Plastic nose cone attachment point

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Joekeyo

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There is some controversy about the molded into attachment point on an PNC as being weak. Is this a real problem? If so, I am interested in any suggestions on how to beef it up
 

cwbullet

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I 3D print the cones and add a beefed up attachment. I guess you could print one and glue it in.
 

Joekeyo

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Great idea if you have a 3D printer. I should have said factory manufactured PNC or something similiar. I really appreciated you taking the time to respond, regardless.
 

K'Tesh

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One of the things that I recommend... Don't attach the parachute to the plastic, and the shock cord separately. I use fishing swivels to attach the shock cord to the nosecone, and another to the parachute, and clip it to the shock cord's swivel. This way the strain of deployment is taken by the metal, and not on the nosecone. This should work from LPR up to HPR (with the swivels swapped out for quick release links), presuming that you've not added lots of nose weight to the nosecone. When you get to the larger heavier nosecones, you should be able to use bulkheads and U-bolts to make the connection.
 

Joekeyo

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Ok. I had to read your reply a few times to get it, but I got it. I use swivels on all my 'chutes, so it will be easy to implement your suggestion. Thanks.
 

K'Tesh

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Now for rockets like the PNC-56 Egg Capsule nosecone (Found in the Estes Scrambler, Eggscaliber, TARC assortments, and the old Enerjet 1340/20 kit), with the tiny ring like the PNC-55AC, I cut away the ring, and using a metal BBQ skewer, make a memorial ribbon shape with a length of that. then drop it in from the top and epoxy it in place (closing the hole). I've had ejection performance tests (blowing from the bottom of the rocket to pop the nosecone off), where the top of the payload section or the nosecone of it come away instead of at the transition/booster joint. Of course taping the nosecone on, and gluing the payload section's cardboard to the transition will reduce the likelihood of this happening, the sealed hole further reduces the chances of this occurring in flight.

This problem of popping the payload section off also occurred with a balsa bulkhead, so I advocate for sealing that off with a piece of paper glued in place (name and email address written on it first) to form the "plug".
 

Weldo

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Might be worth a destructive experiment. If you have an old or spare nose cone try pulling on it til you discover the ultimate strength. It might not tell you much since you don't know exactly how much force is going to be applied during flight but it might at least tell you "it's stronger than it looks" or "it's super weak". Just a thought.

Along those lines, in the I mostly set up rockets thusly... I use elastic shock cords since they are included in the kits I build. One end of shock cord is attached to the body tube and the other end is attached to the nose cone. Then I tie a overhand loop in the cord about 1/3 of the total length from the nose cone. To this loop in the shock cord I snap a parachute. This ensures the nose cone attachment always has some shock absorption.
 

CalebJ

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Now for rockets like the PNC-56 Egg Capsule nosecone (Found in the Estes Scrambler, Eggscaliber, TARC assortments, and the old Enerjet 1340/20 kit), with the tiny ring like the PNC-55AC, I cut away the ring, and using a metal BBQ skewer, make a memorial ribbon shape with a length of that. then drop it in from the top and epoxy it in place (closing the hole). I've had ejection performance tests (blowing from the bottom of the rocket to pop the nosecone off), where the top of the payload section or the nosecone of it come away instead of at the transition/booster joint. Of course taping the nosecone on, and gluing the payload section's cardboard to the transition will reduce the likelihood of this happening, the sealed hole further reduces the chances of this occurring in flight.

This problem of popping the payload section off also occurred with a balsa bulkhead, so I advocate for sealing that off with a piece of paper glued in place (name and email address written on it first) to form the "plug".
Any chance you have a picture of what you're describing with the skewer? Not quite following, but I just finished an Eggscaliber and haven't launched it yet. Would love to ward off any issues ahead of time. Thanks!
 

crossfire

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A toggle bolt with an eye bolt work great and is very easy to do. I have been doing this for years
 

Buckeye

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There is some controversy about the molded into attachment point on an PNC as being weak. Is this a real problem? If so, I am interested in any suggestions on how to beef it up
Depends on the rocket. Estes - not a problem. HPR, heavy - maybe.
 

BABAR

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At least for Low Power Rockets, I never use the "built in" attachment ring. I drill two holes in the cone, sometimes I need to use a curved needle, but I thread a short Kevlar loop through the holes. I have had the "built" in attachments break off easily.
 

K'Tesh

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Any chance you have a picture of what you're describing with the skewer? Not quite following, but I just finished an Eggscaliber and haven't launched it yet. Would love to ward off any issues ahead of time. Thanks!
upload_2020-4-9_6-32-30.png
 
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