Deepest crater competition

[roytyson]

Well, certainly not as impressive.

 

[MattJL]

I've seen plenty of very dangerous impacts of high powered model aircraft, including one where someone got hurt when they were clipped by a wing at high speed. Just because things like this happen doesn't mean someone is going to come take our hobby away from us. What grounds would they use? There are many far more dangerous hobbies out there that continue unabated even after serious safety incidents.

Clearly we have to exercise all due caution but worrying that threads like these are going to get our hobby closed down seems like a gross over reaction.


Tony

My two cents, as a university HPR team member - I worry more from the university-regulation end of things than I worry about the government stepping in. Generally, the recurring theme is that people who have no clue about a thing make very poor decisions when regulating that thing, and I feel that someone might look at a thread like this and, without fully understanding the context of what happened, go off and make a blanket ban to avoid the slightest risk of getting sued.

Hell, we can't even have multirotors on campus. There weren't any major incidents (and I think it's very difficult to get seriously injured by a multirotor), but we just can't fly 'em.

In some ways, that might be for the best, because I have serious concerns about the hubris of uni teams getting tangled up into bad-to-actively-dangerous engineering decisions, but I'd also prefer to avoid any risk of this hobby getting shut down in addition to that. One person having an unfortunate lawn-darting incident at some range somewhere isn't going to make a dent in the hobby, and can indeed be amusing, but a spectacular failure from a uni team... that's a bit more of an issue.

 

[ArchitectOfSeven]

Rapid combustion and detonation are two different things.

An unburned motor certainly could have catoed. My gripe is with the term “detonate”.

We can argue about what terms we do or do not like but given extreme enough conditions I'd guess that nearly any fuel-ox combo can experience supersonic burn rates. As a mundane example gasoline and air usually deflagrates but high enough pressure makes it detonate. Gasoline is not by definition an explosive but it certainly can function as one if you try to add too much boost to your car engine. Apcp is by all definitions a fuel and NOT an explosive. Give it enough pressure though and I bet the burn rates would get there.

 

[ArchitectOfSeven]

I am going to ask this bluntly: what is the purpose of this thread? I agree we should watch the term explosion and detonate.

Really it was to share pictures of crazy crashes. The semantics argument just popped up from analyzing the crater and trying to figure out what caused what effect.

 

[cwbullet]

I would suggest that you not use the term detonate or explosion. As someone who has extensive experience with seeing and treating the after-effects of explosions. This does not look like one. This looks more like a kinetic effect. A high-speed ballistic impact can have similar effects but is not a detonation or true explosion.

 

[grouch]

Really it was to share pictures of crazy crashes. The semantics argument just popped up from analyzing the crater and trying to figure out what caused what effect.

Have you not read anything on TRF? People spilt hairs on the definition of splitting hairs. It's what goes on here. The picture is cool, the possible long term impact is not.

Scenario, a local club club member has been courting a farmer for the last 6 months. He has all but convinced the farmer to let a small launch take place on his property, and what a nice property it is. Only the local farmer has the internet and spends 18 minutes searching to see the type of people he would be welcoming onto his land. See pictures of huge holes caused by rockets. Calls go unanswered from there on out. Happens man.

 

[ArchitectOfSeven]

I would suggest that you not use the term detonate or explosion. As someone who has extensive experience with seeing and treating the after-effects of explosions. This does not look like one. This looks more like a kinetic effect. A high-speed ballistic impact can have similar effects but is not a detonation or true explosion.

Noted.

For everyone here this stuff is really a reminder that multi-stage and high velocity flights with large rockets is inherently risky and demands careful scrutiny. I'm pretty sure that rocket had an angle lockout for 2nd stage ignition but it still pulled a u-turn mid-burn and did that. Keep your eyes in the sky when anything is flying. Often awareness is the biggest part of staying safe.

 

[blackjack2564]

No big deal...I have seen this before. Usually accompanied with a mushroom cloud. [really]

When hitting ground at such high speed the front closure compresses the fuel, under EXTREME pressure & heat [friction]... the obvious then happens. [not going to say it]

The motor does not even need to be lit & it will happen under the right conditions. I have pics of an event I witnessed at Blackrock, they will not be posted. 2-stage where upper did not light and full stack came it screaming still together...think of how much energy is released on impact.

You can make water do the same thing under extreme heat and pressure.
Ever see a crater in a city bock where a building use to be....from boiler's letting go? [or water heater]
But the ATF hasn't decided to regulate water...lol

You really should not post this crap unless you can explain it at same time. It just gets too many arm chair quarterback trying to explain something engineers know instinctively.
You get too many far fetched...not based on any science screw ball answers.

Most of us who screw up badly...don't broadcast it. EX is pushing the limits and when you do that sometimes $h231tt happens...lol

 

[cwbullet]

When hitting ground at such high speed the front closure compresses the fuel, under EXTREME pressure & heat [friction]... the obvious then happens. [not going to say it]

But, you can get the same effect from kinetics. This is not detonation. Just to be clear.

Detonation

(from Latin detonare, meaning 'to thunder down') is a type of combustion involving a supersonic exothermic front accelerating through a medium that eventually drives a shock front propagating directly in front of it. Detonations occur in both conventional solid and liquid explosives.

We are not using explosives so I would argue this is not a detonation.

For the same reason, there is not enough BP in it to cause an explosion of any significance to cause the cloud of black smoke. The kinetic effect with dust could couse a similar effect.

 

[Steve Shannon]

Fair enough. I just wonder what else you would call it if it rapidly combusted during the extreme compression period of impact?

Deflagration

 

[MClark]

But ATF does regulate water. In the homeland security act they buried the safe explosives act. It says any chemical used in the manufacture of explosives is regulated!

 

[blackjack2564]

You bring up a valid point Chuck..... water cannot explode/detonate..but yet they call it an explosion when boilers let go.
Calling an event something, does not really define what happened. There is the rub, especially when rockets are involved.


Your right Mark...I forgot there is a material data safety sheet on water. I used to carry the book on the job.

 

[Steve Shannon]

If you were a landowner and a local club came to you asking if they could launch high power rockets on your land, and then, while doing due diligence to learn about high power rockets you found the picture at the top of this thread, what would your answer likely be?
We’re no better than what we display to the world.

 

[grouch]

If you were a landowner and a local club came to you asking if they could launch high power rockets on your land, and then, while doing due diligence to learn about high power rockets you found the picture at the top of this thread, what would your answer likely be?
We’re no better than what we display to the world.

I seem to recall a wise but ugly man saying something very similar.

 

[cwbullet]

Locked at initiators request