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-   -   RV-3B Dave's in Colorado (https://vansairforce.net/community/showthread.php?t=85658)

David Paule 07-24-2014 08:59 AM

With the left tank now all drilled (but not deburred, I'm saving that until both tanks are ready), I'm working on the right tank. As of last night the top surface is drilled and clecoed to the ribs and the bottom surface is marked but not drilled.

It's strapped down to hold it in shape for the drilling. But no clecoes in the photo - l must have taken the photo before drilling the top. Well, just use your imagination. They're in there.

Also you can see those handy square .063 tabs that I'm using to hold the skins fair. The tabs are an inch square, with a #40 hole drilled 1/4" from the edge in the middle of a side. All edges rounded. Someone should make these and sell them....



Dave

David Paule 07-30-2014 08:42 PM

Both Tanks Drilled
 
Both tanks are drilled, skin to baffle and ribs, and skin to the spar flange. The spar flange holes are pilot holes for now.

Gettin' closer.... Closer to deburring and dimpling and countersinking, anyway. I left all that to do at once and shortly there won't be any excuse and I'll have to do it.

Dave

David Paule 08-27-2014 05:51 PM

Doing the Gooey
 
Yes, I ran out of excuses and started assembling the tanks. Here are the inboard and outboard ribs:



More recently all the parts are riveted on and the -6 rivets too. Those were easy. And the blue tape's gone.

Then I put the stiffeners on using tank sealant. When cured, I started riveting them. This was taken before I got the tape off the first side.



I'm now riveting up the second tank's stiffeners. My work is outpacing the photos.

Dave

David Paule 09-05-2014 04:35 PM

Still Gooey
 
The tank stiffeners are riveted on, as well as the filler cap rings and the drains. I've been using the more syrupy type A tank sealant to dot the rivet heads and add additional sealing around the perimeter.



So far, with the end rib assemblies and the stiffeners, I've used 132 grams of the regular type B sealant and 81 grams of the type A sealant. I expect that another 20 or 25 grams of the type A will finish sealing the end ribs. Sealing around the fancy sealed nutplates takes a bit.

I started using hardware store plastic syringes with the ends cut off to open up the applicator end, and found that it wasn't necessary. I get better results and use less type A sealant with the normal narrow stock end.

Dave

David Paule 09-11-2014 07:58 PM

With a whole afternoon available, I used the tank sealant to glue five of the six ribs to the skin for one of the tanks. I didn't glue the inboard rib yet because I need to rivet the skin/ribs before I slip in the vent tube, and the inboard rib needs to be off to do that.

Five ribs and a bit under 80 grams of sealant. Previously, I'd abraded the parts, cleaned 'em and taped off the parts I didn't want to get sealant all over. Today I recleaned them, got them all goopy with tank sealant and then clecoed the ribs to the skin.The only really messy part was putting those #4 nuts on the clecos to get more clamping pressure. The clecos push some sealant through the hole and that gets on the small nut. And of course that's working blind, by touch.

Fun day.



I think I used something like seven or eight pairs of gloves. if it hadn't been for those silly little #4 nuts it would have been one or two pairs.

The photo was taken after I'd pulled the tape out. That's another fun job, reaching in and pulling out tape that's got tank sealant on it. After I took the photo, I clecoed in the baffle just to ensure that the tank would cure while it was held in the right position. Without the baffle it didn't have any shear stiffness.

Dave

David Paule 09-25-2014 11:02 AM

Quick update on the tanks.

I've got the left tank riveted but haven't yet dotted the rivet heads with tank sealant. Also the inboard rib is still out pending the vent line installation.

The right tank is assembled and glued and clecoed, all but the inboard rib, and is curing.

I borrowed a #8 nutplate tool to drill the nutplate attachment holes on the spar flanges but haven't actually drilled the #40 holes yet. The screw holes have been drilled but not countersunk.

Dave

rightrudder 09-25-2014 01:11 PM

Lookin' good, Dave! I went QB on the wings, so I'm missing this rite of passage. :o I'm sure it will feel great to apply that last dab of sealant and finish them up.

dave4754 09-28-2014 09:39 AM

Excellent work
 
I have done the left tank completely and I wouldn't worry about your use of gloves, as I bought a box and have almost used it all. About one half of those went into tank construction.

I offer this as a question though, it would be a concern to me that any tape might have been left behind to cause a clog in your fuel system. I bet you already know this though. :rolleyes:

Nice work!

David Paule 09-28-2014 01:29 PM

You're right - we've got to be careful to get that tape off while the sealant is still wet. I didn't do that with the first set of stiffeners and spent some happy hours listening to the radio as I worked the tape free of the cured sealant.

Got it all and then went back with the thinner type A sealant and resealed those sealant edges.

Learned that lesson!

To date, the tanks have used 333 grams of the usual type B thicker sealant and 112 grams of the thinner type A. But I've got a way to go. And "used," in this context, included sealant that's still in the mixing containers and syringes.

I haven't even bothered with the SEM gun I bought.

This shows the rivet dotting that I did yesterday on the top ribs of the left tank using the type A sealant in a syringe. I didn't do the bottom rivets because I didn't want the sealant to run. It's like honey and it might not, but I didn't want to risk it.



I decided to do the top first so that I could get the vent tube in place before proceeding.

You'll note that one rib seems to be reversed compared to the other. The right rib in the photo is the outboard rib. The plans say to have the flange outboard, which would be consistent with the other rib, but that doing it this way is optional for more fuel. It's about half a gallon and hey, I LIKE having more fuel. Beats the alternative.

Dave

David Paule 10-13-2014 08:12 PM

Well, a friend came over and helped me rivet the tank skin to ribs on the right hand tank. We'd already done the left tank, and I'd installed the inboard rib on that tank.

Dave


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