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Adding Auxiliary Fuel to your RV

Your RV Aux Fuel is Where & Gals? Select 1 or 2 Options (comment, attach photos)

  • Wing Tip Aux Fuel - Wet Fiberglass or Separate Badder/Tank

    Votes: 10 12.3%
  • Wing Fuel Between Front and Rear Spar

    Votes: 1 1.2%
  • Wing Fuel Leading Edge

    Votes: 13 16.0%
  • Cabin Fuel Tank Pax Seat, Bag Compartment (Perm or Temp)

    Votes: 13 16.0%
  • 0-10 Gal

    Votes: 12 14.8%
  • 10-20 Gal

    Votes: 12 14.8%
  • 20-30 Gal

    Votes: 9 11.1%
  • +30 Gal

    Votes: 7 8.6%
  • No Aux Fuel - Personal Bladder Overflow Light Always On

    Votes: 39 48.1%

  • Total voters
    81

gmcjetpilot

Well Known Member
Looking for suggestions, designs, recommendations of ways RV'ers added Auxiliary Fuel. Recent thread about longest range RV's, reminded me I would like to add some range / endurance, say 16 to 20 Gal (not extreme range). Over years I've seen the following (not an exhaustive list):

> Wing Tip - Aluminum tank inside Wing Tip or Wet fiberglass wing Tip
> Wing - Running Span Wise Aluminum Tube through Rib lighting Holes
> Tank (Race Car Safety Type) In Cabin - Passenger Seat or baggage compartment.

The goal is keep CG nominal and of course structurally sound and safe. I like the idea of something that can be added or even removable. Reading the recent thread many extreme range RV's used the leading edge for fuel. If anyone has some details, let us know. Bottom line if you are staying in CG and Gross Weight Limits you are limited to how much fuel you can add. The extreme range RV's were flown as much as over 30% published gross. I calculated assuming 1150 lb empty, 1800 lb gross, 35 Gal Max Aux Fuel: Solo (180 lb pilot) / No Bags / Full Wing Tanks.

If you add 120 lb passenger, 15 Gal Aux is Max. That is almost 2 hours more endurance, which is good for another 310 miles. Even a little AUX fuel is a good thing for serious cross country. RV-7 range is 765 to 935. Adding 15 Gal gives 1040 mile to 1260 mile range.
 
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I’m not flying yet, but I built outboard leading edge tanks (see “Tuckey tanks”) with about 13/side. Main purpose is tankering fuel (planning to run mogas when possible), not really long nonstop legs. I figure I’ll have enough to get anywhere in the southeast and back without having to buy gas.
 
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Although not quite the capacity you are looking for - I am installing the fuel bung kit in my tanks for the Hotel Whiskey Extended Range Tanks. In the -10 it gives 15 gallons (combination of tip tank and tube through ribs) of extra capacity. There are several destinations I'd like to make from the central US and it seems like the -10 is just an hour short, so this should be just what I need.

For more (pipe dream someday), I'd install a 40 gal ferry tank over the rear seats to make that hop over to the other side of the pond :D
 
Hi George
We already had a couple of thread on the subject...

Received my 25 USG (94 lt) TurtlePac Seat https://www.turtlepac.com/products/collapsible-jerry-can-fuel-tanks/ drum a couple of hours ago... pricey, but looks rugged and high quality. My new inflatable co-pilot should be quickly and easily installed/removed and doesn?t weigh a ton. Other advantage, no vent line required.

PS
Pity to be still grounded by CoVid...
 
Built 22 Gal Aux for PAX Seat

Designed and built a .090 thick aluminum tank last year for my flight to Idaho and back.

Did 1009 miles in 7 hours even on one of the legs. Still had 9 gal in main tanks. Gravity fed. Sump was formed by tilting the tank to fit the seat back. Used seat/shoulder harness to secure.

Used rubber hose, filter and valving to get fuel to the Vans fuel selector valve. Did use a section of clear tygon tubing to verify fuel flow just before it entered the Vans selector valve.

A friend saw what I was up too, volunteered to weld it up for me. Lucky Break!

He was an experienced marine fuel tank builder, his TIG welding skills are astounding. No leaks after one pass with his TIG torch.

