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

ijustwannafly 10-15-2014 09:30 PM

So dave, when you do a plans built kit like this. I know you have to drill all the skins with a fan spacer and such is anything drilled for you? Or do you literally get a box of stamped parts and thats it

David Paule 10-16-2014 09:03 AM

There are probably a dozen parts that come with holes, and that includes the main wing spars, which are drilled and riveted (except for the holes on the spar flange that attach to the skin, those aren't drilled). None of the skins, ribs, bulkheads, etc., come with holes.

Take a peek up to post #99 for a look at the right tank still undrilled. The first photo shows the undrilled ribs and the next, the skin. Here's how I drilled those holes.

1. I carefully located the ribs in the jib and secured them in place. I used a bit of brass tube as a bushing to back-drill through the spar to get the aft flange holes, removed the ribs, and opened them up to #30. Post #51 shows that. Then I clecoed them to the spar and put some threaded rod through their leading edge.

2. Place the skin in position and do any trimming to get the aft top edge in perfect alignment. Use the Howe fittings to strap the skin into place, see post #75. This is kind of an iterative process.

3. When I was happy with the fit, I removed the skin and drilled the top skin for the the spar flange holes using a handy jig I'd made from some scrap 4130. The jig rides on the edge and locates a position 1/4" in from the edge; I still need to mark the spanwise locations. Then I removed the ribs from the wing jig.

4. I located all the holes on the rib flanges top and bottom and drilled just the top rib flange's holes.

5. Replaced the ribs and skin with the Howe fittings and straps and drilled and clecoed the skin to spar flange holes, securing the skin into position.

6. Starting at the aft-most holes, I back-drilled and clecoed every top rib flange hole in the skin. At the leading edge, I had to hold the skin to the ribs, but that wasn't hard, just a bit awkward.

7. With every top hole clecoed, I made a table of measurements locating every single hole in the bottom except the spar flange holes. I measured everything as many ways as I could, paying special attention to external references so that I could transfer the hole positions to the skin.

8. Strap down the skin again with the Howe fittings, and when satisfied (it takes me a couple tries to get it right) measure and mark the hole locations on the bottom of the tank skin.

9. I didn't bother using a center punch. The vinyl holds the drill position well enough. Starting at the most forward, blindly drill through the rib and skin. I could see the mark on the ribs so I knew it was okay. Placing a cleco in each hole as I went along, I drilled about 1/3 to 1/2 of the way to the aft edge. Then I stopped.

10. I removed the bottom skin clecos and Howe fittings and straps and opened up the bottom and checked the holes. This let me assess how I was doing. I didn't do this on both tanks because on one of them I could see the marks on the ribs better through the holes and knew that everything was okay, so I just kept going.

11. When the clecos were in every hole, I drilled through the spar flange on the bottom.

At this point all the ribs and the spar and skin are all drilled. There's been a cleco in every pair of holes.

This was probably more information than you wanted, eh?

Still, this is the major reason I chose the RV-3B kit, so that I'd have a number of fun problems to solve. In that regard, it hasn't been a disappointment. But I can't say that it's going together quickly or that I haven't made plenty of mistakes - my scrap pile is big. Still, all in all, I'm making progress.

Dave
RV-3B -- Some thinking required

HFS 10-16-2014 11:16 AM

When The Real Fun Starts!
 
Wait until trying to jig the fuselage if you want some real fun!

David

Ironflight 10-16-2014 06:07 PM

Quote:

Originally Posted by HFS (Post 925650)
Wait until trying to jig the fuselage if you want some real fun!

David

Second that! Of course, you can take the easy approach - build the jig precisely, mount the bulkhead on the jig precisely - then close th ebuild manual, put away the plans, and build an airplane around the bulkheads. Many of the measurements don't quite add up anyway, so don't sweat them - just make it all work!

Oh - no pre-drilled holes in anything.

David Paule 10-17-2014 08:53 AM

You're Getting Ahead Of Me!
 
I'm looking forward to the fuselage, I've got to admit. The engine is standing by and so is the finish kit. I even picked up something for the cockpit: an ARP carburetor ice detector, like the one in my Cessna 180 that works so well.

But for actually building it, that's in the future. All I have right now is anticipation and, well, this:



It's a Frye steel jig, folded up so I could haul it in my pickup (yeah, these jigs fold - cool!) and it's not set up for an RV-3B. I don't have instructions for it - but I do have a bundle of small parts that comes with it. If anyone has instructions, give me an email or PM please. As it is, I'm expecting some "real fun" just getting it to work. But since it's already built a couple of airplanes, this one should be easy for it.

Someday.

Dave

David Paule 10-22-2014 11:31 AM

Spar Flange Nutplates
 
Right now, the top skins are off the wing so that I could install the spar flange nutplates and the autopilot roll servo and things like that. Before, I hadn't countersunk the tank nutplate holes (they had been pilot-drilled and on the tank skins, dimpled), and had to at least countersink these to get the tanks back on when they're complete.



The countersinking of these holes wasn't well-documented in the RV-3B manual. I used the tip given in "27 Years of the RVator," to open them up to .365 to .375 inches outside diameter. It took some fiddling to get there since the one-flute countersink bit was .377 inches diameter. Interestingly, I noticed in the RV-14 wing section on Van's revisions page, that for the RV-14, the max countersink outside diameter is .370 inches. No minimum is listed.

Dave

David Paule 11-01-2014 07:15 PM

Playing With the Gooey Stuff - Tips
 
After riveting up the tank skins and ribs, the edges of the tank sealant looked like this:



Then I saw this:



And went back into the tanks with some of that type A sealant in a plastic syringe and a tongue depressor that I rounded off to 1/4 inch radius. In the how-to, a mill is 1/1,000 inch, so 250 mills is 1/4 inch. I've got a little more to do but now they're looking like this:



Have to admit, this part was fun.

Dave

ijustwannafly 11-01-2014 07:56 PM

Looking good Dave! now i know who to call for help my with tanks!

David Paule 12-14-2014 07:42 PM

The outboard leading edges are riveted on to the spars.



I didn't forget the rivets through the rib flanges to the spar web.

If you look closely you can see at least one of the alignment strings through the holes in the front and rear spar that let me check for twist. And the landing light lens and stall warning vane are visible too, all on the left wing, the one in the background.

Dave

rockwoodrv9 12-14-2014 08:27 PM

Looking good Dave.


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