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  #1  
Old 07-12-2021, 05:25 PM
FireMedic_2009 FireMedic_2009 is offline
 
Join Date: Nov 2016
Location: Tampa, FL
Posts: 235
Default Header tank for RV3

I have an RV3B which has the wing tanks. I do a fair amount of xcountry flying and would like to add a 10 gal header tank. I figure that wouldn't be a big deal since the early RV3's had a 25 gal header tank. One cubic foot = 7.5 gal so 10 gal = 1.33 cubic foot. (10"L x 10"W x 24"H or somewhere along those dimensions). I do have avionics behind the panel mounted on a tray takes up half the depth behind the panel but there is room extend the tank behind the tray with the avionics.

Any suggestions as to aluminum thickness and attachment points and/or anything I should consider. I figure attachment points on the bottom corners and 3 along each side of the vertical attached to the firewall and have a couple of internal ribs horizontally for strength. I can put a float at the top of the tank with a rod that floats up as the fuel gets to the top of the tank so I don't over fill spilling out.

Empty wt = 760 lbs
w\Wing tanks (30 gal) = 180 lbs
Gross wt as test by builder = 1200 lbs
That leaves 260 lbs - 60 lbs for header tank = 200 lb pilot
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  #2  
Old 07-12-2021, 05:36 PM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
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I'd copy the fuselage tank in the plans as much as possible for the size. It's on drawing 32 and the thumb drive is still $10 from Van's if you don't have one.

Dave
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  #3  
Old 07-12-2021, 05:42 PM
jrs14855 jrs14855 is offline
 
Join Date: Apr 2008
Location: Lake Havasu City AZ
Posts: 2,593
Default tank

.050 thickness is typical, Pitts uses 1100 aluminum I have used 5052.
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  #4  
Old 07-13-2021, 11:45 AM
David Paule David Paule is offline
 
Join Date: Dec 2009
Location: Boulder, CO
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The plans say, for the stock fuselage tank, use .050 3003-H14 for the ends, and .040 for the wrap-around part and the baffles.

I wonder if you can find a suitable tank at Spruce, Wick's or Wag-Aero?

Dave
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  #5  
Old 07-14-2021, 12:31 AM
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Lufthans Lufthans is offline
 
Join Date: Dec 2017
Location: Hilversum, The Netherlands
Posts: 169
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I run a custom car workshop and would be happy to fab a tank for you. Shipping costs may be prohibitive though as we're in Europe....
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Resurrecting an RV-3B
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  #6  
Old 07-17-2021, 11:49 PM
FireMedic_2009 FireMedic_2009 is offline
 
Join Date: Nov 2016
Location: Tampa, FL
Posts: 235
Default I was able to get a set of plans

I was able to get a set of plans. The plans have a lot to be desired. There are a fair amount of questions. For example, the fuel vent is in front of the tank and the fuel fill is towards the front as well. When the plane is being filled the rear of the tank is low. It appears to be when the plane is in level flight the rear of the tank is a little higher than the front of the tank. In level fight with the tank full, the fuel will be dumped overboard through the fuel vent so you definitely have to keep the fuel level a couple inches from the top.

I'm not sure how you seal off around the fuel fill without it being permanent since I would like to remove the upper skin to access the avionics, brakes, batteries, etc. I know to get to those items I would have to remove the fuel tank but I think is would be a lot easier and quicker doing that than doing it through the cockpit. I could use a 1/4" ring around the fuel fill so I can put 6 screws through the top skin around the fuel fill with a gasket to seal out the water.

I'll have to move my avionics closer and reorientate it to give some depth to the tank. I'm figuring it out little by little. I'm certainly going to have to modify it but it might be more planning/figuring it out than building it
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  #7  
Old 07-18-2021, 10:26 AM
David Paule David Paule is offline
 
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Location: Boulder, CO
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Quote:
Originally Posted by FireMedic_2009 View Post
I was able to get a set of plans. The plans have a lot to be desired. ....
Welcome to RV-3 building.

Had a thought that if your header tank were filled from the wing tanks by a transfer pump, they would not need an external filler port. It would still need its own vent, independent of the wing tanks.

The transfer pump could probably be a normal Facet pump. The header tank would have a return to the wing tank... you'd have to do a bit of thinking to make it all work with no surprises but I expect that it eventually would work fine, once you ironed out the details.

Dave
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  #8  
Old 07-18-2021, 10:49 AM
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Ironflight Ironflight is offline
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Join Date: Jan 2005
Location: Dayton, NV
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Just a suggestion - if what you want is additional fuel, consider alternative places to put it than a header tank. The Hotel Whiskey tanks that add fuel to the wings might be a model for you. In my old Grumman Yankee days, we added tubes in the lightening holes in the wing ribs to add considerable fuel. Wing or tip tanks would be a lot less invasive as a modification……

Paul
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