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Date: Sun, 17 Feb 2013 17:53:57 -0600
From: Charlie England <ceengland7@gmail.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Intake progress
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Thanks, Steve. You're right about Tracy's manifold. I was able to go 
slightly longer (Tracy said that his is just starting to come 'on the 
pipe' at that rpm but he was limited by the -4's narrow cowl). My bells 
will end up at about the same distance from the wall as Tracy's. I'm 
just holding the plenum box up there for size reference. It's hard to 
see in the pics, but the plate, plenum inside wall & tubes are all 
screwed/clamped into wood 'tooling' so nothing will move when I start 
permanently attaching the components.

Charlie

On 02/17/2013 04:45 PM, Stephen Izett wrote:
> 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.
>  From memory Tracy's runners may have been a little shorter and the bell mouths closer to the end of the plenum,
> 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:
>
>> 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. :-)
>>
>> 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.
>>
>> 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.
>>
>> 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>--
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