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Auxiliary tank

Anyone tried to put an auxiliary fuel tank in the rear baggage area in the RV-8?
Any ideas? How can I get the fuel into the engine from there?
Thanks

Pablo Fern?ndez
Miguel Scalise
RV-8 LV-X418
130 hs TT
ROJAS, BA, ARGENTINA
 
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Anyone tried to put an auxiliary fuel tank in the rear baggage area in the RV-8?
Any ideas? How can I get the fuel into the engine from there?
Thanks

Pablo Fernández
Miguel Scalise
RV-8 LV-X418
130 hs TT
ROJAS, BA, ARGENTINA

Yes Juan it can be done!



This tank is my adaptation shamelessly stolen from fellow teammate Robert Gibbons. It's a 16 gallon circle track racing tank. It sits on a ramp to clear the flap actuator tube. Dry break fittings on the hoses allow quick disconnects for fuel feed and venting. The standard Vans fuel selector valve has an unused port that is now used as the Aux position. The hose lays in the cockpit. The vent line is in the aft baggage wall. The tank is strapped down in the baggage comp and via the rear seat belt. With the tank all the way aft there is room to reverse the rear seatback hinge and it will then rest against the mid cockpit brace.







An email with all the listed parts and links.

Wizz,

Here is the list of all the parts for the tanks Greese, Leggs, and I have.
A little over about 500 bucks for the parts.

Mutha/ Badger

Begin forwarded message:

From: Jon Thocker
Date: October 23, 2012 10:53:31 AM EDT
To: Smokey
Subject: Tank parts

Smokey and others,

Here is a list of parts and links for the 16 gallon tank I am using:

First is the actual tank http://www.jegs.com/i/RCI/821/1161C/10002/-1?parentProductId=755349

The dimensions given online do not match the actual dimensions the tank is smaller measuring more like 23 x 17.5 x 11 instead of 25 x 19 x 11
the tank came in a box marked RCI so it probably matches the dimensions for the RCI tanks in the Summit Racing catalog.

Hose parts:

Fuel feed

http://www.summitracing.com/search/?keyword=220122&dds=1 fuel tank AN reducer from -8 to -6


http://www.summitracing.com/parts/AER-FCA0606/ -6 hose 6 feet

http://www.summitracing.com/parts/SUM-220687/ reducer to fuel feed line 90 degree hose end -6

http://www.summitracing.com/parts/SUM-220690/ -6 hose end need 2 for splicing in a fuel filter


http://www.summitracing.com/parts/RUS-650133/ a cleanable fuel filter


https://www.pegasusautoracing.com/productdetails.asp?RecID=5543 90 degree quick disconnect -6 hose


https://www.pegasusautoracing.com/productdetails.asp?RecID=3411 qk disc plug -6 an female




Fuel vent

http://www.summitracing.com/parts/EAR-9892084ERL/ reducer from AN -8 to -4


http://www.summitracing.com/parts/SUM-220487/ reducer to fuel vent hose 90 degree hose end -4


http://www.summitracing.com/parts/SUM-220982/ -4 hose 10 feet , need 3 ft


https://www.pegasusautoracing.com/productdetails.asp?RecID=3032 qk disc -4 hose


https://www.pegasusautoracing.com/productdetails.asp?RecID=4254 qk disc plug -4 an female



https://www.pegasusautoracing.com/productselection.asp?Product=3239 AN bulkhead 90 degree need 1 -6, 1 -4


https://www.pegasusautoracing.com/productselection.asp?Product=3226 Straight bulkhead fitting for connection on fuselage bottom -4 AN

https://www.pegasusautoracing.com/productselection.asp?Product=3237 bulkhead nuts

https://www.pegasusautoracing.com/productselection.asp?Product=3235 coupling nuts AN -6 and -4


https://www.pegasusautoracing.com/productselection.asp?Product=3236 AN flare sleeves -6 and -4


http://www.vansaircraft.com/cgi-bin...l=c&browse=hardware&product=altube&action=add Aluminum fuel line



http://www.vansaircraft.com/cgi-bin...l=c&browse=hardware&product=altube&action=add aluminum vent line



http://www.aircraftspruce.com/catalog/topages/470-fh.php?clickkey=4587 tubing bender



For my installation I built a ramp to go over the flap actuator tube 3/4 inch oak plywood measuring 22" long by 18' wide, with a 2" x 3" x 18" and a 1" x 3" x 18" stacked, to support the front of the ramp fwd of the actuator tube, then another 2" x 3" x 18" positioned aft of the actuator tube to further support the ramp mid span

I'll follow up with some pics.

