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Fuel Return?

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ericparlow(at)hotmail.com
Guest

Posted: Mon Jan 29, 2007 3:14 pm Post subject: Fuel Return?

Looking for input and suggestions on plumbing a fuel return.



I'm planning ahead and installing it in preparation for a future electronic 

fuel system.



And farther out the diesel engine.................  



Both systems will require a fuel return to the tank.



With the Subaru's(Eggenfellner) needing this now I assume it's being done 

already.

They have a good instruction page on how to install a return in -6A on their 

site.



ERic--

jesse(at)saintaviation.co
Guest

Posted: Tue Jan 30, 2007 9:58 am Post subject: Fuel Return?

This is how we did it in the tunnel (the line on the right above the brake

line is the return line).  It can then go out to that tank or can "T" into

that line and you will want to pull from the other tank when purging the hot

fuel (if you are doing it that way).  Has anybody else lined up the fuel

system to allow for straight lines connecting the pump, filter and flowscan?

Am I missing the reason they are not lined up  to start with?



Hope this helps.



Jesse Saint

Saint Aviation, Inc.

jesse(at)saintaviation.com

www.saintaviation.com

Cell: 352-427-0285

Fax: 815-377-3694



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LloydDR(at)wernerco.com
Guest

Posted: Tue Jan 30, 2007 10:58 am Post subject: Fuel Return?

The one caveat I would like to put out there for Alternative engines

users, is that in the Eggenfellner install, and any other that will

require a high volume pump, the fuel should be returned to the same tank

that it was drawn from, preventing an overflow situation. This is why we

use a duplex fuel valve, so it automagically rolls the return line to

the correct tank.

Dan

N289DT 



--

ericparlow(at)hotmail.com
Guest

Posted: Tue Jan 30, 2007 1:01 pm Post subject: Fuel Return?

Jesse,



Does your fuel return have a separate selector?



We plan to use the Andair duplex valve (p/n FS 20-20-D2) using -6 lines for 

both supply and return.

We also built a "shelf" off the floor of the tunnel to mount the 

filter/pump/sensor to.

This allowed us to put 2-3" of insulation directly on the tunnel floor under 

the pump/sensor.



Also, we wrapped the brake lines with nylon spiral wrap in the tunnel.

After the insulation was packed into the tunnel for a trial fit we found the 

brake and fuel lines could chafe on the shop heads of the rivets directly 

below them in the tunnel.



Here's a few pictures of the lines, valve, pass-thrus, parking brake, and 

the center console.



ERic--

40014, N104EP



----Original Message Follows----

From: "Jesse Saint" <jesse(at)saintaviation.com>

Reply-To: rv10-list(at)matronics.com

To: <rv10-list(at)matronics.com>

Subject: RE: Fuel Return?

Date: Tue, 30 Jan 2007 12:57:43 -0500



This is how we did it in the tunnel (the line on the right above the brake

line is the return line).  It can then go out to that tank or can "T" into

that line and you will want to pull from the other tank when purging the hot

fuel (if you are doing it that way).  Has anybody else lined up the fuel

system to allow for straight lines connecting the pump, filter and flowscan?

Am I missing the reason they are not lined up  to start with?



Hope this helps.



Jesse Saint

Saint Aviation, Inc.

jesse(at)saintaviation.com

www.saintaviation.com

Cell: 352-427-0285

Fax: 815-377-3694

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jesse(at)saintaviation.co
Guest

Posted: Tue Jan 30, 2007 4:30 pm Post subject: Fuel Return?

No, it always goes to the left tank.  It is only plumbed in as a purge valve

for fuel servos that allow you to pump cold fuel through the system and get

the hot fuel out to eliminate the hot start problems.



Do not archive.



Jesse Saint

Saint Aviation, Inc.

jesse(at)saintaviation.com

www.saintaviation.com

Cell: 352-427-0285

Fax: 815-377-3694



--

pitts_pilot(at)bellsouth.
Guest

Posted: Tue Jan 30, 2007 6:04 pm Post subject: Fuel Return?

I've read about 6-way valves and purge valves etc., but haven't had 

anyone tell me why the return (for any reason) can't be Td into the line 

somewhere between the selector and the mechanical fuel pump.  It seems a 

far simpler solution to me.

Linn

do not archive

millstees(at)ameritech.ne
Guest

Posted: Tue Jan 30, 2007 6:35 pm Post subject: Fuel Return?

