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Who said building and testing rocket motors in your basement is dangerous?
“This is the first static test with our homemade tar/oxygen hybrid rocket motor. James Turner and myself (Eric Stackpole), and two of our friends, Jeff Bernard and Caleb Lesher did this project last summer because we wanted to learn more about how rocket engines work. We built the rocket in James’ garage in Humboldt County, CA completely out of parts we got at the local hardware store. We had previously done a little over 20 tests with polyethylene, but none of them came close to this having much power (note the shaking of the camera when the rocket fires.) The camera did not capture them, but we could clearly see shock diamonds (indicating a supersonic exhaust velocity) running the entire length of the plume. We would have begun working on getting run times longer and perfecting nozzle geometry, but parents made us stop the experiments completely after our first test. There are several even larger rockets we built that we are waiting to be run if we get the chance. Admittedly, we did not know the rocket would be this powerful, and the fist thing we did after this test was build an enclosure with one foot thick walls filled with sand. We’ll post more clips as we develop our rocket program.”
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April 16th, 2007
Sweet Zombie Jesus!
I wish they would have hooked it up to a force-gauge in order to see how much thrust they got out of it!
April 16th, 2007
Sweet Zombie Jesus indeed! They should be thanking him that they still draw breath, and have all of their bodily appendages. My college advisor lost 4 fingers and his eyesight because of similar inattention to safety precautions. “It’s only fun until somebody gets hurt”.
April 16th, 2007
Damn, i want plans for this
April 16th, 2007
Yeah, these guys are real rocket scientists.
April 16th, 2007
Where are the outtakes where they blow themselves up
April 16th, 2007
If there are out takes they would end up on youtube, everything ends up on you tube.
April 16th, 2007
This is massive
April 16th, 2007
Yeah, as in massively foolish. What part of “shrapnel” is not understood? Google LDRS to see it done right. None of this “holding a pipe bomb in a vise” stupidity. Shop goggles, yeah, right. Go forth and be safe, guys.
April 16th, 2007
Once they get them working well enough, they should mount them on an R/C plane.
April 16th, 2007
Yeah, this is far from safe, needs a massive warning at the begging of the video
April 16th, 2007
The outtakes would probably include the house burning down…
April 17th, 2007
I totally agree with Marty - standing beside what’s basically a pipe bomb is just so stupid - a good rocket motor is a narrow balance between a damp squib and a bomb - you find out by blowing a few up - by all means do the experiments, build a better rocket motor - but use some common sense, build a bunker and do it right
April 17th, 2007
Interesting work guys! And, although Paul and Marty are exaggerating by comparing it to a
pipebomb (both oxydizer and fuel in a sealed container, completely different from their
rocket), I am glad you have seen the (right kind of) light concerning safety issues.
Oh, and a simple electronic ignition would also help, just take a car battery, a car ignition
coil and a spark plug. That way you can light the booster flame from a distance.
Looking forwards to your upcoming tests!
April 17th, 2007
You’d think these were the kinds of kids who’d already be very familiar with fuses; I can’t imagine why anyone volunteered to stand right behind it with a lighter. Not sure I’m looking forward to the outcome of a wooden rocket shield used indoors either.
April 17th, 2007
They would achieve a greater specific impulse if they used nitrous oxide instead of oxygen.
The fears of this type of rocket motor exploding are being overstated, “Spaceship one” built by Burt Rutan used a very similar solid/gaseous bi-propellant design as well.
This was specifically to avoid the problem that has plagued solid rocket motors since year one:Namely, once you light them they can’t be put out until all the fuel/oxidiser mix has been burnt. As seen on Challenger.
Tha oxidiser can be stepped down in this design, or turned off completly, this causes the motor to flame out
I do agree with a remote ignition system though
April 17th, 2007
It is important to note that the burn rate is limited by the oxidizer delivery rate on this kind of motor. This means that there is no chance for a “runaway” reaction that results in detonation. At the same, time, the motor is still dangerous. Without a shield of some sort (a real shield, not plastic woodworking goggles), pressure could build up internally which results in detonation.
Failure to restrain the motor might be an even more severe threat. Ever seen a welding tank get it’s head knocked off? That rocket might get a lot of velocity before it tears off it’s oxygen supply.
Overall though, hella cool. My wife says I am not allowed to build one
April 17th, 2007
I can just see the explosion when Dad gets the letter from the insurance company that wrote the policy on this house. That’s ex-policy, of course.
April 17th, 2007
SWEEET, this is quite inspiring! (j/k!)
April 17th, 2007
what’s with the music and dramatic setup, they say themselves in the video that they are replicating previously described rockets from the internet.
April 17th, 2007
Sure hybrids are easier to ‘tune’ but you still don’t stand beside them the first time you fire them up (or ever) - I’ve flown nitrous hybrids dozens of times so I do have a little experience - as I said above a rocket motor is a balance between overpressure in the casing (ie boom!) and underpressure (no thrust) - it’s hard to manage, has to match the burn profile of the grain - these guys are burning tar - not the most stable of fuels - all it takes is a big chunk to come loose (surface area bumps up, burn rate goes up) and block the nozzle (pressure spikes until the back pressure on the oxidizer shuts it down)
April 23rd, 2007
[…] via […]
April 25th, 2007
Man that was awsome i need something like that!!! can i have the plans???
April 25th, 2007
I am not the creator, it is just featured here, click on the Youtube logo (bottom right in the video window) to view the authors video page. Or click this link.
http://www.youtube.com/watch?v=lQ9Pg649MhE
April 25th, 2007
Man thats sweeet!!!!! Dude can u send me the plans on how to make One?????
April 28th, 2007
man where do you get this stuff????
