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Author Topic: Inboard Tanks  (Read 1347 times)
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bob werle
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« on: November 03, 2009, 07:35:10 PM »

I have never thought about this type of tank mounting till I built a profile All Americam Jr. and find a space problem between the motor and the wing. Do you need a special type of tank and is there any special way to mount it?
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blklion
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« Reply #1 on: November 04, 2009, 08:51:41 AM »

Not sure how much room you have but I have used wedge tanks with the pickup tube that comes out the top or bottom of the tank on some models and on others where there is little to no room for the tank I've placed them in the wing itself with the pickup tube coming out the leading edge. If you do that just make sure to glue a piece of ply across the backside of the leading edge where the pickup tube exits so it's reinforced.
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The Kiwi
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« Reply #2 on: June 06, 2010, 06:09:36 PM »

I think Hal deBolt was still using spark ignition and gasoline longer than other designers. With those, fuel mileage was greatly superior to glow and glow fuel, so small tanks were all that were required.

I've seen a great many successful inboard setups that used various Sullivan plastic clunk tanks on the inboard side of a profile model. You do have to take off "lean" to accommodate the additional fuel pressure from centripetal force.
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Kiwi

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gcb
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« Reply #3 on: August 26, 2012, 12:58:04 PM »

I think Hal deBolt was still using spark ignition and gasoline longer than other designers. With those, fuel mileage was greatly superior to glow and glow fuel, so small tanks were all that were required.
Diesels use less too.

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I've seen a great many successful inboard setups that used various Sullivan plastic clunk tanks on the inboard side of a profile model. You do have to take off "lean" to accommodate the additional fuel pressure from centripetal force.

Wonder if a Uniflow would help regulate pressure on an inboard installation? Although i have heard of inboard installations, I have never used one. They should be great on something like a Whipsaw that doesn't have much room.

Another possibility is to use a wedge tank that is wide but short. I would suggest checking the dimensions you need then check tanks on the Brodak site. You might find the Perfect (pun intended) one for your setup. (pun = Brodak bought out Perfect brand tanks).

Perhaps something like this 1 oz. tank:    http://brodak.com/wedge-fuel-tank-1-oz.html 


George
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NormF
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« Reply #4 on: August 26, 2012, 09:35:14 PM »

We've been putting clunk tanks on the inboard side of our FliteStreaks and it works very well. Like Kiwi says, set it on the lean side and it richens up in flight. A lot more room for the tank and plumbing.

Norm
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greggles47
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« Reply #5 on: September 05, 2012, 08:25:09 AM »

I might be worth trying a normal sized tank inboard, feeding a smaller tank outboard. Effectively making the smaller one a chicken hopper tank. This way you'll overcome the lean/rich problems of an outboard tank or a wider tank outboard with a wide feed.

Outboard tanks with the feed too wide will of course lean out in the air more or less depending on how wide the feed line is.

Greg
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TimWescott
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« Reply #6 on: September 05, 2012, 10:37:55 AM »

Hayes tanks work very well for CL models.  If your LHS doesn't have them, Brodaks does.  I haven't mounted one inboard, but the folks in the know say that it works better to have one inside than outside.  There's no need for a header tank.
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greggles47
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« Reply #7 on: September 06, 2012, 06:15:18 PM »

Tim,

I don't know the Hayes tank.

How is it different from a uniflow tank?

Is there any details of the construction that make it operate inboard without leaning out significantly in the air?

Regards

Greg
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TimWescott
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« Reply #8 on: September 06, 2012, 06:30:46 PM »

Hayes tanks work very well for CL models.  If your LHS doesn't have them, Brodaks does.  I haven't mounted one inboard, but the folks in the know say that it works better to have one inside than outside.  There's no need for a header tank.

I have mounted one outboard.  @#$%
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TimWescott
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« Reply #9 on: September 06, 2012, 06:39:53 PM »

Tim,

I don't know the Hayes tank.

How is it different from a uniflow tank?

It's a brand of clunk tank.  The construction is different from the DuBro or Sullivan tanks.  They just seem to work better for CL than DuBro or Sullivan.

They are not uniflow tanks, however.  They're just plain ol' tanks from that perspective.  (And, unlike DuBro or Sullivan, you don't have the flexibility of making them into uniflow tanks).

Is there any details of the construction that make it operate inboard without leaning out significantly in the air?

Maybe we have a terminology problem?  Inboard tanks are mounted on the line side of the airplane, where you can see them when you fly.  Outboard tanks are mounted on the tip weight side (usually the engine side) where they're hidden from the pilot by the fuselage.

Outboard tanks will tend to lean out in flight vs. on the ground, due to centrifugal action.  Inboard tanks actually richen up a bit on launch, as the centripetal acceleration tends to push fuel into the needle valve.

Any non-uniflow tank will tend to lean out as the fuel gets used up -- I guess I wasn't really paying attention to that, because I'm using motors (OS LA25 and FP20) that, when run with muffler pressure, are pretty insensitive to the effect.

There's no reason you couldn't use a uniflow tank on the inboard side -- the only issue is that you still need to have the pointy side outboard to feed fuel properly.  This means that you either need to carve a V-shaped notch in your fuselage or you need to mount the tank on bearers of some sort.  It also means that many pre-manufactured tanks are going to have the tubes coming out in all the wrong places.

With a uniflow you'd still have the "richen on launch" effect, but not the "lean out in flight".
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kiwibrit
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« Reply #10 on: November 04, 2012, 08:11:13 AM »

Hmm.  I make my own tin-plate uniflow tanks for combat-type wings (and have not found a wedge shape necessary in my tanks which have a low height to width ratio).  I've been using the wings to learn aeros.  I'm thinking of building something like a Miss BJ for an old Webra 40 as my first true stunt model - maybe with the tank inboard if I have reduce the nose moment.  Might use a wedge for that.  Must say I can't see that there would be any significant difference in centrifical force between inboard and outboard mounts on the lien lengths we use. 
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