Rocket Challenge on Discover

I believe they took it out of context from one of the articles they cited in their basement bomber brochure.

Anecdotal evidence.

You keep saying NFPA sets.

NFPA rented a room that NAR and TRA went to with a team of folks and wrote that crap.

The crap was then submitted to and rubber stamped by, the "full NFPA COMMITTEE" and published in the NFPA codes and made available for sale to all localities nationwide for a fee. A fee that keeps NFPA in cadillacs, condos, airplanes and salaries with teeth.

Believe me when I tell you. This is absolutely NAR's and TRA's doing.

That means they can fix it with the stroke of a pen!!!!!

Jerry

Attender of several NFPA meetings.

If you look at range safety requrements for sounding rockets, guided grockets are worse. Unguided sounding rockets are very reliable and predictable. They go where you point them with modest well understood dispersions. However, guided rockets can go horribly wrong.

HPR rockets are not sounding rockets. Many HPR rockets are of unproven design and/or construction, with unknown performance and dispersion statistics, and without the engineering analysis and testing behind them that sounding rockets have. They can be as predictable as sounding rockets, but more often, anything can happen and they can go anywhere.

Alan

If the rocket is coming in ballistic, there's only one place to look -- up. If there's nothing over head, stay put. Admittedly, a rocket coming directly at you will have a very small cross-section, but that should be off-set a bit by the fact that there would be very little relative movement.

I agree.

To some extent I agree with this, on the other hand I think the person has to bear some blame for not paying attention to the launch.

Which is why they have thrust termination systems.

Which is at the root of the problem in even attempting to limit the range area which needs control and protection.

Brett

Ray is 100% right. MIT did a study with rain with a still person, and a walking person, and a running person, and the faster you travel the wetter you got.

This was instructive to a wide variety of ballistic impact events.

Data matters.

Jerry

Alan scrawled:

This is a good example of a wildly exaggerated hypothetical scenarios being used to justify emotionalized rulemaking. Heads blown off? What you are using to prep your rocket, an entire open keg of BP??

I agree. So why are you exaggerating the dangers of rocket prepping?

It may surprise you to know that I also agree with this. It _does_ look bad to have people smoking while prepping rockets. I certainly wouldn't recommend or condone it. But I do object to concocting wild exaggerations of the danger in order to justify rule-making.

I beg to differ, at least a little, Jerry.

This might be true if we were shooting ballistic water droplets, but we're not.

When you obtain data like this, you need to then look at the underlying reason for the effect. In this case, it's obvious. The water droplet is falling towards the ground at a relatively low terminal velocity (I have no idea of the actual velocity, but if you can see raindrops coming down, it's slow). As you walk forward, you will come in contact with more of the droplets that were falling. In other words, a droplet that just misses your forehead will contact your chest as you begin to walk forward. A droplet that was a several inches in front of you will hit you in the stomach or leg. And yes, if you run faster, you will contact more droplets. However, you can infer an upper-end to this, as the most droplets you could contact would be those that you would come in contact with in the amount of time it takes for the droplet to fall from the height of your head to the ground.

Another aspect of the 'water droplet' experiment measuring 'wetness' simply demonstrates that if you 'spread' the water droplet across an area, you get 'wetter' (i.e., if I'm running, a drop of water will leave a 'streak' in my hair, whereas if I'm standing still, it will (somewhat) stay in one spot due to surface tension, etc.).

This, however, is NOTHING like a rocket coming in ballistically. At the speeds that a rocket would be coming in (if ballistic, not a fouled-up recovery), the amount of time that you would have for the rocket to travel from your head to the ground is so miniscule that it only increases your probability of getting hit by a miniscule amount (finite, but tiny).

Now you run into the Catch-22 of the situation. If someone calls out "Incoming!", if you stand absolutely still without looking up you very marginally decrease your probabilistic chances of being hit (but not enought to matter). If you look up, have time, and actually see the incoming object, then moving just marginally away from its prospective impact point will save you. However, if the object is actually heading for you; and you look up, and either don't have time or don't SEE the object, you're either blind or dead.

