lights, and reflective glass on the outside reduce energy consumption (pp. 361-362). For an entire industry to take such a massive step towards reducing waste is quite impressive. This attitude has spilled over into other industries as well. The aerospace industry has looked at various ways to reduce physical waste. One such way the this industry is trying to reduce waste is by looking at massive stockpiles of formerly flyable parts, and giving it the chance to fly again.

The sun rises on the final resting place for many loyal servants. Their remains sit in this plot of land by the thousands. They were brought here at the end of their lives and laid to rest in this massive graveyard. However, there were no priests, no services, and no mourners, for this place is an airplane boneyard. There are hundreds of these boneyards located around the world. The largest ones are located in the middle of deserts such as the boneyard at the Mojave Air and Spaceport in California. There are smaller ones at many civilian airports such as the boneyards at El Alto International Airport in La Paz, Bolivia. These boneyards are a treasure trove of equipment that can be salvaged. In La Paz for instance, old World War II era transport planes are kept so that their parts could be scavenged, and used to keep the critical Bolivian meat hauler fleet airborne.

At Mojave and other large boneyards around the world, airlines and large manufactures strip parts such as tires from these aircraft just to keep maintenance costs low.  However, many manufacturers want to do more than just cannibalize for parts; they want to be able to recycle entire airplanes and reuse the raw materials to build new aircraft. Many airlines are in the process of replacing older, less economical aircraft with newer, more efficient ones. American Airlines, for example is in the process of replacing its aging fleet of almost three hundred McDonnell-Douglas MD-80s with newer aircraft such as the Boeing 737 and Airbus A320 series. That is a lot of airplanes that are going to be put to pasture.  There are some ideas floating around on what to do with all of that material. One plan put in place by the European Union is called the “Resource-Efficient Europe 2020 Strategy.” This plan aims to reduce the environmental impact of the import and processing of raw materials such as cobalt, titanium, aluminum, and nickel, which are some of the most common metals used in aircraft. Several major firms, such as Airbus and Boeing want to be able to reclaim up to 95% of aircraft materials (“Old Airplanes Find an Afterlife as Recycled Resource” para. 2-3).

There is an industry wide push to not only reuse parts, but also to build the next generation of aircraft with parts and materials that can be more easily recycled. The industry has been under pressure for a while to produce more sustainable planes. There are many benefits in reusing materials from retired aircraft:

  • Airbus estimates that recycling the aluminum from an aircraft is 90% more energy efficient than raw production.
  • Recycling helps lower the strain placed on our limited supply of these critical metals.
  • Recycling also reduces the amount of abandoned planes at both civil and military airports. (“Old Airplanes Find an Afterlife as Recycled Resource” para. 12).

There are still limitations to recycling aircraft materials. Many aircraft components, such as engines, require raw materials or pure alloys. There is also an issue regarding the profitability of recycling aircraft parts. Most aluminum smelters have a minimum amount of aluminum that they process in order to remain profitable. Derk-Jan van Heerden, who works for Aircraft End-of-Life Solutions in the town of Delft, Netherlands, estimates that melting down several hundred airliners will yield 60,000 metric tons of aluminum, but that the typical smelter requires 150,000 to 200,000 metric tons to be profitable (“Old Airplanes Find an Afterlife as Recycled Resource” para. 13, 30). While it may not replace raw material production, recycling aircraft can at least give manufacturers another source of materials. Reprocessing these valuable metals will help take some strain off of our depleting supply.

These boneyards are a potential treasure trove for the aerospace industry, and it will take a lot of planning in order to use this material source to its fullest. However, maximizing the yield of recyclable materials should be no problem to an industry that thrives on pushing the boundaries of our technology. They will be able to figure out a method of recycling that will help cut down on more waste. If all industries could show the same interest in reducing waste, even if it is for purely financial reasons, then it could spur the changes that are needed for the average person to reduce the waste in their own lives.

McKibben, B. (2012). Waste Not, Want Not. In R. Frohock, K. Sisk, J. Glover, J. Cross, J. Brubacker, J, Alger, …, R. Brooks (Eds.), Academic Universe: Research and Writing at Oklahoma State University (pp. 363-367). Plymouth, MI: Hayden-McNeil Publishing.

Myers, J. (2012). Truth in Architecture. In R. Frohock, K. Sisk, J. Glover, J. Cross, J. Brubacker, J, Alger, …, R. Brooks (Eds.), Academic Universe: Research and Writing at Oklahoma State University (pp. 361-362). Plymouth, MI: Hayden-McNeil Publishing.

EurActiv. (2012, November 14). Old Airplanes Find an Afterlife as Recycled Resource. EurActive.com. Retrieved from http://www.euractiv.com/specialreport-resource-efficienc/old-airplanes-find-afterlife-rec-news-515957

What Airbus is Doing to Help Improve Sustainability in Aviation.

http://www.airbus.com/innovation/eco-efficiency/

This website is made my European Aviation Manufacturer, Airbus.  It details the different areas where sustainability can be achieved.  It talks about how sustainability starts with design, then it goes into supply chain, which is where the materials necessary for the aircraft come from and how they are created.  The next step is manufacturing, which mainly focus on efficiency and sustainability in the factories where the aircraft are assembled.  It then talks about operations sustainability which mainly focuses on fuel and air traffic management which has a massive impact on emissions.  The final point is about aircraft end of life, which is mainly concerned with dismantling and recycling.  All of these topics have a general overview, good quality images, and then they go into more detail with respect to their subtopics.  There is a lot of good information on this site. There are also links to other sites, for example there is a link to a business that specializes in aircraft end of life matters, its called Tarmac Aerosave.

However, it was still created by one company and it touts a lot of what airbus has done instead of what the industry as a whole has done or is planning on doing.  It kinda makes it seem like airbus is the only taking this environmental matter seriously which is incorrect.  Boeing, Embraer, Bombardier, and many smaller companies, universities such as the Massachusetts Institute of Technology, and government agencies such as NASA are also tackling this issue.   But the information is relevant to my topic and very well organized.

Essay 4, How Did I Get This Far?

It all started when I put my major out there on the internet in Blog Post One.  With that post, everyone who reads this blog knows that I am pursuing  a degree in Aerospace Engineering.  I first started to formulate my thesis question around the time of writing Essay 1.  Essay one was about relating the article we read in Academic Universe called Waste Not, Want Not.  This article was about our ability as a society on producing various kinds of waste, be it pollution, garbage, or wasting money.  It also talked about ways to reduce waste.  I related that to aerospace engineering by talking about reusing aircraft parts and materials that are just sitting in hundreds of airplane “graveyards” all over the world.  I then decided I wanted my research thesis to continue that line of thinking, but talk about increasing sustainability instead of reducing waste.  By the time Essay Two rolled around I had developed my thesis  into, “How can airplanes be made more sustainable?”  I found out that when I was looking for topics to use in my research that there was a lot of discussion on various methods of achieving that goal.  Everything from engines and fuel, to design and structure where considered in the various articles that I chose for my paper.  With the arrival of Essay 3, I was able to look back on the process that had carried me this far.  It was interesting to think about how an entire semester of research and writing will boil down to just one paper. Now I am in the process of writing Essay 4 and I am interested to see how all of my work will affect the content of my paper.