From: "Charlie England" <flyrotary@lancaironline.net>
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Subject: Re: [FlyRotary] Re: fuel system peer review
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Date: Tue, 21 Mar 2017 15:55:54 -0500
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I did consider it, but that would mean 3 xfer pumps instead of 1+backup. 
I'd still need a pair of injection pumps. In the same vein, I considered 
the little turbine style in-tank pumps for that purpose, but then I'd 
need a positive shutoff valve for the aux tanks. I also considered them 
for injection pumps (lighter, smaller, lower power consumption) but 
they're actually harder to mount with any configuration flexibility and 
I'd again need a separate positive cutoff (gerotor pumps are positive 
cutoff when not running).

Thanks,

Charlie

On 3/21/2017 10:33 AM, Ernest Christley wrote:
> At the point you're at, what would be the downside to simply putting a 
> pump in each tank, and using a rotary switch to select?  Having the 
> main tank with the return wired in with the ignition, so that it is 
> always running to avoid the return overfilling the tank.
>
> On Mar 20, 2017 5:26 PM, Charlie England <flyrotary@lancaironline.net> 
> wrote:
>
>     1st, let me define my delivery architecture. I like Tracy's idea
>     of feeding the engine from one tank, and transferring aux tanks to
>     the main tank. I understand the downside of being unable to switch
>     tanks, but many a/c (including turbines) supply from one tank, so
>     that's my choice. It avoids the need for a duplex fuel selector,
>     which I like. Effectively, I have 3 'aux' tanks, and I'm using the
>     stock (3 inlet) Van's RV fuel selector to feed redundant transfer
>     pumps in parallel.
>
>     I know that most have a separate return port in their tank(s) for
>     regulator return. With my need for aux transfer, my original plan
>     was to 'T' the aux transfer line into the regulator return line,
>     which I'm pretty sure has been done before.
>
>     I'm currently working on installing both injection pumps in the
>     fuel tank, conceptually similar to standard auto practice for the
>     last couple of decades: no risk of vapor lock with the added bonus
>     of a very clean installation. The regulator will be in the
>     wingroot, just outside the tank, with the manifold pressure line
>     running to that location for pressure control. (Deadheading fuel
>     to the fuel rail has been done on both cars and a/c successfully;
>     I believe it's an option on the new SDS system being marketed to
>     Lyc drivers now.)
>
>     The recent thread on fuel pressure changes while running both
>     injection pumps got me thinking. If it's typical to see only a
>     couple of PSI change when running both pumps, has anyone
>     considered running the transfer line into the regulator? The
>     reason I'm considering this is twofold. It provides a 'final
>     option' for short term fuel delivery if both injection pumps are
>     lost, and, because the regulator is in the wingroot, I would need
>     to run only one fuel line to the supply tank.
>
>     I'll be using gerotor style transfer pumps (positive displacement)
>     and the aux selector has an 'off' position, so backflow won't be
>     an issue.
>
>     A quick & dirty sketch is attached, diagramming the idea.
>
>     There would never be more than 2 pumps running at any time, since
>     transfers would only happen in cruise flight. Can anyone poke
>     holes in this arrangement?
>
>     Charlie
>
>
> --
> Homepage:  http://www.flyrotary.com/
> Archive and UnSub:   http://mail.lancaironline.net:81/lists/flyrotary/List.html


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    <div class="moz-cite-prefix">I did consider it, but that would mean
      3 xfer pumps instead of 1+backup. I'd still need a pair of
      injection pumps. In the same vein, I considered the little turbine
      style in-tank pumps for that purpose, but then I'd need a positive
      shutoff valve for the aux tanks. I also considered them for
      injection pumps (lighter, smaller, lower power consumption) but
      they're actually harder to mount with any configuration
      flexibility and I'd again need a separate positive cutoff (gerotor
      pumps are positive cutoff when not running).<br>
      <br>
      Thanks,<br>
      <br>
      Charlie<br>
      <br>
      On 3/21/2017 10:33 AM, Ernest Christley wrote:<br>
    </div>
    <blockquote cite="mid:list-9592657@logan.com" type="cite">
      <div dir="auto">At the point you're at, what would be the downside
        to simply putting a pump in each tank, and using a rotary switch
        to select?  Having the main tank with the return wired in with
        the ignition, so that it is always running to avoid the return
        overfilling the tank.</div>
      <div class="gmail_extra"><br>
        <div class="gmail_quote">On Mar 20, 2017 5:26 PM, Charlie
          England <a class="moz-txt-link-rfc2396E" href="mailto:flyrotary@lancaironline.net">&lt;flyrotary@lancaironline.net&gt;</a> wrote:<br
            type="attribution">
          <blockquote class="quote" style="margin:0 0 0
            .8ex;border-left:1px #ccc solid;padding-left:1ex">
            <div dir="ltr">
              <div>1st, let me define my delivery architecture. I like
                Tracy's idea of feeding the engine from one tank, and
                transferring aux tanks to the main tank. I understand
                the downside of being unable to switch tanks, but many
                a/c (including turbines) supply from one tank, so that's
                my choice. It avoids the need for a duplex fuel
                selector, which I like. Effectively, I have 3 'aux'
                tanks, and I'm using the stock (3 inlet) Van's RV fuel
                selector to feed redundant transfer pumps in parallel. </div>
              <div><br>
              </div>
              <div>I know that most have a separate return port in their
                tank(s) for regulator return. With my need for aux
                transfer, my original plan was to 'T' the aux transfer
                line into the regulator return line, which I'm pretty
                sure has been done before.</div>
              <div><br>
              </div>
              <div>I'm currently working on installing both injection
                pumps in the fuel tank, conceptually similar to standard
                auto practice for the last couple of decades: no risk of
                vapor lock with the added bonus of a very clean
                installation. The regulator will be in the wingroot,
                just outside the tank, with the manifold pressure line
                running to that location for pressure control.
                (Deadheading fuel to the fuel rail has been done on both
                cars and a/c successfully; I believe it's an option on
                the new SDS system being marketed to Lyc drivers now.)</div>
              <div><br>
              </div>
              <div>The recent thread on fuel pressure changes while
                running both injection pumps got me thinking. If it's
                typical to see only a couple of PSI change when running
                both pumps, has anyone considered running the transfer
                line into the regulator? The reason I'm considering this
                is twofold. It provides a 'final option' for short term
                fuel delivery if both injection pumps are lost, and,
                because the regulator is in the wingroot, I would need
                to run only one fuel line to the supply tank.</div>
              <div><br>
              </div>
              <div>I'll be using gerotor style transfer pumps (positive
                displacement) and the aux selector has an 'off'
                position, so backflow won't be an issue.</div>
              <div><br>
              </div>
              <div>A quick &amp; dirty sketch is attached, diagramming
                the idea.<br>
              </div>
              <div><br>
              </div>
              <div>There would never be more than 2 pumps running at any
                time, since transfers would only happen in cruise
                flight. Can anyone poke holes in this arrangement? </div>
              <div><br>
              </div>
              <div>Charlie</div>
            </div>
          </blockquote>
        </div>
        <br>
      </div>
      <pre>--
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