Madcow Frenzy External Fin Fillets for Slotted Fins?

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o1d_dude

'I battle gravity'
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Building a Madcow Frenzy and have never built a rocket with slotted fins.

I'm now at the point of laying down the external fin fillets and am wondering how I should treat the slots. Do I taper the fillets at the slot as if they are each a single fin? Do I draw the fillets out and bridge the slot?

If you have done fillets on slotted fins I'd be interested in hearing what you did.

Thanks!
 
IMO, Kit the Frenzy's fins are so close together I am going to carry the fillet across the gap. Here is my build thread for the one I am currently building (I will be posting an update in few minutes.

https://www.rocketryforum.com/showthread.php?125496-L2-scratch-built-3-quot-FrenzyXL-clone-that-was-going-to-be-a-Thor-clone

I have made a few changes like the zipperless coupler on the fin can and added a thrust plate.

Edit: Oops, my fins ended up a little further apart than I thought so I may have to split the fillet, as it might be hard to carry it across a 1" gap ( I am not using a kit for my FrenzyXL its a clone)
 
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What's the matter Kit, those flat fins confusing you? :tongue:
 
I tapered the ones on my Frenzy as well between the fins. Looks better IMO.
 
Dunno why I didn't just look through the CJ 3" Blackstar tutorial. D'oh!

Thanks for gently pointing me in the right direction.

Each fin will be tapered separately. I think it looks better, too.

Thanks to all who shared their builds.
 
What's the matter Kit, those flat fins confusing you? :tongue:
Actually, I haven't built a tube fin rocket since 2010 but have been looking at the 4" tuber parts sitting on the workbench...but I like the look of Ari's 4" Bluefin Tuba better.
 
Actually, I haven't built a tube fin rocket since 2010 but have been looking at the 4" tuber parts sitting on the workbench...but I like the look of Ari's 4" Bluefin Tuba better.

Having some withdrawals?
 
Ok, I read the Darkstar tutorial over again, cut some 1" gray PVC conduit, and went to town with the technique.

This was my first time masking off fillets the "scientific" way. Normally I just lay down the tape by eyeball using the LAR method where LAR means "looks about right"....which of course it wasn't.



I have to say this is much easier than what I was doing before with all the tape repositioning and such. Have already learned that rolling the pipe section while marking helps to lay down long marks. I was able to mark two sets of fins before having to apply the the Magic Marker/Sharpie to the pipe again. Great tip. Thanks, CJ!

Tomorrow I will bust out the epoxy and additives and pull some fillets.

For those following along, the "dots" in the joints between fin and body tube are where I injected the internal fillets. I added extra centering rings so as to have a bulkhead at the top and bottom of each fin. This keeps the epoxy from running around inside the fin can.View attachment 263907
 
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Keep it up Kit, your a day ahead of me, so I get to see the results of yours before I do mine..:D

The trick with the fillet shaping conduit I knew about, the one with the sharpie is pure genius (I hope CJ doesn't get offended by being referred to as "genius"):D
 
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Keep it up Kit, your a day ahead of me, so I get to see the results of yours before I do mine..:D

The trick with the fillet shaping conduit I knew about, the one with the sharpie is pure genius (I hope CJ doesn't get offended by being referred to as "genius"):D

I think Crazy Jim would rather be known as a "Rocket Scientist...but not exactly!"

As to my fillets, they will normally pass the 5-10 foot examination, not particularly worthy of praise or critique. The Rusto Metallic Midnight Black and Rusto Stops Rust Crystal Clear Enamel overcoat on my fin cans hide a lot of imperfections.
 
i do them individually.

9863948015_c1f29fe4f5_c.jpg
 
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