May 2nd, 2007
Very impressive work and nice design. As for all the safety concerns people have been voicing… Is it dangerous? Of course, but its far from a pipe bomb. a pipebomb is a confined explosive as someone earlier has stated, and yes, rocket motors are known to cato (Catastrophe At Take Off) but in this deisgn that is EXTREMELY unlikely. Hybrids are some of the safest and most efficient designs around. Since the oxidizer and the fuel are not chemically bound until they are ignited, the only way for this particular rocket to explode would be for the internal pressure to spike. The most likely cause for this would be a fuel that melts too easily (such as the polyethylene they were previously testing which can suddenly create too much surface area) but even in this situation you have a force ( in this case the oxygen) forcing the excess pressure out the nozzle. Someone said fuse??? This isnt exactly the kinda of rocket you light with a fuse buddy, fuses are for solid propellants at best, but shouldnt be used on rockets at all.
I think we should cut these guys a break, I love doing this sort of stuff, and i typically find that kids that are smart enough to build a more advanced rockets are also aware of the danger around them. They DID notice what they were doing was a little dangerous and immediately too measures to make it safer using what they had available.
Congrats to you guys for doing a great job, looking forward to seeing your next step!
May 5th, 2007
that was great i hope that i can get the chance to try it
May 6th, 2007
if the us gov found out about this theyd probably ban them cause somone would turn it into a rpg or something
May 8th, 2007
I’m sure the US Government is fully aware of homemade rockets like these…
December 24th, 2007
Very nice…..I hope they see this… www.NEFAR.com
January 15th, 2008
So much misinformation…so little time…
1. They are only creating 5 lbs of thrust. Barely enough to the lift the fuel and tank 10 feet in the air. What I have seen so far is not a rocket motor but a glorified torch. A real hybrid rocket motor looks like this:
http://www.contrailrockets.com/Videos/TMT306/TMT9.1.22.wmv
or this:
http://www.youtube.com/watch?v=7K8GmLmjsBI
2. This kind of testing should NEVER be done inside a residential structure of ANY KIND. Even a garage. This has house fire written all over it.
3. Ross, REAL hybrid rockets are ignited with IGNITERS which places the rocketeer way way far away from the rocket and not a hand held torch with the user only 2-3 feet away from a possible CATO. It is possible and I have seen a dozen or so launches in person with hybrid rockets ignited in this way. The igniter breaks the seal between the NO2 and the fuel and ignites it all at the same time.
4. Want to see real hobby rocketry? And do it safely? Check these sites out:
www.nar,org
www.tripoli.org
This stuff in the video is great. It’s reassuring to see young people so enthusiastic about scientific endeavors. However, what they are doing is suicide. They need to be doing this kind of stuff outside and using a remote ignition system with sandbag bunkers around the “motor.”
January 15th, 2008
David, I am agreeing with you. A fuse and an igniter are vastly different things and with hybrid rockets I have built I have only ever used an igniter (I’m pretty sure a fuse just wouldn’t work). As for your explanation of a possible CATO, I believe it to be incorrect, let me explain. On almost all hybrid rockets, the actual fuel is not overly flammable in the form before oxidation, therefore if the seal were to break (which I have seen before in a rocket of a friend of mine) the NO2 MAY light and most likely will burn itself out quickly or in a worse case scenario cause the casing and/or nozzle to explode. This is known as engine failure and it is EXTREMELY dangerous, but in no way are you risking that same kind of cato you would get from a liquid, or even solid propellant rocket as there is no mix of the oxidizer and fuel (the oxidizer burning by itself is hardly explosive but could cause enough pressure for an explosion of sorts. Regardless of any of this, we have seen that the nozzle simply flies out when the pressure builds (a nifty, although probably not very reliable, safety mechanism), so as long as someone doesn’t stand behind the nozzle (and if they do, Darwin is in motion) everything should be fine.
And I agree, this testing really should be done outdoors. I’m giving them the benefit of the doubt that they took many safety precautions and much thought before igniting, and may have limitations for reasons unknown to us.
January 19th, 2008
Hi all,
This is Eric from the video. I stumbled upon this site and read your comments. I wanted to clarify that we are doing a lot more to improve safety. The power of the tar rocket was much greater then we had anticipated for that test and all of our work thereafter has been outdoors in a test stand with sand filled walls and with us a good distance away. We’ve also developed some remote ignition systems but we are still working on what design will work the best for our purposes. Since we’ve hosted the videos, there have been more then 50,000 views and it seems like almost as many comments. With so many eyes on us, we want to demonstrate doing everything the right way, but we don’t want to sacrifice innovation and the ability to “just try something”. I suppose this is the dilemma many businesses face. Despite all of the support and advice we’ve gotten, the greatest hurtle has been just getting the guys together. Hopefully we’ll be able to get enough done to post another video soon. As always, we appreciate the encouragement and advice.
February 6th, 2008
I won’t waste time with underlining safety issues; I assume you understand them now. However I am very interested if you have continued with the experiments using external sourced Oxygen and tar based propellants for your motors. I want to encourage you to continue! You may be on to something here. I am particularly interested in the remote ignition systems you have tried and/or are using.
April 11th, 2008
i was just looking for info on how to build a hybrid rocket and i stumbold on this site. i am doing my science experement on what is the cheepest way to get a craft in space and like you i have bilt a hybrid rocket. i just have one tho. i also have built a 4 stage soled rocket and a 2 stage rocket. i like how you are makeing these out of simpil stuff but i know you get this a lot bee safe i got a 2 degree bern all on my arm because my 4 stage rocket bloo up when i had it in 4 difrent holding units i bilt. and from what it looks like i think you are deeling whith a vary powerfol tar rocket so be safe.
sorry for my bad gramer i am not so hot in inglish and i am just 14.