The rudder is 45" tall and 21" deep. Somebody else would have to do the math. I normally have elevons on my rc's and though cuffs have worked great for tip stall, I'm going to try tip fences just for drill. The flat plate design would also lend itself well to a foam and fiberglass/carbon construction, which is more what I have in mind at this time.I like that one a lot, but you are going to need a taller fin and rudder. I think you could also get away with simple triangular inverted-taper flaperons like so, which could help prevent tip stall at low speeds by washing out the outer sections of the wings. That has the makings of a fantastically quick and easy aluminum-tube-and-gusset, fabric-covered sport plane.
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You for sure have the Langley Lippisch L-13/ DM-1 wind tunnel study, but some may like having it here. The image of so called 'Spinning top' 'Peonza' looks rather a concrete building than a flying machine. German flying disc images look most counterfaited, the Schriever's machine is impossible to go airborne, according to experts. 'Urban Legends' Blessings +On the visibility questions with the Piana-Canova, I think it's important to remember that even his designs were not pure diamond shapes. One obvious modification would be to compress the area forward wing area and stretch the aft wing area to make a kite shape that follows the 25% chord of the airfoil allowing a straight main spar from wingtip to wingtip. I would also "snip off the points" on all four corners leaving what is in effect something very close to the Zimmerman planform but made with straight lines. Here is a pure diamond (blue) and the 25% chord kite shape (orange) overlaid on the PC.100:
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Another approach to the visibility issue might be a pylon-mounted pusher engine behind the cockpit, allowing the cockpit to moved as far forward as possible for maximum visibility with clear leading edge sections if needed.
That was just one of the dozen or so flying saucers proposed by AVRO of Canada. They only built a two-seater, low altitude saucer and it barely got out of ground effect. Unfortunately it suffered such bad stability problems that the program was cancelled. Modern electronics might be able to stabliize it in the hover.If we’re going to get into fantasy flying saucers, I’ve always had a soft spot for this little hot rod