Swoopy Cardboard Fin BT-60 Rocket Scratch Build

[brockrwood]

I am starting a third rocket project in less than two weeks. Not bad for me!

I have been noodling the idea of a simple, BT-60 rocket but with decorative “swoopy”, “diesel-punk”, Flash Gordon/Buck Rogers style fins.

I hand-drew the shape I wanted and then traced it onto dense, stiff, 3/32” cardboard.

I cut out three of these fins using very heavy duty scissors. (I did not have the patience to use the hobby knife on this very dense cardboard.)

I have an Estes 18” body tube and the Estes three nose cone pack to choose a nose cone from.

I have a 24mm motor mount and other parts needed.

Question: Which nose cone looks most appropriate for a Flash Gordon/Buck Rogers sort of rocket?

Question: Can I use Elmer’s Carpenter’s Wood filler on the cardboard fins? They have a slightly rough texture. I am going to try it unless there is a reason not to. I think I had better try to fill them before gluing them on.

Question: No stuffer tube needed? I think this bird will be light enough to fly on B6 or C6. I may fly it on one of those engines using an adapter. The body tube is only 18” but it is a BT-60. A B6 or C6 ejection charge will eject the nose and the laundry without a stuffer tube, don’t ya think?

 

[les]

Question: Which nose cone looks most appropriate for a Flash Gordon/Buck Rogers sort of rocket?

Question: Can I use Elmer’s Carpenter’s Wood filler on the cardboard fins? They have a slightly rough texture. I am going to try it unless there is a reason not to. I think I had better try to fill them before gluing them on.

Question: No stuffer tube needed? I think this bird will be light enough to fly on B6 or C6. I may fly it on one of those engines using an adapter. The body tube is only 18” but it is a BT-60. A B6 or C6 ejection charge will eject the nose and the laundry without a stuffer tube, don’t ya think?

From my point of view, the "pointiest" cone (the one that is closest to the body tube)

Try the filler on a piece of scrap cardboard. Make sure you do both sides at the same time to avoid warpage.

For the length of the body tube shown, I don't think you need a stuffer tube,

 

[brockrwood]

For paint, I am thinking of going with a metallic copper color paint I have in inventory. Again, I am trying for a “Flash Gordon” look.

I wonder if there is a little spaceship “cockpit” or “canopy” I can print out onto cardstock and then glue onto the body tube or nose cone (would be easier to glue to paper body tube).

 

[kuririn]

Kinda reminds me of the Space Cruiser Excalibur.
http://www.spacemodeling.org/jimz/est1339.htmThere's a canopy template you can use with that or choose a template from one of the other plans.

 

[neil_w]

Try the filler on a piece of scrap cardboard. Make sure you do both sides at the same time to avoid warpage.

Yes, I'd be worried about the water content of the CWF not being a good match for cardboard (I am not a fan of cardboard as a fin material in the first place.)

An alternative is to treat with CA and sand smooth... then use CWF on top of that to finish if necessary (might not be).

 

[kuririn]

Yes, I'd be worried about the water content of the CWF not being a good match for cardboard (I am not a fan of cardboard as a fin material in the first place.)

An alternative is to treat with CA and sand smooth... then use CWF on top of that to finish if necessary (might not be).

Or paper the fins.

 

[brockrwood]

Yes, I'd be worried about the water content of the CWF not being a good match for cardboard (I am not a fan of cardboard as a fin material in the first place.)

An alternative is to treat with CA and sand smooth... then use CWF on top of that to finish if necessary (might not be).

Hmm. I have used this same type of cardboard (back of a legal pad) for fins on a previous rocket. I did not fill the fins in any way. Just primed and painted. The fins are sturdy enough but the “ridges” in the cardboard are clearly visible under the final coat of paint.

 

[DigBaddy]

For paint, I am thinking of going with a metallic copper color paint I have in inventory. Again, I am trying for a “Flash Gordon” look.

I wonder if there is a little spaceship “cockpit” or “canopy” I can print out onto cardstock and then glue onto the body tube or nose cone (would be easier to glue to paper body tube).

