Mailing List flyrotary@lancaironline.net Message #65519
From: Charlie England ceengland7@gmail.com <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Fuel System Design for High wing Aircraft
Date: Mon, 20 Jan 2020 12:57:15 -0600
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Thanks for that link; I've been sorely tempted to do it, but the hassle of removing an RV7 tank for service (*much* worse than a -6) finally made me give it up. If there was a convenient place for a 'header' tank in an RV, I'd still give it some thought.

I'm sure that Steve already knows this, but a heads-up to anyone else thinking about doing this. The web page for this controller says 'just about any 12V pump will work'. NOT true. Several years ago, I spent some time on the phone with a Walbro engineer discussing the PWM control idea. He was very clear that the GSL series pumps that most of us have installed should not be used with PWM controllers. The reason he gave is that gerotor style pumps  (and I suspect this would also apply to roller-vane pumps) can have relatively short lives if PWM-controlled, because the PWM signal causes the gears to 'hammer' against each other.

The proper style pump for PWM is a 'turbine' pump. The pump is basically a fan on the end of the motor shaft; works *kinda* like a water pump impeller. Which brings up another caution about the info on that web page. They show a turbine pump installed as an in-line pump; an application you will never find in a car. They are probably getting away with it in the bike because the bike's fuel tank is higher than the pump.  Turbine pumps are not 'positive displacement' pumps like the gerotor pumps; they cannot 'lift' fuel or self-prime. So installing them in-line in a low wing a/c could be very hazardous.

Just thought the above was worth mentioning.

Charlie

On 1/20/2020 11:57 AM, Steven W. Boese SBoese@uwyo.edu wrote:
The following site lists an inexpensive fuel pump controller for use on a returnless system.


I have purchased one of these and am in the process of installing it my rotary engine test stand for evaluation.

Steve Boese

On Jan 20, 2020, at 9:24 AM, Charlie England ceengland7@gmail.com <flyrotary@lancaironline.net> wrote:

The holy grail is a returnless system, to finish out the automotive style injection. :-)

Ed did use a very small header tank; logic was that the recirculated fuel never stayed in the tank long enough to begin to heat up. But he didn't vent the header back to either main tank. I always thought that the unvented header was going to be the cause of his next 'glider' flight. If you add a vent line back to the main tank, it'll work safely. (My BD4 had a similar system, but for a different purpose; the BD main tanks had a tendency to unport in uncoordinated flight.)

There are other options, too. We can talk.

On Mon, Jan 20, 2020 at 7:58 AM Bobby J. Hughes bhughes@qnsi.net <flyrotary@lancaironline.net> wrote:

What is the best method for handling return fuel in a high wing? Fuel return to a small header tank sized to keep fuel temperatures low? I think Ed Anderson may have used a small header in his RV6.

 

Asking for a friend with an airplane addiction.

 

Bobby



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