Gas tanks: How much fuel and where?

[JoseSantos]

Hello community:
I want to be able to use mogas on my plane. I plan to use a UL 520 iST engine. LOTS of questions...

I understand mogas with ethanol will cause delamination on the tanks if they're not properly sealed. What's the recommended ethanol resistant sealant?
The UL 520 iST is turbocharged, I assume less tolerant to leaning. Therefore I would like to have 52-54 gals fuel. There are several options:
I have the header tank (10 gal). I have the outboard wing tanks (15 gals ea). I've seen 360's that have the middle wing section used as a 17 gal tank per side.
I can open and seal that middle section, good for 34 gals, and use the outboard tanks as 5 gals/side. I am also installing the extended wing tips.
And to top the confusion, I've read that sometimes the whole leading edge can/has been used as a gas tank.

Not wanting to reinvent the wheel, taking all advise seriously, hoping some Forum members have more info of what I could find (very little actually).

Jose Santos

[Ryan Riley]

Jose, that sounds like a big project. I've heard good things about the UL engines, but it'll be a one-off for your LNC2. You are correct about the 360s having 17 gal per side. Hopefully someone else knows about stuffing more fuel into the plane. Be advised, even with the 60 lb weight saving the UL provides, if you go over the 17 gal/side, you'll be eating into your useful load.

Also, do you know if the engine will fit the stock cowling with the mounting position farther forward than the Lycoming mount? I assume you'll need to move it forward for CG?

Keep us posted on your project!

[JoseSantos]

Hello;
There is a LN 360 at my airport (KAEG) that has the 17 gal/side inner wing tanks. I built mine with the 15 gal/side outer section. I'm thinking that the 17 gal/side will add 2 gal/side with the possibility of having space to add another 5 gals on the outer sections as the mission requires. However, I want to have all the info about the ethanol resistant tank sealant before reinventing the wheel and opening up my wings. Will try to post pics.

If my recall doesn't fail me I read some time ago one of our Aeronautical Engineer forum members did some calculations of the UL 520 iST on a LN... numbers were somewhere in the vicinity of 250 kts at 15,000 ft. That is what made me give the UL 520 serious consideration. The downside is the mandatory O2 tank and the estimated 10 gal/hr fuel burn.

[Tom McNerney]

Old thread but I wanted to clarify wing fuel tank capacity.

Built per the plans there are two position for the fuel cap. Either inboard of the aileron bellcrank bay which yields 15 or maybe 17 gallons, or outboard of the aileron bellcrank bay near the wingtip bulkhead which yields 20 or 21 total wing capacity.

If you were to want more in the wings, I know of at least one airplane that had a wet leading edge but that requires some clever spar work and fuel cap placement. You'll gain a lot but the cap / vents need to work properly at the upper end of the tank. Also, that becomes one heavy wing..

One a side note, 250 kts at 15k in a 360 airframe is optimistic for a lot of reasons.

[Chris Zavatson]

One a side note, 250 kts at 15k in a 360 airframe is optimistic for a lot of reasons.

For sure. That is right at twice the horse power needed compared to a stock 360 doing 200 kts at the same altitude.


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[SHANE O'DAY]

It is a misconception that mogas contains ethanol, Mogas from the airport actualy does not, nor does any fuel labeled ethanol free at your local automobile gas station. Getting the right octane for your engine is a whole other consideration, you can get auto fuel in much lower octanes which may or may not be acceptable for your engine.

[Steve Cantarutti]

More fuel is possible. My 360 has 69 gal capacity; 9 header and 30 per wing. With full fuel and an otherwise empty plane, I would need to lose alot of weight to remain within gross.