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Date: Tue, 10 Aug 2004 06:55:59 -0600
From: Bob White <bob@bob-white.com>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] returnless fuel system
Message-Id: <20040810065559.3397ecd9.bob@bob-white.com>
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Hi Todd,

I haven't seen Jim Weir's conversion circuit, but it seems to me that
when the tank is empty it wouldn't matter what fuel was in it, so what
you need is a pot to adjust full scale when you fill the tank.  There
may be a little shift in the zero when full is adjusted, but your
accuracy should be much better.

Congratulations on the new family member, and best wishes for a good
nights sleep.

Bob White

On Tue, 10 Aug 2004 00:39:40 -0700
"Todd Bartrim" <haywire@telus.net> wrote:

>     First I'd like to thank everybody for their congrats on & offline,
> everybody is still doing fine, but sleep is still at a premium.
> Definitely no time for flying :-(, maybe in a few days.  No jump seat
> in the 9 yet, but I'm already planning it :-)
> 
>     Second I need to say that even though I seem to have found a
>     successful
> fuel system, I do regret not adding fuel return fittings in each of my
> 6 tanks. A simple 1/4" bulkhead fitting with a cap is not too much
> $$$, or weight and it will allow simple plumbing changes if ever
> necessary. While I have 30 successful flight hours on my returnless
> system, it is prudent to remember that I only have 30 flight hours on
> my returnless system.:-). And none of this flight time was down south
> where your idea of summer & winter are vastly different than up here
> in the great white north. At this point I'd recommend that you install
> return fittings while it's still easy to do. I wish I had, however if
> I had I may not have ever tried this system and only went with a
> conventional system. Even if my system continuous to be successful, if
> I ever have a reason to remove my tanks, I will add return fittings
> with caps.
> 
>     I may have this opportunity. I currently have capacitive fuel
>     sensors,
> which are read by an E.I.sensor. I bought the components to build a
> converter as per Jim Weirs plans from a past KitPlanes article, in
> order to display on the EM2 which needs a 0-5 volt signal. However I
> find that auto fuel seems to vary in it's capacitance. When properly
> calibrated they are very accurate, but put in fuel from another batch
> and the readings are less accurate, put in fuel from the original
> batch and they are accurate again. Start adding pre-mix fuel and of
> coarse they're inaccurate again. I'm unsure if it is the fuel itself
> that has dielectric variations or possibly the dye used to mark the
> fuel as off-road use only? I've noticed that the purple colour seems
> to vary as some batches seem to have almost no colour while others are
> very dark.
> 
>     In any event, while I will still leave the capacitive probes in
>     place, I
> think I will order a set of float resistive sensors to display fuel
> info on the EM2. If I do this I will add the return fittings and then
> possibly I may add an electric fuel tank selector valve that I have,
> except that it will be used to select fuel destination instead of
> source. In it's normal un-energized state it will continue to operate
> as a returnless system, but when energized it will return to a wing
> tank. In the event of an unexpected vapour lock, I can just hit a
> mom-on push button to return to a wing tank. My concern with this is
> that these fuel tank selector valves are meant to be located on the
> suction side of the fuel pump, so I'm unsure how well they would work
> in the return line.
> 
> Bottom line... Install the return fittings while still it's easy!
> 
> Todd Bartrim        (trying to think of a way to burn diapers for
> fuel)
> 
> RV9Endurance
> 13B Turbo Rotary
> C-FSTB
> http://www3.telus.net/haywire/RV-9/C-FSTB.htm
> 
>              "The world will always have a place for those that bring
>              hard
> work and determination to the things they do."
> 
> 


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