Mailing List flyrotary@lancaironline.net Message #59625
From: Ed Anderson <eanderson@carolina.rr.com>
Subject: Re: [FlyRotary] Re: Intake progress
Date: Mon, 18 Feb 2013 12:28:19 -0500
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
No, Rich,  that is with the 2.85 gear box and new prop.  With the old 2.17 and 67/72 takeoff RPM was 5200-5600 depending on OAT.  5600 was on a very good day.  The large air mass pushed back by the larger but slower turning prop with the 2.85 makes a very noticeable difference in acceleration on take off.  Great for the small field I operate out of.
 
Ed

Sent: Monday, February 18, 2013 10:59 AM
Subject: [FlyRotary] Re: Intake progress

Ed,
 
going to the new gear box, are you still taking off at 6000-6200 RPM WOT or did that change?
 
Rich
 
In a message dated 2/18/2013 7:22:54 A.M. Central Standard Time, eanderson@carolina.rr.com writes:
Never had it on a dyno, Steve, but based on fuel flow and performance, I see 17.0 17.5 GPH WOT at take off (6000 rpm) which would equate to roughly 175HP on a 70-90 F day.  On a cold day <50F I see 19-20 gph (at 6100-6200 RPM) WOT on Take off which would give approx 190 HP - increase in performance is quite evident on the cold days.
 
But, again no dyno time or data.  But, when I went from my old 2.17 gearbox and 67/72 prop to the 2.85 and 74/88 prop - that really is what changed the performance dramatically - particularly for take off and climbout, surprisingly top speed also increased around 4-6MPH TAS.  First take off took work to keep it on the runway (I'm glad Tracy warned me) with all the right rudder I had.  I have since learned in my RV-6a that letting it get to around 40 mph before apply full throttle makes take off less exciting {:>)
 
 
Ed

Sent: Sunday, February 17, 2013 6:17 PM
Subject: [FlyRotary] Re: Intake progress

Ed
What do you guestimate your HP to be and at what RPM?

Cheers

Steve Izett
On 18/02/2013, at 7:03 AM, 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...)
>



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