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APCP help


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#21 RedAir

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Posted 12 April 2019 - 09:11 AM

Thanks Arthur! I am definitely counting on a few catos before I get it right! I read somewhere that cardboard tubes can take around 1000psi but that seems really high!

Edited by RedAir, 12 April 2019 - 09:11 AM.


#22 gdeputy

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Posted 15 April 2019 - 09:45 AM

Contact Burnsim at  BurnSim@blastzone.org they should be able to help you with installation info.

 

Hey, BurnSim Author here.   Sorry, but it currently only runs on Windows.    Some folks have got it to run under emulators or something, but i'm not a mac guy...

 

The advice to find a mentor and a local Tripoli rocketry club is dead on.    And dont waste your time with epoxy, crappy binder for APCP.   You want R45/htpb.   https://www.rocketmotorparts.com/ is a good supplier, there are others.   Most of us doing 'research' motors are buying supplies from surplus suppliers and then splitting it up.    There's lots of word of mouth, so and so is buying a drum of something, doing a group buy, etc...



#23 Arthur

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Posted 15 April 2019 - 04:01 PM

Remember that if an APCP motor fails while running, there may be a crater, some metal shrapnel and a blast wave. You do not play with one of these in a home environment.

 

The binder is to turn the fuel into a hard but rubbery mass that is slightly flexible enough to stand handling and burning without fracturing.



#24 dagabu

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Posted 15 April 2019 - 06:44 PM

Thanks G, nice stuff! https://www.rocketmo...9_16484450.aspx

 

Arthur, are you speaking of metal rocket motor casings? IMHO, whistle rockets have a much more impressive CATO, APCP is just too slow when going up to have even made the explosives list beyond 'low explosive'. 

 

https://www.atf.gov/.../60711/download


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#25 Arthur

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Posted 16 April 2019 - 12:28 AM

Yes! An over pressured metal case or an under designed metal case will simply fragment, possibly more so at temperature. 


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#26 gdeputy

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Posted 16 April 2019 - 12:49 AM

Yes! An over pressured metal case or an under designed metal case will simply fragment, possibly more so at temperature. 

This is why TRA safety codes require use of 6061-t6 aluminum in cases.  They dont fragment, they split open and flatten out.   In extreme cases there is still the possibility of fragments, but its extremely rare.   I keep a 38mm case that split open in my office to remind me that failure is always an option.   I was way too close to that one when it went bang.  

Folks are doing APCP motors quite often all over the US.   I've personally flown up to 'P' impluse motors, which is about 70 lbs of propellant producing around 70,000 NS of thrust.   Much larger stuff goes up every year at Black Rock launches.  Well, some go up and some go UP.   Good times.  



#27 dagabu

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Posted 16 April 2019 - 04:43 PM

N was our largest, we got shut down in 2006, &*^&%#$&(*^ ATF!!!


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#28 gdeputy

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Posted 17 April 2019 - 09:57 AM

ATF is not in the APCP regulation game anymore.     Tripoli and NAR filed a federal lawsuit and won, to get ATF out of regulating non-explosives, like APCP.  



#29 Arthur

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Posted 17 April 2019 - 10:58 AM

A properly designed casing is great when used with the right nozzle. There are however youtube tutorials demonstrating how to use PVC pipe and fittings, Which I consider suspect!!!

 

A cato with a bottle rocket of say 10 grams content is a bit different from a cato with a high power rocket with 10 to 50 KILOS of fuel inside.



#30 gdeputy

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Posted 17 April 2019 - 11:15 AM

A properly designed casing is great when used with the right nozzle. There are however youtube tutorials demonstrating how to use PVC pipe and fittings, Which I consider suspect!!!

 

A cato with a bottle rocket of say 10 grams content is a bit different from a cato with a high power rocket with 10 to 50 KILOS of fuel inside.

 

Agreed.    PVC is a crappy motor case material, IMO.    Yet, lots of people use it. 






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