Dye Flow Testing: Not long after I got the first cowling mounted and ready to fly, hangar neighbor Joe asked me if I wanted to do flow testing on my cowling.  Joe worked in a lab at Lockheed Skunk Works.  I was intrigued.  The next day he brought me some orange and yellow powder and mineral oil.  After putting dots all over the cowling, I was ready to go test.  Nothing has been the same since. 

Flight testing of the first cowling prototype showed flow reversals in a couple of places where I didn't expect. I moved a couple of high spots down about 1/2 inch and low-and-behold, the flow reversal was gone. A more 'cost conscience' corporation wouldn't have bothered.