RE: Optimal Fuselage Design
Barry,
The “coke-bottle” fuselage shape was originally applied to the “Century Series” of fighters of the late ‘50’s when they found the first one couldn’t go thorough the speed of sound due to transonic compression drag. So they applied a modification of a 1930’s theory by a NACA engineer named Dr. Richard Whitcomb that became known as the “area rule” to the F-102. He had an amazing career spanning most of modern flight, including the development of winglets.
I arrived at the expanding fuselage through a different path. A very long time ago, I was reading a general aviation magazine a short article about a guy who had a Piper Cub airplane that wanted a third seat. So he just cut the fuselage down the center and stretched it wider to make the rear seating area wider. So he ended up with a three seater with the pilot in front, and a double seat in the back. What caught my eye was a single sentence where he claimed the airplane was 5 mph faster after the change. The way it was written, you could tell the writer didn’t d believe it. So I had just got back into Quickie racing with the then new Nelson engine and decided to try it.
I was just developing a design call “Thumper” where I first used it. I wasn’t yet into short fuselages or the pinched “NACA Duct” tail, and the tank was still in front of the wing. But the results were stunning, as if I was flying a clean airplane and everyone else were pulling drag chutes. At that time Dodgers and Revlutions were the hot designs. I took the Thumper to Medford in 1994 and won every heat, and lapped most of the airplanes there. It was radar’ed on the course at 172 mph, while most of the rest were in the high 150’s and mid 160’s.
Bob