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Subject: Re: [FlyRotary] Intake progress
From: Stephen Izett <steveizett@me.com>
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Date: Mon, 18 Feb 2013 06:45:51 +0800
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>

Hi Charlie
I think it looks very much like tracy's RV4 setup so hopefully get the =
same good results.
Is Tracy getting ~200HP @ 7500.
=46rom memory Tracy's runners may have been a little shorter and the =
bell mouths closer to the end of the plenum,=20
and I thought he would have liked slightly longer ones.
Re plenum volume - nice thinking me thinks.

Steve Izett
Renesis 4 port Glasair SIIRG nearing completion.


On 18/02/2013, at 4:41 AM, Charlie England wrote:

>=20
> Now that everyone's awake again, I thought I'd send a pic of my intake =
progress (RV-7 Renesis with James Lyc cowl). I played with a couple of =
different materials for the bell mouths. I tried gluing up some 1/4" =
plexi from an old windshield, but used super glue instead of proper =
plexi cement (which I wasn't able to find locally in a hurry). The 1st =
try popped apart on the lathe; the 2nd turned out ok. Next effort was =
with 3/4" MDF (medium density fiberboard). That went well, until I put a =
little too much side pressure on the ring (homemade cutting tool) after =
undercutting the center section. Overall tube lengths will be ~11 3/4" =
block surface to bell ends. The plenum is *much* bigger than most tuning =
sites recommend. I figure that I can experiment with plenum size by just =
stuffing it with rigid foam to take up some volume, if needed. Going the =
other way wouldn't be so easy. :-)
>=20
> Since I don't have Mark's TIG skills, I thought I'd ask what others =
have used in joining thin wall tubing to 1/4" aluminum plate. Aluminum =
brazing rod? High temp epoxy? JB weld? I do intend to add bracing from =
the plate to the plenum assembly to take some of the cantilever & =
vibration stress off the tubes.
>=20
> I'm using this length and concept because Tracy has had great luck =
with both HP & BSFC on his Renesis with a similar configuration. =
However, I'm curious about how others have adapted the common Helmholtz =
intake tuning formulas to the rotary. Would anyone care to 'show their =
(math) work'? Renesis users would be better for me, but any calcs would =
do. When I tried to adapt the common formulas to a rotary, I was getting =
'interesting' results, so I'd like to know if I got lost somewhere while =
trying to plug rotary 'valve' timing into the formulas.
>=20
> Charlie
> (Sorry for the sideways iphone pic; I guess you can pretend that =
you're looking down on it...)
> <photo.JPG><Attached Message Part.txt>--
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   =
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