Why should I join Tripoli or NAR?

With no offense intended to the OP...

The fact that this individual considers Tripoli's rule against use of PVC for motor cases to be a "limitation [to his] freedom" is exactly why Tripoli has to have a hard fast rule against the use of PVC, among other necessary rules, like certifications.

Too many inexperienced, uninformed, or ill-informed individuals that do not know any better. That's why we need rules. To protect the inexperienced and uninformed, as well as those around them.

To the OP...

Believe it or not, the use of PVC for your motor cases is the biggest limitation you have on your rocketry activities. Running the much lower chamber pressure required to keep the PVC from shattering is seriously limiting the delivered specific impulse of your propellant.

You can join Tripoli, go to some launches, meet some great people, have a hell of a lot of fun, and learn a whole heck of a lot.

Or not.

Your choice.

I am a NAR member, so I don't do research motors. However, I do read the threads from time to time and there was a great one a while back about what happens to PVC if used as a motor case. Someone here might be able to find it. If I recall correctly, each pressurization of a PVC pipe weakens it by about 20%. So after only two uses it is down to about 64% of its original rating. The other problem is that when PVC fails, it shatters and you get shrapnel. Aluminum is used in RMS cases because it rips, but stays in one piece. If you do nothing else, research aluminum cases and switch to those.

Zeus-cat said:

I am a NAR member, so I don't do research motors. However, I do read the threads from time to time and there was a great one a while back about what happens to PVC if used as a motor case. Someone here might be able to find it. If I recall correctly, each pressurization of a PVC pipe weakens it by about 20%. So after only two uses it is down to about 64% of its original rating. The other problem is that when PVC fails, it shatters and you get shrapnel. Aluminum is used in RMS cases because it rips, but stays in one piece. If you do nothing else, research aluminum cases and switch to those.

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Ahhhhhh, I think traditionally PVC is a one time use thing only but I agree with the prohibition in the TRA rules against using it. If anyone is using the stuff more than once that is "REALLY" flirting with disaster. Kurt

I don't get why you would want to use PVC over some kick ass Loki hardware anyway. I mean seriously, sexy annoed blue cases and too sweet for words graphite nozzles verses toilet plumbing.

To the OP, sounds like you already made up your mind. Be safe and fly safe with or without Tripoli. My only real offer is the community side of things. There is a huge pool of knowledge you could tap if you were plugged into it, not to mention things are more fun when there is people around to share in your success.

grouch said:

I don't get why you would want to use PVC over some kick ass Loki hardware anyway. I mean seriously, sexy annoed blue cases and too sweet for words graphite nozzles verses toilet plumbing.

To the OP, sounds like you already made up your mind. Be safe and fly safe with or without Tripoli. My only real offer is the community side of things. There is a huge pool of knowledge you could tap if you were plugged into it, not to mention things are more fun when there is people around to share in your success.

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+1

Teddy