Balsa wood fins

[Dee55]

Ok I've got a kit coming that has balsa wood fins. I have about 6 unassbled basla fin rockets. Low powered ones. This kit that I am waiting on has already has cuts in the tube for the fins but the other kits I have does not, I do have a fin alignment tool tho. But any advice on getting the balsa wood fins right. Don't wanna rocket going out of control on launch because of bad fin alignment lol

 

[lakeroadster]

What's the kit you have coming? 4 fins or 3 fins?

If it's 4 this works and is easy to make.

 

[jrap330]

Ok I've got a kit coming that has balsa wood fins. I have about 6 unassbled basla fin rockets. Low powered ones. This kit that I am waiting on has already has cuts in the tube for the fins but the other kits I have does not, I do have a fin alignment tool tho. But any advice on getting the balsa wood fins right. Don't wanna rocket going out of control on launch because of bad fin alignment lol

Sand down the root edge.... Make you fin markings on tube, use jig, pattern with the kit and a door frame or aluminum corner bracket to aid in marking, sand body tube a bit at markings. Use double glue method..apply glue to fin and tube wait a few minutes or until dried and then applied glue to fin.......eyeball straight down the tube and hold the fin on until it adheres before letting go. Or follow instructions on your fin jig...The Black Brant II with shiny/waxy tube took me 4 times before fins adhere to that tube. Worst case I every had. Yes I did not sand the tube. So don't get discourage as I did.

If a fin is slightly crocked and you don't want to reattached it....you rocket will still fly fine, I have 1-2 rockets..no issues in flight.....I am assuming you have NOT flow yet and that is why you are worried.

 

[dr wogz]

for fin aliment, make one of these:

(Go to Post #12 for my aliment jig)
https://www.rocketryforum.com/threads/3d-printed-29mm-fin-can.142087/#post-1720057

 

[neil_w]

All the jigs are great. Generally they are not *necessary* though.

Just make sure you have good *straight* guide marks on the body tube. Ideally, place each fin *next to* line, so you can see both the line and the fin root at the same time. Not only does this allow you to make the fin straight, it ensures consistent placement of the fins around the body. Eyeballs can take you the rest of the way. If it's not 100.000% perfect the rocket will still fly.

This is something you'll get a little better at with each rocket you build.

Another suggestion: use good grabby glue like Titebond II, use the double-glue joint method (which you should, anyway), and the glue will grab pretty quickly and the fin will stay in place pretty quickly. However, make sure the glue is really set or the fin is secured in a jig before you walk away from it.

 

[JeromeK99]

If alignment guides are great and all... but as previously said, not necessary.

Take your time. Mark your tubes. On even numbers of fins, glue them across from each other. Unless they are off by a big difference, your rocket will most likely still fly straight. The more you build, the better you will get. Its a learning experience.

 

[BABAR]

https://www.rocketryforum.com/threads/quickest-way-to-attach-a-fin-or-kill-a-boy-scout.156104/
Jump to Post 28

No amount of effort will save you if you don't draw the lines straight. But once you get the lines straight, here's a trick that just about guarantees fins will be aligned right. You can usually hide the cheater in the fillet once fins are firmly in place

 

[Knuckledragger]

I use a piece of aluminum 90 to lay along the BT to draw the alignment marks then use the same piece with hobby clamps to hold the fins in place while the glue dries. A small piece of blue tape on the tip of each fin keeps them from wiggling out of alignment. I used my V2 as an example cause it was in hand at the time but I've used that on all of my 4F rockets with no problem. If you cut a notch in the center of two pieces of aluminum 90, you could mount all four fins at once. If its three fins, I use bar magnets and a 6" piece of plate steel from the big box store as a base to hold the fins vertical while the BT rest on an old rocket motor case taped to the appropriate height

 

[afadeev]

But any advice on getting the balsa wood fins right. Don't wanna rocket going out of control on launch because of bad fin alignment

Rocket can NOT get out of control due to a minor fin alignment imperfection.
It may not fly as high, or not look as good, but unless you glue your fins perpendicular to the direction of the thrust (longitudinal line of the rocket), or omit a fin or two altogether, your rocket will fly just fine.

Now, if you want to make it look pretty and perfect, then by all means, use a fin jig.
I do. It makes perfect placement and alignment super-easy.
But as other have said - it's not necessary.

Eye-balling the angle works 98% as good!

 

[BABAR]

Rocket can NOT get out of control due to a minor fin alignment imperfection.
It may not fly as high, or not look as good, but unless you glue your fins perpendicular to the direction of the thrust (longitudinal line of the rocket), or omit a fin or two altogether, your rocket will fly just fine.

Now, if you want to make it look pretty and perfect, then by all means, use a fin jig.
I do. It makes perfect placement and alignment super-easy.
But as other have said - it's not necessary.

Eye-balling the angle works 98% as good!

True. Not sure about high power, but on low power rockets, especially with on board video, it is rare (but to me really I impressive) to see a flight with almost no rotation.

Sounding rockets (and some model rockets, I think Apogee SloMo is the most recent commercial version) were sometimes intentionally made to rotate to reduce weathercocking, at a cost of a certain amount of altitude.

https://www.apogeerockets.com/Rocket-Kits/Skill-Level-3-Model-Rocket-Kits/Slo-Mo
$28 plus shipping.