Perhaps you can borrow how I made the cockpit in this build. Pretty easy to do.

https://www.rocketryforum.com/threads/digbaddys-retro-thingamabob-build-thread.172391/

 

[brockrwood]

Or paper the fins.

If I paper the fins, do I still fill them in any way? I would still have to fill the leading edge, no? The “swoopy” shape makes these a pain to work with.

I used the tough cardboard because

a) I hsve a lot of it; and,

b) I feared the long, thin tails of the fins would break off if I used balsa.

These cardboard gins might bend or even crease, but I don’t think they will break. If a fin bends after a hard landing, I will just bend it back. .

 

[kuririn]

Search postings on papering fins in this forum by K'tesh and Neil_w.
They are the gurus, and I use their tips regularly.
Don't need to fill the fins before papering because the paper is the smooth surface you're trying to get. The adhesive you use will give the fin added strength. The exposed edges need to be filled and sealed. Some use white glue, some use CA.
If the cardboard fins crease just straighten them out, sand off any paint/primer to expose the paper, paint with CA, sand smooth and touch-up with a brush, and you're good to go.

An alternative to rough cardboard is glossy matte mat board. Just primer and paint:



Work smarter, not harder.
EDIT: Changed glossy to matte. Added pic of mat board fins on my clone A.S.P. build below.

 

[brockrwood]

Search postings on papering fins in this forum by K'tesh and Neil_w.
They are the gurus, and I use their tips regularly.
Don't need to fill the fins before papering because the paper is the smooth surface you're trying to get. The adhesive you use will give the fin added strength. The exposed edges need to be filled and sealed. Some use white glue, some use CA.
If the cardboard fins crease just straighten them out, sand off any paint/primer to expose the paper, paint with CA, sand smooth and touch-up with a brush, and you're good to go.

An alternative to rough cardboard is glossy mat board. Just primer and paint:
View attachment 528376
View attachment 528377

Work smarter, not harder.

Where do I get glossy matt board? Hobby Lobby?

 

[kuririn]

I got some from Amazon

Where do I get glossy matt board? Hobby Lobby?

Correction: Mat board usually comes in a smooth matte finish. (See what I did there?) Doesn't need to be glossy to get a glossy finish. Does need to be smooth. I got some from Amazon, but art stores also carry it as well as craft stores. Check your local Hobby Lobby.

 

[Woody's Workshop]

1/32 balsa is available in 3 and maybe 4 inch widths. Make your own balsa ply wood and 3/32" fins (Standard).
Would be a good choice for this fin design.
The single paper sheet wouldn't work well with this fin design, but a 2pc would be just fine.
You can also get 1/16" balsa, and you could laminate cereal box cardboard to them with the finished side out for light sanding and painting.
A couple alternatives to just cardboard core and an rely on bending a "Kink" back out of cardboard.
As for the nose cone, I would use the short one. I think it would look better with those fins.
I would also use a long engine mount tube, it will help keep recovery towards the top and help with stability.
These are just my own thoughts, and I've built lots of scratch rockets that failed not taking everything into consideration.
But I haven't had a failure in years, unless you consider loosing them to the wind and tree Gods!

 

[BABAR]

Great design. No matter what you make them out of, those thin fin tips are going to be delicate. Wondering if you could use some chopsticks or other material to add strakes (maybe punkish ones?) that might strengthen them.

 

[brockrwood]

Wondering if you could use some chopsticks or other material to add strakes

I like that idea! Maybe those big, decorative toothpicks?

 

[BABAR]

Configuration 3 looks both practical AND cool!

 

[cls]

I use Bristol Board for making 3D stuff like canopies, odd cones, transitions, etc Michaels craft stores has it in the art paper section.

It's sturdy stuff: long fibers, medium weight, but not too thick and heavy. Takes primer, paint, and CA and wood glue very well.

I remember TVMs book has a nifty section on making folded paper stuff for rockets.

