John,
At risk of repeating myself, I would like to add to John's comments.

I ran a similar test, but included the rest of the fuel system (Andair
valve, fuel filters, fuel rail, fuel pressure regulator, etc.) and found
out that my system would not reprime unless I cracked open a line
downstream of the pump.  With the addition of the bypass bleed circuit,
I have confirmed that one dry pump will draw fuel up from the floor
(approx. 18") through the Andair valve and be up to pressure in about 10
seconds.  "Time to prime" is significantly reduced by running both
pumps.  I have repeated the test using auto fuel in hot Texas temps and
get similar results.

Mark S.
Lancair ES w/20B


-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of John Slade
Sent: Tuesday, June 14, 2005 1:27 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: fuel pump mounting ( fuel system architecture)

I did an experiment with the pump on a 4 foot bench, and a gas can
on the
floor. The pump primed itself with no difficulty. Having said that,
a
scenario like this in a plane would be just asking for vapor lock.

-----------------------------------------------

Hi John, I like your test but do not understand your conclusion.

The conclusion wasn't based on the results of the experiment :)
It's my understanding that you need to replicate the temperatures and
pressures for the experiment to be entirely valid.

If the pump will prime with a 4 foot negative head that sounds good to

me.
But this only proves it works on the bench under atmospheric pressure
and
ambient temperature.

John

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