Turtle Buddy Ferry Fuel Bladder

[Peter M]

Hi there

I've decided to tick off one of the entries on my bucket list later this year and fly from New Zealand to Australia (via Norfolk and Lord Howe Islands). My RV-6 (with 180Hp Mattituck O-360) has sufficient endurance with a brisk tail wind or no wind to fly the three sectors that range from 320 - 485nm. However, there's not enough safe endurance for my liking particularly if I strike head winds that prove stronger than forecast.

For flight planning purposes I use 35 litres/hr; my actual usage over the life of the aircraft is 31 litres/hour; I can get it down to 28 litres/hr when cruising at 6000 - 8000'. To provide me with an additional hour of fuel I plan to install a 40 litre Little Buddy portable fuel bladder from Turtlepac (see http://www.turtlepac.com/en/products...l-bladder.html). My plan is this:

The Little Buddy will be strapped to the passenger seat. It's designed to take up the shape of the seat with the fuel outlet positioned at the lowest point where the seat cushion meets the backrest.

The fuel hose will be connected to the centre mounted fuel selector via a fuel tap and drip-less fuel connector. This will allow me to remove the Little Buddy for re-fueling and when not in use.

My fuel selector has Off, Left, Right and an empty position at 6 o'clock. The empty position appears to be serviced by a port that's not connected. The Little Buddy will be connected to that. I presume the fuel selector was Vans supplied (I didn't build my aircraft).

I don't see the need for a fuel pump. As the seat is higher than the main tanks I believe fuel will be gravity fed and the engine pump and auxiliary electric fuel pump will be able to source fuel from the Little Buddy.

Takeoff and landing will be performed using a main tank. The Little Buddy will be used in cruise and when there's sufficient height to completely drain the bladder and let the engine stop.

How does this plan sound? Has anyone had experience with a similar fuel arrangement? Please let me know if I haven't thought of anything as I appreciate any advice on this important consideration for my trip.

[rv7boy]

My only comment is make sufficient runs over dry ground to make sure it (and you) work properly before heading out over the water with it. I'm remembering Lindbergh had the luxury of a trip across the USA to sort things out before he headed off to Paris. Of course you don't have as many valves as he did!

Good luck!

[Captain Avgas]

Originally Posted by Peter M

I don't see the need for a fuel pump. As the seat is higher than the main tanks I believe fuel will be gravity fed and the engine pump and auxiliary electric fuel pump will be able to source fuel from the Little Buddy.

I don't think that the fuel from the ferry tank will be gravity fed (at least not all of it) but I don't think that really matters. The engine driven fuel pump can suck fuel up from the fuel tanks so it will be able to do the same from the ferry tank.

I believe it is standard practice in the certificated world that the ferry tank fuel is pumped into an aircraft tank (hence the little 12 volt fuel pump). That is the safest option but of course it requires special plumbing. Pumping it into an aircraft tank means you can use all of the fuel in the ferry tank without having your engine quit. I think you might find that Turtle Pac will advise you strongly to pump the fuel to an aircraft tank rather than just source it to the fuel selector. I recommend you ring them and talk to them about the pros and cons of both options. It's an interesting topic so if you speak with Turtle Pak you might like to report back to this thread on what they say so that others may be better informed also.

However if you opt to pipe it straight to the selector you will not be the first in the Experimental category to do so. But in that case you would certainly want to test it out a couple of times over dry land as Don Hull has recommended before you ventured out into the Tasman.

If there wasn't a massive difference in price, I think I might also be tempted to go for the Turtle Pac Big Buddy (2 hours fuel) rather than the Little Buddy (1 hour fuel). In a tight spot it might be better to have a big buddie rather than a little buddie.

There's a whole lot of water out there in the Tasman Sea and lots of things can go wrong including erroneous weather forecasting. You may remember the Pel-Air Westwind ditching with 6 on board that occurred off Norfolk Island in 2009 when they couldn't land due to bad weather. Extra fuel gives you more options.

