can somebody explain to me why hybrid rocket motors are regulated by the nfpa? I mean Nitrous oxide and plastic/paper/whatever are NOT explosive as far as I know. Nor it it considered a flammable solid as it doesn't become such until it ignites. I don't think NO2. Sure a hybrid rocket could explode I suppose under the right circumstances, but so can this can of gasoline that I have in the back of my truck. Isn't this another case of over-regulation? Is there any danger of hybrid rocket motors being outlawed because NO2 is a greenhouse gas?
The NFPA (National Fire Prevention Association) is a non-profit organization. They do not regulate anything, but they do develope codes that are used by agencies that do regulate. This includes several codes that cover the manufacture and//or use of rocket motors. Being concerned with fire prevention, there is no requerment that something is explosive. NO2 is an oxidiser, the fuel is flamable, and rocket motors will start fires.
There are several problems with nitrous oxide from the regulatory point of view, although I think the NFPA involvement is far more for flight operations than the motor systems themselves. Nitrous is not an explosive, but does have some rather unforgiving properties that encourage controlled access. It is a strong oxidizer, an anesthetic, an asphyxiant, sought after by certain druggies, and can be used to help create certain categories of explosives. Therefore I am required (I don't know if this is just the distributor I use or everywhere) to keep the nitrous in locked storage and keep an inventory and discharge record. The distributor claims this is a Homeland Security requirement, and N2O is just one of 40 gases on their list. Most of the others are truly nasty stuff. This may be because I am getting medical/industrial grade nitrous, without the odorant. Don't really know.
With that being said, however, access to nitrous is pretty easy. Local speed shops are happy to fill your tank (at around $5/pound). To obtain nitrous from the local industrial supplier I simply had to go down and establish my bona fides -- I provided copies of my driver's license, NAR card, and a nifty package of information I printed off the Internet concerning the use of nitrous in rocket motors. Given that, the distributor was more than happy to sell me the stuff-- at $2.10 a pound.
As far as hybrid rockets exploding, N2O is a monopropellant under the right circumstances, and if a hybrid motor goes "monoprop" you can kiss it goodbye... there will be confetti. The conditions which produce this condition are complex, but the design of monotube hybrid motors can allow this to happen if conditions are just right (or wrong, as may be). A major player in the effect is the gas pressure at time of launch.
BTW, nitrous oxide is N2O, and is indeed listed as a greenhouse gas. NO2 is nitrogen dioxide, some truly nasty, toxic stuff, and a major contributor to air contamination.. As to whether N2O can be outlawed as a greenhouse gas, I have yet to hear that rumbling, although the day may come.
Flyer certification has absolutely nothing to do with LEUP's or any alleged "explosive" properties of propellents. Certification is intended to show that the flyer has at least a minimal level of knowledge and skill for the use of high power motors.
That is not entirely true. The point of user certification is to get users registered and listed so that authorities can round up the usual suspects when the need arises.
Bull. You can get the required user certification to fly hybrids without showing any knowledge of hybrids, of flying of a hybrid motor. I'm not suggesting that hybrid motors should be sold to minors.
Hybrid motors are a pain in the ass (or back) and are lower performing than APCP motors. However, they can be shipped, stored and used by rocketeers who cannot get LEUP storage. Those that can get LEUP storage are still forced to pay a high price for that privilege.
NAR HPR user cerebration expires within a year of NAR membership expiration, so continued use of small hybrid motors imposes the unreasonably high tax of NAR membership. (Please do not get side tracked on membership dues.)
I'm not sure where I would set the bars for "small" hybrid motors. Certainly Hybrid motors of less that 62.5 grams of propellant should be open to purchase and use by adults without any licensing and certification barriers. Since there are no large "explosive" or hazardous propellant grains involved, no hazmat shipping, LEUP storage etc. involved, I would suggest that hybrid motors of up to 4 Oz. of propellant mass should be available to adults without the additional burden of certification and licensing fees. (The FAA LMR limit.)
Now certainly there are still issues with igniters and ejection charges and the matter of what small hybrid motors the market may provide. I'd still like hybrid motors to be certified, for safety and performance assurance. While some advocates may say the future of HPR is not solid, I would say the future of hybrid motors depends on the outcome of ongoing litigation and future regulation and certification issues.
This apparently changed during the BoT meeting at NARAM. But all I have to go on is the recording of the NAR meeting posted by Chris Taylor. I sent an e-mail stating that I thought that their reasoning was flawed but I haven't heard anything in return.
The reason, as near as I can tell, is because NFPA 1125 has a specific section for high power hybrids but not one for model hybrids. There is nothing in any of the NFPA codes that says all hybrids are high power.
Woody, my post had nothing whatsoever to do with our current ATF situation. It was about flyer certs, not LEUPs. The clear, historical fact of the matter is that flyer certification was instituted long before the ATF attempted to assert control over our hobby, and flyer certs never had anything to do with LEUPs or ATF regs. Flyer certs (originally called "consumer confirmation") were intended solely to placate the NFPA. What part of that concept do you have trouble grasping?
It takes me less time to prep a Hypertek motor than it does an AMW or Aerotech reload. I know, I've timed it. Very similar in effort to a PRO38. On the launch pad the setup is similar in complexity to hooking up a standard igniter. The launch procedure is more complex because you have to watch for a complete fill (the most common cause of problems in my experience) and then switch the controller from fill to fire. Yeah, I know... it requires skill. What a pain.
On the flip side, I can purchase and store my Hypertek M grain completely permit free. Most PRO38's, on the other hand, require a LEUP and Storage magazine. Which one is a royal pain?
Yeah. WHEN it all works. WHEN the stem isn't screwed up, WHEN the GSE isn't leaking, etc. etc.. Requires skill...ha ha, Mr. smartass. Requires luck is more like it. You hybrid fanatics are so defensive it ain't even funny.
I have a permit, and I spent less time getting that than I've seen spent in the attempt to launch one hybrid rocket.