NASA General Aviation Propulsion Diesel Engine - Research Paper Example

Introduction The success of Wright Brother’s in 1903 provided impetus to the aviation industry to add innovation to conventional piston engines and models for a better flying experience. The layout and the engine capacity of the aircrafts have changed from two –stroke to four strokes. Multivariate engines of different mechanical layouts, cooling types and cycle types have been used but the need for a fuel and cost efficient engines has always been felt. At present air-cooled, spark-ignited and horizontally opposed four-stroke engines are used in the aviation industry. NASA’s General Aviation Propulsion (GAP), started in the 2000, is one of the programs that have pioneered to revolutionize the aviation industry and transform the development of engines of future. The aim of the program is to develop an innovative engine which ushers in affordability, comfort and reduced cost for the aviation industry. The new engine is to reduce noise and vibrations and load on pilot for monitoring the plane, thereby adding greater comforts to the passengers. The aim of the paper is to discuss on GAP programme implications in the aviation industry and describe the working and usage of two engines developed as a part of the project. The paper also analyzes the challenges faced during the development and aviation industry in general. The advantages of new engines in terms of cost and efficiency have been dealt in detail in the paper. The new programme has been developed by NASA in collaboration with Advanced General Aviation Transport Experiment (AGATE). GAP Diesel Engine The GAP engine runs on 200 HP, liquid cooled, two stroked engine that runs on jet fuel. The engine is expected to cost half the price of conventional engines of 200 HP. This would make the new engines a major success in terms of fuel efficiency by reduction in the dependency for leaded gasoline thereby improving maintenance, passenger comfort and ease of use. Teledyne Continental Motors, Aerosance Cirrus Design, Hartzell Propeller, Lancair and Mod Works together partnered with NASA to develop diesel engine, an advanced piston engine. Although being heavy diesel engines are the reliable engines which combine technologically advanced construction coupled with two stroke engine. The GAP diesel engines offers noise and vibration free facility to the passengers with low speed propellers, feasible technology to use. Fig.1-Revolutionary diesel engine developed in the GAP program With less than one-fourth of fuel consumption as compared to the current engines, the new GAP engines offer reliability, comfort, and greater control over the design and process flow of the engines. The innovative design tends to make the engines almost half the cost of mass production of current engines. The engines runs at speed of 2200RPM and generates temperature which is 500 degree Fahrenheit lesser than the existing engines. The cylinders with four exhaust valves, no intake valves, two stroke engines and low induction temperature makes the engines perpetual in operation. The FJX 2 Turbofan Engine These are environmentally suitable engines with most efficient propulsion system. These are the highly reliable, less emission and noise free engines with most advanced technology. The major deterrent to these Fig.2- FJX–2 turbofan engine developed in the GAP engines are high operating cost which has kept the production to a standstill. However, the production of these engines has reduced the cost of small turbine engines by one-tenth and revolutionized the industry. The powerful engines have not only shrunk the distance of travel but also provided impetus to travel at 440mph. With 85-100 pounds in weight FJX 2 produces thrust of 700 pounds which is only 25% of the weight of the existing propulsion engine. Simplified design, less components, and automated manufacturing techniques have made the turbofan engines cost efficient to existing engines. Although not so fuel efficient, the engines consume less fuel during takeoff-landing process. The engine is develop in collaboration between NASA Glenn and William International along with its allied partners such as Cessna Aircraft, California Drop Forge, Chichester Miles Consultant, Cirrus Design, New Piper Aircraft, Forge Metals, VisionAire, Producto Machine, Scaled Composites, and Unison Industries. Due to high cost of fuel, these engines have not been able to make inroads into the market and are mostly used by luxury carriers in niche market. Components and Working of the Engines The GAP engines comprise of two set ups:- Intermittent Combustion(IC) Engine Element- This would define new paths for entry level aircrafts. Turbine Engine Element- This would create market