I've done numerous over water crossings in light singles (but not as big a pond as the Tasman). I swear that as soon as I get to the point where I can no longer see land behind me or in front of me the engine always sounds like it's running rougher.

[bkthomps]

turtle buddy = $1800-2000

ATL Fuel Cell = $300

I never understood the increased price justification so i got the ATL fuel cell

[Peter M]

Bob

Thanks for your thoughts.

Yes - TurtlePac warn that the engine should not be fed direct from the Little Buddy but I don't really understand why. They claim there is a risk to the engine fuel pump if the bladder is exhausted. Neither I nor my engineer can understand why. Perhaps its because there is no air in the bladder and it's designed to collapse as fuel is drawn. When all fuel is exhausted I guess the pump could begin to try and suck a void. However my engineer tells me that my fuel pump is a conventional "click/clack" style which is not likely to be damaged by such an event.

My preference is to avoid any modification to the existing fuel lines and to keep the installation tidy. Installing a pump and running lines through the vent or fuselage side to top-up a main tank is not preferred if it can be avoided.

I'd really like to hear from someone who has drawn directly from a ferry tank in the manner I've suggested and what their experience of that was.

I had considered the Big Buddy but I'm worried that it may interfere with the control stick movement.

Thanks for your interest in my plans

[rmartingt]

Another option to look at would be the Hotel Whiskey tanks that fit in the lightening holes in the wings; I think they cost about the same as your turtle buddy. I believe they hold about 4.5gal per side, so a total of about 34L. And you can leave them in and not have to take up a passenger seat. That's probably what I would go with if I were retrofitting instead of building extra fuel in from the start.

[Captain Avgas]

Originally Posted by rmartingt

Another option to look at would be the Hotel Whiskey tanks that fit in the lightening holes in the wings; I think they cost about the same as your turtle buddy. I believe they hold about 4.5gal per side, so a total of about 34L. And you can leave them in and not have to take up a passenger seat. That's probably what I would go with if I were retrofitting instead of building extra fuel in from the start.

The OP says in his orginal post that he did not build his RV6 so I'm guessing that he is reluctant to want to embark on build modifications.

[Mark Albery]

I had considered a similar set up when I flew US to UK, but ended up using a polyethylene motor racing tank from Summit Racing. There are lots of sizes and shapes to choose from.

Apart from the cost saving, I didn't like the idea of feeding straight from a bladder to the fuel valve and pump. The normal method with a bladder tank is to transfer to a depleted fuel tank.

You do have to consider venting with a rigid tank, but that's not too difficult.

That spare port in the Van's fuel valve proved very useful. You just need to mark the tank pointer with an 'aux' position.

If you use it in cruise you can run the tank dry and don't really need a quantity gauge.

[Vlad]

Originally Posted by Mark Albery

I had considered a similar set up when I flew US to UK, but ended up using a polyethylene motor racing tank from Summit Racing. There are lots of sizes and shapes to choose from.



....

Can you expand on this Mark?

[Captain Avgas]

Originally Posted by Peter M

Bob

I'd really like to hear from someone who has drawn directly from a ferry tank in the manner I've suggested and what their experience of that was.

I believe that Jon Johanson ferried an RV6 from the US back to Australia with a collapsible ferry tank in the right seat. He simply piped it to the vacant port of a standard Vans fuel selector.

He can be contacted at: http://www.flymore.com.au/about.html

Or email him at: info@flymore.com.au

But bear in mind that sometimes you have to wait a bit for a reply.

As for using the Big Buddie, maybe it would fit if you disconnected the passenger joystick. It is removable.

Interesting comment from Turtlepac about concerns with the standard mechanical fuel pump sucking on a vacuum. Of course one has to be extra cautious with any modifications to a proven fuel supply system. Fuel systems are not an area that lend themselves to "intuitive" changes. You are wise to be researching this before proceeding.