Badger

The Jiffy tite fittings are available from Summit but are harder to find online




I'll try to get a pic of the tank installed later today.
 
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I've done something very similar to Jon, but using the front locker.

I just needed an extra 10 gallons to have comfortable reserve for a planned ferry flight.

If you have the Van's fuel valve then plumbing in is very simple. Remove the pipe thread plug and screw in a pipe thread to 3/8 hose adapter. This is how Jon Johannson plumbed in his ferry tanks on his round-the-world trips and avoids the need for a transfer pump.

The electric boost pump has plenty of dry lifting capacity to prime the line, but it's still a good idea to ground run from the aux. tank after filling it, then switch to the standard tanks for take-off.

The polyethylene tank will need to be secured. You could buy the tie-down straps that they sell for the tanks, but it's cheaper to just bend up some strips of 1/8*1/2 alloy and bolt down to the floor.
 
For my 9A, I've been planning a ferry tank fuel setup since an around-the-world trip is on my retirement bucket list. I have return lines to both tanks on my plane, I just tapped into the right wing return line and put a port there. A small facet carburetor electric fuel pump will be more than enough to pump the contents of a ferry tank into the return line and into the right wing tank, and then the rest of the fuel system operates as normal.

I've got the outboard wing leading edges converted to additional fuel tanks as well, giving me right at 70 gallons in the wings. With a 40 gallon ferry tank in the passenger seat to keep CG happy, that should give me California-to-Hawaii range with a 2 hour reserve. That's the longest non-fuel leg you'll find on the globe, if you can make that then you can go anywhere you want. Yes, that would be an over-gross takeoff and returning to the airport that heavy would make for an overweight landing inspection, I'm aware of that. In all likelihood the airplane would only be asked to do that 5 or 6 times in it's life.
 
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I'll try to get a pic of the tank installed later today.[/QUOTE]

Just to let you know there's myself and I'm others who are keen to the installation.
 
I'll try to get a pic of the tank installed later today.

Just to let you know there's myself and I'm others who are keen to the installation.[/QUOTE]

Sorry Peter,
I'm in the middle of a move and without Internet at at home, I'll post more pics soon!
 
Jon,

With that much fuel so far aft, what is your method for managing CG throughout the flight? I would expect that you tap into the rear tank last, trying to maintain the aft CG as long as possible if for nothing else, the reduction in trim drag. Obviously, you normally have the airplane within CG with zero fuel, but we are all supposed to land with reserve fuel - might as well be in the rear to keep the CG as close as possible to the takeoff configuration. I bring this up because I'm having the same internal debate concerning a planned fwd fuse tank mod for a Rocket. Of course, the fwd tank has a shorter arm than the rear tank, so if you can make it work (CG management), then it should be even easier for me.

...oh Mark, thanks for the reminder about the unused port on the fuel selector - that will make my mod a little easier.
 
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BTW, though the "circle track" fuel cell pulls fuel from the top, the "drag race" version usually pulls from a small sump on the bottom... Might work out better in some installations. These things come in all sizes from 1 to 20+ gals too, so chances of finding what you need are pretty good.
 
Jon,

With that much fuel so far aft, what is your method for managing CG throughout the flight? I would expect that you tap into the rear tank last, trying to maintain the aft CG as long as possible if for nothing else, the reduction in trim drag. Obviously, you normally have the airplane within CG with zero fuel, but we are all supposed to land with reserve fuel - might as well be in the rear to keep the CG as close as possible to the takeoff configuration. I bring this up because I'm having the same internal debate concerning a planned fwd fuse tank mod for a Rocket. Of course, the fwd tank has a shorter arm than the rear tank, so if you can make it work (CG management), then it should be even easier for me.

