Nosecone template

[dixontj93060]

Not to get into too much detail on this high-performance build, but suffice it to say I want to add a couple of layers of material to this PR VK nosecone (and then likely use a wirebrush/flapper to remove some thickness from the walls internally). In any case, how have you guys/gals made complex curve templates before? My current thought is to use Saran Wrap, mark with a Sharpie and then cut out the template. There is little stretch in the material I am trying to apply (at least on one of the layers) and thus I will be careful not to stretch the Saran Wrap too much. But my real question... Is there a better way?

 

[isobig]

I've used VCP to printout NC templates which worked quite well.

 

[maxvelocity]

Not sure if this will work for what you are trying to do but when I need to figure out the shape of the cloth for a nosecone half to be made in a two part mold I use a piece of paper towel. I press the paper towel in the mold then use a sharpie to mark the edge, cut along the line then trace onto printer paper for a stiffer template for tracing onto fiberglass cloth. Gotta use the nicer more pricey brands cause they conform to the shape where regular paper is too stiff to. Maybe this helps?

 

[SCP]

Another "yeah" for VCP...................

 

[KenRico]

Uhh, cant you add layers to the inside to thicken the walls? It is not plastic or wood that you are 'building up' , am suggesting build in

Kenny

 

[NateB]

I have used this software for making cone templates. https://www.conelayout.com/. It might not get a complex as you need, although you could wrap the material, trim as needed, then sand and fill.

 

[dixontj93060]

Uhh, cant you add layers to the inside to thicken the walls? It is not plastic or wood that you are 'building up' , am suggesting build in

Kenny

I need heat resistant ablative layering on the outside of the nosecone. The inside of the cone holds all electronics and recovery system.

 

[dixontj93060]

I've used VCP to printout NC templates which worked quite well.

Can you please provide a reference link.

 

[dixontj93060]

I have used this software for making cone templates. https://www.conelayout.com/. It might not get a complex as you need, although you could wrap the material, trim as needed, then sand and fill.

Looks like this is conical only, correct?

 

[kjohnson]

Can you please provide a reference link.

https://lmgtfy.com/?q=vcp+rocket

You want that first one...

kj

 

[dixontj93060]

https://lmgtfy.com/?q=vcp+rocket

You want that first one...

kj

Thank you. I thought it was a graphics or solids modeling program and was putting in those search qualifiers which, of course, got me nowhere.

 

[dixontj93060]

https://lmgtfy.com/?q=vcp+rocket

You want that first one...

kj

I am sorry, this program (VCP) is archaic--I had to go into Windows XP emulation mode to run it. Thanks, but no thanks.

In any case, I think I was unclear regarding the use of the word "template." I don't need a nosecone "profile" as provided already in Rocksim, I need a surface area template so I can cut out material to be applied to the complex curve of the nosecone outer area. NateB was close with the program he referenced, but I don't believe it supports Von Karman nosecones, only conical.

 

[kjohnson]

So the way that I make up my patterns for making fiberglass cones is to take the projection of the shape, and make a cross shape of 4 of those joined in the middle that will become the tip. The 4 petals overlap a bit. I usually use at least two layers, rotated to keep the overlaps spread out around the mold. You could use something like this https://www.info-central.org/?article=125 to produce the profile of the petals.

If that's not precise enough for you, you may want to look into some of the pattern development software packages, but they are more likely to find you a solution to a straight cone than to anything like an ogive or secant shape.

kj

 

[dixontj93060]

So the way that I make up my patterns for making fiberglass cones is to take the projection of the shape, and make a cross shape of 4 of those joined in the middle that will become the tip. The 4 petals overlap a bit. I usually use at least two layers, rotated to keep the overlaps spread out around the mold. You could use something like this https://www.info-central.org/?article=125 to produce the profile of the petals.

If that's not precise enough for you, you may want to look into some of the pattern development software packages, but they are more likely to find you a solution to a straight cone than to anything like an ogive or secant shape.

kj

KJ, I appreciate that. I am probably making this way too complicated. I am using very light Kevlar and fiberglass so a bit of overlap isn't going to really hurt much.

 

[ECayemberg]

To elaborate on KJ's point, if you were to measure the diameter at several "stations" along the cone, it would be fairly easy to create the petals with an accurate profile such that overlaps were minimal or non-existant.

For example, using four petals and mostly arbitrary numbers for a 4:1 nose:

Station 0: Base dia of 2.27". Circumference =7.13". Width at station 0 is 7.13"/4 quadrants = 1.78"
Station 4: dia of 1.75". Circ.= 5.50". Width at station 4 is 5.5/4 = 1.375"
Station 8: dia of .9". Circ. = 2.83". Width at station 8 is .7".
Station 10:dia of .25". Circ.= .79". Width at station 10 is .2".

Using a best fit line in CAD, Excel, or other programs will get you close.

Are you using epoxy for the matrix in this application?

-Eric-

 

[dixontj93060]

Well Eric, yes get that, and as much as I like the math... but more importantly given I'm not starting from scratch but have the nosecone in my hands, I figured better doing than thinking in this case. Took some thick plastic, pinched it around said nosecone and marked it. Cut out below fits within a percent or two--good enough for me.

 

[CCotner]

Not to get into too much detail on this high-performance build

I need heat resistant ablative layering on the outside of the nosecone

op:op:op:

In all seriousness, though, you can buy professional grade ablatives.
https://www.dowcorning.com/applications/search/products/details.aspx?prod=01596551&type=PROD
https://www.dowcorning.com/applications/search/products/details.aspx?prod=01096397&type=PROD

These go for sale on ebay fairly regularly. You can also make your own paste-type ablatives using normal or high temperature epoxy and glass hollow microspheres or ground-up cork. These kind of ablatives don't try to peel up layers of fabric in the event of excessive burn-through.

 

[dixontj93060]

op:op:op:

In all seriousness, though, you can buy professional grade ablatives.
https://www.dowcorning.com/applications/search/products/details.aspx?prod=01596551&type=PROD
https://www.dowcorning.com/applications/search/products/details.aspx?prod=01096397&type=PROD

These go for sale on ebay fairly regularly. You can also make your own paste-type ablatives using normal or high temperature epoxy and glass hollow microspheres or ground-up cork. These kind of ablatives don't try to peel up layers of fabric in the event of excessive burn-through.

I appreciate that. May consider for a future build.