After searching the Vansairforce forums for threads on types of primers, I quickly found there is many opinions and recommendations. I stopped at one of the local auto parts to pick up a can of Dupli-Color self-etching primer. I am not wild about the, color, because it is too dark, the paint went down very easy, two light coats the skin is complete.
Today I went by the NAPA store to pick up a can of 7220 self-etching primer. I use this for the spar and the two ribs. The "skeleton" has been riveted together and is ready for the skins to be Cleoed and drilled.