I remember reading somewhere that venturis used to be mounted on the

belly, &

that they were much less likely to ice up when mounted there. Given

Tracy's

experience with his muffler, it seems that drag from a venturi in

the

cowl air

exit path should be negligible & it should be fairly well shielded

from

icing.

Any thoughts on this?

Charlie England

why not put a venture inside the cowel and duct high pressure to it and

dump used air from the venturi back out of the cowel. if a negative

pressure

at the exit could be generated so much the better. also you can use

intake

manifold vacuum to drive the gyros when the venturi is not working. all

you

need is to y the various vacuum sources and put one way valves in each
source line. I used a large venturi and must use a pressure regulator to
reduce the vacuum. works fine.
smale@ncinternet.net

Great idea.  Much easier than the pop-out venturi I thought about.
BTW, my friend Bernie Kerr has a backup airspeed indicator that is fed from
the cooling plenum on his Lycoming powered RV-6.  Almost no error compared
to his primary ASI so there is considerable pressure recovery even on these
aircooled engines.
Tracy Crook
tcrook@rotaryaviation.com
www.rotaryaviation.com

 
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