missed out cream of tartar in chiffon recipe
It will most likely turn out fine.  Cream of tarter is sometimes added when beating egg whites to enhance the stability of the foam that you form.  The egg whites beat into peaks on their own, but the cream of tarter is an accelerator of this process and also a bit of a preservative of the structure when you're folding in the rest of the batter. A bit of an "insurance policy" if you will.

And no, it won't affect the taste either.