Weight is around 30 lbs, tank holds 22-gal, with a 1/4 gal left in bottom when empty (no more flow). Used AN6 fittings for tubing.

Vent line was drilled to outside in the PAX side NACA inlet for cabin air. Small AN 90deg elbow fitting with opening towards the front for positive PSI.

I can take some photos of the tank after work tonight if that would help.

Mike
 
I added an additional bay on the outboards ends of my RV-9A tanks. It was a very difficult process as my tanks were QB :)(). Would have been a much easier job on a standard scratch build. I gained 3-3/4 gallons per side for another hour of flight. A lot of work for such a small gain, but I basically just wanted to extend the range and reserve a bit. Not a fan of wing tip tanks as it has a large weight arm and it adds complexity to the fuel system with feed lines and pumps.
 
I'm in the process of building tanks similar to the Tuckey Tanks, except I've kept the standard leading edge rib spacing. I've added some additional structure and done some analysis to justify this. I skipped one rib bay where the facet pump and filter will be, then used the next two as the ER tank. This gives about 8 gal per side, or 16 gal total. I figured any more than that would take up too much useful load.

This was has not been a trivial amount of work. Without looking at my logs, probably 50 hours per side and I haven't final riveted the tanks yet.

I need to do a real write up of this, but here are a couple pictures. Some of the parts are primed with AKZO, but I intend to strip them and apply an actual fuel tank primer to the ER tanks only. I figure that they will be empty a significant portion of the time and are more likely to corrode.

cLVunsxYQrEWOoCN97s3pFH1Gk2KrFsecPYBZepbhsdkQ5Z7EFatExN8TXiGAmj8CL0CganddtNUdac6V7Q7oV8clJrKTBZnaCeiHBD5aDwksQT7B17eVX7jVUmIuWaFKpqqM3geTNvmc6UIRP0Q_ECLYqmzaY5pHp0t2e5d3c1ZDGr-7Onn7TqCkLyoH90xcdI5gw2gV1fzAW5YNzIzZ40BGrRsCX_L2Zvicl9SDTPAuB79o_xeN0C6Wq9RjWGhl52fRHFlivUwqZRPcfDgHAppyg2QJdVy6E-NRHBa-J_QxWNkv5-ZWSIG2_sD4CEhC5NooMJxqy-TuEGldWhcSENKM86oyY9DIqpKUFkBPVvNNVUWDT7zRKupYrZGiIzEjUw16OR9XOBEyJG55sWEyBk_baX6xFhqo8XyjltTxYy6bTqV5G7d7dwrKaqFfXzamw5ZxFYHL4ue_LBtjyiYGjkkQQVdESSsvfrltp9xZjA2yxKTkE9z7j3o8cwKJwqqApUnxjdPf4En52YYK6rgamkqf9u-eg1vxzmcNI7rYNchthGnJbUUq5sz_ZMzNQo8rNPaFOOBLZB6mPfZmDA-ilKJ3CAzvtpReu0QOnaTb9sFpQ5sAGApk9F9wKmUUuc3NVohcXdRPPLd2HJD85TZk3kB-sVsTBY-ISKU0VbCrpMfRuAOPV_xTGD0t-QwlsmYmdez6j-YAhVhXM0ksIYNGTalls2EuusdhKjw7omq4YHbXA_prQrZSX4=w1000-h1763-no


