Thanks for your reply Paul. I wasn't going to have a engine cowl to test my new airframe but thought I could use the practice making one and I was right. My attempt to use tri stock to allow sanding round corners was only partially successful. My next attempt will use contest balsa for rounding and glass for strength. I understand avoiding 90* angles. The German speed cup planes use very rounded cowls but it seems the front opening is less then the finned area unless the head is not included since it is not covered. The head fins are above the cowl on mine. I am testing the airframe with a TT 46 Pro and will move to a speed engine and new cowl if things work well.