3" Semi-Scale Bullpup Build

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
How the heck do you exactly duplicate the shape / contour ??

Teddy
 
I'm just curious because I have no experience with wood nose cones. Do you hollow out the center or just leave them solid?
 
How the heck do you exactly duplicate the shape / contour ??

Teddy

One trick that Sandman told me about is to hold a smaller nose cone in your view so you can compare the shape. I've also printed out the nose cone profile from Open Rocket and used it the same way.

186_shaping.jpg
 

Attachments

  • 076.JPG
    076.JPG
    102.2 KB · Views: 19
I'm just curious because I have no experience with wood nose cones. Do you hollow out the center or just leave them solid?

No, they're solid. It would be difficult to hollow them out, and it's something that I've never tried.
 
This is the rocket I turned the smaller elliptical cone for. I call it Gooniot. It's a 3" upscale goony Patriot.

P1050964.JPG

P1100150.JPG

P1100151.JPG
 
I ordered an Aerotech aluminum retainer for the Bullpup. It was only $11.19 at Tower Hobbies. It's a lot nicer than I thought, especially for the price! I actually ordered two before New Years, when they had a free shipping promotion. I should have ordered 3 or 4.

https://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXEVSP&P=7
 

Attachments

  • retainer01.jpg
    retainer01.jpg
    113.5 KB · Views: 17
  • retainer02.jpg
    retainer02.jpg
    192.9 KB · Views: 13
  • retainer03.jpg
    retainer03.jpg
    210.5 KB · Views: 15
  • retainer06.jpg
    retainer06.jpg
    109 KB · Views: 14
One trick that Sandman told me about is to hold a smaller nose cone in your view so you can compare the shape. I've also printed out the nose cone profile from Open Rocket and used it the same way.

The thing to remember is that OR's default nosecones are NOT accurate at all. However, some have made efforts to create accurate simulations of them.

Example: The PNC-60AH

OpenRocket's default shape:
11679468584_301e0e754a_c.jpg




And mine:
17024512132_9751bce6b7_c.jpg


While mine does have that annoying bump at the joint area of the hemispherical front to the Ogive rear of the nosecone, it's certainly a lot closer to the actual part than that pointy Ogive shape.
 
K'Tesh, you get squared away in life, you should get RodSim too.
I still haven't been able to install OR, still thinks it's a pdf, I finally gave up on that.
I'm curious if all of RocSims parts are correct?

I was curious on those AT retainers Quack, thanks for letting all us that don't know how they are.
I assume they work with both reloadable and single use engines?
 
I was planning on using a u-bolt in the forward centering ring for the recovery anchor. But the smallest one I could find is too big. So...

u-bolt01.jpg

u-bolt02.jpg

u-bolt03.jpg

u-bolt04.jpg
 
Someone on the forum told me about this a few years ago. Cable (wire rope) clamps use small u-bolts. I found these at Home Depot. They're just about the right size. I made a backing plate from 1/2" x 1/8" aluminum bar. It'll even fit a 3/16" quick link. But I plan on doing something else that I did once before.

cable_clamp01.jpg

cable_clamp02.jpg

cable_clamp03.jpg

cable_clamp04.jpg

cable_clamp05.jpg

cable_clamp06.jpg

cable_clamp07.jpg

cable_clamp08.jpg

cable_clamp09.jpg

cable_clamp10.jpg
 
I've been feeling under the weather lately (I caught that nasty virus), so I haven't gotten much done on the build. All I've managed to accomplish is to mount the u-bolt in the centering ring.

143.jpg

144.jpg

145.jpg

147.jpg
 
I've been feeling under the weather lately (I caught that nasty virus), so I haven't gotten much done on the build. All I've managed to accomplish is to mount the u-bolt in the centering ring.

Know what you mean,had a cough that went into my chest.I have not had one in a few years.Waiting for the doctor to call something in for me.Hope you feel better my friend.
 
Using nylon spacers as I usually do, to set the position and keep it level, I epoxied the forward centering ring to the motor tube. I also covered the u-bolt nuts with epoxy to keep them from working loose.

155.JPG

157.JPG

159.JPG

162.JPG
 
I got the motor mount epoxied in. I only epoxied the forward centering ring, so I can remove the aft ring later to put internal fillets on the fin tabs. Towards that end, I had drilled two holes in the aft ring to put screws in to pull it out with.

165.JPG

175.JPG

176.JPG
 
When I put the tailcone in, I noticed a problem. I had cut the body tube slightly off kilter. I thought about trying to trim it with an Xacto knife, but decided I could cut it more accurately with the bandsaw. Placing the protruding motor tube against the fence, and using the miter, I rotated the body tube allowing the blade to trim it square. I have some cleanup to do on the body tube, but it seems to have worked pretty good. At least it's better than it was.

168.JPG

170.JPG

172.JPG

173.JPG

174.JPG

166.JPG
 
Got the fin slots cut. Time to dust off the ol' fin alignment jig.

177.JPG

178.JPG
 
Back
Top