Mailing List flyrotary@lancaironline.net Message #59621
From: Charlie England <ceengland7@gmail.com>
Subject: Re: [FlyRotary] Re: Intake progress
Date: Sun, 17 Feb 2013 19:23:18 -0600
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Thanks Ed; that's the kind of info I needed. I bought a pack of rod from one of the local welding supply houses, so I'm hoping that it will be high quality stuff. I bought a batch from them a couple of decades ago & didn't have any luck with it, but I found the old stuff & took another shot at it with improved technique & got what seems to be good results. If yours has been flying that long, I should be fine. The injector bungs will supply some additional support, and added X bracing from plate to plenum will hopefully be all I need. My tubing is only .030 wall, so I guess I'll give it a little extra help. :-)

Anyone care to take a crack at the tuning formula? Here's an old RX-7 forum thread about tuning calcs. It seems to have at least one glaring error, but he ends up with with Mazda's port length.
http://www.rx7club.com/general-rotary-tech-support-11/heres-how-figure-out-intake-runner-length-199788/


I'm confident that my (Tracy's) design will work, but I'm still interested in the science/engineering behind it.

Charlie


On 02/17/2013 05:03 PM, Ed Anderson wrote:
Looks good, Charlie

No welder myself, however when it came time to attach  0.049 wall aluminum tubing to the cast aluminum stock manifold (see photo attached), I found a brazing rod for aluminum that worked great. 

Used a butane torch (more BTU/min the better) to first heat the casting (your plate would be easier) and then brought the flame close to the tubing - but not playing on the tubing.  touched the brazing rod to the intersection and it did a great job.  Been flying for 8 years with that throttle body (blue half moon) stuck out on the end without any additional support and still OK.

Here is the website for the rod I used successfully - before trying this rod, I probably had 10 lbs or various rods that I never had any luck with, but this worked.


http://www.aluminumrepair.com/
 

Ed

--------------------------------------------------
From: "Charlie England" <ceengland7@gmail.com>
Sent: Sunday, February 17, 2013 3:41 PM
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: [FlyRotary] Intake progress

>
> 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...)
>



> --
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html
>



> -----
> No virus found in this message.
> Checked by AVG - www.avg.com
> Version: 2013.0.2899 / Virus Database: 2639/6110 - Release Date: 02/17/13


--
Homepage:  http://www.flyrotary.com/
Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html

Subscribe (FEED) Subscribe (DIGEST) Subscribe (INDEX) Unsubscribe Mail to Listmaster