How to attach through-wall fins to tail-cone?

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jlabrasca

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I am guessing this has been discussed many times here, but nothing too useful popped up when I searched.

I've got two designs in progress. A 3 inch diameter WAC Corporal and a whimsical 4 inch thing of my own design. Both designs call for fins that conform to the tail-cone. The best idea I can come up with is to build the fin-can assembly separately. Do the internal fillets from the forward end, then couple it to rest of the airframe.

I it has also occurred to me to assemble the tail-cone from sections fitted between the fins.

Is there a better way to do this?
 
Follow the link to see how I did it with my downscale of the Binder Design Velociraptor.

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I used both K'Tesh's info (boy, that looks weird with two apostrophes) and the instructions/build threads for the Wildman sport V2 when I did my Big Daddy based F25 Firelily.

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The best idea I can come up with is to build the fin-can assembly separately. Do the internal fillets from the forward end, then couple it to rest of the airframe.

My L3 rocket was a v2 (with boat tail, obviously). This is what I did.

further details: I epoxied the fins just enough to have them attached to the motor mount, as well as external fillets to hold everything in place. Then I removed the forward centering ring (which was only sitting in place- not epoxied in), and did internal fillets. Then replaced the centering ring and epoxied everything down. This made sure everything was strong enough, and the fin/motor mount assembly was straight.
 
There are good instructions for building the fin can and filleting from the top for the wildman demon 98.

Follow the link to see how I did it with my downscale of the Binder Design Velociraptor.

Thanks (x4). So that's two four votes for a separate fin can assembly, filleted from the forward end?

Thorfire I didn't know the term "injected fillet" Thanks for that. I've looked it up.

Charles_McG -- I like the Firelilly. It should be a 4X cluster, though, yes?
 
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When I built Chester's Cheeto Chaser IV I used cedar strip "fillets" that were epoxied and screwed in place.


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...The F25 was a single motor.

My younger Boyo keeps wanting me to do a 10" full scale F25. :)

That's what I get for trying to show off my rocket-knowledge. In my head, I see the plans for the (F55?) Firelilly in a Doubldeday Science Service pamphlet, possibly checked out from my elementary school library. Its probably confabulated.

My daughter is less specific in her instructions. She's placed an order for single stage 8-fin rocket (none of which may be strakes or canard fins), which requires at least two people to carry to the pad.
 
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