Originally Posted by
tdracer
They went as far as to do a demonstrator aircraft (I'm thinking it was a DC-9 but don't hold me to that), replacing one engine with the unducted fan prototype. I don't know how fuel efficient it was, but the counter-rotating props were so noisy it quickly became a show stopper.
Yes, the MD-80 prototype was retrofitted with the GE36 propfan/UDF:
quickly acquiring a reputation as one of the most efficient ways of converting jet fuel directly into noise.
