Tank Ribs

[Scott Spencer]

I am having a heck of a time fitting the ribs to my tank skins in the cradle. I used the same procedure as the thinner ( .025 vs .032) outboard leading edges (which worked great) but there is no way I can get the bottom holes aligned without resorting to the following somewhat scary procedure. I ripped two pieces of two by lumber to 7 3/4 inches and while the tank is still in the cradle I stack these on the aft rib flange - then a take a 1" strap clamp from the lumber down right next to the pre drilled holes and torque it down - ALOT - to finally get the holes aligned where I can get clecos in all of them. Seems to work ok so far (two ribs done), no skin deformation, but it seems like a LOT of force to use. After I release the strap the clecos hold just fine. What’s everybody else had to do???

Thanks
Scott

ps. the ribs are all properly adjusted - its the heavy, not very well pre-formed skins that are a problem.

[captain_john]

Scott,

I too have had difficulty in fitting the ribs into the skin initially.

I have found that by pulling the skin out of the cradle part way I am able to get a couple of clecoes into the nose and work my way rearward.

After a few fit ups things tened to go together easier. After it was dimpled, it seemed to "pop" right together.

Be patient and review your technique.

Hope this helps.

CJ

[Scott Spencer]

I tried that - but no luck. I found myself applying so much pressure by hand I was concerned about bending something. At least the straps distribute the load over the whole skin. My main concern is deformation at the front of the leading edge but that has not happened with the two ribs I've done so far.

Thanks

[Dan A]

Scott,

Make sure your rib flanges are exactly 90 deg. to the rib sides. If they are not you will have a hard time fitting them to the skin.

Dan

[Scott Spencer]

Thanks for the advise – But the problem I was having wasn't with the
ribs, which were all true with 90deg flanges but with the skins
themselves which did not seem to be nearly pre-formed enough. In
particular the radius at the leading edge was not very well matched to
the ribs. I clecoed the top side of the skin first (every hole) then
using as much force as I could by hand I could not get any of the
holes closer than 1/8" to each other which was too far to force a
cleco. The method I described in my first post using a band clamp has
done the trick though. It left the tank looking just like it should
with no deformation – it was just nerve wracking to have to apply that
much force to make it all work.

[tshort]

Scott-

There was a simliar thread in the matronics RV-10 list last week ... someone's solution was to use a couple 2x4's to gently adjust the bend of the skin just a little - apparently with little force it made a huge difference. IIRC, he felt his skins were bent a little too much, however.
You can view this thread at www.matronics.com

Thomas

[captain_john]

Another thing I did that made the installation of the ribs better was that I used the 2" maroon Roloc disc on the leading edges of the ribs and smoothed out the jagged edges. Just round them off and make them curve smoothly.

KnowwhatImean?

CJ