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Spencer Original Design

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Rockiedog2

Well-Known Member
Joined
Dec 11, 2012
Messages
2,652
Here's a few pics of the original design I've been working on for not quite 2 years.
Builtup spars mostly copied from the Double Eagle but shortened from 12' to 9'. RV3 tail. Wing area, airfoil(23012), aspect ratio, tail arm, aileron area and control throws are all RV3. Drag wire setup is Pitts. Torque tube aileron control and fully balanced ailerons. O-200 Continental and 70" Warp Drive 3 blade. 27 gal fuel in 2 wing tanks and a header tank. The wing tanks are the exact airfoil shape and won't be covered. That was a mistake...ran into all kinda stuff on that...I didn't foresee how much time and head scratching would go into the tank mounts cause of course they have to bear the airloads of the tank area. And they got heavy as my welder guy had to go to 050 to weld it. 9# each. To do over I would put the tanks in the wing and do 032 and Prosealed riveted seams. Probably save maybe 6# total. The uncovered wing panels weigh 40# each with the tanks installed so that would have been a significant % savings. The strut braced gear has a unique shock strut setup...very light, simple and a bit crude and elegant at the same time. I'll try to post a drawing.
I had the spars, lift struts and gear leg professionally analyzed. The rest of the airframe is pure eyeball engineering and TLAR. This is my 6th build so I do have a fair feel for what will probably work for me altho I would stop short of recommending my stuff to anybody. I have no idea what the redline is....will have to sneak up on that. The formula says the stall speed is 51 mph at 950 GW so that's LSA legal. With flat tip plates and VGs the stall should decrease to about mid 40s. The cruise speed can be kept LSA legal with the GA prop. If you don't care about LSA the thing should easily run up near small Continental powered Tailwind speeds. And oh yeah it's a single seat.
The original design goal was to build it to 500# EW. Last preliminary weighin showed projected 525 so not too far off. Go to light weight accesories and some detail weight reduction and we got near 500. Not too bad for a cabin monoplane that can be considered a fairly serious xcountry and utility plane. But it's bare bones and raw. That's the way I like em. It's really blind on the ground due the steep stance. That due an attempt at the Aviat 110 Special(Monocoupe descendant) look...very studly IMO. And it's narrow geared and tall...I've always liked flying little airplanes that challenge you just a little bit.
The mutt in the pics is my roomie Rockie. He considers himself the inspector. In the first pic he's laughing his a** off that his roomie thinks he can maybe design an airplane. Smart dog...

Any comments, suggestions, observations welcome....I'm a pure shadetree

Joe Spencer in Mississippi



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