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Fuel Tank - larger

I know of a modification where a removable, flat, 5 gallon poly tank is placed in the baggage compartment and connected to the filler neck of the main tank via a pump powered from the 12V accessory port. Those with that mod might choose to provide pics and discussion.
 
fuel tank

I have a 20 litre ( 4 gallon ) flexible bladder that sits on the main fuel tank and is connected via an outboard fuel tank connection to the main tank
when I have used 20 litres from the main tank I reach over an open the valve and let the fuel drain into the main tank the bladder is removable and easy to carry so I also use it to transport fuel to the plane
 
if you search auxillary tanks there is a thread on poly tanks used in race cars. lots of sizes , more or less square and i believe they are ''spun''. also most are around $200 for 20 gallons. i think i saw a 24 gallon too.
 
crashley said:
I have a 20 litre ( 4 gallon ) flexible bladder that sits on the main fuel tank and is connected via an outboard fuel tank connection to the main tank
when I have used 20 litres from the main tank I reach over an open the valve and let the fuel drain into the main tank the bladder is removable and easy to carry so I also use it to transport fuel to the plane
Click to expand...

What bladder are you using for this purpose? I looked at a sturdy one from Australia but that was so expensive that I had a sticker shock and dropped the idea.
Still would like to get a bladder for refueling auto gas while on a cross country though.
 
in the race car fuel tanks i referred to in an earlier some have foam which i suppose is to prevent splashing if tank is ruptured. wouldn't this act as a baffle?
 
crashley said:
They modified it by putting in a drain plug which I connect to the main fuel tank via a flexible fuel line
Click to expand...

Ashley, how do you secure the bladder in the aircraft, and what does the fuel drain system look like? I had already planned on getting one or two of these bladders to transport fuel on the ground when travelling, but I'm not so sure about plumbing one directly into the tank. How well does it drain without opening a relief air vent?
 
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Van's larger tank?

I can appreciate the difficulty in designing a fuel tank that will always have the fuel 'outlet' covered - ie, no interruption in fuel flow to the engine no matter what the sustained bank angle, dive or climb of the airplane is.

And I appreciate that anyone or company which produces a larger RV-12 fuel tank for sale may be asking for litigation if an airplane using their tank augers in BUT, really, how difficult would it be to design a larger - say 25 gallons total - fuel tank for the 12? Or is it really rocket science??? I'm asking for an additional five gallons - ie, a LARGER tank from Van's. That would be a tank that is about 2' longer.
 
Other things to consider!

E. D. Eliot said:
say 25 gallons total - fuel tank for the 12? Or is it really rocket science??? I'm asking for an additional five gallons - ie, a LARGER tank from Van's. That would be a tank that is about 2' longer.
Click to expand...


No matter how big you make it, someone will want "just 5 more gallons".
You want 5 more gallons. The next guy will want 5 MORE gallons. Where should Van's draw the line?
Each 5 gallons adds 30 more lbs. to the baggage compartment.
25% more fuel coming forward in a crash.
 
Gotta agree, Mel

Yep, 'just five more gallons' can be a never ending plea - on the other hand, a twenty five gallon tank would give me a conservative 3 1/2 hours of flight with my reserve requirement of at least one hour reserve fuel. There are also the W&B and aircraft performance issues as weight increases. So, there is a point where it becomes impractical to add 'just five more gallons' - I am sure that Van's engineers gave a lot of thought to this issue during the engineering phases of the design. I hope that there is room inside of the RV-12 design parameters for 'just five more gallons'... Maybe not - that is why I am hoping that Van's will produce a 25 gallon fuel tank if it is safe and practical to do so. I certainly am not qualified to design and install such a tank!