...oh Mark, thanks for the reminder about the unused port on the fuel selector - that will make my mod a little easier.
Mike,
You're over thinking this, there is no rear seat pax. I burn the fuel out of that tank as fast as I can. No way I want to lift that tank out with anymore than the half gallon that is unusable do to tilt. Incidentally the fuel pick up is in the left rear corner of the tank, all the way at the bottom.
With my firewall battery and Hartzell prop it is almost impossible for me to be out the aft CG, so I don't even worry about landing CG. I'll leave reducing trim drag to racers and engineers!:D
 
Yes, I redid my W&B spreadsheet to incorporate a front and rear tank so I could play with the numbers and it is not as bad as I thought it would be. Clearly, it is not a critical condition as long as you pay attention to the loading.
 
Thanks Jon for sharing your setup. I followed your lead and added a 32 gallon tank that sits in one rear seat. I could easily add another 32 gallon tank in the other rear seat if i wanted.

My main purpose is to just use up the empty seats and to ferry cheap fuel. I don't plan to fly to Hawaii, though i almost could. ;)

This is my new range circles with the Aux Tank.

90 gals
1560 sm radius for 8.5 hours
780 sm radius without refuel

cicdicae.png
 
It may not do the RV-8 guys any good but I have a set of long range tanks that will fit the RV-6-7-9 for sale. They fit in the cutout in the back of the seats and do not use any of the baggage space. Total of 14 gallons which is good for about an additional 300 miles. 419 360-7414
 
Seat back tanks

It may not do the RV-8 guys any good but I have a set of long range tanks that will fit the RV-6-7-9 for sale. They fit in the cutout in the back of the seats and do not use any of the baggage space. Total of 14 gallons which is good for about an additional 300 miles. 419 360-7414

Any pictures? Materials of construction?
 
Jon - I'd like to see if you could add to this thread.

Specifically, I'd be very appreciative to see a couple pics of it installed.
  • a pic of the fuel vent installed in your plane
  • a pick of the hoses when in use

Also, any fueling procedure tips ?
 
All I can say is you guys are totally hard core or have cast iron backsides...LOL. I am either bored/sore after an hour or two!
:eek:

But I AM loving that idea of ferrying cheap gas. My home field is always a $1.50 more than everyone else and no amount of commen sense discussion will convince them they will sell WAY more fuel if they are just competitive with the 10 other fields all within spitting distance. Sometimes you just can't fix stupid.
 
Aux Tank in Rear Baggage.

I just installed a smaller tank (12 gal) in my RV8 baggage area without changing anything regarding rear seat. I just needed extra fuel for Tanking and return fuel from some of my destinations in Thailand. The Tank is from RCI near Dallas (www.rciracing.com), although it was a Amazon order for me. The model is 2121A and it goes in and out of baggage area very easily. Just fold seat back down as normal. Only ground tested so far. I put 1 gallon of fuel in it and turned on Facet pump (Carbureted Engine) the pump self primed and I was able to start engine and ground run for about 5-10 minutes. I only plan to use it in cruise but good to know it will work in ground attitude. Also with plumbing installed I can easily take Rear seat out and put in a larger tank if I get more adventurous. The plastic cans you see in background are what I carry for runs into local gas stations if 95 mogas is available at destinations. I fly with them empty.
Just another option in the Aux Tank category.
I hope the picture link works.
Regards
Gary M.

Aux%20Tank1.jpg
 
FACET fuel pressure against vent line pressure

I am considering the installation of an aux tank system in the baggage compartmet of my RV8.
Since I intend to transfer the fuel from the aux into the main tank, a friend of mine mentioned the point of overpressure in the main tank when the main tank gets completely filled.

