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Scale 112" Republic Twin Seabee (scratch build)

Len

30cc
Hi gang.
A buddy( Rob) and I have been sitting on plans to build a giant scale Sea Bee for a couple years. In the mean time we bought a GP sales Sea bee kit an assemble it with an electric power system. Overall, its a good flying plane, but the lack of prop clearance limits the power and thrust you can have.
Moving to the scratch build project, we took a set of plans and had them blown up to the size we wanted.

Since this is a scratch build, not laser cut parts, no fiberglass cowl or floats, we'll be making our own.

The plane is being designed to accept the EVO 20cc motors. http://www.horizonhobby.com/20gx-20cc-(120-cu-in)-gas-engine-with-pumped-carb-evoe20gx2
They're on order now and I expect to have them this week. We already have an EVO 33 in a Hangar 9 Beaver and couldn't be happier with the performance, so its a no brain-er to use a pair of 20cc motors in this build.
The plan shows a single engine plane, so we'll be modifying to make it a twin.

First thing we're doing is building the wing. This will be the most difficult part of this build so we'll tackle it first.
The wing is a three piece setup, with the center section originally designed to stay with the fuse. We'll change it slightly and make the center section wider, incorporation the dihedral and the two motors. Doing this, the outer wing panels will simply slights right onto the wing tubes.

Off we go.
We cut most ribs out of 1/8 balsa, the rest are 1/8 a/c ply where the motors will attach, The panels will be capped with 1/8 liteply.
After that was accomplished, we clamped them all together with a ply rib on each side and touched up the tops and bottoms with a sanding block. The spar cutouts were also sanded to perfection while they were clamped together.

Setting the ribs aside, we designed out spar system and build the spar box. Our plan is to build an A/C ply spar, which incorporates a hollow for the 7/8 aluminum tube which attaches the outer panels. West Systems epoxy and a bunch of clamps will soon produce a bullet proof center spar.

The build will take time, we only get a couple evenings a week to work on the plane, so I hope you'll stick around and see what the results are.

LEN
RcAerotowing.com
Team Horizon

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Len

30cc
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The spar was allowed to cure and then trimmed to size. Very strong.
Our motors arrived from Horizon Hobbies, wow, these are really nice motors. Excellent machining and great muffler system.


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Since I had a little time, I figured I'd take a look at the center section and start laying out the motor locations and Nacelle/cowl lines.

Believe it or not, I think we're pretty close the first time.
 

Len

30cc
The wing tubes and sleeves arrived are here, so we're now able to start construction of the wing panels.
We've decided to build the two outer panels as a test and motivational move..
The panels are straight forward.
There will be a ply doubler for the wing tube as it passed through the ribs. To cut the center hole perfectly in the ply double, I purchased this slick adjustable drill bit from Hanson, WORKS AWESOME.



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Len

30cc
The tube fits pretty tight between the upper and lower spar's, then we plan on using tri-stock to fill the corner, plus the sheer webs. It'll be pretty much a solid piece when all completed.

If it was only relying on the ribs, there would be a plywood doubler at each rib.

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The left outer wing panel has been just about complete.
Sheeting was added, trimmed and sanded. We're adding knuckle hinging to the trailing edge, so I ripped and angle on a piece of 3/8 tri-stock so it would match the slope of the airfoil, the one on the bottom edge was left square.
After is all sheeted, run a dowel with sandpaper on it to get the correct shape.



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Len

30cc
Making a knuckle hinge pocket is pretty easy and really nice in the end.

Put triangle stock on the TE, top and bottom, sheet the surfaces, then sand the triangle stock with a dowel wrapped in sandpaper until you get the profile you want.
We'll do the mating half later in the build, along with the hinging detail.

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Len

30cc
Ok, so this post will get us up to date on where we are with the build.

The right wing is now at the same point as the left wing and its time to start the center section.

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Here you can see Rob holding the two outer panels up to the center section spar box that was created in post 1.

We'll start the ribs for that hopefully today.

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Len

30cc
Thank you guys for posting your subs, I'm happy to be here and looking forward to hearing your comments as we proceed .

We're always open for comments and suggestions. No question is a dumb one if we don't know the answer.
 
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