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PRE-FABBED FIN FILLETS? DO THEY EXIST?

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ozwald

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Greetings All. It would seem that last week I was surfing a rocket vendor and thought that I saw pre-fabricated or printed fin fillets that have the radius and can be glued or be made removable. I am building my FB BB II with a removable fin/motor mount module that can be removed and the fillets would be mostly aesthetic but serve a minor structural use. Am I dreaming or has anyone else seen something like this? Any help will be appreciated. Thanks Oz
 

T-Rex

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I have not seen them prefabbed, but it stands to reason the you could use some triangular balsa or basswood to make them. Just sand one side to match curve of the body tube. I would also guess that they could be 3d printed though that could be costly.
 

ozwald

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I have not seen them prefabbed, but it stands to reason the you could use some triangular balsa or basswood to make them. Just sand one side to match curve of the body tube. I would also guess that they could be 3d printed though that could be costly.
That's actually a great thought but I know I saw some somewhere, driving me mad :)
 

mikec

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That's actually a great thought but I know I saw some somewhere, driving me mad :)
I thought Giant Leap had something like this at some point, I can't find it on their website now.
 

Winston

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I have not seen them prefabbed, but it stands to reason the you could use some triangular balsa or basswood to make them. Just sand one side to match curve of the body tube. I would also guess that they could be 3d printed though that could be costly.
I made an openSCAD fin generator that implemented a fillet, but I eventually plan to make it into a fin can generator since I don't trust fin/body tube adhesion for the entire fin/fillet unit. While PLA itself is very strong, I don't trust epoxy adhesion to it although surface roughness could intentionally be designed in to help with that. Because of the removable supports required under the curve of the fillet during 3D printing of the fin shown, the underside won't be perfectly smooth anyway, but I still don't trust it enough.

 

rstaff3

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I saw an 11.5" diameter rocket that used moulding strips as fillets. They were screwed down, no steenkin' glue required.

I know this is not helpful, but I couldn't resist.
 

ozwald

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I saw an 11.5" diameter rocket that used moulding strips as fillets. They were screwed down, no steenkin' glue required.

I know this is not helpful, but I couldn't resist.
Actually, you are not far off from what I want to accomplish. I am building the motor mount and fins into a coupler that will slide into the bottom of the airframe. Since I want no external fillets because I have a wrap I don't want huge fillets on the portion of the fin that meets the tailcone. Was thinking assembling then screw on some fillets as a finish and to assist the lower fin interface
 

RocketFeller

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ImageUploadedByRocketry Forum1489225644.165046.jpg

ImageUploadedByRocketry Forum1489225739.556938.jpg

These aren't exactly fillets, but I used cedar strips glued and screwed to the tail cone and fins on this rocket.
 
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