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  #1  
Old 05-02-2011, 10:15 AM
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Brantel Brantel is online now
 
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Default Tip: Put more vent holes in the high part of the tank ribs!!!

Tip for all those building their own fuel tanks.

Put a good sized vent hole at the top of each internal rib of the tank at the high point. (Think of how your wing will be sitting when your on the ground getting fuel, this point will be different on the TD vs the Tri-Gear)

Otherwise you will spend many minutes/hours over the life of your plane waiting on the air to work its way out of the tanks so you can fill them all the way up...
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  #2  
Old 05-02-2011, 10:42 AM
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I second that. Especially on taildraggers. Having just converted the 9A to a 9, it clearly takes longer to get the air out.

greg
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  #3  
Old 05-02-2011, 10:53 AM
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Yes indeed.....wish I'd have thought of it when I had the tanks open.
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  #4  
Old 05-02-2011, 11:09 AM
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I hadn't really thought about a fix to the "slow fueling" issue (probably because I didn't build my tanks), but it sure would be nice to come up to a solution to this little "nuisance". I almost always pump my own fuel, even when the fuel station is full serve - just so I know I am getting the tanks full.

Paul
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  #5  
Old 05-02-2011, 11:23 AM
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Kahuna Kahuna is offline
 
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Default

FWIW,
Having had the slow filling tanks on various RV's, I put in larger holes at the lower and upper sections of the rib for fuel and air flow in my last set.
You cant find a fuel nozzle that flows faster than my tanks can fill now.
This is of particular concern cause I often have folks filling my plane when Im not present and I more often than not used to not get filled up. Could leave as much as 5gallons a side of air when I checked a top off. Not good.
That problem solved with holes at the bottom and top for flow.
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  #6  
Old 05-02-2011, 11:27 AM
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I agree. Those with stock tanks need to always verify the "topoff" provided by the line guy. They almost always never get em full unless I warn them about it. Either that or they dump a ton of fuel out on the wing and ground by pumping too fast!

Sure wish I had known about this issue when I was elbow deep in pro-seal!
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  #7  
Old 05-02-2011, 11:32 AM
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704CH 704CH is offline
 
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Default Maybe Van's fixed on recent kits?

So I saw this thread and of course had to go back and check my tank construction from about a year ago.. I was really kicking myself for not thinking about this during my build.. But it looks like there is a hole already in the stock ribs for this purpose? In the pics from the pointer below you can see that besides the vent line hole there is another 1/4 inch or so hole at what would be the top of the tank rib.

At least there is something there, but I suppose another hole, or larger hole would help speed things up..

http://www.704ch.com/2009/12/left-ta...d-as-they.html
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Last edited by 704CH : 05-02-2011 at 11:42 AM. Reason: Clarification..
  #8  
Old 05-02-2011, 11:43 AM
Pilottonny Pilottonny is offline
 
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Red face Fuel moves to the outside quick!

I did the same (larger holes at top and bottom of the ribs). No problem fueling, but there is a reason for those baffles (with smallish holes)! I do see the fuel level in one tank reduce a lot, due to it moving outward quickly, when not flying coordinated. That made me wonder what happens on a long slip. Will all the fuel move to the outside bays, leaving nothing for the engine to sip from?

So now, when I need to slip to loose altitude, I do it in the direction so that the fuel in the active tank does not move away to the outside bays.

Regards, Tonny.
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  #9  
Old 05-02-2011, 11:51 AM
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Mine had those holes as well. They are not big enough to do the job. They eventually vent the air....if you wait. Something most line guys won't do.
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Check out my RV-10 builder's BLOG
RV-10, #41942, N?????, Project Sold
---------------------------------------------------------------------
RV-7/TU, #72823, N159SB
Lyc. O-360 carbed, HARTZELL BA CS Prop, Dual P-MAGs, Dual Garmin G3X Touch
Track N159SB (KK4LIF)
Like EAA Chapter 1494 on Facebook
  #10  
Old 05-02-2011, 11:56 AM
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Greg Arehart Greg Arehart is offline
 
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I suppose the fix to the fuel sloshing at low levels in uncoordinated flight would be to put a little flapper door made from a couple pieces of scrap Al hinge material on the inside of the hole - basically a one-way valve that would let fuel in (toward the pickup) when fueling but keep it from going the other way too fast if you are slipping or otherwise uncoordinated.

And I see no reason why one couldn't enlarge the hole in the top (or add another), unless there is a structural issue.

cheers,
greg
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Last edited by Greg Arehart : 05-02-2011 at 12:02 PM.
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