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fytrplt
 Post subject: Re: Aux Fuel Tank
PostPosted: Sat Oct 17, 2015 3:55 am 
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Tom,

Each wing with four of the five bays wet will hold sixteen gallons with virtually all of it usable if you plumb it right.
With the main full at twenty-nine gallons, you would have sixty-one gallons capacity. That is what Bill and I have. You are right that the wings are empty most of the time. A good sealing job won't leak with only occasional use. We never fill the wings up and usually only put five or ten on each side yielding three or four hours with a one hour reserve. These figures are for a fuel flow of ten gallons per hour.

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Bill Williams
 Post subject: Re: Aux Fuel Tank
PostPosted: Sat Oct 17, 2015 7:53 am 
I know it's a lot of extra effort to rebuild the tanks, but it's worth the extra time. You say that your time frame is 2.5 hours, well coming back from KD Sunday we went up on top (CAVU) at Huntsville and did not see the ground until Brooksville Florida. I have the original John Walton drawings for the tanks in your wings and can show you some pointers on rebuild. At least make two bays fuel, that will give you an extra 16 gallons.


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flyingfool
 Post subject: Re: Aux Fuel Tank
PostPosted: Sat Oct 17, 2015 11:09 am 
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Thanks guys.

I ultimately think you are right now that I know keeping the sea to "dry" for the majority of the time is not a leak concern.

If I go thru the work to set a single bay, may as well go all the way. If I going to mess with prose mess and pulls etc. it is only incrementally more effort. In for a penny, in for a dollar!

I'd love to have a copy of the drawings you used.

The only problem I see with the set up you and Bob have is if the full indicator signal on the main tank to shut off the aux pumps fails and overfills the main. But after all the hours and years experience hi guys have should be proof enough for me of the success.


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fytrplt
 Post subject: Re: Aux Fuel Tank
PostPosted: Sat Oct 17, 2015 2:58 pm 
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You will immediately know if the tank overfills because you will smell and feel it in the cockpit! Besides, we have a light system that lets you know when the pumps are running. If it comes on steady, you have exhausted the wings, which we keep a clock on, or the overfill shutoff has failed.

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leewwalton
 Post subject: Re: Aux Fuel Tank
PostPosted: Sat Oct 17, 2015 5:52 pm 
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I'll bring this up just to stir the pot. Bob and Bill have a very user/operator friendly system, that being said I like (as did my dad) leaving the main tank system alone and changing out the two way on-off valve for a three way on-main-wing selector. This eliminates pumps, floats, lights etc. Just take off on the main and cruise on the wings until empty then switch back to the main to finish it off.

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James Grahn
 Post subject: Re: Aux Fuel Tank
PostPosted: Sat Oct 17, 2015 8:21 pm 
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I don't know what engine you are planning, but 8gph is conservative. With 29 gallons in a standard main, you should easily get 3 hours plus a reserve. If you want more, put more. There are a few times I could use more. Not often.
Cubes


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leewwalton
 Post subject: Re: Aux Fuel Tank
PostPosted: Sun Oct 18, 2015 5:19 pm 
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Cubes makes a good point. With an 0-360 it makes sense to have additional fuel, with the new airplane I'm flying 3:15 legs. That's plenty for me.

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jrevens
 Post subject: Re: Aux Fuel Tank
PostPosted: Sun Oct 18, 2015 9:49 pm 
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Me too, Cubes & Lee. I can do a 3.5 hour leg with .5 hour reserve, but much prefer 2 to 3 hours. That's plenty for me between leg stretching & potty breaks. I have the standard 29 gal. tank, & average 180 mph at 7 gph or less with my 160 hp O-320. Of course, that's mostly at 7500 msl or better, making about 120 hp or less. If I was flying around sea level like a lot of guys, the fuel burn increases.

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dan
 Post subject: Re: Aux Fuel Tank
PostPosted: Mon Oct 19, 2015 7:17 am 
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7 GPH is what I did comming home from Utah John, Seems I always plan at 2- 2.5 hrs per leg and if it goes a bit over I am OK. MY Bladder seems to fill before my tank get down to the 10 gallons left mark. I am a cronic coffee drinker, and I slurp on water when I am at cruise in the cockpit so its my own fault. I keep one of those soak up relief rigs at hand for when my bladder reaches the overflow mark. Sitting at cruise 12,000ft, trim set, all is steady, take a few pics, slurp some water or tea and sit back and relax, terrible aint it...Dan


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flyingfool
 Post subject: Re: Aux Fuel Tank
PostPosted: Mon Oct 19, 2015 11:47 am 
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Well I plan on building a full S18. And I'm really leaning towards an O360.

