Pop rivets in subpanel?

RVNewsletter · Post by **RVNewsletter** » Sun Jun 15, 2008 10:03 am

I got myself into a situation where I SHOULD have riveted the subpanel on the bench (it's a long story but when I put those canopy frame stops in, I kinda locked in the subpanel components).

I can still get to some of the holes with a gun and bucking bar -- or a squeezer -- but there are more than a few spots where I'm just asking for trouble with that method and I risk really banging things up.

Is there any reason I can't use some LP4-3s here? Like in those two diagonal rows of three on that rib/bulkhead to panel connection (the rib/bulkhead where the fuel vent line snakes up).... or on the holes that connect the various parts of the subpanel together?

cjensen · Post by **cjensen** » Sun Jun 15, 2008 10:18 am

I can't see a reason why this would be a problem in the least. I did use a couple of blinds in my subpanel because I was just plain lazy...

My thought is, if they can be used to attach ribs to the spar in the wing with Van's blessing, a few in the subpanel structure isn't gonna hurt a thing.

Post by **bullojm1** » Sun Jun 15, 2008 10:30 am

Bob,

Personally I would use the MSP-4? Cherry rivets. From what I recall, they are much stronger than the LP4-3 rivets.

cjensen · Post by **cjensen** » Sun Jun 15, 2008 11:29 am

bullojm1 wrote:<snip>MSP-4? Cherry rivets. From what I recall, they are much stronger than the LP4-3 rivets.

I'd like to see the proof on this. I've had this conversation with our shop guys, and while we use Cherry Max rivets (because that what our suppliers have), they've never been able to explain the difference, or show me the proof that they are different.

I'm not presenting an argument here, I'd just like to see it.

I also don't think the sub-panel is structural. Sure it probably does add some stiffness to the structure, but it's not a structural part of the airplane. Am I wrong?

Post by **bullojm1** » Sun Jun 15, 2008 1:46 pm

I agree that the subpanel isn't all that structural, but if Bob has some MSP rivets, I think they would be the closest strength to the solid rivets.

I couldn't find any data sheets on the LP4-3 rivets, but they do seem pretty soft. Brad Oliver did some r&d and determined the MSP's were stronger. Here are his thoughts on it: http://www.rv7factory.com/log/061026.html

weezbad · Post by **weezbad** » Mon Jun 16, 2008 6:56 am

IIRC msp are monel and stainless and lp4's are aluminum. you can always use cherry max which are as strong as solid. some rivets end up more or less hollow when pulled and others self plug. the ones that shaft stay in are stronger. cherry q rivets are strong. LP (low profile) means less material in the head, but MAYBE a different alloy (stronger?)
MSP's are used in the push rods but probally due to being monel. i think lp4's would be fine in the sub panel but when in doubt use cherry max or cherry Q. they do cost quite a bit more, but a handful is not gonna make a financial difference. it would cost 10,000$ to use them on the whole plane however?

from spruce: cherry max:
"Due to the large bulbed blind head, similar to a solid rivet, the Cherrylock and CherryMax rivets are especially suited for double dimpled or high vibration applications. They can be used as replacements for some solid rivets and are excellent for use in fiberglass or composites as the rivet spreads in a way that prevents crazing or cracking of the material."

cherry q :Structural-Self-plugging rivets HIGH SHEAR STRENGTH Cherry Q Rivet mandrel plugs the entire length of the rivet sleeve, providing full shear strength values for structural o...

cherry n: Unusual mandrel design of Cherry N Rivets holds rivet and mandrel firmly together prior to installation and insures positive mandrel retention in the installed rivet.

RVNewsletter · Post by **RVNewsletter** » Mon Jun 16, 2008 10:33 am

Very helpful. I've put a couple of LP rivets in (there's two vertical rivet holes on the side of the front side skirt . It's impossible to get a bucking bar in there. And I got one LP4 in one of those two diaganol rows of three on the subpanel when my #2 son pulled up to the hangar door (open and enjoying the Father's Day breeze).

He had brought me a hot fudge Sunday for Father's Day and wanted to hang out.

So we sat, eating ice cream, watching the B-25 land at KSGS. He wanted to do some building and I found I'd missed a small clip that had to be fabricated. So we made a pair. Took much longer than if I were doing it myself but what the heck. Never did get back to popriveting, which is OK because now that gives me time to order a handful of CherryMax rivets.