Ribs,Rivets and "Bonding Tape"

[Siegmann]

I do not know what year Airstream made the change, but my '98 has the reduced rivet frequency on the outside skin along the ribs (compared with more vintage units), with the substitution of a "bonding tape", that Airstream claims adds strength (as well as thermal isolation). In the last few years I've noticed that I can press on the outside skin along several ribs, and for some distance along the rib the skin moves in a short distance before contacting the rib. The skin is clearly is not "bonded" to the rib along its full length. The skin is bonded at all the rivets, no rivets are popped and the exterior skin is smooth and looks just like when it was new.

As I understand it, much of the shell strength in the semi-monocoque design should come from the outer skin being bonded to the ribs. If the "bonding tape" is releasing over time, should this be a major concern? Also, can anyone else tell me if they have noticed that this has occurred on their rigs?

[Siegmann]

Just thought I'd try one more time. Has anyone else noticed this?

[perryg114]

I have also been concerned about the fewer rivets. Seems like it is based on cost savings and not the end result. More rivets is better and I can't imagine any tape staying stuck for long.

If you are not popping rivets or getting cracks in the skin, then you are not in danger of structural failure.

Perry

[Siegmann]

Yes, my skin is fine. Not even a wrinkle. Thanks for your comments.

[idroba]

High strength bonding tape will last and hold virtually forever. It is commonly used now to hold the mounting for solar panels on the roof of Airstreams and other RV's. This is not the stuff you buy at the hardware store. Don't worry about it.

[Siegmann]

As I noted in my original post, if I press on the outer skin along a rib where there are rivets, the skin has no give, and is held tight to the rib. As I move down the rib, below the rivets, to an area with no rivets, when I push the skin moves in about 1/8" before contacting the rib behind it. The skin is clearly not bonded to the rib. Maybe it was that way when new. Is it possible that when they built it, they did not press the outer skin in to contact the bonding tape all along the rib? The lack of bonding is along several ribs scattered around the rig, but only for 1-2 vertical feet at each rib, and generally above the mid-height rub rail.

[doorgunner]

I was once in a hangar looking at a SR-71, it was leaking all over the place. It was explained to me that was a design necessity. At the 71 gained speed the friction would heat up the skin, it would expand and seal. Then hook up to the tanker, fly the mission and return to base.
You need to just tow a bit faster, it'll be fine.

[cwf]

Originally Posted by doorgunner

I was once in a hangar looking at a SR-71, it was leaking all over the place. It was explained to me that was a design necessity. At the 71 gained speed the friction would heat up the skin, it would expand and seal. Then hook up to the tanker, fly the mission and return to base.
You need to just tow a bit faster, it'll be fine.

hahahah!!! That's true about the SR-71.. it was a leaky mess when still.. maybe the fuel made it slide through the air easier.. hahaha...no... the skin did expand.. amazing aircraft.. imagine what they are doing now...

My 1999 Excella recently popped a few rivets at the bottom beltline. Between the C-channel and the skin was a very durable tape. The 'glue' was gone. No mo sticky.

I think it is possible that as long as the rivets are intact, you should be ok. If you notice any movement along the belittling, address immediately.

[Mixter]

Originally Posted by Siegmann

As I noted in my original post, if I press on the outer skin along a rib where there are rivets, the skin has no give, and is held tight to the rib. As I move down the rib, below the rivets, to an area with no rivets, when I push the skin moves in about 1/8" before contacting the rib behind it. The skin is clearly not bonded to the rib. Maybe it was that way when new. Is it possible that when they built it, they did not press the outer skin in to contact the bonding tape all along the rib? The lack of bonding is along several ribs scattered around the rig, but only for 1-2 vertical feet at each rib, and generally above the mid-height rub rail.

Are you sure there is tape between? Seems to me that would add difficulty to the manufacturing process... that would mean they would have no flexibility to maneuver the rib once they squeeze it into place, as it would stick every time they touch the outer skin and have no ability to shift into the proper position. (they first prepare the shell skin, then come in after and install the ribs to stiffen up the shell- correct?)

I'm not overly impressed with the quality of manufacturing and workmanship so far..... as many of us are re-engineering even the vintage series. Honestly, I'm to the point where I'm feeling every change they made to (reducing the amount of rivets in this case) is simply a move to reduce costs and they justify because the amount of rivets used is "sufficient".

I can tell you that the bonding tape they used to stick my windows in, simply turned to dust with the heat over time. This leaves a significant gap with an inferior mechanical bond because the rivet cannot seat properly.... If they are using that bonding tape within the structure of the frame at the ribs, this is set up to be a failure point.

My bet would be that theres no tape behind that skin where you can push it in....

[Zil]

any possibility of using something like pop rivets to add some support?

[Mixter]

I wouldn't. Firstly because they leak. Secondly because they are not strong. I think that would be counter productive.

I think cwf hit it- "if the rivets are intact" it should be ok. They just designed it with less rivets...

[dkottum]

Maybe they used too many rivets on the older models. More holes, more leak possibility.

Are there any failures due to rivet frequency either way.

[Mixter]

Originally Posted by dkottum

Maybe they used too many rivets on the older models. More holes, more leak possibility.

Are there any failures due to rivet frequency either way.

Good point!

[cwf]

I used pop rivets called 'Cherry Max' recommended by Top.. I barely had strength to set them!! they are some wicked PopRivets and I am confident they are equal to the stock. Time will 'tell' for sure.

[Siegmann]

Mixter, I just found my original '98's glossy brochure. Under the list of "features" they included, and I quote-- "thermal barrier between outer skin and structural ribs reduces temperature transfer to interior, improving insulation and allowing fewer exposed rivets". Unless they accidently left it off, my model should have the bonding tape.

On a recent visit to the Airstream webpage, regarding the bonding tape, they have added the phrase "increased strength" to the description. Ah, but they don't say for how long....