SMALL AIRCRAFT PROPULSION SYSTEM Small Aircraft Propulsion System, The Development Of EJ22 Turbofan Engine, Key To Creating A Small Aircraft Transportation System

Small Aircraft Propulsion System, The Development Of EJ22 Turbofan Engine, Key To Creating A Small Aircraft Transportation System

NASA's General Aviation Propulsion (GAP) program has turned vision into reality. At the beginning of the GAP program, NASA promised to transform small aircraft by developing revolutionary new engines and demonstrating them in the year 2000. These radically advanced engines will enable the general aviation industry to produce innovative, affordable engines for the commercial market.

Although current general aviation engines are good and have served their purpose well, they require considerable pilot attention, intrude on passenger comfort with noise and vibration, and are costly to buy, operate, and maintain. (Christensen 1997)

The Eclipse 500TM, a six-passenger jet made possible by revolutionary EJ22 turbofans, which are commercial derivatives of the GAP FJX-2 turbofan. Credit: NASA

The new GAP engines will change all of that, along with our ideas about what general aviation propulsion systems can be. With their smooth, quiet operation, they provide comfort never before enjoyed in general aviation light aircraft. New engines are crucial to truly new airplane designs. The GAP engines are bringing about a revolution in light aircraft affordability, ease of use, and performance.

These new engines are key to creating a small aircraft transportation system in the United States. The potential is especially strong when the benefits of the new propulsion systems are coupled with those of cockpit and airframe technologies developed by the NASA-FAA-industry Advanced General Aviation Transport Experiment (AGATE) consortium. (Flemisch 2003)

The GAP Diesel Engine

The jet-fueled GAP diesel engine will make possible outstanding new propulsion systems for entry-level aircraft. Such aircraft are usually characterized by a single engine, up to four seats, cruise speeds of 200 knots or less, and easy, well-mannered handling.

The GAP program goal for piston engines was to reduce engine prices by half while eliminating the need for leaded gasoline and substantially improving reliability, maintainability, ease of use, and passenger comfort. To achieve this goal, Teledyne Continental Motors and it's industry team (Aerosance, Cirrus Design, Hartzell Propeller, Lancair, and Mod Works) partnered with NASA Glenn to develop a highly advanced piston engine, the GAP diesel engine. Diesel engines are known for being reliable but have been considered too heavy for use in general aviation. Combining the two-stroke operating cycle with innovative, lightweight construction makes the GAP diesel engine competitive with current piston aircraft engines.

The GAP diesel engine, combined with advanced-design low-speed propellers (from related NASA-industry research), offers very quiet operation for both passengers and airport neighbors. Additionally, the new engine is very economical to operate. It has been designed to burn readily available jet fuel at a low fuel consumption rate of about 25 percent less than current engines. (FAA Advisory Circular 2002)

Revolutionary diesel engine developed in the GAP program. Credit: NASA

This engine provides pilots and passengers with the same kind of quiet, easy-to-use power that we have come to expect in our ...