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TbPtLRj9yhbEVR1B0YuyA3FIAGrBsAq9hlkf_713IBmZznGT6tyosOXaq6wAAkflgvq3ics4sOmi_AgJmhZw0YEDpzfdf3cJLMpviel6yhwy2tUY05CsBnedXXykj-AYtpF-dGaf31_UhSEXTEpF10lS5bNU2Fq7WecQugVsaVuqLCECpM9zhppP-psULjJi-RMsab4Sjk-sjF5OZ4VKgNBgDY3lP4Xw0TmwRkWM-IB1wwUhPjxTd1lF__dzFU25rHAGKVbFhumyXN7pSYBNmuD_YZ8J4RRUgeAIzghqMMDXpPTkKGzZpO2N5_4yufO1BWDzDd72ilTaGWRJZWsGiioyTMxEtbVISB1fVgDaC-TKLNku568jwbmTeLkJt--ujA91tuzwaUs0k9SpZ2XDrzOgcoeKRMzTTmijEmWB3MUNlW0JGjRhLxmOU9NiWmAA0hneHt0DbE48mNrQYsW-BF9q8meNrmBmTOL8B-Yjl7B_e3g7bLg_iAZkULLUSdaUUuFZG7PGWp8yh0yHxOTqggMhm8WC2VFQJH9R1fayXe-lg1OvFfak0Hkej0GlN_toD1E2hlNzOOTr52782uT_H8nDLEs0vKFsj_mAKpOlyC-KTLBHCcG8n3A-C15FTx2e_rnF2x-s-rmv65S1pSkiC1d1sjG7LSoaqcPYk0CWtjqy3JaaWuiOI3Z-hqVrjAHi8SiO7yxhElxWlmR5G6O7EYY1RIiAjKdsmyWRgUKk0bkz19QnNUIIpic=w423-h564-no
 
RV Extended Range

For the last leg of my world flight, I installed a 66g TurtlePac and 20g TurtlePac (reserve) bladder tank on the passenger seat pan. Additionally a custom 22g fiberglass/foam tank was mounted behind the pilot's seat. A 1/4" thick plywood partition was installed between seats to keep the TurtlePac tanks from encroaching in the pilot's space.

With 127 gallons total, the RV-9A has a range of 2750 nm with 20+ hours of endurance. Take-off roll is about 5,000 ft (at sea level) before the wing starts to fly. I was very careful to build up speed to 90 knots in ground effect before starting my climb. C.G. was slightly beyond aft limits, and the auto-pilot can be enabled once reaching cruise altitude. To minimize stress on the aircraft, the first 8 hours of a 17 hour flight were flown at 130 knots TAS.

open
 
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I've been thinking about this as well. Trying to decide whether or not to go QB wings with Hotel Whiskey tip tanks, or slow build with additional outboard tanks, or do nothing and rely on an in-cabin temporary solution only when needed (perhaps with pre-installed plumbing during the build?).

Hotel Whiskey seems like it might be an "easy" solution since many others seem to have gone that route and presumably support would be available from the vendor, etc., but adding additional outboard tanks during a slow build *seems* like it might be a "cleaner" solution, but I haven't been able to find much detailed documentation on this mod and am not am confident enough to tackle designing it myself from scratch.
 
I used 4" irrigation pipe, aluminum, in the leading edge. Carries 9.87 gal of fuel.
Plumbed the tanks together like a Cessna and fed the fuel into the vacant port on the Vans stock fuel selector. Real simple plumbing. Cost was about $200 for everything.
From Denver, it's nonstop to KOSH and one stop, Sun&Fun.
System has worked fine for 1000 hours.

Joel
 
I put 7 gallons plus behind the pax seat in my 6 using a smoke oil tank. Plumbed it into a transfer pump with built in check valve under baggage floor and into a main tank. Works fine. I burn some fuel out of the main to make room and start pumping. Turning on the transfer pump starts a timer on my EFIS.

That said, the stock 38 gallons exceeds my bladder range. I don't know about everybody else, but I gotta get out and walk around every few hours, too. Basically, all I really use the aux tank for is to tanker fuel from where it's cheap and bypass more expensive gas. Don't think I'd install one if I hadn't already. I just didn't want to be the one that made everyody stop early with their 42 gallon tanks. Running LOP at altitude, I'm good for about 175kt TAS so the stock fuel is actually way plenty.

Ed Holyoke
 
I used 4" irrigation pipe, aluminum, in the leading edge. Carries 9.87 gal of fuel. Plumbed the tanks together like a Cessna and fed the fuel into the vacant port on the Vans stock fuel selector. Real simple plumbing. Cost was about $200 for everything. From Denver, it's nonstop to KOSH and one stop, Sun&Fun. System has worked fine for 1000 hours. Joel
Joel questions:

> 9.87 Gal - Is that total for L and R sides?
> You plumb direct to valve, one or two tanks?
> What do you do for vents of Aux tank?
> How do you fill Aux Tank(s)?

