Todd,
There is absolutely no reason to retain the side ports for aircraft use. Richard Sonn tried that on his single rotor and. Found the side ports to be no help at all. The reason for the side ports is low speed operation in the car. We will never need to run slow enough to need them.
Bill JepsonSent from my Verizon Wireless BlackBerry
From: William Archer <archerwt@gmail.com>
Date: Thu, 6 May 2010 14:51:23 -0700 To: Rotary motors in aircraft<flyrotary@lancaironline.net> Subject: [FlyRotary] Re: Gravity Feed
It's a smaller pport that retains balanced side ports, too.
Todd
On Thu, May 6, 2010 at 1:50 PM, George Lendich <lendich@aanet.com.au> wrote:
Todd,
What do you mean by a semi PP.
George (down under)
Bill,
Sorry, it's a high wing (Bearhawk) that won't be upside down - ever. I figured the airframe would give me 1.5 psi for a downdraft carb; maybe 2 psi for an updraft? I always thought I would be totally electronic but I love the setup on my 170: all gravity from both tanks all the time. The only fuel-related activity I have is making sure there is enough and then regularly sumping tanks and keeping the gascolater screen clean.
I am building a semi-pport and will try to run it with a gravity-fed Holley 2300. At worst, I might have to add a pump or go with a Marvel Schebler MA-4/5 caliber aircraft carb.
Todd
Todd, High wing or low wing? The key is if you have a high wing there is at least a minimum pressure available. Anything aerobatic or low wing will need pumps. Bill Jepson
Anyone who knows feel free to explain to me why a Marvel-Schebler updraft can feed 300 hp with gravity but pumps are needed for Webers or Holleys. I understand the updraft gets another 18” of pressure but am assuming it is simply by design that the response is improved with a few lbs of pressure. Since we aren’t too worried about throttle response as long as it doesn’t stumble, would a gravity-fed Holley be a waste of time?
Todd
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