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Countersinking or Dimpling the Flap Spar

I am going to deviate from the instructions here. I am in no way suggesting that anyone copy what I'm doing. Now that I have covered my butt, here's what I'm going to do with spar. The flap spar has two flanges, one is at a perfect 90 degree angle and the other is not. I have heard that some of the other builders were dimpling the spar rather than countersinking it. The rear spar on the wing is the same thickness as the flap spar and I don't see why you can't use the same procedure on the flap spar as the wing spar, but with one exception. The bottom flange on the flap spar is not at a 90 degree angle, so dimpling this flange will bend the flange out because there is not enough room for the small diameter dimple die to sit flatly on the interior of the flange. The top flange is at a perfect 90 degree angle, so the small diameter dimple will work fine. So I am going to countersink the bottom flange and dimple the top flange. This will make me to use longer rivets and have to dimple one of the end flanges on each rib.

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