Linn:



There are 2 reasons why that idea is not advisable. 1. The fuel is hot

coming from the injectors, and needs to be cooled in the fuel tank prior to

returning to the engine.  2. to maintain ballance, you need to return the

fuel to the same tank that you took it from, so you do not over fill one

tanks, and empty the other.  Your idea would immediately return the hot fuel

to the engine, increasing the likelyhood of vapor lock.



Steve Mills

RV-10 40486 Slow-build

Naperville, Illinois

finishing fuselage

Do Not Archive

--

jesse(at)saintaviation.co
Guest

Posted: Tue Jan 30, 2007 6:54 pm Post subject: Fuel Return?

I can't imagine why you couldn't do it that way, but if you are trying to

purge hot fuel and replace it with cold fuel, it is better to put the hot

fuel on the tank side of the selector so you can get cold fuel out of the

other tank from the side you are putting the hot fuel in.  I think Allen

Barrett said that just mixing the hot fuel with the cold fuel aft of the

firewall would be good enough, but I like the idea of sending it to the

tank.



Does this make sense?



Jesse Saint

Saint Aviation, Inc.

jesse(at)saintaviation.com

www.saintaviation.com

Cell: 352-427-0285

Fax: 815-377-3694



--

ericmpmail-rv10(at)yahoo.
Guest

Posted: Tue Jan 30, 2007 6:55 pm Post subject: Fuel Return?

I've put a return line into the one tank I have built

so far. It is easy to do and I just ordered extra

fittings. In case of ECi engine or diesel, etc.



As to why not to T it back to the incoming line, this

could result in vapor lock. The return line is

pressurized relative to the line from the tank and you

could end up with a fairly high recirc rate (hotter

every loop). Also, I understand that bubbles in the

return fuel line are possible even in normal systems.



You also have the possibility of pressure instabilites

if the line from the tank is small or restricted. Pump

adds X+ pressure to inlet pressure and therefore total

pressure could be higher than expected at fuel

injectors, etc. Final fuel regulator should take care

of this but it is the recipe for a feedback loop.



If you run a tank dry, you may have enough air in the

loop that the pump cannot prime. another issue is it

might build air pressure, preventing draw from a tank,

or vapor lock during ground soak, or ?



Fuel contamination, switching tanks does not "clear

the line" immediately due to local re-circ.



I'm sure there are others. You can try a bench mockup

and look at potential failure modes.



These are good questions to ask of any fuel system.



Eric

40150



--- linn Walters <pitts_pilot(at)bellsouth.net> wrote:



 	  Quote: 	
		   

 <pitts_pilot(at)bellsouth.net>

 

 I've read about 6-way valves and purge valves etc.,

 but haven't had 

 anyone tell me why the return (for any reason) can't

 be Td into the line 

 somewhere between the selector and the mechanical

 fuel pump.  It seems a 

 far simpler solution to me.

 Linn

 do not archive

bob.kaufmann(at)cox.net
Guest

Posted: Tue Jan 30, 2007 7:27 pm Post subject: Fuel Return?

On the Helio Courier, we would run the left tank down an hour, and then burn

from the right tank until we made it run to the point of trim plus half of

what we expected for the remaining flight.  We did this because all of the

return went into the left tank and that was one way of keeping the aircraft

in some semblance of trim.  We never had a problem with hot fuel operating

in some of the places we flew out of, even when the conditions were less

than perfect.  Less than perfect would be the most positive way of

describing it.  We would do a lot of takeoff and landings, in "hot"

environments with out a fuel problem.



Bob K

91/89 to go.



--

LloydDR(at)wernerco.com
Guest

Posted: Tue Jan 30, 2007 7:51 pm Post subject: Fuel Return?

If you are using an alternative engine that has high flow, you would

eventually heat the fuel by looping it, this is why it is returned to

the tank and mixed. But if you are using a Lyco, Jesse states that it is

just a small amount of fuel for the return to dump the hot fuel.

Hope this helps

Dan

 



--

BPA(at)bpaengines.com
Guest

Posted: Wed Jan 31, 2007 4:37 am Post subject: Fuel Return?

Actually sending the fuel back to a tank is the ideal method. But if

your wings are sealed, that would be a job and a half I would think. The

whole idea is to cool the engine driven fuel pump. To 'T' the hot

between the selector and the engine driven pump would be a last resort.



Allen

--

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