The LE outboard of factory tank makes sense to store fuel, but the LE is held on with 3/32 rivets, so weight would have to be limited to 30 lbs (5 gal). I suppose you could oversize fasteners. Whisky Hotel Aviation tank is like that with a small header in the wing tip. They have vents in wing tip and use a 12v pump to transfer into the mains (after they are used partly).

The circle track fuel cell in the passenger or baggage seat could be done, but it takes cockpit / baggage area space. It is good for 16 Gal easy, up to 20-22 Gal. It also can be completely taken out (except for plumbing on AC side and quick disconnects).
 
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I?m not flying yet, but I built outboard leading edge tanks (see ?Tuckey tanks?) with about 13/side. Main purpose is tankering fuel (planning to run when possible), not really long nonstop legs. I figure I?ll have enough to get anywhere in the southeast and back without having to buy gas.
I googled and searched VAF Forums.. for Tuckey Tanks. I found a dead link to Patrick "Glider" Fuel Tank. Can you guide me to reference.
 
You could increase your takeoff weight for additional fuel, but keep the landing weight the same..............
 
I have been dreaming about adding extra fuel to my -9 and here is how I would do it, when I'm ready to mess up my paint.

1. Start with an Andair five way valve: L-Outboard, L-Inboard, Off, R-Inboard, R-Outboard. Simple and easy to operate with no electric pumps to fail.

2. On the Z-brackets that support the inboard tanks, drill a hole and run a fuel line through them with connectors on both ends so the tank can be remove independently, if needed.

3. There is about a 6" gap between the outboard most rib on the standard tank and the first rib of the leading edge. Make a six inch wide "cuff" that goes from the top of the leading edge spar all the way to the bottom of leading edge spars. Plate nuts and screws around the periphery of the spars and inboard and outboard tanks. By removing this cuff, you will have a lot of access between the two tanks to do any maintenance you may need.

4. Build a new outboard leading edge (I would be happy with two bays a side.) and secure them with Z brackets and platenuts. If a Z bracket falls in a lightening hole, I would cover the hole so the plate has a place to be secured to. The extra tank would be plumbed to the tube I inserted through the Z brackets in step 2, above.
If you go with the irrigation pipe idea, I would still go with the full leading edge cuff so you can access the fittings and do any maintenance you may need.

5. I would do a coil vent like the HR's use and stick the vent down through the bottom of the wing, on the outboard section. That way the tanks are vented separately and fed separately via the Andair valve.

Good luck and let us know what you do.

(I'm happy with the 36 gallons in the standard -9 tanks but there are times when I wish I had a couple of hours more endurance.)
 
100 US Gal total at this speed & burn...
165Kts @ FF 10 GPH w/ 91 Gal Remain. That is nice. 165kts x 8 = 1320 nm Approx range with 1 hour reserve (my personal rule). Not including distance already traveled.

Paddy tell us about your tank. Did you make it yourself? If so some details, materials, constructions, plumbing. Thank you.
 
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I installed a 10Gal tank from SummitRacing in the rear baggage area of my RV-8. It feeds the engine via a 3-way-fuel-valve. Easy removable, just two bolts and the connectors on the aft baggage bulkhead. The tank is fully certified with all the G and crashloads as per JAR/FAR 23.
It takes up most of the baggage area which is bad, but I was not allowed to put additional fuel in the wings.

JYdy9fE.jpg
 
120 Gallons in RV10

RV-10 N16YS (Bought not Built) came with 120 Gal capacity. Builder John Nys says he was surprised to see how well the same stock 30 gal tank fit into the outboard section of the "slow build" wings. Says he assist/built several this way. The outboard tanks gravity feed to the inboard due to Dihedral so only the inboard tanks need sending units. We keep locking caps on the inboard tanks and only add additional fuel to outboard tanks as needed. And NO the gravity feed line is too small for the fuel to run quickly back to the outboard tanks in a normal steep bank or 2 minute turn. But Majority of the time we fly with only approximately 60 to 70 gallons total so as not to place undue stress on the wings if there is an early landing. One time we did fuel all the way to top off and the inner fuel caps seeped enough to leave minor blue stain the tops of both wings. With that much tankage and burning 11 GPH the fuel capacity is 3 times the Bladder capacity. It is very rare to need more than 70 Gals between comfort stops.
 