BTW, speaking as someone who has had similar situations (i.e., flying in a private plane with someone heading DIRECTLY towards us), it is very hard to see an object that is actually headed RIGHT towards you.

This almost leads me to believe that the safest way to react in a situation where someone yells "Incoming!" is to look up (and keep looking up), and if you don't see the incoming object, run like hell. Keep running until you either see the object or run into a lamppost ().

David Erbas-White

The rules are in an NFPA code that States are implementing as law, based upon previous NFPA code adoptions. That the codes may have been "rubber stamped" speaks to the incompetence of the stamping authority whose job it is to CONSIDER the rules authored by members and/or sub-committees. It is not an individual blame issue, it is a broken process issue. In the context of sitting on the committee, the voting NAR/TRA members ARE the NFPA.

I was amazed the NFPA took it upon itself to incorporate so many extraneous "rules" on rocketry within a fire protection code. It's just like the BATFE trying to regulate an activity instead of a substance.

I've been away from rocketry for too long, I guess. I was not witness to the self-serving bureaucratic takeover of the hobby. Then again, I did see it happen to amateur radio and firearms and am seeing it happen to the Internet; I guess I shouldn't be so surprised.

Our problems are just symptoms of a much more serious disease which is eating away at our society.

Aw, now I've depressed myself. Think I'll just go work on my new delivery system, uh, explosive device, that is, model rocket and get ready for tomorrow's joint live fire training exercise, er, sport launch.

And if you are at a big launch and someone is 25 feet away and has a better aspect ratio of the rocket they will tellyou to run NOW!! If you are by yourself you will look up and have the possibility to take it between the eyes with no help.......there is security in numbers......we continually hear of an RC plane guy who got hit by his own propellor and bled to death because he was 'all by himself'. While larger launches have more people to hit, they have more people to warn anyone in harm's way. Common sense with regard to motor distances and the ability for one human to help another seems to work quite well. IMO Estes are the most dangerous simply because of their small size at it's smallest aspect ratio..........give me the big launch. Humans help other humans, and the LCO MUST have someone with binoculars to track the minimum diameter screamers in the event of an auger in.

I have some nice video of an Estes landing 10 feet from me at an organized launch, didn't have to move, everyone else gave me the info I needed.......if I can find the video I could post it.......the sound is cool. Shhhhhhhhh-thwop

I agree the difference for arocket is miniscule for the velocity reasons you state. But there is one :) At least mathematically.

This was on MythBusters recently.

Joel. phx

Do they really have a formal veto power, or is it just that nobody in the NFPA administration really wants to be seen to be publicly saying "no" to Our Nation's Bomb Squad?

-dave w

Effectively a veto power. The NFPA won't put anything in the model code that conflicts with federal law. Guess who's interpretation of federal law is considered.

That is an overstatement.

most recently that's our old friend David Shatzer, roaming HPR purchasing agent for the BATFE:

David S. Shatzer US Bureau of Alcohol, Tobacco & Firearms Explosives Study Group

NFPA (National Fire Protection Association) Principal, Technical Committee on Explosives Principal, Technical Committee on Pyrotechnics Principal, Technical Committee on Special Effects

- iz

RayDunak> Guess which federal agency has the controlling vote on the NFPA? _Nothing_ gets

A rocket can hit any spot, at least any within the potential ballistic range of a rocket (including any given azimuth via an oddball tip-off or whatever).

I think you better qualify this statement for our government buddies who are not above taking comments out of context.

A rocket may unpredictably hit any arbitrary spot within its range ...

In the absence of a guidance system, where a rocket hits is determined by a myriad of factors which render intentionally hitting a precise spot highly statistically improbable.

I'm sure one of you can word this better, but you get the point.

You blame the rocket for coming in ballistically because in that situation if a person happens to be where the rocket is going to hit, its not that persons fault for being in that spot and its not their fault for not being able to see it and try to run away from it in time.

To some extent I agree with this, on the other hand I think the person has to bear some blame for not paying attention to the launch.

A few: