Dangerous rockets

[Bj]

This is why you should be careful with rockets...

Sugar Rocket (22 Pounds)

(2" PVC, 21" Long;6 Pounds)

Rocket w/ cam

Small, but still dangerous

I wanna try that someday... when I get bullet proof glass...:lol:

 

[SlyCoopersButt]

Really playing roulette with rockets. Pretty erratic flights. Especially the rocket that tended to make corkscrew trails. (Like the Quake II Railgun smoke!) And a cameraman nearly getting a coke can of possible boom in the chest?

I personally wouldn't even think about launching any rocket without building a personal bunker so even a direct hit would be safe.

 

[RocketMan_Len]

It's no wonder we have such a hard time convincing people that rocketry is a safe hobby, when confronted with idiots like those.

Looking at the flight video, I'd guess that they have NO idea of what materials to build fins from - it looked like they used stiff cardboard and duct-tape to put that together. It's no wonder they were having so much trouble with stability.

The sad thing is... those Darwin-Award candidates are likely considered 'so cool' by their friends.

 

[Oceanic]

nice vids

i wonder what propellant they use

 

[Scrooge McDuck]

i wonder what propellant they use

KNO3/Sugar (according to video titles). Some have a pretty long burn time!

 

[spec10]

KNO3 (german: Kaliumnitrat / (Kali-)Salpeter) with Sugar is the most common hobby propellant afaik. But forget about having fun with rockets here in germany, laws are pretty tight.

 

[Bj]

KNO3/Sugar (according to video titles). Some have a pretty long burn time!

The one that was 21" long had a long burn time, but from what I know of KNO3/sugar it is a slow burning mixture. It needs to be a core burning (instead of end to end) to be able to get any thrust.

The guys in the movie must have done something different, because following the logic of a cored burn(or whatever its called) a 21"long 2" wide should burn the same amount of time compared to a 5"long 21" wide, the only difference is thrust. These guys must have done something different (ie burn end to end) to make it burn for so long.

 

[RocketMan_Len]

My guess - the don't *really* know what they're doing... and got either the formulation or the nozzle-size wrong. The first video looked like an overpressure failure, and a couple of the others looked like the nozzle was too large.

 

[RisingFury]

The first one that blew up probably had too small exhaust hole. Those don't blow up right away, because they burn from the inside out. As the surface area of the mixture inside gets larger, more mass has to escape at the same time and it will overload and blow up.

Me and my friend had the same problem the first time we made our own rocket motor and tested it on the ground.

 

[Juanelm]

If one ignores the risks, the flight in which the fins disintegrated in flight is quite funny.

 

[spaceranger]

You can see what happened to the "fins" on that camera phone rocket ... :lol:

Might as well have duct-taped nerf "stabilizers" on ... egads

---------- Post added at 01:49 AM ---------- Previous post was at 01:41 AM ----------

When I was in late elementary school, I had a friend with an older brother nearing graduation from high school. There were very few older kids around, so this guy got all his younger siblings' friends together and taught us how to make matchbook rockets (come to think of it, this was instrumental in my interest of physics in general, later in life).

We'd cut out a rectangular section of a pie tin, roll it into a cylinder with a cone tip (he was picky about how we did the nose ), attach cardboard fins and stuff it full of match heads. We were surrounded by Norway Pine trees (20+ meters tall) and the best match rockets we launched (about a couple out of ... er ... lots ... I can't believe the neighborhood let us get away with so many ... :rofl went higher than the tree tops.

My point: a lot safer than this stuff ... and cheaper ... we didn't even really have to know how to read ... freakin' kids these days ... :j/k:

 

[Brad]

Nimrods.... Sorry I can't think of a better term to discribe what they are doing. Of course it is all in good "clean" fun until one of their rockets wipes one of them out, cause serious property damage, or kills someone. Then it is termed an accident.... an accident my eye.

 

[Nerull]

Really playing roulette with rockets. Pretty erratic flights. Especially the rocket that tended to make corkscrew trails. (Like the Quake II Railgun smoke!) And a cameraman nearly getting a coke can of possible boom in the chest?

I personally wouldn't even think about launching any rocket without building a personal bunker so even a direct hit would be safe.

I hope you take the same approach to cars. Far more people are killed or injured driving to a organized rocket launch than in them. (Where, as far as I know, the fatality rate is still 'zero').