... And NO the gravity feed line is too small for the fuel to run quickly back to the outboard tanks in a normal steep bank or 2 minute turn. But Majority of the time we fly with only approximately 60 to 70 gallons total so as not to place undue stress on the wings if there is an early landing. ...

In a coordinated turn, the fuel is pushed down, as if the plane was sitting level on the ground and won't try to back-feed to the outboard tanks.

Also, while in the air, the weight in the wings is supported by the air. However, the taxi and landing loads would be a major concern.
 
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RV-10 N16YS (Bought not Built) came with 120 Gal capacity. Builder John Nys says he was surprised to see how well the same stock 30 gal tank fit into the outboard section of the "slow build" wings. Says he assist/built several this way. The outboard tanks gravity feed to the inboard due to Dihedral so only the inboard tanks need sending units. We keep locking caps on the inboard tanks and only add additional fuel to outboard tanks as needed. And NO the gravity feed line is too small for the fuel to run quickly back to the outboard tanks in a normal steep bank or 2 minute turn. But Majority of the time we fly with only approximately 60 to 70 gallons total so as not to place undue stress on the wings if there is an early landing. One time we did fuel all the way to top off and the inner fuel caps seeped enough to leave minor blue stain the tops of both wings. With that much tankage and burning 11 GPH the fuel capacity is 3 times the Bladder capacity. It is very rare to need more than 70 Gals between comfort stops.

Without a checkvalve, fuel level will equalize between inner and outer tanks.

This may make spin recovery impossible with weight on the wing tip.
 
I have Whiskey Hotel tanks in my RV-8 and generally leave them empty for local flying but they are very nice for cross-countries. The extra 9.5 gallons makes flight planning and weather contingencies easier.

Jim
 
I made each wing tip a 9.5 gal tank. The result is 60 gals of fuel in an RV-7A, making 6.5 Hr legs possible...
 
Rv6A auxiliary fuel tank install

I added an automotive type aluminum racing tank behind the seats (in the baggage area). I?ll do a full post of the installation but the gist of it is as follows...
17 gallon tank, aluminum, sourced on amazon, but had to ship it to Arizona because California...
Vertical orientation to keep CG as good as I can. (Tank is 17? tall almost as wide as the baggage, and only about 6? from front to back) with full fuel 55gal, myself 165lbs, and a 200lb pax, and minimal baggage I am near the aft limit, but still within. At 235lbs for a pax I am at the limit.
Custom welded tabs for mounting.
Custom welded outlet bung, on the bottom for gravity feed. (2oz unusable fuel)
Special ordered a 3 position fuel valve from Andair, no John Denver style valves here. Aluminum hardline to the fuel valve.
Vent line plumbed to belly in-line with flap trailing edge.
Can be installed/removed in about an hour.
Swapped fuel sender for a Hull effect type, seemed like a better choice.

Gets me anywhere I need to go. Mainly deep into Mexico.
 
RV10 Aux Tank

Paddy tell us about your tank. Did you make it yourself? If so some details, materials, constructions, plumbing. Thank you.

I designed the tank and sent it to a welder to fabricate. It's made of 1/8" 5052 and has 2 internal baffles, a float sender unit and a small sump for the gravity feed. The plumbing consists of a finger strainer in the sump, an in-line filter and AN-6 supply hose. The hose has a JiffyTite quick disconnect to a fitting on the side of the tunnel just ahead of the rear seat bulkhead. Inside the tunnel, there's a hard line to the 3rd port on the Vans brass fuel valve.

The tank is secured in the front with extruded hinge riveted to the forward edge of the seat pan. The rear uses the existing hinge for the rear seatbacks as well as AN-4 bolts to the rear seatbelt anchors. The breather is a hard line that connects via AN fittings at the top of the tank and on the side of the tunnel. There's an elbow from the side of the tunnel to the inboard side and down through the floor to the vent stub on the belly.

The tank can be removed or installed solo in about half an hour. When I made my transatlantic trip, I brought the rear seats with me in the baggage compartment and installed them in Ireland so I could take my family up.

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