Wrapping a NC with CF

[wighty44]

I'm working on a project that I believe needs to reinforce (protect) the NC to withstand a Mach 1-1.5 flight. Due to the rules involved I must use the plastic NC that came with the Mega Der Red Max kit. My initial thought was to apply a Carbon Fiber wrap over the NC.

Although I've applied CF to cylindrical objects, I'm having difficulty trying to come up with a template that I can use to apply the sheet CF to a parabolic cone and have it lay flat.

I tried looking for a cutout template for that shape, or application techniques, but have struck out. So I thought I'd see what expertise (or suggestions) might come from TRF members...

 

[BLKKROW]

This may not be the answer you are looking for, but if you are in the Mach 1.0-1.5 region for a short amount of time the nosecone will be fine.

 

[wighty44]

Kyle, I'm open to all comments and appreciate your input. I haven't yet had a Mach 1 flight and thought the added protection would be needed. If it isn't then that certainly helps with my options. Thank you.

But I'm still interested in knowing how I might wrap a conical NC with CF...

 

[AlphaHybrids]

I would use a carbon fiber sleeve. You can put it on the nosecone and then pull it taut. Then slather with epoxy.

Edward

 

[tfish]

Years ago my youngest son modified an Estes Fat Boy to fly on Aerotech I435 motors. He needed to use the space in the nose cone to accommodate the length of the motor. Once he cut the "bottom" off the shoulder, the nose cone lost a bunch of it's strength. He ended up glassing the inside of the nose cone to add strength back to it. IIRC he scratched the heck out of the inside of the nose cone to give the epoxy a place to grab onto. He then blew up a balloon inside to smooth thing out.

info only....

Tony

 

[dixontj93060]

This may not be the answer you are looking for, but if you are in the Mach 1.0-1.5 region for a short amount of time the nosecone will be fine.

+1.

 

[fyrwrxz]

Foam it. High temp paint (barbeque/header/block/piston caliper, etc). I would think an airframe of that diameter would have a hard time staying above Mach for very long.

 

[dhbarr]

Foam it. High temp paint (barbeque/header/block/piston caliper, etc). I would think an airframe of that diameter would have a hard time staying above Mach for very long.

It's not the whole NC you need to worry about heating, it's that rounded-over tip. Honestly roughing it up and smoothing it back w/ metallized epoxy would probably get you there ( but again, likely overkill ).

 

[cherokeej]

Generally, nosecone shapes are laid up using long, skinny isosceles triangles over lapping each other.

 

[dlb]

Have NC 38mm(fibergrass) survived mach 2.5, no paint any more, but she ready to rock again...

 

[wighty44]

It's not the whole NC you need to worry about heating, it's that rounded-over tip. Honestly roughing it up and smoothing it back w/ metallized epoxy would probably get you there ( but again, likely overkill ).

What additive is used to metallize epoxy, and do you have a source? This sounds like a plausible (and much easier) option.

 

[dhbarr]

What additive is used to metallize epoxy, and do you have a source? This sounds like a plausible (and much easier) option.

Just use JB Weld most likely, it's already fairly temperature resistant and chock full o' metal.

Disclaimer: this is just me thinking out loud, I haven't actually done this or stepped through the calculations.

Hard to think of a way a harder stronger metallish nose would cause any harm, just didn't want to misrepresent

 

[wighty44]

Have NC 38mm(fibergrass) survived mach 2.5, no paint any more, but she ready to rock again...

Unfortunately the MDRM NC is not FG - it's molded plastic.

 

[rocketguy101]

Generally, nosecone shapes are laid up using long, skinny isosceles triangles over lapping each other.

or...you could use my paper cone technique to cut conical wraps...see the Apogee newsletters #409 and #410

 

[75Grandville]

I would use a carbon fiber sleeve. You can put it on the nosecone and then pull it taut. Then slather with epoxy.

Edward

+1 on this. There is a guy here of the forums who is also a member of UROC who does this, with _beautiful_ results. I've done it myself, however, the results are less beautiful. His advice (we were talking about this very topic about a week ago at a launch) was to only use CF sleeves. The sleeves with Fiberglass add neat colors, but are less stretchy/compressible.

Soller Composites sells all sizes and weights.

 

[wighty44]

...Soller Composites sells all sizes and weights.

Actually I just visited their website and saw a product that may work and take less effort - Carbon nanotube resin. I spent a few minutes on the phone with them discussing that product. They also believed the resin would bond well with the plastic NC.

Now I think I might use the Carbon nanotube resin mixed with CF shards (~1/8"). "Paint" it on, let cure to a tack, and apply a second coat. Then sand smooth, apply a finish coat, then polish.

 

[boatgeek]

The bad news is that for a material that doesn't stretch (say paper or sheet metal), you can't make a parabolic nose cone from sheet materials. You need the desired surface to be made up of cones or cylinders to do it (aka developable) and a parabolic nose cone isn't. That said, carbon fiber cloth before it's epoxied has a fair amount of stretch, so you might be able to make it work. You will have to do something exciting with the very tip of the nose, since otherwise you'd have lots of layers overlapping. Many suggestions above.

 

[rms]

I have flown plastic nose cones to 1-1.5 mach with no issues. Add protection if you want but I don't believe it is required at those anticipated speeds.



Greg

 

[wighty44]

I appreciate the responses from those who have had the "mach experience" and noted the kit NC should be fine. Doing nothing is still an option...

 

[Handeman]

+1 on the doing nothing. If anything, I would fill the top half with expanding foam just to give it some structural stability if you do get near Mach 1.4 -1.5 and it does actually heat some.

 

[Coop]

My instinct is to tell you to foam it and forget it, but I suppose I should ask how long you expect to be pushing that NC at your expected peak velocity. If you had mentioned it, I did not see it...


Later!

--Coop

 

[markkoelsch]

Fill it with two part foam. No carbon fiber needed. Much easier and very effective.

 

[wighty44]

My instinct is to tell you to foam it and forget it, but I suppose I should ask how long you expect to be pushing that NC at your expected peak velocity. If you had mentioned it, I did not see it...

The present model shows the velocity just over 1,200 FPS and at Mach 1-1.2 for 1-1.5 sec.

 

[wighty44]

Fill it with two part foam. No carbon fiber needed. Much easier and very effective.

Any particular brand of foam?

 

[markkoelsch]

Any particular brand of foam?

PML two part urethane. Can also buy it from Wildman.

I suggest you test/play with it a bit first.

 

[ksaves2]

The present model shows the velocity just over 1,200 FPS and at Mach 1-1.2 for 1-1.5 sec.

You don't need to do anything with it for that amount of time. Foam if you want to. If the rocket is tail heavy will add some mass to the nosecone. The PML foam Wildman sells you can adjust the density with the mixing technique.
Kurt

 

[amarillo_rocket]

I've gone over mach with several rockets with plastic nosecones with no issues. These were 38mm and above rockets. Since your kit is an Estes kit with a fairly thin plastic nosecone you may need to put a little foam to stiffen the nosecone. I don't think you will have an issue since it's such a short period of time slightly above mach but the extra insurance of a little foam won't hurt. If the nosecone softens slightly the foam should help it retain it's shape and being thin it will cool quickly.