Of course, a large rocket which has not been built properly will never make it past the RSO table, especially not with experimental propellants.

 

[Bj]

(Where, as far as I know, the fatality rate is still 'zero').

True, but I still would like a bullet proof shield bunker, especially when these kinds of things happen.

Heads UP!

I think that would get your heart racing.

Though I wonder why high powered rockets are not launched at a slight angle? They could go up a few hundred feet off course, then if the parachute fails then it will land a ways away, and if the parachute goes correctly, it can drift back to where it launched.

 

[Nerull]

They are, often. It depends on launch site and rules, though. There are usually constraints so that any rockets that fail to deploy and come down ballistic fall in a 'safe zone' where spectators are not allowed. For a high altitude rocket, a slight angle can make a big difference in impact range.

 

[Linguofreak]

Yeesh... I'm not even into rocketry and I can tell these kids need some adult supervision...

 

[n72.75]

Brain Dump:

Both High powered rocketry and hobby rocketry can be fun and safe if people just would follow some guidelines set down by the NRA.

I know of people who have lost hands of fingers due to accidental pipe bombs. On the other hand my dad and and his brothers use to do all kinds of crazy rocket crap when he was in high school and he had loads of fun.

This is just another example of what I like to call the gunpowder phenomenon: Within 20 paces of where I am sitting right now are all the ingredients for about ten lbs of gunpowder. the recipe for gunpowder is relatively simple, with no trouble at all I could make some. What a lot of people don't realize is that the manufacturing process is extremely complicated, you have to take into account: temperature, pressure, humidity, lighting, and a whole slew of other things.

There is a similar phenomenon happening with the people in these videos, they don't know about forces and vectors, or nozzle throat diameter and combustion chamber pressure, nor do they know about dynamic pressure acting on the fins or material strength chamber pressure. All they know is that they saw something cool on the Internet and they want to do it to, usually with minimal work or brain activity.

I am a smart person, I know calculus, physics, and linear algebra, and I have a tremendous understanding of the workings of, both the aerodynamics of rockets and the workings of their engines. I have flown many rockets built from scratch and from kits; I never once have had the urge or the need to build my own engines however. Mostly this is due to the fact that it would be dangerous, impractical and would preform much worse then what professionals can do. At come point in my life though, I do plan to build my own rocket engines, not just as a hobby, but also for a living.

In this fall 2009, I will be going of to college to study Aerospace Engineering with the hope of one day getting my PhD.

So there is my position on rocketry.

Okay that was to long a post, I really need to spend more time away from the forums and interacting with other people, although whenever I talk to people about my interests I am afraid that I am going to get a toilet swirly.

Thats all for now.
Over and out Cap Com.

N72.75 (The Illustrious Matthew Webb Hume)

 

[Artlav]

We'd cut out a rectangular section of a pie tin, roll it into a cylinder with a cone tip (he was picky about how we did the nose ), attach cardboard fins and stuff it full of match heads. We were surrounded by Norway Pine trees (20+ meters tall) and the best match rockets we launched (about a couple out of ... er ... lots ... I can't believe the neighborhood let us get away with so many ... :rofl went higher than the tree tops.

My point: a lot safer than this stuff ... and cheaper ... we didn't even really have to know how to read ... freakin' kids these days ... :j/k:

Match heads? That stuff still gets quite a punch:

That's how one of my first "model rockets" looked like after landing, aluminum tube body fueled by pulverized and packed match heads.
Not quite sure what happened - it seemed to catch up in earnest just after start, already in the air, after which the rest burnt in split second.

Looks to me it's dangerous enough for kids not to use.

 

[CaptnDave]

Has anyone ever tries a hydrogen-fueled rocket? I've thought about it, but I'm not sure how to pressurize hydrogen and an oxidizer that much... How about liquid or gaseous fueled rockets?

 

[tori]

Artlav, I have a 2mm steel splinter in my knee from a matchhead pipe bomb going off, looked exactly like yours, so yeah, those things are nowhere near safe.

A lot of these videos illustrate the second rule of rocket safety quite well - The rocket always knows exactly where you are.

CaptnDave, hybrid (liquid + solid) motors are currently the most practical non-solid motors in amareur rocketry. They're usually paraffin or epoxy based grains with liquid N2O as oxidizer. A Czech group (can't remember the name) has tested LOX + LPropane pressure-fed engine on a stand, but that's about all I can remember. They're way too complex and expensive for a hobby lifter.