Barbara Selby
Headquarters, Washington, D.C.                                             
March 14, 1994 (Phone:  202/358-4701)

Linda S. Ellis
Lewis Research Center, Cleveland
(Phone:  216/433-2900)


RELEASE:  94-41

HIGH-SPEED ENGINE CYCLES TAPPED FOR FURTHER RESEARCH

     A NASA-industry team has chosen two engine cycle concepts 
on which to focus the next 3 years of propulsion research for a 
next-generation supersonic airliner.

     The "mixed flow turbofan" and "FLADE" (fan-on-blade) 
concepts were selected from six candidate engine cycles being 
considered in NASA's High-Speed Research Program, which is 
developing technology to make a future U.S. supersonic airliner 
environmentally compatible and economically practical.

     "Both concepts promise to meet the economic and 
environmental goals for a new supersonic airliner," said NASA 
program Director Louis J. Williams.  "Concentrating our 
propulsion research on these designs brings us one step closer 
to making this type of airplane a reality." 

     NASA and industry selected the mixed flow turbofan and 
FLADE concepts because studies showed they were the best 
candidates in terms of direct operating costs to the airlines, 
noise reduction, adverse atmospheric effects and technological 
risk.  Both concepts should reduce engine takeoff noise while 
maintaining good performance at supersonic speeds.

     These engine cycles cut jet noise by mixing low-energy air 
with engine high-energy exhaust flows during takeoff.  The 
mixed flow turbofan has a secondary, slower-moving airstream 
that bypasses most of the engine's turbomachinery but rejoins 
the airflow before reaching the engine exhaust nozzle. The  
FLADE is a modified turbofan engine that introduces an 
additional airstream up front in the engine fan. 

                            -more-
                              -2-


     NASA and industry will study these two concepts for the 
next 2 years before choosing one of them on which to focus 
technology development in the remaining years of the High-Speed 
Research Program.  After that choice is made, large scale tests 
of the critical propulsion components -- inlet, fan, combustion 
chamber and nozzle -- would be done between 1998 and 2001, 
giving industry the data it needs for an informed decision to 
build a new supersonic airliner.
                             -end-