Mailing List flyrotary@lancaironline.net Message #63703
From: Tracy <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Heat Soak & Fuel Purge valve- Another half baked idea?
Date: Wed, 23 Aug 2017 11:03:56 -0600
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Good info.  Do you know if these PWM regulators work with any EFI pump or are they for the turbine type pumps only?  Charlie England showed me a turbine type specifically designed for this kind of setup.

Tracy Crook

On Aug 23, 2017, at 10:19, Matt Boiteau <flyrotary@lancaironline.net> wrote:

There's a few ways to modulate the fuel pump correctly. The MegaSquirt EFI system can handle sending PWM out to the fuel pump to maintain the correct psi.

Ford has a Fuel Pump Driver Module (FPDM) that takes a PWM input signal, outputs PWM at 20-30 amps driving current (fuel pump or any accessory). 

For SSR relay route, Hella H41773001 handles 32A 

I'm not sure, but also a nitrous solid state relay might work too. All of this is untested, just saved up in my research folders for version 2.0 of plane. Finding a good external fuel pump is the hard part. Aeromotive A1000 handles PWM, but at a price ~$400. Can't find any external Walbro's that will, only internal.


- Matt Boiteau

On 8/23/2017 10:51:37 AM, alex <flyrotary@lancaironline.net> wrote:

What fuel regulator do you guys recommend?

My current setup uses a duplex fuel valve (came with the kit) drawing fuel from either L or R front tank and returning it to the same tank. The L & R rear tanks pump their fuel into their respective front tanks, via a facet pump on each wingtip.

I like Tracy's idea of regulating fuel pressure by modulating the fuel pump. 

As a crude method I had considered a DC controller on the primary pump a while back to get more "electrical" range out the batteries when crossing water with a possible alternator failure, but that's a project for a few years away.

What's everyone using on their conventional return system setups and any reasoning behind it?

Alex Molteno


On Aug 23, 2017 2:21 PM, "Tracy" <flyrotary@lancaironline.net> wrote:
I went 'returnless' for simplicity of fuel plumbing, simplicity of installing a fuel flow sensor between regulator and fuel rail and because vapor lock is not a problem on the high pressure side of the system.  In my experience, Vapor lock only happens on the inlet side of the fuel pump.  If you eliminate it there, any heat soak problem after shutdown will quickly clear itself on startup.  

Since the pump and regulator is not in the tank, my system is not truly returnless since the regulator must have a return to the tank (unless you implement fuel pressure regulation by modulating the fuel pump power).   

I only feed and return from one tank, the other tank just refills the feed tank via transfer pump which Ts into the feed tank return line.  

Tracy



Sent from my iPad

On Aug 23, 2017, at 06:23, Matt Boiteau <flyrotary@lancaironline.net> wrote:

What was your reason to go return-less?

I have 4 tanks in the wings split between the middle spar. Front left & right, Back left & right. Instead of having a selector valve for each tank (plus their return lines), I made 1 tank the main header tank. Fuel supplies and returns to it. And the rest of the tanks feed the main tank using transfer pump. No selector valve, full return system.

-Matt Boiteau

On Aug 22, 2017 17:36, "Todd Bartrim" <flyrotary@lancaironline.net> wrote:
By opening manually, I meant just opening the oil hatch on the top of the RV cowl to let it cool. With that up in the air it would be difficult to miss and if I did miss it during a pre-flight, then I'd probably not be doing a good job of my pre-flight inspection.
But I do think it's a good idea and one that I may have given more serious consideration to if I'd known about it earlier this year when I was doing fiberglass work on the cowl.
At this point though it looks pretty easy for me to add the fuel purge to the injector header, so unless somebody talks me back from the ledge, I'm probably going to jump. Just as soon as I finish a solar mod on my boat so I can take my kid fishing tomorrow.

Todd

Todd Bartrim

On Tue, Aug 22, 2017 at 12:28 PM, Thomas Mann <flyrotary@lancaironline.net> wrote:
>Cheaper, lighter and probably safer to just open the door manually.
__________________________________________________________________________
Cheaper: Depending on the alternative? Probably
Lighter: Again, depending on the alternative????
Safer: Doubtful. These things are pretty much foolproof and have been used in aircraft already for just this purpose.
       With a front hinged vent door I cannot see a benefit to using a manual mechanical method of operation.
       If you do use a mechanical actuator ..... don't forget to come back and close it.
 
All in all, it's sounds as those this would not be a good solution for you.
 

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