The open rotor engine, which has also been called an unducted fan
and an ultra-high-bypass engine, has the axial fan mounted outside of the engine nacelle.
GE, Snecma and NASA in May plan to begin running a 1/5 scale unducted fan
(UDF) rotor on a test rig at the NASA Glenn Research Center in Ohio, an experiment that is both forward looking and retrospective.
Picture: How it started back in the late 1980s, the pioneering GE36 UDF or unducted fan
engine--for which its maker General Electric could claim "dramatic fuel savings"--was never launched commercially as fuel prices fell sharply at the turn of the decade.
The Old Heads are Marty Hemsworth, a pioneer of aviation's first high-bypass engine (he is providing overview critique); Joseph Al-ford, a design consultant who has contributed to the development of virtually every GE engine program over the past 50 years; Art Adamson, regarded as the father of Ge's ultramodern high-tech unducted fan
engine (Tucker describes Adamson as "an innovative man who can always suggest 8 to 10 ways to solve a problem"); and Mel Bobo, the former chief engineer of GE Aircraft Engines, who retired in 1990.
CFMI is "actively pursuing counter-rotating fan technology, as well as open rotor designs that build on the experience of the unducted fan
from the late 1980s" under the LEAP56 initiative.