Question is: Did anybody consider an overpressure in the main tank produced by the Facet pump?
Will the pressure of the fuel pump overrule the incoming pressure produced by the vent line?
I know that this is an unusual question but may be that someone already discussed this in this forum.
Thanks for answering
Stephan

RV8
#82979
 
That is a real concern that not many consider. A friend tested it (test rig; not an actual tank) using a fuel injection style pump (higher flow/pressure than a Facet), and found that once the tank is full and fuel is being forced out the AN4 vent, pressure in the tank can go over 10 psi; enough to rupture the tank. I'd still worry with a 6 psi Facet.

The way to manage is to either burn enough out of the main to accept all the fuel from the aux, or use a timer or level sensor to control the transfer pump. A timer is simpler, but you need to establish transfer rate in your particular install, and make sure you burn enough from the main before activating the timer for transfer.

Even if there were no risk to the tank structure, there's no point in pumping fuel overboard. :)

Charlie
 
Thanks Jon for sharing your setup. I followed your lead and added a 32 gallon tank that sits in one rear seat. I could easily add another 32 gallon tank in the other rear seat if i wanted.

My main purpose is to just use up the empty seats and to ferry cheap fuel. I don't plan to fly to Hawaii, though i almost could. ;)

This is my new range circles with the Aux Tank.

90 gals
1560 sm radius for 8.5 hours
780 sm radius without refuel

cicdicae.png

Either you're young or you also added an additional tank to empty your bladder ! I wouldn't be able to fly so many hours if I wanted to :):)
 
That image looks familiar. My RV-8 has long legs now too ...

RV-8_AUX_range.jpg


The green circle is for no-refuel round-trip flights and the yellow circle is for one-way flights.
 
Long range tanks

It seems that many of us have similar ideas/dreams. I have been measuring and calculating for some time. I haven?t seen anyone mentioning bladder tanks..these have several advantages over rigid designs, easier space conforming is just one.

For further range, I saw our Round the world friend had what appears to be an external belly tank in one photograph. One article I read quoted him as claiming a 3,000 mile range. Does anyone have any further information?

The real difficulty in planning for my trans Atlantic plans are domestic objections!
 
T-fitting?

I?ve read a lot about the different types of setups. I have the Andair FS20-3, which only has a left and right option. There is no extra port like the Van?s valve.

Anyone have experience in adding a T to either the left or right side and adding the auxiliary tank to that? I?m looking at the Kitplanes article and was going to mimic that, except for the fuel valve.

https://www.kitplanes.com/adding-an-auxiliary-fuel-tank-to-an-rv-8/

Would adding a T be problematic? I do have a boost pump but I?m thinking that once the wing tank was empty, there would be a problem.

I could always get the Andair FS20-5, which gives you left, right, main, and off.

Thoughts? Experience?


Thanks


Don
 
I haven't done it yet but I'm planning it - with the return lines back to the tank, I'm going to Tee into the zero-pressure return line and use a small Facet pump to move the fuel from the bladder tank to the return flow going through the Andair duplex valve and back to the tank. The nice thing about this is that as you are pumping fuel from the bladder tank to the wing tanks, you can choose which tank you pump it to by selecting it on the Andair valve.

Of course, that only works if you have returns and a duplex valve...
 
Don,

I'm really good at spending other people's money...

I would sell your current Andair valve and install a new one that had the extra ports you need. That will help keep your fuel system simple. If you can only get a valve for four tanks, plumb two together for your single aux tank so you never hit a dead port.
 
Absolutely, I would not just put in a T fitting in one line. That would sooner or later lead to a disaster.
You have a couple of choices. One is getting another Andair fuel selector with an extra input port. Another is to run a line straight from the aux tank to one of your wing tanks. Then you can simply refill that main tank when it gets low. I do exactly this with my RV-4 and it works great.
 
I installed a 10 Gal tank from summitracing. It is in a tray to catch any spills and can be installed in about 10 minutes. There is a Facet pump at the tank and the fuel line is installed under the floorboards and is plumbed into a separate inlet in the selector valve which I ordered from Andair. It gives me around 220 NM extra range.

https://imgur.com/JYdy9fE

https://imgur.com/xWwBGYA
 
Done.

