C-sink or dimple center section bulkhead flange

[alpinelakespilot2000]

I'm trying to figure out whether I'm supposed to countersink or dimple the anodized center section flanges where they attach to the bottom skin.

I know I was supposed to countersink the bottom skin in 4 places where the floor stiffeners will eventually go (so that the stiffeners will lay flat on the bulkhead flange), but am not sure about the rest. Since the plans specify countersinking the skin only in those four places, does that imply the rest of the bulkhead gets dimpled? While the bulkhead flange only appears to be .040, it's also anodized and I'm worried about any potential distortion.

Thanks for any clarification.

 

[Pmerems]

Dimple where you can

The 0.040 gets dimpled except where noted on the plans.

Paul M.
RV-4/RV-7A fuse/finishing

 

[alpinelakespilot2000]

Thanks for the replies. Dimpling is the consensus I guess? Anything that has to do with the spars has always made me extra cautious.

 

[scard]

I dimpled.

 

[wingtime]

either one you like

I countersunk mine thru the center section skin. I saw this method on the Orndoff fuse video. I called Vans to be sure and I was told either method is just fine. The forward bottom skin dimples nest into the countersunk holes.

 

[mikehoover]

Dimpled mine too

Dimpled mine. Everything came out perfect after riveting it all together.

 

[alpinelakespilot2000]

Just dimpled it last night--it turned out just fine, but I did wince the first time I heard that hard anodizing being squeezed between the dimples! Thanks to all for the replies.