The general area is called pattern development. Study it, you'll learn how to lay out lines on 2D material so it does the right thing when folded in to 3D shapes. Girls use it to make garments, boys can use it to make all kinds of stuff.

 

[DigBaddy]

Configuration 3 looks both practical AND cool!

Agreed!

 

[lakeroadster]

I'd suggest just using Rustoleum 2 in 1 Filler & Sandable Primer on the fins. When you first spray it, it will look like it has lint in it. No worries. sand it and spray it again. After a couple applications it'll look fine.

I did this on the coupler I installed over the damaged tube on my Rocket Sled Rocket. It looked fuzzy, but after I sanded it and reapplied the primer it came out great.

P.S.: Those fins, and the swords... has a Klingon look to it.

 

[BABAR]

P.S.: Those fins, and the swords... has a Klingon look to it.



I can imagine that rocket would just tear around Uranus!

 

[lakeroadster]

Wait, @BABAR, you're misquoting me... (stupid new computer software)

 

[BABAR]

Wait, @BABAR, you're misquoting me... (stupid new computer software)

Sorry, when I erased the extra stuff, I couldn’t get the cursor out of the box.

 

[lakeroadster]

Sorry, when I erased the extra stuff, I couldn’t get the cursor out of the box.

Yep... new software update makes this a pita.

 

[brockrwood]

Or paper the fins.

@kuririn The paper is drying on the fins! I will let you know how it turns out tomorrow!

 

[brockrwood]

@kuririn The papered fins are ready to trim!

(Thought: Should I have just papered the whole sheet of cardboard, front and back, and THEN cut out the fins?)

 

[Jeff Lassahn]

(Thought: Should I have just papered the whole sheet of cardboard, front and back, and THEN cut out the fins?)

I do this a lot with balsa fins. I draw up a fin template on a piece of paper, glue the template to one side of the balsa, glue another piece of paper to the other side, let it dry, then cut the fins along the template lines.

It works great, but you have to be careful to glue the two sides without waiting too long and weight everything down to keep it flat when it dries, otherwise things tend to warp while drying.

One thing I really like about this method is that you don't have to retrace the template pattern onto the fin stock.

 

[brockrwood]

Cutting ‘em out.

Definitely going to just paper the whole sheet of cardboard next time. Then I only have to cut out the fins one time.

 

[brockrwood]

I do this a lot with balsa fins. I draw up a fin template on a piece of paper, glue the template to one side of the balsa, glue another piece of paper to the other side, let it dry, then cut the fins along the template lines.

It works great, but you have to be careful to glue the two sides without waiting too long and weight everything down to keep it flat when it dries, otherwise things tend to warp while drying.

One thing I really like about this method is that you don't have to retrace the template pattern onto the fin stock.

Great idea! Just print out the fin template sheet of paper and glue THAT to the material you are going to use for fins. That saves two steps!

 

[Jeff Lassahn]

When I'm feeling ambitious I'll lay out all my fins and stuff in a computer drawing program then print that out and glue it to the fin stock. Presto, all the fins are the same shape and size and everything ends up with the wood grain going the right direction, unless I messed up the original drawing. If you're using cardboard you don't care so much about grain direction but it's still a convenient way to do stuff.

 

[brockrwood]

When I'm feeling ambitious I'll lay out all my fins and stuff in a computer drawing program then print that out and glue it to the fin stock. Presto, all the fins are the same shape and size and everything ends up with the wood grain going the right direction, unless I messed up the original drawing. If you're using cardboard you don't care so much about grain direction but it's still a convenient way to do stuff.

My cardboard (stiff back of a legal pad) actually has a grain. I discovered this while working with it.



It is definitely easier to bed longitudinally, “with the grain” than perpendicular “across the grain”. Just like balsa. Or a ham steak.

Unlike balsa, the cardboard will bend but it won’t “snap off”.

I am liking stiff carboard more and more as an LPR building material. It is cheap (or free), easy to work with, and not prone to breaking or tearing.

Downside: It is heavy. The cardboard fins weigh a lot more than comparable balsa fins.