The themes of technological innovation, entrepreneurship, and organizing

Technical Development Directions

Through observation of the current sector’s movement toward sustainable aviation, we found that various levels of innovative ideas have been proposed and developed. There are two main di­rections: One direction of innovation is to reduce fuel use by (1) lighter weight, (2) low air resistance aircraft design, (3) lean combustion and a high bypass engine, (4) an optimized electric system and (5) optimized flight routes Another direction is to replace fossil fuel by 6) biofuels. We discuss each innovation from (1) to (5), while considering (6) as a separate direction below:

1. Light weighting of aircraft: Weight is as critical as cost in aircraft development, and resistance to the severe environments of heat, load, and fire is required aircraft mate­rial. Replacement of metal by Carbon Fiber Reinforced Plastics (CFRP) is expected in this sector. According to the panel discus­sions of the CAIR seminar in Feb 2010, however, simple replacement by CFRP won’t bring enough reduction of weight because a drastic change of structural design is also needed to benefit from the use of CFRP. NASA is currently investigating a “fail­safe” structure design instead of “safe-life” for lightweight composite structures in its research project, “Pultruded Rod Stitched Efficient Unitzed Structure” (PRESEUS) (Collier 2010).

2. Lowering air resistance of the aircraft: NASA is now conducting research about a Blended Wing Body (BWB), which can con­tribute to the reduction ofboth aircraft weight and air resistance by integrating the wings and the fuselage. In Boeing’s newest prod­uct, innovation in aerodynamics is achieved through state-of-the-art Computational Fluid Dynamics (CFD) technology and advanc­ing wing technologies like multi-function ailerons and high-aspect ratio wings with CFRP (Blackner, 2010).

3. Improving fuel efficiency of the engine:

Improvement of fuel efficiency is pursued in two directions, improvement of propul­sive efficiency and thermal efficiency. A higher bypass ratio, of the air that passes around the engine to the air that passes through the engine, is effective in improv­ing the propulsive efficiency by reducing the passed air flow speed. A higher bypass ratio, however, confronts the problem of the hypersonic rotation of blades and en­gine size. Mitsubishi announced the use of a geared turbo fan (GTF) engine made by Pratt & Whitney in the Mitsubishi Regional Jet (MRJ). Pratt & Whitney has developed a speed reduction gear which can improve propulsive efficiency with very high bypass ratio. The open rotor engine which allows a very high bypass ratio is now under devel­opment in many institutes and companies. The development of the open rotor must challenge safety and mounting issues. For thermal efficiency, the main issue has been how to make higher pressure and temperature in a combustion room possible without NOx increase. In Europe, a unique alternative cycle process with an intercooler system is now under investigation on a long-term basis.

4. Optimizing the electric system: The output from jet engines are used not only for pro­pulsive purposes, but also for electric power generation and the power of the hydraulic and heating systems. GE and Boeing have developed a non-engine-bleed system in the 787, which replaces the bleed air heating and de-icing system by changing the engine’s output to an electric signal. The replacement can remove a lot of weight from the hydrau­lic system. An idea to store electricity, will cause an increase of aircraft weight due to the weight of the battery. In fact, there is an inbalance of supply and demand in electric power generation. During the take off and climb, the engines generate a lot of power. On the other hand, during the cruise, the cabin requires a lot of electricity for air condition­ing, meal preparation, etc. Research is being conducted to minimize the inbalance and to effectively use the engine output by genera­tion and storage of electricity. Furthermore, the Japan Aerospace Exploration Agency (JAXA) is conducting hydrogen and fuel cell hybrid engine research with which an aircraft can cruise with fuel cell power and then use a hydrogen gas turbine engine when the fuel cell power is not enough.

5. Optimizing the flight route: Currently, aircrafts fly to their destination in zigzag for various reasons such as political and technological issues. While many political efforts to encourage effective use of airspace with airlines, military operators, business and general aviations of different countries are being made globally, a new air traffic management system which can optimize the route according to the airports’ particular environments and latest climate reports, are being developed and are under international agreement negotiation. The FederalAviation Administration’s (FAA’s) Performance - Based Navigation (PBN) system, which allows aircrafts to take preferred routing and trajectories, is an example of an innovative development. Test flights ofPBN conducted and have shown a significant reduction of fuel consumption as well as other benefits like optimal use of air space, reduction of pilot/ controller voice transmission, etc.. The major technological challenge is how to manage plural operations safely without an additional load of works on operators and navigators.

6. Development of Biofuels: Airlines still have few choices when it comes to jet fuels (kerosene) because jet fuels for aircraft are strictly controlled by international standards. Any compound change in fuels, even without combustion characteristics change, need to be approved for safety and reliancy. On the other hand, relying only on kerosene is a menace to the airlines in terms of future energy security and high prices. For energy diversity generally, the fuel candidate must be handled like oil so that XTL such as Gas to Liquid (GTL), Coal to Liquid, and Biomass to Liquid (BLT) have been chal­lenged. For alternative aviation, too, “drop - in” fuel which can replace current jet fuels without change to aircrafts has been actively investigated (Okai, 2010). The use of XTL products produced by new industry pro­cesses, which have been developed for more than thirty years, have been approved by the American Society For Testing and Materials (ASTM), an international standards for aviation. Synthetic gas from natural gas, coal, or biomass are being processed in the Fisher-Tropsch process to log chain paraf­fins and are finished in hydroprocessing and separated into final XTL products. ASTM D7566, a standard for Aviation Turbine Fuel Containing Synthesized Hydrocarbons, which was issued in Sep. 2009, accom­modates up to 50% blends of conventional aviation turbine fuel with synthesized hydrocarbon blend components produced from coal, natural gas, or biomass using the Fischer-Tropsch process. For low carbon jet fuel, experts say that biofuel is technically feasible. While 1st generation biofuels often produced from seeds or grains such as wheat, are criticized for their strong adverse effects regarding food shortage in developing na­tions (Hansen et al., 2009, Schaltegger et al.,

2005) , 3rd generation biofuels derived from algae avoid this criticism since they can be grown on soil or in water that is otherwise unsuitable for food production (Sustainable Aviation, 2010, Ito, 2010). Many test flights have been completed by Boeing, Airbus, and many research institutes (Blackner, 2010, Szodruch, 2009). According to Shell (Ito, 2010, Bauldreay, 2010), the cost of produc­tion due to the longer refining routes, and the cost of feedstock and poor yields are the big obstacles when the biofuels try to replace the kerosene.