Be sure to leave some extra space when fitting your tank. The tank material
continues to bulge and sag for quite a while, when subjected to the weight
of the fuel load. We followed the directions in the manual, and then had
quite a struggle to displace the tank enough to install the starboard wing.
It remained stable in that position while we finished building, but then
drooped downward after being filled with fuel for several weeks. We keep it
hangared, with the wings installed, so the tank cannot drop lower than the
top of the wing spar. I wonder if we would have a problem if it were kept
on its trailer instead.
Similarly, the front of the tank bulged forward (between the spacers that
are supposed to hold it back), interfering with the aileron cross-link
pushrod. We moved one end of the pushrod to the front of the bellcrank,
thus gaining about 10mm of clearance. Further bulging has reduced the
clearance to about 5mm, but it seems stable now. 10mm of clearance is not
too much to leave between the tank and everything it could possibly
interfere with.
Dave DeFord
N135TD
----- Original Message -----
From: <clevelee@cswebmail.com>
Subject: Fuel tank positioning
> I know this has been commented upon before, but I believe it bears
repeating for those who are getting close to installing their fuel tanks.
>
> The instructions, as recently as November 2000 for the XS, advise to place
a 2CM spacer under the top of the fuel tank (upside down in the cockpit
module)before glassing in the anchor brackets. With this spacer, the bottom
of the tank is flush with the bottom of the cockpit module. This is well
and good, but the wing spars will not fit in with the tank in this position.
>
> Thanks to an e-mail from Chris Napier who gave me a heads-up regarding
this position I was double attentive to the possibility of the problem, and
almost didn't catch it. The problem is quite real.
>
> Using a 3/4" x 4" piece of scrap wood, I fabricated a template that
replicated the width of the spars at the pin location (the widest area of
the spar). I held the piece of wood up to the wing spar at the pin bushing,
and holding the wood vertically and centered widthwise on the hole, scribed
the hole location with a pencil through the bushing, and scribed a line at
the top and bottom of the spar across the width of the wood. I then cut the
wood along the lines and drilled the 1/2" hole.
>
> Holding the template in place with the 1/2" bolt used to locate the
bushings in the cockpit previously, one can sight along the bottom edge and
see if there will be interference of the spar with the forward ledge of the
tank. On the other side, you can hang the template off the bolt as it
protrudes through the metal spar guide already bonded in place.
>
> I found, similar to Chris, that the correct spacer height for the top of
the tank off the inside of the horizantal portion of the seat back was
closer to 1 CM, rather than 2. This results in the bottom of the tank not
being flush with the bottom of the cockpit module - which is a good thing -
as it allows room for the 3 + 1 ply brace to be laminated.
>
> Cleve
> A198 Mono XS
> Detroit, MI
>
>
> ___________________________________________________
> The ALL NEW CS2000 from CompuServe
> Better! Faster! More Powerful!
> 250 FREE hours! Sign-on Now!
> http://www.compuserve.com/trycsrv/cs2000/webmail/
>
>
|