Rocket Challenge on Discover

I am not ignoring you - I am giving it some thought. The crux of the problem it to ensure that no one is unprotected in the potential impact area. Three ways to solve this:

1- figure the potential impact area and keep people out 2- provide protection 3- make impacts safe even after a failure

There are problems with all of these. A combination of the first two is used on professional ranges - people are kept out of potential impact zones, and the impact zone it limited by flight termination if the trajectory exceeds the restricted area. People who cannot, but virtue of the task, stay out of the impact/explosion zone, are provided protection. 3 is just not practical beyond modrocs.

I see no reason that a similar approach can't be followed by HPR. The only real challenge it coming up with some way of limiting the trajectory without resorting to a flight termination system - which is clearly impractical.

Brett

Reply to
Brett Buck
Loading thread data ...

Again, Ray, you are going down a slippery slope where you don't have the expertise to be commenting on safety. A whole can of BP has no place at a launch. Only a small amount is needed for all the ejection charges for the flights made by someone for a whole weekend. People should be encourages, if not required, to leave the whole can home. It doesn't take a cigarette to set it off... just a dry day in the desert. A can of BP will remove all the windows in a vehicle, or a limb of a person.

Some>

Reply to
John DeMar

Your units are in acceleration times energy, not a common unit. Typically, the energy in a moving object is expressed as kinetic energy and the units are in foot-pounds from the equation:

ke = 1/2 m * v^2

A .44 magnum has about 500 ft-lbs of muzzle energy, depending.

With that as a reference, a 50lb rocket at 40fps contains about 1242 ft-lbs of energy. At 400fps it is a hundred times that. Scaling down, your Alpha prang example would posess about 39 ft-lbs of energy and the modroc under chute, about .2 ft-lbs.

The danger from kinetic energy is from how much of it a target absorbs and how the absorbed energy is dissipated. A bullet dissipates all of it's energy over a very small area. A simple punch can generate enough energy to kill someone, but usually doesn't unless there is a knife or other weapon in the hand to focus the energy on a small area.

Reply to
Gary

"Various modeling events"???

What are they doing hit roofs?? Sounds like your locals need to move their launch site. Also sounds like the individuals involved need to take more personal responsibility for their flight failures instead of dragging the insurance into it.

Nope, but the fact that a human can watch for the rocket and move out of the way is a very valid counter-argument.

We do as much as possible to limit risk, but it can't be eliminated entirely.

The solution to this is for people to pay attention.

First off, this is NOT a professional endeavor. It's a sport, and risk is an accepted part of it just as there is risk in hunting, racing, skydiving, and just about any other recreational activity. It isn't possible to eliminate all risk without eliminating the recreational aspect of it.

Secondly, your claim that the range did not meet the criteria of "one mistake does not result in serious injury or death" is clearly false, as there _were_ mistakes and none of them resulted in serious injury or death.

Reply to
RayDunakin

lbm, not lbF - since I was simply comparing to one another.

Ok. 1 oz alpha = .0625 lb = .00194 slugs 50 lbf HPR model = 1.554 slugs 160 grain 30-06 bullet = .022864 lb = .000711 slugs

.5*.00194*(20 fps)^2 = .3885 ft-lbf (alpha under chute) .5*.00194*(200 fps)^2 = 38.85 ft-lbf (alpha lawn dart) .5*1.554*(40 fps)^2 = 1243 ft-lbf (hpr model under chute) .5*1.554*(400fps)^2 = 124320 ft-lbf (hpr lawn dart) .5*.000711*(2000 fps)^2 = 1422 ft-lbf (30-06 typical home reload charge)

and while we are at it -

22 "short" rimfire energy (formerly used as "shooting gallery rifle" - public use with minimal protection) = 80 ft-lbf

To summarize: (never mind that the energy dissipates upon contact)- modroc lawn dart high powered deer rifle HPR model lawn dart > 87xhigh powered deer rifle

How many rifle ranges allow people to wander around unprotected downrange?

Brett

Reply to
Brett Buck

This is the point where you are scaring me, Ray.

The criteria is (restated), "it should not be possible for serious injury or death to be caused as the result of a single mistake, it should only be possible as the result of multiple mistakes". This does NOT mean that "if a mistake occurs, and nobody is seriously injured or dies, that class of mistake is irrelevant." Following that logic leads you right down the path of "foam has been falling of the shuttle for years, and we've only had to replace tiles, so it must be safe."

David Erbas-White

Reply to
David Erbas-White

They are launching into an open-to-the-public area with no range access control in the possible range of an off-nominal flight. Even with a 1500 foot altitude limit in place (which in and of itself led to one of the aforementioned incidents), and probably 3500 feet to the buildings in question.

