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Subject: RE: [FlyRotary] Re: fuel pump mounting ( fuel system architecture)
Date: Tue, 14 Jun 2005 15:15:26 -0500
Message-ID: <87DBA06C9A5CB84B80439BA09D86E69E016C1A1E@MAIL01.austin.utexas.edu>
Thread-Topic: [FlyRotary] Re: fuel pump mounting ( fuel system architecture)
Thread-Index: AcVxGjwVcxvfcUjpSVOfcbsiymHRzgAAzlhA
From: "Mark R Steitle" <mark.steitle@austin.utexas.edu>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>

Jim,
I don't think it matters if the bleed is at the highest point, but it
won't hurt either.  It only needs to be able to relieve the back
pressure so the pump can prime.  Once that happens the pump will take
over and push all the remaining air out of the system.

Mark S.

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline.net] On
Behalf Of Jim Sower
Sent: Tuesday, June 14, 2005 2:49 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Re: fuel pump mounting ( fuel system architecture)

OK  This is what I've been trying to find out - whether it will reprime=20
with downstream head pressure (like connected to rail, regulator). =20
You've convinced me it won't.  Successful reprime with bleed circuit=20
sort of confirms my plan to put a "permanent" bleed circuit from a=20
deliberate high spot in the high pressure circuit upstream from the rail

back to the supply tank.
Should help with both reprime and vapor lock issues ... Jim S.

Mark R Steitle wrote:

>John,=20
>At risk of repeating myself, I would like to add to John's comments. =20
>
>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.=20
>
>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)
>
> =20
>
>>>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.
>>>
>>>     =20
>>>
>>-----------------------------------------------
>>
>>Hi John, I like your test but do not understand your conclusion.
>>   =20
>>
>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.
>
> =20
>
>>If the pump will prime with a 4 foot negative head that sounds good to
>>   =20
>>
>me.
>But this only proves it works on the bench under atmospheric pressure
>and
>ambient temperature.
>
>John
>
>
>
> =20
>
>>> Homepage:  http://www.flyrotary.com/
>>> Archive:   http://lancaironline.net/lists/flyrotary/List.html
>>>     =20
>>>
>
> =20
>
>>> Homepage:  http://www.flyrotary.com/
>>> Archive:   http://lancaironline.net/lists/flyrotary/List.html
>>>     =20
>>>
>
>
> =20
>

>>  Homepage:  http://www.flyrotary.com/
>>  Archive:   http://lancaironline.net/lists/flyrotary/List.html