Hi Mike,

I thought about this too when building our S7. Our KF is an older model which came with pop rivets and maybe the current kits have gone to the flush rivets - can't argue against them looking better. I don't have any RV build time so can't speak to the comparisons. I did visit with a couple A & Ps in our club at the time - these guys had more aluminum experience than I will ever have as they worked on Boeings. In both cases, both indicated the pop rivets were fine on the KF flaperons. Because of the thin skin on the flaperons - alternatively they suggested solid non-flush rivets and indicated they would have no advantage over the pop rivets in this application. These guys suggested staying away from the flush rivets because of the thin skin on the flaperons; although I think I have heard of people using the flush rivets with great care - these are experimentals and we do experiment - maybe that is what is done on the newer kits.

I decided to stick with the pop rivets and was also advised that a KF will not see any measureable drag reduction by getting away from the pop rivets.

One option I can think of setting flush rivets is to do a very careful and very shallow countersink - but I haven't experimented with this at all and I am not sure there is enough material thickness.

Sincerely,

Dave S
KF 7 Trigear
912ULS Warp Drive