Fin alignment on a D Region Tomahawk

[highflyer1968]

Just wondering what people think.

went to my friends place the other day and he is building this rocket and the one fin is not perfectly lined up. Seems to be tipped over a bit. What do you think will happen in flight? Is it safe to fly like this?

your thoughts on this

 

[Bat-mite]

It's safe to fly if the fins are attached securely. It will probably roll a little. Some rockets have canted fins on purpose. No problem that I see.

 

[highflyer1968]

Great I would let him know

 

[Flyfalcons]

It's fine, build on.

 

[DavidMcCann]

It's safe to fly if the fins are attached securely. It will probably roll a little. Some rockets have canted fins on purpose. No problem that I see.

its not canted. its quite possible it'll fly straight. it's tilted.... which affects.... almost nothing.

 

[grouch]

You are missing a prime opportunity to screw with him. Tell him the RSO won't even let him put a motor in it much less fly it. You know, rocket hazing.

 

[lcorinth]

Tilted and canted aren't the same thing. This is a cosmetic problem, not a real flight problem. Maybe it'll roll, maybe it won't (most models roll somewhat), but it will be safe.

My first MPR rocket (Estes Partizon) has a tilted fin. Drove me crazy when I noticed it, but flies fine. I'm finally giving it a paint job. Launch with confidence.

 

[ActingLikeAKid]

Tilted and canted aren't the same thing. This is a cosmetic problem, not a real flight problem. Maybe it'll roll, maybe it won't (most models roll somewhat), but it will be safe.

+1 on this. Like the difference between pitch and yaw, and a big reason why TTW fins are a great idea for beginning rocketeers - a few degrees of tilt away from "pointing at the center of the rocket as you look at the end" isn't going to hurt anything. But "canted so that they aren't parallel to the body" is a big deal and will affect flight a lot.
TL;DR for anyone reading this: If you turn your rocket upside down and hold it vertically, you should not be able to see the sides of your fins.

 

[mpitfield]

Ah the old "good enough". Personally not my thing and if it were mine, before I laid down the fillets, assuming there will be fillets, I would remove the fin and do it properly.

 

[Coop]

This is one of the things that can happen if certain precautions are not taken to prevent it during the build. Next time, I am pretty sure you will look out for this. That is called "experience," which is merely a euphemism for "already screwed up like that before." No big deal, let it fly.


Later!

--Coop

 

[OverTheTop]

As long as it is attached properly it should not be a problem. Don't tell anyone and they will never know :wink:

 

[Bat-mite]

Ah, I should have realized the difference between "tilted" and "canted." I stand corrected. Carry on.

 

[DavidMcCann]

For next time, the benefit of four fins is you can clamp opposing fins to a straight board and make sure they're perfect

 

[DavidMcCann]

Ah the old "good enough". Personally not my thing and if it were mine, before I laid down the fillets, assuming there will be fillets, I would remove the fin and do it properly.

itd drive me bonkers too. But, shouldn't affect flight

fin guides are my favorite thing ever, and I almost want a router or laser just to make them.

 

[Bat-mite]

itd drive me bonkers too. But, shouldn't affect flight

fin guides are my favorite thing ever, and I almost want a router or laser just to make them.

Put my Formula 200's fins on perfectly with just a payloadbay.com template and foam board. Whole thing was less than $5. But if you really need a laser tool .... :wink:

 

[mpitfield]

itd drive me bonkers too. But, shouldn't affect flight

fin guides are my favorite thing ever, and I almost want a router or laser just to make them.

I have a few tools now for fin alignment. The first was the large fin alignment guillotine jig, which has proven pretty handy for cutting paper tubes as well. Beyond that I picked up a cutting mat, a decent metal ruler, some foam board, a can of spray contact cement, and a good supply of blades. As Bat-mite, linked, there are at least a couple of sites where you can input your specs, print a template, glue it to the foam board and cut out a really decent fin guide, which I am sure you are aware of.

But to your desire for a CNC for this purpose, I couldn't agree more, it really does a nice job. I have had Winarcher, AKA Nat, CNC me a few fin guides and the nice thing about them is, they are very accurate, and they last. The foam board ones can also be accurate and last, but compared to Nats, you need to handle them with relative care, and they are only as accurate as you make them.

 

[AfterBurners]

I have a few tools now for fin alignment. The first was the large fin alignment guillotine jig, which has proven pretty handy for cutting paper tubes as well. Beyond that I picked up a cutting mat, a decent metal ruler, some foam board, a can of spray contact cement, and a good supply of blades. As Bat-mite, linked, there are at least a couple of sites where you can input your specs, print a template, glue it to the foam board and cut out a really decent fin guide, which I am sure you are aware of.

But to your desire for a CNC for this purpose, I couldn't agree more, it really does a nice job. I have had Winarcher, AKA Nat, CNC me a few fin guides and the nice thing about them is, they are very accurate, and they last. The foam board ones can also be accurate and last, but compared to Nats, you need to handle them with relative care, and they are only as accurate as you make them.

I tend to eyeball everything, but having a jig of some sorts does help, but I'm just too cheap to buy one. The shipping alone would kill you!

 

[DavidMcCann]

But to your desire for a CNC for this purpose, I couldn't agree more, it really does a nice job. I have had Winarcher, AKA Nat, CNC me a few fin guides and the nice thing about them is, they are very accurate, and they last. The foam board ones can also be accurate and last, but compared to Nats, you need to handle them with relative care, and they are only as accurate as you make them.

I'm pretty sure these are from Nat on my Zodiac. Then the Madcow ones for my tomach were nicely laser'd. The ones i cut by hand are usually fairly nice, but only as good as my hand and eyes.