for new propulsion system for lighter aircrafts. The GAP engines are built using “uniblock” construction which signifies that the case halves, cylinders and cylinder heads are part of the single complex aluminium castings. This reduces the weight of the engines and cost of production. There is no “top overhaul” since the cylinders are the part of engine system. The engine posses’ single lever power and fuel control which allows for more induction air than used into the existing system from turbocharger. The output is dependent on the fuel input into the engines. Hartzell constant-speed prop fitted in the system which has a speed of 2200 RPM. Although the prototypes use single turbocharger, the production engines are equipped with dual turbos to counter failure of turbocharger. The GAP engines provide full take-off power in the range of 6000-10,000 feet. The system consists of horizontally opposed, four cylinder, liquid cooled, two stroke, compression ignition engine. GAP diesel engines consume fuel at the rate of 0.36lb/hp-hr as compared to in the range of 0.41-0.49 lb/hp-hr for the existing engines. No fuel-air mixture ensures proper noise and vibration free environment for the engines. The GAP engines were demonstrated in Cirrus SR20, Lancair Columbia, and Piper Senaca IV. The Turbofan engine had been demonstrated in 2000 V-Jet II. Challenges in development Some of the challenges which bother the development of GAP engines are The weight of the prototype is more than 300lbs which is considered higher in terms of aircraft engine weight. The endurance tests at projected 3000 hours TBO still remain a distant dream for these engines, which makes acceptability an issue. Durability has been another area of concern where the engines do not make perfection. Revamped market strategies have to be developed which discusses about the needs and wants of the existing market. NASA’s aeronautics advisory committee’s General Aviation task force report (1993) states that “replacing today’s outdated light aircraft propulsion systems is perhaps the most important factor in revitalizing the light aircraft market.” Advantages of GAP’s programmes Engines over existing engines The aim of GAP programme is to bring about a revolution in the engine development system for aviation industry thereby fostering safety, reliability, ease of use, and operating efficiency of the aircrafts. The GAP diesel engine targets to reduce fuel consumption by one-fourth and hence provide the most efficient cost structure to the industry. Use of low speed propellers reduces noise and vibrations thereby protecting the environment around airports from dangerous noise levels. The highly advanced method of production along with lighter engine components reduces the cost of the engine by almost 50%. Intermittent combustion engines reduce the cost of engines by one-half and ensure reliability, ease of use, less maintenance, and passenger comfort. Use of turbofan engines directly influences the price of small turbine engines making cost of travel cheap. With approximately 4:1 bypass ratio, the turbine engines are fuel efficient and zero noise engines over existing engines. Reduction in the number of engine components and automation of the development process has further reduced the price for engine thereby making it competitive to the existing piston based engines. Such aircrafts are expected to have advantage over bad weather and reduce the cost of travel time. The engines would use advantage of weight and aerodynamics to reduce the fuel consumption during take-off and landing, thereby revolutionizing the aviation industry. Conclusion The GAP programme has revolutionized the aviation industry with the introduction of diesel and turbofan engines. The engines have not only reduced cost and fuel consumption but also made travel cheaper and convenient. Innovations which tend to further reduce oil consumption and make aviation a better flying experience have always part of NASA’s GAP programme. NASA’s initiative has provided with the high performance light weight materials which have introduced revolution in the engine propulsion techniques. With the concentration to improve price to performance ratio GAP has combined innovative ways to provide ease of operation of the users. The GAP programme aims to make flying not only convenient and affordable but also fun and noise free for passengers. References Busch M.(2000) GAP Engine update. Airventure Oshkosh. Retrieved from http://www.avweb.com/news/reviews/182838-1.html?type=pdf NASA (2000). Small Aircraft Propulsion: The Future Is Here. NASA Facts. Retrieved from http://www.grc.nasa.gov/WWW/AST/GAP/ Rozenkranc M. & Ernst J. (2003) Diesel Engines for Aerospace use. Israel Aircraft Industry.5-10. Read More