Fin edge finishing

[DMKiefer]

Why don’t I see people round the leading edges or from what I’ve seen posted, any edges on the fins anymore. I grew up through the 70s and learned to round all the edges of the fins except for the root edge and I think the instructions even called for that. I know it makes little difference but to me, rounded edges look much better.

 

[dhbarr]

Breaking the edges, rounding, beveling, true airfoiling -- I see them all from time to time.

 

[AfterBurners]

Some models look good with rounded fin edges and others don't.

 

[Spitfire222]

I get the impression that some people are simply more interested in getting the rocket in the air as quickly as possible, so finish work like that is put off in favor of a rapidly ready-to-fly model. It doesn't alter the performance of models that much anyways.

 

[afadeev]

Why don’t I see people round the leading edges or from what I’ve seen posted, any edges on the fins anymore.

I do it all the time, on just about all of my rockets.
The only exception being FG or CF fins that come pre-beveled.

I grew up through the 70s and learned to round all the edges of the fins except for the root edge and I think the instructions even called for that. I know it makes little difference but to me, rounded edges look much better.

Some models look good with rounded fin edges and others don't.

The few times I rushed and left fins square (e.g.: when helping Scouts build and paint their rockets, by the dozen), I could never get an even coat of paint on the square fin edges. Either that, or the paint on the fin edge would chip easily.

Long story short, if I'm going to paint it, the fins need to be either rounded, beveled, or air-foiled.

YMMV

 

[AfterBurners]

I do it all the time, on just about all of my rockets.
The only exception being FG or CF fins that come pre-beveled.





The few times I rushed and left fins square (e.g.: when helping Scouts build and paint their rockets, but the dozen), I could never get an even coat of paint on the square fin edges. Either that, or the paint on the fin edge would chip easily.

Long story short, if I'm going to paint it, the fins need to be either rounded, beveled, or air-foiled.

YMMV

If you stack sand the fins and get all the edges you shouldn't have too much trouble. I always paint the edges first before painting the rest of the rocket. This way I can clearly see what type of coverage I'm getting.

 

[dcastle]

A rocket is an aerospace vehicle. Control surfaces which are not at least rounded are simply wrong ....

 

[Ronz Rocketz]

I have also noticed the lack of rounded edges. It bothers me when I see a Honest John without airfoils, not that my airfoils are the best but I tried.

 

[watheyak]

The only rocket I've ever made that has square edges is my Mega Der Red Max. I spent extra time making them super square with zero fillets. I think MDRMs look funny with rounded edges.

 

[BABAR]

Der MicroMeister, God bless him, used to say that while true airfoiling (teardrop rounded front, tail end tapered to a point) was optimal, rounded forward and rear fins were a great improvement in aerodynamics over flat edges. Rounded edges or flat are much more DURABLE than a true tapered tail. So rounded edges are best compromise between durability and performance.

For LOOKS, it really varies. Some rockets, like FlutterBye, look really good with flat edges. Others don’t.

When I paper fins, I usually do a full wrap around paper, so I leave edges flat. They don’t go as high, but they work fine for me.

 

[Senior Space Cadet]

The rocket I'm just finishing, my first in the last twenty five years or so, has 1/8" thick airfoil shaped fins.
Next rocket(s) I build will probably have 1/16" fins and just round the edges.

 

[Jozef]

The only rocket I've ever made that has square edges is my Mega Der Red Max. I spent extra time making them super square with zero fillets. I think MDRMs look funny with rounded edges.

Not sure what looks funny about this one. Moderately airfield leading edge. Tip and TE are square.

 

[DAllen]

I'm trying to decide the best way to round over some 3/8" thick fins....Current thought is to glue some 3/8" round dowels on them and then fill in the gaps between the round stock and flat edge of the fin. Would love to find some half round trim/moulding in the 3/8" dimension but I don't think anyone makes that. Also considering trying to cut the 3/8" dowels in half lengthwise but that sounds like masochism to me.

 

[Nytrunner]

Also considering trying to cut the 3/8" dowels in half lengthwise but that sounds like masochism to me.

Belt sander! (or power sander of your choice)

 

[neil_w]

Why don’t I see people round the leading edges or from what I’ve seen posted, any edges on the fins anymore.

I think it depends on where you are looking. Lots of folks round, bevel, or airfoil their fins. All of my rockets are rounded.

But ultimately folks do what makes them happy. Some folks fill tube spirals, some don't. Some fill balsa grain, some don't. Some paint, some don't. Etc.