I would never argue with any of my peers but as far as the amount of fuel in the tank, if you auger it in, it won't matter how much fuel there is in the tank. And if you flip it upon crashing somewhere, you may end up with the tank and/or its contents somewhere near the panel - full of gas or not - possibly the same result, unless it just wasn't you day to die. I accepted the possibility of this scenario when I ordered the RV-12 kit.
 
i too would like the option of 25 gallons. doesn't mean i always want to fill it up, i may want the full baggage load but i would have the option. as i am not planning to use a rotex i have been thinking about alternative tanks. i also think it would be very do able to safely secure a poly tank with straps that have a little give rather than rigidly mounting a sheet metal alum. tank.
i have a few years to think about this.
 
Mel said:
No matter how big you make it, someone will want "just 5 more gallons".
You want 5 more gallons. The next guy will want 5 MORE gallons. Where should Van's draw the line?
Each 5 gallons adds 30 more lbs. to the baggage compartment.
25% more fuel coming forward in a crash.
Click to expand...

Mel...I'm with you on the volume issue. But 25% additional fuel coming forward in a crash. Me thinks "any" fuel coming forward in a crash would be sufficient for the bbq! Might as well have a big bbq as a little one!

For thoughts that want a couple more hundred miles occasionally.....get a Big Buddy (18 gal bladder) that has a transfer pump.
 
Gimme five, minutes, more,
just
five minutes more.....

I love that song.

OK, you young bucks don't know what I'm talking about....

neither does my wife.....

Gimme 10 gallons more, just 10 gallons more....

then, I could do KCLM to PAKT:


From: CLM -- Port Angeles WA (William R Fairchild Intl)
To: PAKT -- Ketchikan AK
Alt.: 8,500 ft. Profile: N737G
Time: Fri Nov 15 03:32 (UTC)

No-wind option selected.
Routing options selected: Direct.
Flight plan route:
Direct
Flight totals: fuel: 24 gallons, time: 5:14, distance 529.8 nm.

Ident Type/Morse Code | | Fuel
Name or Fix/radial/dist | | Time
Latitude Longitude Alt. | Route Mag KTS Fuel | Dist
---+--------+---------+-----| Winds Crs TAS Time |------
1. CLM Apt. | Temp Hdg GS Dist | 0.0
Port Angeles WA (Willia |--------+----+---+------| 0:00
48:07.2 123:30.0 3 | Direct 23.7 | 530
---+--------+---------+-----| N/A 306 101 5:14 |------
2. PAKT Apt. | +0 C 306 101 530 | 23.7
Ketchikan AK |--------+----+---+------| 5:14
55:21.2 131:42.7 1 | | 0
---+--------+---------+-----| |------

NOTE: fuel calculations do not include required reserves.
Flight totals: fuel: 24 gallons, time: 5:14, distance 529.8 nm.
Average groundspeed 101 knots.

Bob Bogash
N737G
 
Just one factor.

Phantom30 said:
Mel...I'm with you on the volume issue. But 25% additional fuel coming forward in a crash. Me thinks "any" fuel coming forward in a crash would be sufficient for the bbq! Might as well have a big bbq as a little one!
Click to expand...

I wasn't using that factor as the determining factor. Just one more factor.
They all add up, even the minor ones.
 
fuel bladder

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]I use a couple of webbing straps with clips the bladder is normally flat but when full it looks like a pillow It takes about 15 minutes for the fuel to flow into the main tank It doesn't need to be vented as it just uses the vent in the main tank fuel tank when the fuel has flowed into the tank the bladder just lies flat onto of the main tank
 
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Thanks Ashley. It's a simple setup and obviously works well but I'm just a bit wary of transferring fuel in the cabin in flight. I know it's common practice to rig extra tanks and transfer fuel for ferry flights etc, but for now I think I'll probably just use the bladders for re-fuelling on the ground. The bladders are a great idea and don't take up much room when folded up.
 
fuel range

The main reason I use the fuel bladder is it is getting hard to get fuel at a lot of airports here and only one two have mogas so using the bladder saves me putting avgas in
 
Same problem in WA too - small towns and large distances. Very few airports out here would have mogas either, and those bladders will come in handy, plumbed in or not. Thanks for posting the photos, Ashley.

Rich, I think you may be right. Endurance will be limited by the other bladder, not the one with the fuel in it.
 
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