The Propeller--With Some New Twists
General Electric gave the first public demonstration Monday of its new “unducted fan engine,” a turbine engine with a propeller that is expected to reduce fuel consumption on future airliners by 40% to 70%, compared to today’s ducted turbofan engines.
The new engine, dubbed the UDF, is expected to be widely used in commercial aircraft in the 1990s if current tests prove that it reduces fuel consumption and that it can be made relatively quiet.
Two other companies, Pratt & Whitney and the Allison division of General Motors, have formed a team to develop another version of such an engine. It will be tested early next year.
The GE test was the second flight of the new engine, following its successful maiden flight last week. The demonstration took place at GE’s jet engine test center in Mojave.
The UDF powers aircraft with two sets of highly contoured fan blades that rotate in opposite directions. The second set of fan blades smoothes the airflow that was twisted by the first, thereby reducing drag.
One UDF was mounted on a three-engine Boeing 727 in Monday’s demonstration flight (the other two engines were conventional jets), but eventually it will be fitted on the new Boeing 7J7 that is under development. Next year, the UDF will be tested on a McDonnell Douglas MD-80.
