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combatpigg -> RE: 1/2A Biplanes.*** LIMIT***. .010 to .049? *** MAXX LIMIT .15 ***- (12/8/2012 3:39 PM)
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The greatest all around...semi scale RC plane I've ever flown was the Goldberg Ultimate. I believe the structure was purely 0-0-0 between both wings and the tail. The only deviation was a few degrees of right thrust to compensate for the 14 to 15 inch diameter props that many builders were using on it.
Full size span was 54 inches IIRC and I shrank it to about 24" [IIRC] for a 1/2A project. Built it as light as a feather, rigged it with Spiderline pull / pull linkages, HS55s all around, tiny battery & RX, cellophane covering...just did it as light as I possibly could.
IIRC it was 12 ozs RTF.
Tried it with .049-.061 glow..6x3 prop and it was pretty lively but nothing compared to the OS 1.20 powered version
Tried it .049 diesel with 7x3 prop [both TD & AME]..basically the same stuff
Tried Norvel .074 and 7x3 prop..much, much better. Still not enough for KE loops, but now it was capable of everything else in a big way. I still have both of the ones I built hanging in the rafters.
Another 1/2A bipe I built from pictures in a huge book I got at a used book store.
The 1930's DeHavilland Dragon Rapide. It has about 54 inches of span, built 0-0-0, powered with 2 fairly weak TDs fed from a single bladder that has feed lines coming out both ends. All pull / pull linkages, it turned out very light and slightly tail heavy. Not just tail heavy [still very controllable], but "bouncy" in choppy air. So I experimented by filling up the cabin / fuselage with lug nuts and this made it fly better. With both engines running it will hold altitude in KE flight and with 1 engine running it can be held nose up and tilted so that the lone engine running doesn't put it into a spin. 2 TDs running sound cool on this plane that flies like a pretty well powered glider. The engines are hung below the zero line of the plane's vertical CG and they needed considerable down thrust to compensate. I tested for the proper angle with the engines running and the model held at the wing tips loosely to feel for neutral / level AoA. I filed the backside of the Dubro engine mounts to acheive the proper angle. This plane sits in the rafters as well, waiting for another day...it's cellophane covering still looks OK.
I strongly recommend trying both projects if you are a modeler who likes little challenges without spending too much money or time.
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