RE: Optimal Fuselage Design
Frank,
I don’t recall seeing any GA factory tin airplane with an expanding the width fuselage. Every GA airplane that I have ever sat in was narrower in the rear seat than the front seat Of the three mentioned, the Cherokee is by far the slowest. I flew one from the right seat some and can only describe it as being similar to driving a station wagon with four flat snow tires on a muddy road.
Looking at a three view of the Shark designed by Harvery Mace (first flown in 1970), I see the widest point of the fuselage at about the 1/3rd point of the wing. It had wing fillets and a very low aspect wing. It only qualified at 198 mph. He sold it and bought a BOAT, so I guess it’s speed was not so great.
The Nemesis does have the expanding width fuselage. I assume that this was intentional, though when I met Jon Sharp, I was surprised at how big a man he was (around 6’ 2” or 3”, 200+ lbs.). So his airplane cockpit was much larger than most Formula One designs, where they shoehorn a smaller pilot into them.
Lancair uses fillets, but they do pinch the fuselage behind the wing to reduce surface area. But they also start to contract the fuselage width before the trailing edge of the wing.
On Quickies, most meet the height requirement of the rules where the wing is thickest, not at the trailing edge. Meeting the quickie width requirement at the trailing edge to lower drag was not widely known in RC pylon racing circles before I published it in Model Aviation in ’98. You can look it up in AMA’s digital archive. No kits or designers used it prior to that publication, and only a racers in Northern California through Washington had seen it. It always surprised me how slow people were to adapt the concept. I think Chuck Bridge was the first with the Vortex, but I left the area and pylon racing for about three years during the ascension of Randy, though I did call him a win in the ’98 or ’99 championship race
I have since found a really good collection of works on drag reduction written by Bruce Carmichael. It is called “Personal Aircraft Drag Reduction”, self published in 1995. It is 200 pages of charts, graphs, sketches, articles, and references that compose his entire life’s work. Unlike most tomes on the subject, he dives into fuselage design as well as the wing that everyone else seems to stop at. In his final comment on intersection drag he agrees with what I had already found. But his best advice was “Don’t do nothing dumb”.
Bob