Thats how airplanes are held together. There isnt that much stress on the panels.

 

Take a look at the wing of the next plane you fly in. They're pretty strong even panel to panel. Make sure you're following the guidance on rivet spacing.

Some have moved to adding steel in the footbox area for a little more impact protection, but it's not for fear that the rivets won't hold up.

 

Andy,

I plan to go a slightly different route with my attachment of aluminum panels. I never liked the idea of using silicone. It can be messy and it doesn't have good mechanical holding properties. There are also areas of my build where I don't want the look of backside of rivets and/or areas where I can't get a rivet gun. I have a brother of a friend who works for 3M, while out in his boat, I mentioned that I am using 3M products in my build. During the conversation he said they have mechanical tape which could reduce rivets. He dropped some samples by and I did some trials. It really does work WELL. With a 1/4 wide strip 4 inches long, I attached two pieces of aluminum. I had people try to take it apart and it is still together. And in the application, you wouldn't even think it would stick. You can touch the tape and it is hardly sticky to the touch so you can place it easily. It is only when pressure is applied does it adhere. I will be using this to seal my cockpit and to secure those areas that I want to look good or can't reach with a rivet gun.

The tape is 3M VHB.

 

Andy,

It can be messy and it doesn't have good mechanical holding properties.

I dont think you have ever tried to take apart two panels siliconed together. Its NOT permanent but its still very strong especially when riveted.

 

^^ + the silicon isn't 'structural', it's to reduce vibration & provide a weather seal between panels.

I've had a few chances to take apart panels that were riveted and siliconed.. I would not have want to try and wrestle panels apart that were 'permanently' affixed.

 

I would not have want to try and wrestle panels apart that were 'permanently' affixed.

x2 on not wanting to take panels apart that are "permanently affixed".

And if you're like me (and many builders), you'll probably need to (or want to) dis-assemble a few before the build is done.

3M makes a variety of adhesive tapes and they have may good applications in building cars ... and airplanes. My understanding is that many (most) trim strips and logos, etc are now attached with tapes.

I understand also that the Honda NSX body panels are/were assembled with very few mechanical fasteners and are thus very difficult (and costly) to repair if and when needed. I recall a news report years ago of one that was relatively lightly sideswiped and the repair estimate was in the just under 50K.

Lynn

 

I forgot to silicone one of the panels surrounding my radiator (in a rush to get registered), and sure enough, it came loose during my first 80mph run. It didn't fly off the car, but the rivets definitely became loose. After a proper bead of silicone and re-riveting, it holds fine at any speed.

It's the combination of rivets and silicon that seem to provide the real strength. Either rivets or silicone alone wouldn't be enough.

Unless you're 200% sure you won't need to remove the panels in the future, I'd recommend avoiding a permanent adhesive. If you're like me, you'll end up removing and re-installing half the panels in your car for some "upgrade" in the future.

-Ben

 

Oxide, that sounds kinda neat. I wonder how the bond is affected over time with the rather high heat associated with an engine compartment? I also wonder if FFR could do the initial shipment of the panels without using screws and messing up the aluminum? I did find this on the 3M site:

Temperature Exposure
Because of the demanding and diverse applications users have for VHB™ tapes,
durability has always been a key interest in the performance of these products. One of
the first issues for tapes is retention of tack and adhesion after exposure to elevated
temperatures. The VHB™ Adhesive Transfer Tape F-9473PC yielded 92% retention
of peel adhesion after the roll was aged for more than 5 years at 150°F (65°C). The
initial tack and liner release properties were still excellent. The difference in peel
values suggests that a roll of this tape is relatively unaffected by long-term exposure
to elevated temperatures. Bonds made with VHB™ Tapes can tolerate periodic, shortterm exposures to temperatures up to 300°F (150°C) for most Foam Tapes and 500°F
(260°C) for Adhesive Transfer Tapes.

Here is some more info.

 

It's fine.

 

Maybe 3M makes a product which "releases" the bond if needed?

 

Rivet and bond

I have never been a big proponent of silicone sealer, but it works pretty good in a rivet and bond application where it is clamped between the panel and a steel or aluminum piece. The problem is it uses ammonia to cure and it is not real friendly to aluminum over time. Use a high quality kind that is paintable in case you need to paint over it for some reason. A lot of FFR builders have used it, though, and it seems to have lasted for years.

The best products, however are the 3M VHB tape or 3M 5200 brand RTV adhesive/sealant which comes in a tube so it is easier to apply in different locations. It comes in a slow cure and a slower cure. Both are incredible adhesives as well as gap sealers. These are both urethane products that cure with exposure to air. RTV is easier to find locally and comes in black and white colors. RTV is used in challenging marine and aviation applications and will make the panel structural when combined with rivets. As a matter of fact, you could take all the rivets out after the RTV cures and it would still be 98% as strong. RTV takes longer to cure, but that is not a problem in this application. I used masking tape on the aluminum panel to panel joints to make sure that I wasn't applying it where I didn't want it.

Shop 3M 10 Oz. White Marine Sealant at Lowes.com

Ron