Riveting Ribs to Spar

RyanB · #1 10-23-2018, 03:17 AM

Morning Everyone

The plans apparently call for the ribs to only be riveted to the main spar during the skinning process. Why do they call for this? Yes some ribs are attached with blind rivets, but some are attached with AD4 universal rivets which will be a mission to buck whilst skinning. At what stage did you guys rivet your ribs to the spar? So the basic question is why do Vans delay riveting the ribs to the main spar until skin are attached permanently?

Thank you

JonJay · #2 10-23-2018, 09:14 AM

It's possible that the instructions are less than perfect for that vintage. I know on my 6, which is the same laminated box spar design, you rivet the ribs to the spar as you are assembling the wing structure, well before putting it on your wing jig for skinning.
Hopefylly one of the 4 builders chimes in. Otherwise I would call Vans, but it just doesn't make sense.

smokyray · #3 10-23-2018, 12:55 PM

Quote:

Originally Posted by RyanB

Morning Everyone

The plans apparently call for the ribs to only be riveted to the main spar during the skinning process. Why do they call for this? Yes some ribs are attached with blind rivets, but some are attached with AD4 universal rivets which will be a mission to buck whilst skinning. At what stage did you guys rivet your ribs to the spar? So the basic question is why do Vans delay riveting the ribs to the main spar until skin are attached permanently?

Thank you

Ryan,
JJ is correct. My RV4 plans are from 1989 and have several slight discrepancies.
The main reason is so that the D section can be built with solid rivets.
V/R
Smokey

FinnFlyer · #4 10-23-2018, 04:31 PM

The leading edge skin needs to be riveted to the leading edge ribs off the main wing spar (in a cradle).
Then you mount the leading edge assembly to the wing/spar and put in the bolts and rivet the ribs to the main spar (of course together with the rear spar and main ribs). Only then can you start riveting on the main skins.

So you can't bolt and rivet on the ribs until you have made the LE skin/ribs assembly -- the rib holes in the main spar are shared: main ribs and LE ribs.

Hope this helps.

Finn

Quote:

Originally Posted by RyanB

Morning Everyone

The plans apparently call for the ribs to only be riveted to the main spar during the skinning process. Why do they call for this? Yes some ribs are attached with blind rivets, but some are attached with AD4 universal rivets which will be a mission to buck whilst skinning. At what stage did you guys rivet your ribs to the spar? So the basic question is why do Vans delay riveting the ribs to the main spar until skin are attached permanently?

Thank you

n82rb · #5 10-23-2018, 09:17 PM

Also, the last couple of root ribs need to be put in after you completely rivet the next one outboard. So you have access to buck the rivets on the skins.

Bob burns
Rv-4 n82rb

RyanB · #6 10-23-2018, 10:19 PM

This forum is fantastic! Thank you so much guys, this makes sense now

JonJay · #7 10-24-2018, 09:53 AM

Interesting. From a fuzzy memory.....
On the 6, you built all of the wing ribs to the spar, then jigged the skeleton. The Fuel Tank was installed and Main skins where riveted on, then you ran a long 1/4"x20 threaded rod through the tooling holes in the nose ribs to insure alignment. The LE skins where than strapped down into place with cargo straps and drilled. Riveting the top side was easy, then the back side by peeling the skin back and finished up through the lightening holes. The concern I would have is by building the LE assembly in a cradle, how can you insure alignment of the LE skin to the Tank profile. If they don't fit, they don't fit. With the strapping down method, you have some give and take through rib and skin adjustment, and even some shimming if necessary.

It has been a long time, so my memory might be a little fuzzy on sequence, but we never used a cradle to build the LE, only the tanks.

I am not sure if the RV4 wing is any different or if they amended the build manual, or perhaps there is just more than one way to skin this cat (no pun intended).

As long as it makes sense to you and you can move forward, that is all that matters.

RussellT · #8 10-24-2018, 10:48 AM

I skinned my cat similar to Jon except I did the leading edges before tanks but the same way using the straps. You do need the long threaded rod to keep the ribs square and in place, you will be drilling the skins to ribs blind (that's how I did it rightly or wrongly, as a first time builder it was a learning as you go thing). I had everything clecoed then removed and riveted all the leading edge, then riveted it to the spar through the lightening holes. It wasn't that hard, didn't use any pulled rivets. The main top skin went on next finishing up with bottom outer, as already mentioned rivet your way out with the closely spaced root ribs. A good solid jig that holds everything true and accurate is essential.

RyanB · #9 10-26-2018, 12:05 AM

That makes perfect sense, thank you guys.

JonJay · #10 10-26-2018, 09:00 AM

There are a couple older posts that may help with drilling blind.
Search Magnetic Viewer.
Here's one with lots of good ideas.

http://www.vansairforce.com/communit...agnetic+viewer

My neighbor use to market, for the cost of the pieces, a viewer and the little magnets. He doesn't have the kits anymore but if you do the search, you will find references to where you can get a viewer and magnets.
There are other ideas and methods listed in the posts also if you search.

Ah, the good old days. We had to drill our own holes, and walk two miles in the snow to school.