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SS 3x24 fin can

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DJ Delorie

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Just thought I'd share this. The solar sailer 3x24 upscale I'm working on has a reinforced TTW fin system. In the photo, you see the laser cut outer BT, into which goes the inner BT with supports pre-glued between the CRs. The supports do two things: First, they provide extra glue area for the fins and "lock" them into the BT, and second, they give me something to glue the outer BT to so it won't warp. The fins (shown) fit through the BT slots and nest inside the balsa supports. Behind the fin can goes a CP-70 and then the engine cluster. The CP acts as a thrust tube between the engines and the fin can, so I won't have to rely on the glue. The BTs were assembled with epoxy, the fins attached with titebond II.

For scale, the slotted BT-70 is 17" long
 

powderburner

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Hey, that slot reinforcement idea is a really good one!
I have tried to do something similar on the insides of the main BT but it is quite difficult (on a low-power model) to get in there and put the strips in the right places. This looks like a good building tip that should be perserved somewhere?
 

DJ Delorie

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This looks like a good building tip that should be perserved somewhere?
That was part of why I posted it here ;-)

On the SS3 I did last spring, I used TTW fins without the supports and after it was all glued up I noticed the bulges in the BT around the fins (i.e. the landing struts didn't fit right). So I had to figure something out to solve that.

Also, woodworking rules - end grain glue is weak, face grain glue is strong.

Oh - missing step - after gluing in the supports, use a block and sandpaper to sand them to the contour of the CRs so they're in just
the right place to glue the BT to.
 

Fore Check

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Excellent idea!

Keep up the good work!

I'm enjoying following your Solar Sailer builds.
 

DJ Delorie

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Well, here's a bonus picture of the "fleet" so far. Smallest to largest: 13mm x 21", 18mm original from the 1970's, 24mm x 5'6" "Solar Sailer 3", and 3x24mm x 8'9". The smallest has sanded primer on it, the largest is almost done being built. The 18mm one core sampled big time a year ago (which triggered the whole rebuild frenzy).
 

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