Field elevation is about 850 MSL.

So I have to believe average fuel burn will be closer to 9 gph or slightly more??? That would put max range with VFR reserves at 2.5 hours.

I guess I'd rather have wet wings that I don't use very often. And when empty they are no hinderence other than the extra weight for the plumbing and the time it took to construct. Than to have a finished and flying plane wishing I had built the wet wings.


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fytrplt
 Post subject: Re: Aux Fuel Tank
PostPosted: Mon Oct 19, 2015 2:54 pm 
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I built an entire new set of wings after over 1,000 hrs of flying time so I would have more fuel. I haven't regretted it. My 180 burns 15-16 GPH during initial climb. Ten GPH is a good estimate for medium alt cruise. With internal fuel only, I'm looking for a place to land after 2+10.

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Tjarosak
 Post subject: Re: Aux Fuel Tank
PostPosted: Mon Dec 04, 2017 9:43 pm 
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fytrplt wrote:
You will immediately know if the tank overfills because you will smell and feel it in the cockpit! Besides, we have a light system that lets you know when the pumps are running. If it comes on steady, you have exhausted the wings, which we keep a clock on, or the overfill shutoff has failed.


I am interested in knowing how the lights are installer, what type fuel flow sensors you used and any additional information you can provide. I have wet wings that pump into the main, but I am afraid of running the pumps dry and burning them up. I was not the builder and I am a novas.


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SHIPCHIEF
 Post subject: Re: Aux Fuel Tank
PostPosted: Sun May 20, 2018 10:23 pm 
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I'm building a left wing outer panel. The spars and ribs are done, and I'm close to bending the skin and starting to fit it over the spars/ribs.
On the way home from Sedona to the Pacific Northwet, some extra fuel capacity came to mind again.
I am tired of Pro seal; I built the tanks for my RV-8 and repaired RV-4 tanks a few more times. :( I'm thinking welded T-18 tanks have some major 'up-sides'.
I could design a fuel cell:
http://atlinc.com/pdfs/dews.pdf (see "Wedge")
For the inner bay of the wing between the front and rear spar. Preliminary guesstimates = 6.75 gallons? This seems very crash-safe, and adds about an hour cruise time to an O-290 ship.
Bladder tanks behind the spar could have some up-sides too. The dihedral of the panel makes it easy to get the last of the fuel from the back inboard corner and easy to fill from the front outboard corner. easy to vent to the wing tip.
I was looking at the wing center section today trying to figure out how to run the fuel line into the cockpit.
Weight and balance come to mind; The Main Tank is forward of the CG, and the tank I have in mind is about equally aft of the CG. Properly used, landing CG during a long trip might not be so far aft?

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1albee
 Post subject: Re: Aux Fuel Tank
PostPosted: Mon May 21, 2018 4:31 am 
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I have 8 gal. per side wing tanks in a Lyle Trusty wing. When Bill Cordoza had the wing built they vented them to the tips. He was never able to stop them venting fuel overboard until they were about 1/2 empty. I have installed checks in the vents to stop the fuel from going overboard with some success. There is one elect. pump per side that moves the fuel into the main tank (without a valve) causing a separate issue, this allows fuel to find it's way back into the wing tanks (1 or 2 gal's) each side when the main tank is full. Next time I have A/C apart I am contemplating putting checks in this fuel transfer line to stop this issue. I am using Andair check valves that are about $100.00 each that seal or release with a 1/4 lb. of pressure.

Phil
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Jeff J
 Post subject: Re: Aux Fuel Tank
PostPosted: Mon May 21, 2018 8:04 am 
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Whenever I contemplate adding something or moving things around, I like to plug the numbers into a W&B spreadsheet and check all of the numbers. It is hard to know exact weights until the work is done but it is close enough to let a person know if it is feasible. There is at least one spreadsheet that has tables for multiple CG configurations on this site.

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