The SHAPE of the Skywriter fins is correct, but the airfoil on those fins is incorrect for what you want. If you are only looking for the length/width/chord dimensions they are correct.

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When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !