Re: Are "jets" really jets?

From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
Date:         08 Sep 95 02:35:34 
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>A modern fanjet has a bypass ratio of about 5:1, that is five times as
>much air goes through the fan and straight back out as goes through the
>engine core.

Earlier this year, in article <airliners.1995.297@ohare.Chicago.COM>,
Andrew Chuang claimed the bypass ratio of the GE90 was around 9:1 or
10:1, where as the PW4084 and Trent 800 were around 6:1 or 7:1.  Those
are all 777 engines, so 5:1 is probably about right if you consider
"modern fanjet" to be what you'd find on a 747-400 or MD-11 -- modern,
yes, though no longer state-of-the-art.

>But that doesn't mean five times the thrust comes from the
>fan, since the core air comes out the tailpipe a *lot* faster.

Good point.

Karl Swartz	|Home
Moderator of sci.aeronautics.airliners -- Unix/network work pays the bills