Given that the LDRS models were routinely into the 15000 foot altitude range, and at least one was capable of 40000 feet (8 miles), it's reasonable to assume that it could probably go at leat 12 miles horizontally. Were there any habitable buildings within this range? How about habitable RVs?

In other words, one mistake (failing to note the 400 fps, 3" wide lawn dart coming down almost silently from 20000 feet) can result in serious injury or death.

Amateur endeavors should be held to HIGHER standards, given that the activity is, no matter how enjoyable, essentially frivolous. No offense, I enjoy rockets, too.

Wrong. I said it was luck, and you appear to agree.

Brett

Reply to
Brett Buck

And an FTS assumes the incoming fragmented vehicle would be safer than an unfragmented one, which might be the case with blockhouses and protected range facilities, but not necessarily an open crowd; the shotgun effect.

I, too, have been pondering the issues and trying to relate established safety code to real-world criteria. As you say, statistics are not the best method to determine impact zones (or offset distances) when the consequnces of a single mishap are unacceptable (death), but the incredible number of potential failure modes and variables in even a single flight leave little else, except worst-case analyses.

I'm currently trying to identify the primary issues involved in the offset distance/total impulse rules. On the face of it, I can't see why total impulse was used as the parameter for the offsets. And, there is very little info to be found (online, at least) as to the methods used in either assigning total impulse as a safety parameter, or how the offset distances were determined based upon total impulse. It was probably selected based upon established regulations that used total impulse criteria for other purposes. (See Jane. Jane uses total impulse. See Dick use total impulse.) Offset distances will directly affect the "impact zone" you mention.

Reply to
Gary

I could make an argument that the offset distance relates to impulse based on explosive (CATO) shrapnel potential. I have no idea what the reason used actually was, though. Distance/altitude makes more sense from a impact area standpoint.

Brett

Reply to
Brett Buck

have various "robot wars" and similar things..."

Reply to
Ross Hironaka

Duh. I'm not the one who claimed it would be there. That was claimed by those who think a cigarette fifty feet away is some kind of deadly threat. (If there's enough wind to carry a spark from a cigarette fifty feet, why are they prepping rockets anyway??)

Not only is there no need for an entire can at a launch, there is also no need for it to be open for more than a few seconds.

Reply to
RayDunakin

Tater,

That would probably depend on how long he's been a dad. Newer ones can be more protective than any mother. I know because I was like that with my kids. By the time the kids become teenagers he's ready to strap them to a large rocket and let it fly.

ROFL! I remember doing that when I first started building high-power rockets. I remember seeing a semi truck load of huge PVC pipe and saying to my wife, "Wow, that would make a whole fleet of rockets!"

Regards, Michael Newton

Reply to
Michael Newton

An Aerotech Mustang coming in ballistic is potentially lethal as well. Much harder (if not impossible) to see.

I would rather have Abrams tanks and porta potties dropping out of the sky. I can at least see those coming.

And who recovers 50lb. rockets under parachute at 40fps? Under a drogue chute, maybe, but certainly not as a planned landing speed.

Reply to
Kurt Kesler

high powered deer rifle HPR model lawn dart >

87xhigh powered deer rifle

You're comparing apples and oranges. Even if the total energy is the same, there are vast differences in the size and speed of a sport rocket. A bullet is too small and fast to be seen and avoided. A rocket is much larger and slower and can be easily avoided.

Reply to
RayDunakin

Because the people writing the rules know nothing and it did not occur to ask an expert to base it on pressure.

It certainly did not occur to just not write new rules.

Reply to
Jerry Irvine

R O F L!!

The manufacturers and regulators are supposed to be professionals. It is only the CONSUMERS that are suposed to be morons.

Jerry

R O F L

Reply to
Jerry Irvine

Which raises the question. Why would NFPA address something ATF already does and why make it different?

I sense a circular logic arguement :)

One initiated by reg changes by known identified morons.

Reply to
Jerry Irvine

He is not listening Brett.

He cannot comprehend the locic stream Brett.

Reply to
Jerry Irvine

When you quote someone would you be so kind as to say who, even if in shorthand?

You are doing an amazing job of overcoming AOL's newsgroup limitations, but this is yet another one that really is needed.

Reply to
Jerry Irvine

You didn't read what I wrote - did you? The fifty-foot zone is a SAFETY BUFFER. To prevent the possibility that some dweeb with a lit ciggy will get careless and wander over with reckless abandon, and ruin someone's day. Fifty feet is less than

10 seconds, walking time.

You reduce the probability of accidents by preventing the circumstances under which they can occur.

I'll agree with you on that point. Now, answer this question - in a prep area, which of these two have absolutely NO LEGITIMATE REASON to be there... a can of BP (any size), or a dweeb holding a lit cigarette?

Reply to
BB

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.