Large Custom Fiberglass Nose Cone

[DabCat]

I need a large fiberglass nose cone (8" diameter) for my next scratch build. I want to make my own in order to cut down on costs and get more experience with making custom nose cones. My plan is to 3d print a mold, coat it with mold release, then glass the inside with fiberglass cloth. Before I do this, I want to make sure I'm doing the right thing, so I have a few questions.

Anyone who tried this before, did it work well? Any tips, tricks, or improvements?

What other methods does everyone use to make large fiberglass nose cones?

Anyone who made a custom fiberglass nose cone before, how big was it? How heavy was it? What fiberglass cloth and how much did you use? And how strong is it?

Thanks in advance to anyone with answers.

 

[tsmith1315]

A mold is a lot of work to produce a single piece. But you have the advantage of making replacements in the future. Check out John Coker's videos on the subject:

http://www.jcrocket.com/nose-cone-mold.shtml

For a single, I'd be inclined to stack "washers" of foam and sculpt to shape with hotwire/sanding, then cover with glass.

 

[kenstarr]

Check out my method with the stacked washers of foam... https://www.rocketryforum.com/threads/hot-wire-foam-cutter.168908/
Thread is supposed to be just about the foam cutter but the nose cone stuff is in there as well.
Compared to a lot of what I see on the forum, I'm a lowly caveman dragging a club, using rocks and sticks to build a rocket.

 

[David Schwantz]

12" foam NC | The Rocketry Forum

This is how I did it. 6 oz cloth. 3 layers, should've done a couple more. Use resin that will not eat foam.

 

[kalsow]

I don't think Python Rocketry is currently producing nose cones, but their web page has some good tips.

https://pythonrocketry.com/nose-cone-construction
I've built several using similar methods. If I'm building a one-off I start with a wooden dowel as the central axis, add centering rings and tubes to build up the core and shoulder of the nose cone, then add pink foam and turn it to its final shape. Finally, it's covered with fiberglass. If I'm building a plug for a mold, the foam only needs a little glass to make a hard surface for the mold plug.

 

[DabCat]

12" foam NC | The Rocketry Forum

This is how I did it. 6 oz cloth. 3 layers, should've done a couple more. Use resin that will not eat foam.

Thank you, this is really useful to me. I'm definitely going the foam route instead since I plan to make larger nose cones in the future. I have some new questions now.

When you form a foam nose cone, do you form the foam to the exact size you want? Or do you form it slightly smaller to count for the thickness of the fiberglass?

How well did the 3 wraps of 6oz work? Was it too strong or just perfect?

Thank you to everyone who replied.

 

[David Schwantz]

I made the cone the size of my tube since I was going to glass it also. I did 3 wraps on each, size came out perfect but I would now have done 5 wraps on each. Both tube and cone have gotten dings after 5 flights.

 

[DabCat]

What are the advantages to leaving the foam in? I want to cut down on weight as much as possible.

 

[David Schwantz]

Strength and for the most part you will need weight up front anyway.

 

[kenstarr]

I neglected to mention the fiberglass I used for my nose cone was 2 layers of the 9" sleeve from soller composites.
www.sollercomposites.com
It's 9.6 oz/square yard. I've used quite a bit of sleeve from them and I absolutely love it!
I use the epoxy from www.uscomposites.com with either the medium or fast hardener. It won't eat foam like vinylester or polyester possibly will.

 

[David Schwantz]

Ken, how do you use the sleeve? Looked and it has a min and max dia. the min would be a lot larger than the tip of the NC. And at the max will it not spread the weave to much? Thanks, Dave.

 

[kenstarr]

Ken, how do you use the sleeve? Looked and it has a min and max dia. the min would be a lot larger than the tip of the NC. And at the max will it not spread the weave to much? Thanks, Dave.

Ooh, good question I forgot to discuss. This is where things get more difficult. The upper 4 or 5 inches are too small for the sleeve. I debated cutting down the sides so I could wrap it but ultimately used some smaller sleeve that got up near the tip. As for using it... I paint the epoxy resin on the foam center then unroll/slide/fanagle the sleeve down the nose and work the epoxy up through the fabric and wipe off or squeegee the excess. If you can get a second layer on before the first cures that's best for bonding the two layers. As for structural integrity, I can't say. Mine is going to be used on an upscale Der Red Max and I'm looking at a rather low velocity.
Ken

 

[Ez2cDave]

"SORAC" to the rescue !

https://www.rocketryforum.com/threads/12-foam-nc.162415/

Dave F.

 

[DabCat]

Thank you to everyone who replied. I ended up waiting on the project for a while to get some smaller projects out of the way. I used the method with the foam, and I'm very impressed. I finished the cone, but I have not glassed it yet. I'm very happy with the shape, and may do some larger more complex shaped cones in the near future. For anyone reading this and wanting to try it for themselves, I have a few tips based on my experience. Make sure to build your lathe sturdy and accurate. Also, do a lot of passes with the hotwire before sanding. Overall, I love this process and it ended up being much easier than my previous idea. Now I have a lathe and hotwire to do any size nose cones in the future, which is way more useful than a 3d printed mold. Now the real question: does anyone want a build thread for an 8in red max? The plan is to have it done for LDRS and fly it on a 75mm 3 grain L.