I ordered the Andair fuel valve today that will accommodate the auxiliary tank along with both left and right tanks.

Just have to decide what size tank I want to get.

I may have to order some hoses off you Tom!

I?ll post my progress once I start. Ideally, I would like to have 7-8 hours endurance...you never know where I may want to end up!

Don
 
Romeo Victor said:
I am considering the installation of an aux tank system in the baggage compartmet of my RV8.
Since I intend to transfer the fuel from the aux into the main tank, a friend of mine mentioned the point of overpressure in the main tank when the main tank gets completely filled.

Question is: Did anybody consider an overpressure in the main tank produced by the Facet pump?
Will the pressure of the fuel pump overrule the incoming pressure produced by the vent line?
I know that this is an unusual question but may be that someone already discussed this in this forum.
Thanks for answering
Stephan

That is a real concern that not many consider. A friend tested it (test rig; not an actual tank) using a fuel injection style pump (higher flow/pressure than a Facet), and found that once the tank is full and fuel is being forced out the AN4 vent, pressure in the tank can go over 10 psi; enough to rupture the tank. I'd still worry with a 6 psi Facet.

The way to manage is to either burn enough out of the main to accept all the fuel from the aux, or use a timer or level sensor to control the transfer pump. A timer is simpler, but you need to establish transfer rate in your particular install, and make sure you burn enough from the main before activating the timer for transfer.

Even if there were no risk to the tank structure, there's no point in pumping fuel overboard. :)

Charlie

Has anyone come up with a good solution to the accidental overfill problem? Obviously we're going to watch fuel levels and never intentionally over fill the tank. The consequence of doing that is something I worry about. As much as I don't want to vent fuel overboard, I'd much rather vent fuel than rupture a main tank.

Would 1/4" aux transfer line negate any concerns about venting fuel overboard through 1/4" vent lines if an overfill did happen?
 
Has anyone come up with a good solution to the accidental overfill problem? Obviously we're going to watch fuel levels and never intentionally over fill the tank. The consequence of doing that is something I worry about. As much as I don't want to vent fuel overboard, I'd much rather vent fuel than rupture a main tank.

Would 1/4" aux transfer line negate any concerns about venting fuel overboard through 1/4" vent lines if an overfill did happen?

I have outboard and inboard tanks, the engine only draws fuel from the inboards. At the low point of the outboards I have two fuel pickups, one is a direct -6 size line to the high point of the inboard, and the other is a -6 size line through a Facet low-pressure fuel pump to the high point of the inboard tank.

In operation, normally as I burn fuel from the inboards it will pull a slight vacuum, and fuel will automatically flow from the outboard to the inboard via the straight pipe. However - this requires that the inboard filler cap is airtight and does not leak - if it does, then no fuel will transfer and I lose access to all the fuel in the outboard tank. To fix that problem I put the second line in place with the pump to force it across if needed. When the inboard tank is full and the pump is still running, then the excess flows back into the outboard tank via the straight pipe -6 sized line, preventing an overpressure on the inboard tank.

My tanks vent from atmosphere into the high point of the outboard tank, via a rocket-style 45-degree vent fitting on the bottom of the wing, and then through the outboard tank into the inboard tank for flow-through venting. I cannot dump fuel overboard, or overpressure the inboard tank, by trying to overfill the inboard tank with this design. It's worked well for me for almost 1100 hours now.
 
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As much as I don't want to vent fuel overboard, I'd much rather vent fuel than rupture a main tank.

Haven’t read the whole thread and there are, as usual, many different threads all pertaining to the same subject.
I’ve been using my 25USG Turtle tank on most legs of my actual trip, and unfortunately overfilled my right tank twice… yes, I know :eek:
No consequences but the lost fuel, and the smell of gas in the cockpit. Depends of course as to where said vents are installed, mine are in the gear leg fairings. The plumbing itself is as follows: a T installed in the R supply line. The OPs: empty the R tank to about half, switch supply to the left whilst transferring from the aux to the R. Works perfect lest you forget to switch off the transfer pump and valve…
 
Dan 57: what transfer pump are using for the fuselage Turtle tank?

