WingsOnWheels

WingsOnWheels

Well Known Member
Can someone please provide me with the length (span) of the -8 tank skin or rear baffle. I'm working on my RV-6 wings at the moment and am considering a modification to use the -8 tanks to increase my fuel capacity. From what I understand, the airfoil is the same, but the -8 has a longer tank.

I'd like to reduce the length of the outboard section of the leading edge and put the longer tank in. Just looking at some basic dimensions at this point to see if this may be do-able.

Thanks,
 
Some differences

WingsOnWheels said:
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I'm working on my RV-6 wings at the moment and am considering a modification to use the -8 tanks to increase my fuel capacity. From what I understand, the airfoil is the same, but the -8 has a longer tank.
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I don't have the length at hand, but you may want to consider that the tank attachment at the spar is somewhat different on the -6 as on the -7. The -7 uses Z brackets and one row of screws into the spar flanges. The -6 uses two rows of screws and I don't believe it uses Z brackets.

Good luck with your mod. :)
 
Dimensions wont be a problem, but the fit will be. -6 flange depths are different to accomidate the screw pattern which I suspect would leave a gap in the skin fit given the rear spar would hit the flange before recessing against the skin. This is just a guess.
Further, the predrilled -8 tank skins, due to screw seperation, do require the z-brackets, which I am confident would not be the right depth. THsi could be fabricated however.

Would be ideal to snag a -8 bulders tank and set it against the spar for fit.

If it were me, and it was, I would take the geometry of an existing -6 tank and extend that to your needs. That would make life pretty simple.
 
I've worked with a couple of builders regards extra fuel & tank mods. It is a workable situation, but needs to be engineered carefully. Done correctly, tank-to-spar attach structure will hold up even with fuel placed outboard, given the higher loads the fuel will see out there. (due to inertial loads during rolling maneuvers)

The 6 tanks attach totally differently than the 8 tanks do. One notable difference between the existing inboard tank -vs- an outboard LE tank is the attach hardware. The inboard tank has the fuselage supporting the inboard rib, while the outboard tank rib transfers load into an adjacent "sister" rib. This is not trivial structure, and for the outboard LE tank, you will have to engineer/add structure to support the loads.

I suggest enlisting the services of a qualified engineer when making significant structural changes to the airplane.
 
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Taking this additional information into account (Z bracket and attach hardware) it may be best to go back to my initial idea and just add a bay onto the existing -6 tank. I was thinking of either purchasing sheet to replace the skin (but one bay wider) and forming it myself, or purchasing an additional skin from Vans and splicing a section onto the existing skin. For strength and to prevent leaks, the new skin would probably be best. Thanks for all your help.
 
Tank dimension

WOW,

To answer your original question, the tank baffle is 50.5" measured along the chord line.

Best wishes...
 
RBR said:
WOW,

To answer your original question, the tank baffle is 50.5" measured along the chord line.

Best wishes...
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By the way, I'll be down in your neck of the woods mid August and am very much looking forward to it. What is the weather like that time of year?
 
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