From: "Charlie England ceengland7@gmail.com" <flyrotary@lancaironline.net>
Received-SPF: pass
 receiver=logan.com; client-ip=209.85.213.182; envelope-from=ceengland7@gmail.com
Subject: Re: [FlyRotary] Tank vent lines
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
References: <list-10869178@logan.com>
Message-ID: <a2461f79-b26e-d080-60dc-a8aced2f4606@gmail.com>
Date: Fri, 23 Mar 2018 10:19:37 -0500
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101
 Thunderbird/52.6.0
MIME-Version: 1.0
In-Reply-To: <list-10869178@logan.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 8bit
Content-Language: en-US

On 3/23/2018 9:41 AM, Finn Lassen finn.lassen@verizon.net wrote:
> This looks very tempting.
>
> http://www.vansairforce.com/community/showthread.php?t=1062
>
> But can anyone explain the physics of it?
>
> RV vent lines run from the upper tip of the tanks (next to filler 
> hole) and then normally into cockpit, up cockpit wall, loops down to 
> floor and into 90 degree fitting down through floor and pointing forward.
>
> (http://www.vansairforce.com/community/showthread.php?t=1062&page=4)
>
> There is a mention of RV-10 vent lines, that gives the idea they just 
> come out of the tanks and down and out, but no pictures.
>
> Finn
>
> (Still figuring on where to put vent, transfer and return fittings in 
> right tank)

The good thing about the 'stock' design is that it absolutely will work. :-)

The -10 is non-acro; you can get away with less care in venting.

The 'physics' is just that the fuel has to run around the coil a few 
times to get out instead of up to the top longeron. The idea is that if 
some is trapped in a loop due to expansion, it'll get sucked back in as 
you burn off fuel.

  The coiled version is commonly called the 'Rocket mod'; apparently 
it's the go-to design for Rocket builders. I intend to do that with my 
aux tank vents, but the vent port is on the outboard (high) end of the 
tank. As someone in that thread pointed out, when you do it with the 
port on the root end of the tank, you can't get the coil above the 
actual vent 'pickup' point in the tank. If I elected to do the mod on a 
-4's main tanks, I'd move the vent penetration to the outboard end of 
the tank & make my coil there. However, you then have the issue of 
managing the vent's exit to the air, since getting the tank on/off with 
the vent penetrating the leading edge skin outboard of the tank. Perhaps 
you could use a bulkhead fitting in the bottom tank skin at the outboard 
end, with a coiled section of tubing (inside the tank) up to the same 
area as the stock vent line.

Charlie


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus