Last edited by Av8r3400; 12-31-2017 at 09:00 AM.
Just a comment on yours John. Joints like this that are bonded and riveted gain most of the strength from the adhesive, provided the adhesive has sufficient shear strength, which Hysol has. The rivets provide clamp up and squeeze out of the adhesive, and also provide residual strength in the event the adhesive degrades. Case in point is the Aloha Airlines 737 that suffered major structural failure when the fuselage lap joints unzipped the fuselage section above the cabin floor. The primary cause was degradation of the adhesive bondline of bonded and riveted skin lap joints, which then caused high loading on the rivets over time, which eventually lead to multiple fatigue cracks between rivet holes and then bingo, the joint(s) let go. There's a lot more to this story than that but it serves to demonstrate the idea.
With respect to Kitfox, the wing joints are a proven design with many years of safe operation, all having been built to the manual requirements so that speaks for itself. In my particular case, however, I didn't use micro-balloons (or micro-baboons per Larry's redefinition ..!!) for the very reason you said. Maximum joint adhesive strength. But that's a personal choice and something I can do because my aeroplane is Experimental.
David
SS7 Builder
Anyone thought about using cherrymax instead of SS rivets for the spar attach fittings?
If I recall, they are really expensive.
Another question - why would you want to do that? There is nothing wrong with using the rivets furnished in the kit. I think they have been well-proven to be adequate and safe for this application. In my opinion only, you could certainly use the stainless steel CherryMax rivets for the spar attach fittings if you wanted, or the slightly oversized version if you had an oversized hole within the tolerances of that oversized version of the rivet, but as Eddie said, they are very expensive.
John Evens
Arvada, CO
Kitfox SS7 N27JE
EAA Lifetime
Chap. 43 honorary Lifetime
Being an experimental aircraft you can do as you please, that is part of the fun building however for me if the suppling company, aka Kitfox, has a proven history of saftey with their design I will stay with their plans and listed parts to complete the build.
I bought Cherrymax for precisely this use. But didn't use them (duh). As I said earlier, the adhesive does the work. The limiting strength, should the adhesive fail, is the bearing strength of the tube, making the type of rivet used irrelevant. An opinion ... I'd just use the ss rivets with the kit.
David
SS7 Builder
Spend your extra money where it matters, like some nice options you will enjoy.
Jim Ott
Portland, OR
Kitfox SS7 flying
Rotax 912ULS
The other problem with the Cherry-Max rivets (I have them) is that they're big and ugly on the leading edge. I minor consideration, to be sure, but worth mentioning for all you Oshkosh aspirants.