 

[DAllen]

Belt sander! (or power sander of your choice)

Yeah that’s an option I was considering...dowels are super cheap so if I screw one up no biggie. I have a table sander I my try it on later tonight if I can muster the motivation.

 

[Ronz Rocketz]

Airfoils are easy, assuming you’re not attached to your finger tips.

 

[bschultz32]

DAllen, I'm in the same boat as you. I'm currently building a LOC/Precision Mega-Magg with fins made of 3/8" plywood.



When I realized the kit's fins come with blunt leading edges, I was disappointed, but I got distracted by other priorities as the build proceeded. Now that I've read about your plight, I've decided to do something about it. Believe it or not, our solution comes from a DOLLHOUSE manufacturer in Manchester, Michigan! I just placed an order for 3/8" half round basswood on Ebay. The 23-inch-long sections will be here by 06/08/20. I will sand off the paint now on the leading edges and give my fins a proper rounded surface to cut the air with.

On Ebay, search for "Half Round dollhouse 3/8".

I suggest we enter into a gentlemanly agreement that says when we explain to our rocketry brethren how we managed to transform our blunt leading edges into very cool rounded leading edges, we conveniently 'forget' to mention the dollhouse angle.

Bob Schultz

 

[o1d_dude]

Bob, the Mega Magg really lends itself to graphics of the Super Mario character “Banzai Bill” or “Bullet Bill”.

Just saying...

 

[Rocketjunkie]

For sport rockets, I round the fins. If the tip is parallel to the body I leave it square, otherwise it also gets rounded. I save beveling and airfoils for high performance rockets.

 

[RocketTree]

I also round the fins, all except the root edge, of course. Also prefer basswood fins over balsa. You can get the same strength with a thinner profile.

 

[DAllen]

DAllen, I'm in the same boat as you. I'm currently building a LOC/Precision Mega-Magg with fins made of 3/8" plywood.

View attachment 418910

When I realized the kit's fins come with blunt leading edges, I was disappointed, but I got distracted by other priorities as the build proceeded. Now that I've read about your plight, I've decided to do something about it. Believe it or not, our solution comes from a DOLLHOUSE manufacturer in Manchester, Michigan! I just placed an order for 3/8" half round basswood on Ebay. The 23-inch-long sections will be here by 06/08/20. I will sand off the paint now on the leading edges and give my fins a proper rounded surface to cut the air with.

On Ebay, search for "Half Round dollhouse 3/8".

I suggest we enter into a gentlemanly agreement that says when we explain to our rocketry brethren how we managed to transform our blunt leading edges into very cool rounded leading edges, we conveniently 'forget' to mention the dollhouse angle.

Bob Schultz

Hey thanks! Went on eBay last night and ordered some myself.

 

[bschultz32]

DAllen,
My 3/8" half-rounds finally came in from Manchester Woodworks. Now proceeding to add them to my Mega-Magg fin leading edges . . .

Bob Schultz

 

[Alan15578]

Why don’t I see people round the leading edges or from what I’ve seen posted, any edges on the fins anymore. I grew up through the 70s and learned to round all the edges of the fins except for the root edge and I think the instructions even called for that. I know it makes little difference but to me, rounded edges look much better.

I think you hang out with the wrong sort of people, lazy sharp edged squares. You should hang out with more well rounded folks. The only times I use flat edged fins are when they are clear plexiglass and rounding the edges would just mate them more visible.

 

[DAllen]

My 3/8" half-rounds finally came in from Manchester Woodworks. Now proceeding to add them to my Mega-Magg fin leading edges . . .

Bob Schultz

That’s exactly what my half rounds look like that I just got.

 

[bschultz32]

Success! My Mega-Magg's fins now have nice half-round drag-cheating leading edges. Thanks to the dollhouse industry!

Bob Schultz, 06/18/20

 

[jrap330]

Yeah that’s an option I was considering...dowels are super cheap so if I screw one up no biggie. I have a table sander I my try it on later tonight if I can muster the motivation.

If you have a table sander....you did not need to think the issue...way to go....from my shop class in high school....a table sander makes sanding so much easier...problem is....you never know when to stop...so in a second you sanded down to nothing.......dowel is not that good an idea.

 

[lakeroadster]

You might think I'm crazy, but I don't even care
Because I can tell what's going on

It's hip to be square

 

[jrap330]

Concur........

 

[FlyingMonkey]

Square edges photograph better. I always round mine though.