mrShrimp Posted July 29, 2012 Share Posted July 29, 2012 Hi! So yesterday the final ingredients for my first batch of APCP arrived. I plan on doing a static composition test in an open area to measure pressure and check for sparks. I read some other threads on APCP, and people seem to frown on the use of PVC casing because it will melt. I don't know how much truth there is to this, but will schedule 80 PVC be sufficient for what I want to do? Thanks! Also, if there is any other general advice on making APCP that people could give me, I would be very much obliged! Link to comment Share on other sites More sharing options...
nater Posted July 29, 2012 Share Posted July 29, 2012 People here frown on the use of PVC because if your motor has a CATO, the PVC will shatter sending sharp pieces of shrapnel into whatever is close by. However, APCP for HPR has a different set of needs than a pyrotechnic rocket. I have the understanding it needs something to withstand a higher pressure than a cardboard casing to function properly. Keep in mind, most of us here have different goals in mind, and use totally different fuels. Link to comment Share on other sites More sharing options...
Nessalco Posted July 29, 2012 Share Posted July 29, 2012 MrShrimp, First, I'd suggest heading over to Rocketry Planet or a similar forum of high power rocketry folk. They have more info than you want about APCP, it's fabrication, and safe use. High power APCP rocket motors are designed to fail longitudinally at 1500psi - otherwise what you have is a potential pipe bomb. Chamber pressures routinely run 650-1000psi - I have no idea how that compares with pyrotechnic BP rockets. Lower than that and APCP burns too slowly. In the open air it burns like a road flare. Somewhere around I have a video of some guys burning a 11 pound chunk of the stuff in a campfire. Took something like 3 minutes. With that being said, it's a very different deal when you put it under sufficient pressure. Though APCP is no longer listed as an explosive, do not underestimate it's potential for damage - I've seen it turn a 2" diameter x 1/8" wall T6061 seamless DOM tubing nearly inside out when a nozzle plugs. You run a very fine balance between an efficient burn and an explosion. Look for PROPEP and GUIPEP on the web. They are tools that can help you with this. Kevin BTW - APCP will burn through an aluminum casing without hesitation, much less PVC. No matter what type of casing you use, a phenolic liner is *highly* recommended. Link to comment Share on other sites More sharing options...
mrShrimp Posted July 30, 2012 Author Share Posted July 30, 2012 (edited) Actually I decided to use a metal casing just for safety's sake. Thanks! EDIT:Nessalco, I just read your post. Thank you for your help first of all, and the PVC I bought was supposed to max out at 370 psi. Good thing I'm not using it 0_0. By metal casing, I mean a short section of plumbing pipe with a cap and a nozzle on the ends. I am confident that this can hold anything short of CL-20, which was used as a propellant if I'm not mistaken. I have seen videos of people successfully launching short APCP rockets with PVC tubes, but they must have just been lucky. Where would you recommend I buy phenolic liner? Edited July 31, 2012 by mrShrimp Link to comment Share on other sites More sharing options...
THEONE Posted August 1, 2012 Share Posted August 1, 2012 BTW - APCP will burn through an aluminum casing without hesitation, much less PVC. No matter what type of casing you use, a phenolic liner is *highly* recommended. I always wondering what type of liner NASA uses on their SRBs Link to comment Share on other sites More sharing options...
nater Posted August 1, 2012 Share Posted August 1, 2012 Where would you recommend I buy phenolic liner? I have bought from Giant Leap Rocketry with no complaints. Red Arrow Hobbies is another shop that supports our local HPR clubs and vends at their launches. Link to comment Share on other sites More sharing options...
mrShrimp Posted August 2, 2012 Author Share Posted August 2, 2012 (edited) Ok, I made two 9cm slugs today from a half pound of ammonium perchlorate. I will have to drill the cores in these ones, but my friend suggested curing the propellant with a rod of some sort in it, to avoid the drilling, then we take it out after the apcp cures. I still have 1.5 pounds of ap left that my friend and I will mix and test over the course of the week, so I was wondering whether this is what others have done? Should the rod be made of a special material, to keep the polymer from binding to it? Thanks! Edited August 2, 2012 by mrShrimp Link to comment Share on other sites More sharing options...
Short5 Posted August 2, 2012 Share Posted August 2, 2012 While you may get some decent advice here you may find doing a search for high power rocketry, or experimental rocketry, or simply "how to make an APCP rocket" may yield a vast wealth of information specific to what you are trying to do. Given that APCP motors require a hard case they have no purpose, that I know of, in pyrotechnics which seems to be most people's interest and expertise here. Link to comment Share on other sites More sharing options...
Mach25 Posted August 3, 2012 Share Posted August 3, 2012 Try this site. I advise getting the book and the software programs http://www.space-rockets.com/cptech.html Link to comment Share on other sites More sharing options...
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