Mailing List flyrotary@lancaironline.net Message #63670
From: Todd Bartrim <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Heat Soak & Fuel Purge valve- Another half baked idea?
Date: Tue, 22 Aug 2017 02:32:35 -0700
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Hi Andrew;
  One of the problems with putting this stuff out there on the web is that then you've got to keep it updated. Which I haven't. In many, many years. So the original fuel system that I posted so long ago is out of date. Along with much of the thoughts and ideas that I had back then. I guess I'd just assumed my old web site would be slowly ignored as it is so out of date even in it's appearance.
   I did make an updated diagram of my current system, but I can't seem to find it right now. I may have foolishly saved it onto the local hard drive on my work computer.  So I hope that the similarities don't extend to the things that I changed because they turned out not so good.
  anyways, glad to hear of a successful use of the bleed valve. Purging the air was another thought as well since I have too many tanks as well and have added in sensors to allow me to know exactly when the auxiliary tanks are completely dry and the moment that air enters into the first 6" of fuel line exiting those tanks. But air in the system is always a possibility that I'd like to have an escape plan for.
  I should mention that in my previous flight experience I did test this in-flight while high above the airport and found it was much easier to clear air than fuel vapor. My first system with the header tank was particularly troublesome with fuel vapor. But when air was in the line in the system without the header tank, when I ran the tank dry until the engine quit in flight (at 8000'AGL, so lots of room), once I switched tanks and facet pump (boost) on it was surprisingly quick to put the air through the injectors with the prop windmilling and the engine would just smoothly start and go like nothing had happened. Didn't lose more than a few hundred feet. Vapor in the header tank was a different story.

Todd  --- if I stay up any later, you guys are gonna start thinking I'm in Oz too.

Todd Bartrim

On Tue, Aug 22, 2017 at 1:16 AM, Andrew Martin <flyrotary@lancaironline.net> wrote:
Todd. I did similar to your system, probably because you've got the best documented fuel setup I found on the web for rotary powered plane.

My pumps are close to left main tank so dont get exposed to same temps as yours, but fuel rail still heat soaks and is semi returnless.

I made sure I put in a bleed (just some very tiny part I found from a carby kit) between high & low side of regulator mount, Allows pressure to bleed off when pump is off. so pump is not under vapour pressure when trying to prime. Dont seem to have lost any pressure during normal ops.

Also have the solonoid, just in case I need to purge air faster from low pressure side in case I run a tank dry in flight ( 4 tanks so its just a matter of time).

Andrew
--
Regards Andrew Martin Martin Ag

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