Simple cardstock nose cone with bulkhead

[BABAR]

Looking at doing a modification of the CiCi2 glider. No, I am not planning on this to be a card stock build overall. I do however need a very lightweight nose cone for the sustainer and I am thinking that card stock would be a good solution. It is going to go on the front of a 2 inch segment of body tube which will contain the sustainer engine. The problem is that this is motor eject so I will need some sort of bulkhead to prevent the ejection charge from blowing the nose cone off the rocket. Any suggestions on how to create a BT 20 nose cone i.e. that will fit into a B20 tube, Be light, and have a nose cone that won’t blow right through? I was thinking of a piece of card stock bulkhead with dental floss on forward (non motor) side for strength, the floss threaded through the body tube and attached on the outside, with perhaps some glue or a piece of mylar or even just some lighting put on the motor side of the bulkhead the motor to prevent burn through.


Figured I’d use the payload bay transition tool for a guide.

Use zero diameter for forward tube, and bt-20 for the back

https://www.payloadbay.com/transition.php?tube1=0&tube2=0.4460000&length=1
Any hints on mounting a shoulder straight?

 

[Alan R]

I made one of these for my triangle rocket. A cone is not going to be much different.
You need to add a tiny shoulder below your current cone. Below that you add whatever length of shoulder you want. The arc DISTANCE will be the same top and bottom for the shoulder. Doesnt matter much really, because you need a glue overlap.
I would use a compass, point is at apex of cone. Arc length of shoulder is circumference of BT20. I'm guessing that would be very close the same arc as what you have now for the bottom of your nc.
Add a circle below shoulder. this is the bulk head. It should have maybe 3 points extending outward. the points fold up, these are the glue points that attach to the shoulder.

Pic is what I did for my triangle nc... but it was all created with the compass. Closest comparison I have for what you need to do.

 

[Alan R]

something like this? ..

 

[GlenP]

Looking at doing a modification of the CiCi2 glider. No, I am not planning on this to be a card stock build overall. I do however need a very lightweight nose cone for the sustainer and I am thinking that card stock would be a good solution. It is going to go on the front of a 2 inch segment of body tube which will contain the sustainer engine. The problem is that this is motor eject so I will need some sort of bulkhead to prevent the ejection charge from blowing the nose cone off the rocket. Any suggestions on how to create a BT 20 nose cone i.e. that will fit into a B20 tube, Be light, and have a nose cone that won’t blow right through? I was thinking of a piece of card stock bulkhead with dental floss on forward (non motor) side for strength, the floss threaded through the body tube and attached on the outside, with perhaps some glue or a piece of mylar or even just some lighting put on the motor side of the bulkhead the motor to prevent burn through.


Figured I’d use the payload bay transition tool for a guide.

Use zero diameter for forward tube, and bt-20 for the back

https://www.payloadbay.com/transition.php?tube1=0&tube2=0.4460000&length=1
Any hints on mounting a shoulder straight?

You have a 2” tube with the engine, how much length is there remaining for a nose cone shoulder?

 

[BABAR]

You have a 2” tube with the engine, how much length is there remaining for a nose cone shoulder?

In normal cases thus would be a good question, in this case I only need enough motor in the tube to keep it aligned until apogee, then motor ejects. I would prefer as little shoulder as I can get away with, but I need a bulkhead.

 

[Alan R]

In normal cases thus would be a good question, in this case I only need enough motor in the tube to keep it aligned until apogee, then motor ejects. I would prefer as little shoulder as I can get away with, but I need a bulkhead.

just draw one (outline your bt or use a compass), sand it down a bit and glue it inside your cone

 

[Alan R]

Also, I didn't see a glue overlap (join tab) on your cone. .. https://www.blocklayer.com/cone-patterns.aspx

 

[GlenP]

Okay, try this pattern for the Centuri Bug X-24 “Page 3” - another kind of rear eject “glider” ...just cut the motor tube to length. If you coat the inside with a thin layer of white glue you don’t really need a bulkhead, but you could add a cardstock 5 or 6 ply disc if you wanted just below the coupler/glue tab/thrust ring between the tube and nose.

https://forums.rocketshoppe.com/showpost.php?p=206788&postcount=17
It appears that the CiCi 2 design has a vent hole on the side of the sustainer engine mount tube, (as well as on the booster for gap-stage venting) maybe that helps relieve some of the ejection pressure on the sustainer?

 

[grapetang]

If your paper cone is strong enough and the engine is loose enough to eject easily, you won't need a bulkhead nor much re-inforcement.
Options if you do:

• use paper tabs on the inside (or outside) reinforcing the nose/tube joint
• use a thin 1/8" thrust ring with a balsa or heavy cardstock bulkhead in front

My Starfury nosecone was subjected to the ejection charge for rear-eject and it was OK.
Parts Picture
Post #12, https://www.rocketryforum.com/threads/trf-summer-build-off-babylon-5-starfury.134533/