Rand Simberg's Article

Someone in another thread refered to this article and posted a link, but Fox News had lost the article, and I've lost the original thread where
I saw the link. Fortunately, the author has a copy on his blog, so I'm posting the link he sent me.
http://www.interglobal.org/weblog/archives/002722.html#002722
BTW, the entire blog is very well done. Worth reading.
Mark E. Hamilton NAR #48641-SR
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I think "blog" is one of the words added to the dictionary this year.
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Jerry Irvine, Box 1242, Claremont, California 91711 USA
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http://www.interglobal.org/weblog/archives/002722.html#002722
Trying to regulate APCP by requiring High Power rocketeers to get a Low Explosive User Permit will substantially increase the number of LEUP's that the BATFE has to process and track. One can also legally buy lots more than just APCP when you hold an LEUP, so the action of the BATFE could potentially end up increasing the amount of Real explosives (which APCP is not) in the hands of the public. I think the real reason for the action is that BATFE is acting like a typical bureacracy - trying to extend its authority, budget and staff. Rocket engines are actually still exempted from BATFE oversight by 27 CFR 55.141-a-8 since they are "propellant actuated devices", an officially acknowledged position of the ATF up to about 10 years ago. The question where this exemption was discussed was taken out of their Q&A document about 3 years ago - after amateur rocketry became a target - even though the PAD exemption hadn't changed. Attempts by the ATF to illegally regulate these rocket motors is the subject of a federal lawsuit filed in 2000 by a couple of amateur rocketry groups. Still no judgment.
Saying APCP is an explosive is like calling dry ice an explosive since I could put it in a sealed soda bottle. APCP is purposely designed to burn without exploding (unlike black powder, which has a high burn rate coupled with a high pressure coefficient - used in the Estes engines and fireworks) or detonating - even when promoted with a blasting cap or det cord (unlike TNT, a true high explosive. If anything, APCP is a little too difficult to ignite and doesn't burn fast enough. I think the fact that the ATF is trying to regulate something that is actually safer than the alternative tells you that the safety of the public isn't their real motivation. Flying these rockets is already well-regulated by the FAA and amateur rocketry has an exceptional history of safety. Contrast it to the number of people hurt each year by Radio Controlled model airplanes, for instance. Posted by Brad Hitch at July 7, 2003 11:33 AM
I agree 90% with Brad Hitch.
Black powder is not an explosive as tested. Only classified as an explosive for "DOT shipping purposes". 1.1D. However a blasting cap will not set it off. It will not sympathetically detonate or for that matter detonate at all. It deflagrates.
Furthermore this poster made a mistake in that BP has a LOW pressure exponent. It burns at close to the same burning rate at a wide range of pressures. That is one of the reasons it is so suitable to small model rocket motors as well as 12 inch guns.
Jerry
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Jerry Irvine, Box 1242, Claremont, California 91711 USA
Opinion, the whole thing. <mail to: snipped-for-privacy@gte.net>
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wrote:

I don't have a strand burner, so to a large extent I have to depend on published material. What I see in Kirk-Othmer (1993, Vol. 10, pg 111) is that black powder typically has a pressure exponent from n=0.25 to 0.5 at 1000 psia and a burn rate of 10-15 cm/sec. On the previous page are listed a number of CP formulations with pressure exponents from 0.2 up to 0.5, but mostly around 0.3 with burn rates of 8 mm/sec @ 1000 psia. Sutton (5th Ed., pg. 263) lists parameters for the CP in the Minuteman first stage as 8.9 mm/sec and n=0.21. So it may have been more accurate to say "higher" pressure coefficient instead of "high" w.r.t. black powder. I think the conclusion that black powder is alot closer to being an explosive than APCP is valid though, due to its higher burn rate and greater increase in burn rate as the pressure rises. Still nothing like nitroglycerin of course.
Brad Hitch
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