set v. pulled rivets; Lower wing skins

I'm sure this is a rank newbie question, but I'm a rank newbie. Cost, weight, & "that's the way it's always been done" aside, what is the disadvantage of considering pulled rivets at least in the hardest areas to reach on the training edge of the lower wing skins? In flight there is no negative pressure that might try and pull them out, a touch of body filler would seal the hole, and it seems it would be a lot more consistent for a good rivet than having to use a bucking bar blind/by touch. Thanks for your patience; and the info.

I would think pulled rivets would weigh more but regardless, if I were looking to purchase a flying RV, I would not consider one with pulled rivets (other than an RV-12) because it would make me wonder what other shortcuts were taken.

Invite another builder in your EAA chapter over to help set those rivets.

If you use the right pulled rivet (Cherry Max) as a substitute, there should be no issue, but don't fill the rivet head. You need to be able to see that the stem is seated correctly when you do your condition inspections. Having said all of this, I don't recall there being a huge issue with bucking solid rivets in that location.

Bucking bar jig

Before closing up, I made a little wood block jig for the tungsten bar. The jig was cut so the face of the bar would be correct for the row along the rear spar. I added a string lanyard so it couldn't fall. Those were some of the easiest to buck. Find a partner to help and it goes by pretty fast. Cut the toe off an old sock and use it to protect your arm from rib scars.

Mark Dickens said:

If you use the right pulled rivet (Cherry Max) as a substitute, there should be no issue, but don't fill the rivet head. You need to be able to see that the stem is seated correctly when you do your condition inspections. Having said all of this, I don't recall there being a huge issue with bucking solid rivets in that location.

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Don't know about the -14, but the instructions for the -4 and -6 planes specifically allow the entire lower wing skins to be installed with MK319BS pulled rivets.

These are not the usual CherryMax airframe rivets.

Ditto for the RV-3B.

Dave

wirejock said:

Before closing up, I made a little wood block jig for the tungsten bar. The jig was cut so the face of the bar would be correct for the row along the rear spar. I added a string lanyard so it couldn't fall. Those were some of the easiest to buck. Find a partner to help and it goes by pretty fast. Cut the toe off an old sock and use it to protect your arm from rib scars.

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Larry, do you have a picture? The jig, I mean, not the sock.

I think it is more a cost thing. Just for grins I counted rivets that were needed for the bottom skins of the 10 wings. Then figured out what the MK's would cost, vs the standard rivets. It was several hundred dollars for the MK's vs 20 or 30 for the regular rivets.

Just my thoughts.

Lynn

It is almost completely a cost issue and also a small weight issue. Having built a Sonex that is almost completely a pulled rivet airplane, I am very comfortable with the right pulled rivet in almost any location.

There are a lot of different types of pulled rivets made with a lot of different materials and different types of mandrels. In my Sonex, the mandrel is irrelevant to the strength of the rivet.

It would be a lot more costly to build the entire underside of the wing with pulled rivets (and Cherry Max would be overkill) but there is almost certainly a pulled rivet that would work.

My only trivial complaint on the 14 is that there are a few more locations than noted in the plans, for access reasons only, where I think the kit could have just specified a suitable pulled rivet substitute. So far I have accomplished all the really hard ones with no problem. I just wish I didn't have too.

StuBob said:

Larry, do you have a picture? The jig, I mean, not the sock.

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I still have it. The jig that is, not the sock.
The wedge was taped roughly as shown. The forward bottom of the wedge (left) was relieved to clear shop heads on the rear spar. This was for my 7a.

Great discussion all! In fact some of the same issues brought up here by N941 WR were mentioned up front. We also thought perhaps if Vans had spec'd pulled rivets but offered the option on solids for the competition class builders, that might have offered a reasonable out, but it is what it is. Yes, we're on our way with riveting, and not letting a little thing like colder weather stopping our time.
Thanks again for all for your advice and patience. I can only hope my future questions improve along with my experience. Have a safe and Happy New year.

Great photo Larry! I'll pass it along to my brother, just in case.