Quantcast

Fin alignment on a D Region Tomahawk

The Rocketry Forum

Help Support The Rocketry Forum:

highflyer1968

Well-Known Member
Joined
Jul 1, 2015
Messages
103
Reaction score
2
IMG_20170421_103617.jpg



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

Rocketeer in MD
Joined
Dec 5, 2013
Messages
10,986
Reaction score
1,740
Location
Maryland
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.
 

DavidMcCann

Well-Known Member
Joined
May 15, 2016
Messages
2,656
Reaction score
166
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

Well-Known Member
Joined
Apr 9, 2011
Messages
3,800
Reaction score
721
Location
Phoenix AZ
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

Well-Known Member
Joined
Aug 5, 2014
Messages
1,008
Reaction score
32
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

Well-Known Member
Joined
Nov 17, 2015
Messages
1,133
Reaction score
13
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

Moderator
Staff member
TRF Lifetime Supporter
Global Mod
Joined
Jul 7, 2013
Messages
4,903
Reaction score
431
Location
Toronto, Ontario
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

Well-Known Member
Joined
Dec 15, 2011
Messages
1,768
Reaction score
3
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

Well-Known Member
TRF Supporter
Joined
Jul 10, 2007
Messages
4,901
Reaction score
2,134
Location
Melbourne Australia
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

Rocketeer in MD
Joined
Dec 5, 2013
Messages
10,986
Reaction score
1,740
Location
Maryland
Ah, I should have realized the difference between "tilted" and "canted." I stand corrected. Carry on.
 

DavidMcCann

Well-Known Member
Joined
May 15, 2016
Messages
2,656
Reaction score
166
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

Well-Known Member
Joined
May 15, 2016
Messages
2,656
Reaction score
166
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

Rocketeer in MD
Joined
Dec 5, 2013
Messages
10,986
Reaction score
1,740
Location
Maryland
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

Moderator
Staff member
TRF Lifetime Supporter
Global Mod
Joined
Jul 7, 2013
Messages
4,903
Reaction score
431
Location
Toronto, Ontario
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

Well-Known Member
Joined
May 8, 2012
Messages
7,750
Reaction score
425
Location
Somewhere on the planet
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

Well-Known Member
Joined
May 15, 2016
Messages
2,656
Reaction score
166
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.

 
Top