Super Big Bertha homemade fins with tabs, and balsa/posterboard for a 29mm tail section swap.

[86mustang408w]

Well since I needed a tail section and fins, and most companies seem to be out, I just decided to nake my own. I got the grain direction wrong on #3. But with the glue and skins, I feel it will be fine. The 29mm upgrade was just to give myself a little more options. I'm not going to run any H motors in it....yet. But mostly use my 3D printed 29 to 24mm adapter and run smaller black powder.

But back the the fins, I got the 1/4" balsa 10 years ago from balsa machine service but they and other companies still sell it. I chose balsa over plywood. Biggest reason is I don't have the correct tools to do that. But had a hobby knife, and made one template with a tab from poster board off of the best fin on the OG rocket. Then made 4 individual templates from that one out of white dollar tree foam board. They didn't come out precise as I would like but still have to do some sanding, and fitting. Then got a BT-80 body tube I had. Marked and measured fin slots, then cut them. In hindsight I hold off to do those slots after the fins are done to get a perfect fit. But it will be ok. Then I fit the tabs to the 29mm tube, and then made templates on balsa after cutting the tabs to shorten the width. Idk why that number 3 is the wrong grain direction as it was already pointed out. But with those skins on and when that glue dries it won't matter, it will be very strong. Anything enough to break it, will break it anyways at that point regardless of grain direction. Had I not used skins I would have made a new one and put some aerogloss on it for a sealer. But then I used a little drop or two of water in Elmers carpenters glue in a sealable container, and then brushed it on the fin. Putting a little water in the glue makes it a little more easy to work with(I have a bunch of glue and this is nice for fin skins). Then to make sure all the excess glue was out and the surface was flat, I put the fins down on top of wax paper, then used books to put a little pressure on them for a few seconds. Then check the skin placement. Flip it over, brush on glue, and don't be same. After that I put weight in them. Now today ill sand and fit. Ill post more updates but not until later on. You can make own fins,it takes a lot of time and measuring for them to turn out good. Any tips to add, by all means post it up!!

 

[86mustang408w]

Tail section is finished, should have a flight 2morrow.

 

[Raptor 2]

Did you use cardstock 65lb for papering your fins.
When I paper fins I first sand the leading edge to a point. I then fold the paper and insert the leading edge of the fin into the fold and fold the paper down both sides at once and trim the excess all around. This provides a papered front leading edge that is already sanded to a point or rounded. This works well with label paper which has the adhesive already applied to the paper.
I’ve never tried this with cardstock paper.

 

[86mustang408w]

Did you use cardstock 65lb for papering your fins.
When I paper fins I first sand the leading edge to a point. I then fold the paper and insert the leading edge of the fin into the fold and fold the paper down both sides at once and trim the excess all around. This provides a papered front leading edge that is already sanded to a point or rounded. This works well with label paper which has the adhesive already applied to the paper.
I’ve never tried this with cardstock paper.

I'm not sure what it is exactly. Its from the dollar store. I wasn't sure what I would do with the fins, I'm still not. But some builds I used poster board, shipping labels mostly, or copy paper. Then I put CA on the edges, and sand them down a little. Its too much extra work for me and only one good arm to do it that way. But I appreciate the tip. Theres many things I can still do with these fins. I just wanted to get it ready for 2morrow, which it is. But they won't change much. I still have some anding to do, but already did a round of CA on the outer edges and it seems to be good for now plusbits sprayed with sandable primer/filler. I'm getting into plywood more, so this will probably be the last set I make this way for a while.

 

[Raptor 2]

I’m thinking plywood fins are more for HPR rockets. LP And MP both are handle well by balsa and basswood fins reinforced by papering and other finishes. Nice work on your models.

 

[86mustang408w]

I’m thinking plywood fins are more for HPR rockets. LP And MP both are handle well by balsa and basswood fins reinforced by papering and other finishes. Nice work on your models.

Well I had Intended to use plywood! But unfortunately the company I've been using is shutting down, so I had this left over. But the skins over them work out incredibly well. That layer of glue and poster board even with the wromg grain direction on # 3 doesnt matter now. I had never done it bc I figured it was too much work and not necessary, but I've been doing it to all builds since pretty much getting back into this after a 10 years break in May this year. I couldn't have been more wrong about it being a waste of time. I guess it really depends on the rocket, but I would agree plywood and above can really be for minimum diameter high power stuff/beyond(But like I said it does depend on the build). This isn't going to see any huge motors, I feel about 200 feet up an I motor would disintegrate the fins I made. I think it might handle a G, but I'm going to start small and go up. Its finished for a flight, but not finished for good. I'm still thinking about upgrading the shock cord. I could do it like my Leviathan, but would rather have it attached to the eye bolt. This was a build I freshened up, then a fin broke again. So ended with it being 29mm.

I'm kind of using the idea to give most of my rockets even low power fins with tabs. I made one pc fins for my Olympus and cut tube slots/added fin tabs.

 

[86mustang408w]

More balsa fins with tabs, and poster board skins.