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<< Lancair Builders' Mail List >>
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The comments, contributions, and corrections of others are always
welcome.
Fred Moreno<<
Excellent reply, Fred. Your are right in that the real BSFC of an aircraft
engine is unknown because the pilot is the "engine designer" - he can run
the engine any way he wants and suffer/enjoy the consequences. We stopped
doing that in cars maybe 75 years ago. Only one question left - you mention
the potential for a BSFC of 0.4 lb/hp-hr and that seems to be below any I
have seen in real life. Automotive engine testing done at GM (I have pretty
old data, though) shows a minimum of about .42 - .44 for high compression
10:1 engines and .44 to .48 for low-compression 8.5:1 engines. Granted,
this is only 10% different, but that is still a pretty big gap. With a
modern low-friction engine and better air/fuel distribution maybe the .40 is
possible. I am hoping that my V-8 with a compression ratio of about 9.5 can
beat the BSFC an 8.5 aircraft engine by 2 - 4%. Is there a difference in
heating value for aircraft fuel compared to car gas? Don't know.
Gary Casey
LML website: http://members.olsusa.com/mkaye/maillist.html
LML Builders' Bookstore: http://www.buildersbooks.com/lancair
Please remember that purchases from the Builders' Bookstore
assist with the management of the LML.
Please send your photos and drawings to marvkaye@olsusa.com.
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