Message-ID: <001901c3c8c7$92de5fc0$1702a8c0@WorkGroup>
From: "Ed Anderson" <eanderson@carolina.rr.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-2900871@logan.com>
Subject: Re: [FlyRotary] Re: Dumb intake question
Date: Mon, 22 Dec 2003 15:09:55 -0500
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 > >
>
> So there is a tuning effect from EDDIE and from FAW.  Are they the same
thing, or can they be combined for an additive effect?  If the could be
combined, would it be called the FEDDIE?  EDDIEFAW?  FADDIE?
>
>
Actually, the effect from EDDIE is based on the FAW.  The EDDIE is just one
particular application of using the FAW Pulse.  There appear to be basically
two interdependent tuning approaches - one using the inertia or momentum of
the (subsonic) air mass and the other the kinetic energy of the sonic FAW
pulse. Most schools of tuning  are based on some combination, variant, or
misunderstood distortion of those two approaches.

The FAW pulse rides the air flow which can be quite fast say around
300-400ft/sec in some intakes or approaching Mach 0.2.  The speed of the FAW
pulse can be supersonic (well it doesn't quite make it)   rather it can
create sonic shockwaves in the intake if the pulse is going in the direction
of the air flow.  The FAW pulse will on the otherhand be considerable slower
Mach1 - Mach 0.2 against the flow.  This difference can be particularly
great in the exhaust system with higher gas velocities.  It probably should
be considered in the calculation of runner length.  But, then that would
depend if you Pulse travels both ways then the speed of the pulse probably
averages close enough to Mach 1 over that relative short distance not to
bother about.   In the case of the EDDIE the FAW pulse travels upstream
against the incoming flow for 1/2 its trip then down stream with the air
flow for the other 1/2 of its trip, so again the average is probably close
enough to Mach1 to ignore. Actually I calculated about an  2.6" difference
for the average speed FAW vs the Mach 1 speed at 6000 rpm.  So at higher
RPMs it may be something to take into consideration, but at the lower RPMs
your manifold temps uncertainty/changes can swamp that factor.

 So it is correct to state that its an EDDIE FAW    or a ED FAW DIE perhaps
an  EDFAWDIE

FWIW

Ed Anderson