I'm assuming 3/8" transfer line from the Turtle tank and typical 1/4" vent lines?
 
David, I’m using the transfer pump as provided by the Turtle tank. Since my tank sits on the pax seat, I had a long thought thinking gravity could be enough to xfer the fuel. Still, ordered the tank with the pump, and very happy with that decision since the transfers have been working without problems. Installed an additional power outlet (merit 10A type) on the panel.
The install is all 3/8, and the big plus of the Turtle is in not needing a vent :) Fill, try not to have any air left in the tank, install cap, and go fly :)
 
Do you happen to know the pressure and flow capabilities of the transfer pump from Turtle Pac? I'm trying to compare it to what I'll be using. Since you can't over-pressure the wing tanks, that's what I'm hoping to replicate.
 
I have outboard and inboard tanks, the engine only draws fuel from the inboards. At the low point of the outboards I have two fuel pickups, one is a direct -6 size line to the high point of the inboard, and the other is a -6 size line through a Facet low-pressure fuel pump to the high point of the inboard tank.

In operation, normally as I burn fuel from the inboards it will pull a slight vacuum, and fuel will automatically flow from the outboard to the inboard via the straight pipe. However - this requires that the inboard filler cap is airtight and does not leak - if it does, then no fuel will transfer and I lose access to all the fuel in the outboard tank. To fix that problem I put the second line in place with the pump to force it across if needed. When the inboard tank is full and the pump is still running, then the excess flows back into the outboard tank via the straight pipe -6 sized line, preventing an overpressure on the inboard tank.

My tanks vent from atmosphere into the high point of the outboard tank, via a rocket-style 45-degree vent fitting on the bottom of the wing, and then through the outboard tank into the inboard tank for flow-through venting. I cannot dump fuel overboard, or overpressure the inboard tank, by trying to overfill the inboard tank with this design. It's worked well for me for almost 1100 hours now.

Hey Airguy,

Apologies in rssurecting an old thread but do you have a build site for your 9? Or do you have a list of all parts for the installation and operation of your outbioard leading edge tanks? I'm building a 7 and I acknowledge the wing difference but am certainly not wanting to reinvent the wheel and in reading your posts it appears your very happy with how the mod turned out. Thanks
 
Send me your email address and I'll send you all the information Pat Tuckey shared about his ER tanks that Airguy, myself and others have utilized.
 
pressure and flow capabilities of the transfer pump from Turtle Pac?
just noticed your query now David... :eek:

AFAIK the Pump Kit comprises a Holley 12-927 pump, data in the chart. I have not timed the transfer times, but they were about 4 minutes to refill the 3/4 fuel burned from my right 18USG tank.

As I already mentioned somewhere, the only flaw is human performance affected ops, as in forgetting to switch the pump off, and being awaken by the strong smell of fuel, or letting the pump run dry and seize when operating with a closed shut-off valve :rolleyes:
 

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That's great thanks. If that pump didn't damage your tanks, then the little Facet ones I'm looking will be okay too.
 
just noticed your query now David... :eek:

AFAIK the Pump Kit comprises a Holley 12-927 pump, data in the chart. I have not timed the transfer times, but they were about 4 minutes to refill the 3/4 fuel burned from my right 18USG tank.

As I already mentioned somewhere, the only flaw is human performance affected ops, as in forgetting to switch the pump off, and being awaken by the strong smell of fuel, or letting the pump run dry and seize when operating with a closed shut-off valve :rolleyes:

I thought of I were to do a fuel transfer system, I might use a pressure switch that could detect when the pump runs dry, the pressure goes to zero and turns on a light.. something like this set to as light as it can be set..https://www.pegasusautoracing.com/productdetails.asp?RecID=2980

If there’s not enough pressure in the transfer line to set it off, possibly a restricted fitting could work in the line after the switch..
 
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