Stories on Water
Rocketeers' mishaps
As an illustration of how important safety precautions are, I started this collection of stories on water rocket mishaps that were reported from the people of the water rocket mailing list. "Thanks" to everyone who contributed.
Please be aware that none of the things described below are likely to happen to you if you understand why they happened and behave accordingly. "Think always before you act!", as the experienced rocketeers say. I personally do not believe that water rocketry is particularly dangerous, especially if you compare it with other outdoor activities - given that you follow the safety issues.
Keep in mind that this is a worldwide collection with stories from several years - the actual rate of mishap per launch is VERY low. Other activities like motorized traffic, New Year's fireworks, river rafting, bungee jumping (and what not else) are believed to be more dangerous.
Contents:
Results of an
earlier safety poll
Rocket drilled a hole
next to my left shoe
Fins can cut your fingers severely
Bypassing
couple was "divorced" by unstable rocket
Tilting
launcher fires rocket towards the pulling person
Bottle explodes while
guppying
Launching
person almost hit by a rocket from 110 m
Concentrate
while launching - use the right program
$2,000 of damage
and a "anti-ballistics" law
9 year old girl
hit by a rocket from 200 feet
100 gram rocket = 2/3 of the energy of a 38 special Magnum slug !!!
Bruise in the face
Hand Launches are dangerous
Safety issues at Science
Olympiad 2000
Test bottle landed in the
crowd
How to deal with spectator
crowds
Another close brush with
death
Broken hand from hand
launches
Use Safety glasses while
machining!
High winds are no good
for water rockets
PL Premium
(Polyurethane glue) is DURABLE on your hands
Results of an earlier safety poll
From Gordon McDonough vapor"at"trailxxxx
Ulrich, I did this kind of poll a year or two ago, promising to publish the results.
I told of a student of mine who had leaned over a stopper rocket and got knocked down by two liters of bottle at 30PSI. (He was not supervised at the time, by me or anyone else. He was probably knocked over by the surprise. He was otherwise okay, and doesn't lean over pressurized rockets any more.) I regularly have my student hold onto a bottle at this pressure (palms solidly in front of it so we don't break fingers) so they can get a sense of the power and instantaneous nature of the blast.
Years ago there was a story of a child hit by the fins of a falling rocket who required stitches to the head, but it was a second hand report from a news story somewhere. May have been a pyro rocket, but that doesn't mean it couldn't have been a hydro rocket, the lesson is the same.
Except for the relentless but nearly imperceptible damage we are doing ourselves with the bizarre adhesives we use, and the lacerations from our knives, burns from our glue guns, etc., I believe that what you will find is that there are many close calls but no one has ever been injured by a rocket launched by a participant of this group. The one serious injury I remember was a launcher mishap where the operator misjudged the force of the water exhaust and got a banged up hand (broken).
Moral: Be smart, pressure test modified pressure chambers full of water before launching them, make sure those down range (In all possible directions) are aware of what you are doing, stand clear of the launcher, and before you pull the string, think. Respect your rocket, air pressure, velocity and energy. Water rocketry is unquestionably a extremely safe pursuit.
* Unless you want to account for our unbridled enthusiasm for shooting soda-pop bottles into the air. That is possibly the most obvious evidence of brain damage.
Rocket drilled a hole next to my left shoe
From: Bill Roberts, billyleebob"at"homexxxx
My only near "incident" occurred when I lost sight of a "scud" rocket at apogee and the damn thing drilled a hole next to my left shoe. I ducked and covered, but still felt the pressure wave as it passed my head. Lesson learned. (know your launch angle and the wind direction and velocity) A simple plumb-bob will help you to find the vertical unless you live in the So. hemisphere. These pore folks must use (an) helium balloon to achieve the same results.
Fins can cut your fingers severely
From Leo Daly, leodaly"at"au1.ibmxxxx
My first launcher (over a year ago) used a snap hose fitting operated by several pulleys. One day I put the rocket on (cylindrical fin type), pressurized and pulled the launch cable and nothing happened. An examination of the launcher showed the fin had knocked the cable off a pulley. I could not reattach it with the rocket in place so I stupidly operated the hose fitting by hand. Luckily I got my hand out of the way in time and I've still got 10 uninjured fingers. When I realized (several seconds later) how stupid I'd been it gave me the shudders which recur each time I think about it.
Bypassing couple was "divorced" by unstable rocket
From Leo Daly, leodaly"at"au1.ibmxxxx
One day (also over a year ago). I had a rather unstable rocket (liked to go horizontally quite often). I adjusted the fins and pressurized. Just before I launched, I noticed a couple walking along the other side of the oval so I waited for them to get out of range and launched. I had not noticed a couple walking 3 metres behind me, the rocket went up then horizontally, I had to duck and the rocket went past me and right between them a few centimetres either way and they would have got hit. I wish I'd had a camera to photograph their faces. However I had to give profuse apologies.
Tilting launcher fires rocket towards the pulling person
From Roderick McGuire - mcguire"at"teleramaxxxx
Recently, I inadvertently employed a launcher that winds up targeting the rocket right at the person who pulls the launch cord. My launcher is derived from Bruce Berggren's excellent plans at http://www.geocities.com/wrgarage/launcher.htm The basic launcher body is about 6" of 1/2" pvc with a t-joint in the middle. You are supposed to make a stand and plug the launcher into this, but mostly I just pound a small wooden stake into the ground and slip the launcher over this. The launch cord runs from the ring that holds down the cable ties, under the t-joint (about 4" above ground), and then to the person who pulls it.
Well, I needed to backyard test a rocket with fins that trailed far beyond the body so I just used a much longer wooden stake and the t-joint wound up being maybe 20" above ground. As you can guess, this long stake was not firm enough in the ground and pulling the launch cord tipped the launcher right at the launch-person and then released the rocket. I thought that using only 30psi would be safe in this makeshift setup but for a horizontal launch 30psi will send a rocket much faster than for vertical. Anyway, the rocket went 6' over the launch-person's head, crashed into the brick wall of my house only 6" from a window, and broke several parts on impact.
So my recommendation is to keep the launch cord turning point as close to the ground as possible. For my example I should have made a large staple out of a coat hanger, pounded it into the ground, and then run the launch cord through it.
Yours in safety - Roderick McGuire
Paul Grosse uses successfully a dog skewer(one of those large corkscrew things with a large triangular handle on it) for the cord turning point.
Leo Daly uses a bowden tube style launch activator:
"I use a piece of nylon edger cord inside what is known as a spring curtain
line (a long spring covered with plastic). This is similar to a brake cable.
The non moving outside is clamped to the launcher and the movable inside
goes wherever it must go. The benefit is that when you launch, no force is
applied to the launcher itself, unless you're silly enough to pull the outside
instead of the inside."
Bottle explodes while guppying
from a young water rocketeer:
Euhhhh .... When I tried to guppy a rocket for the 2nd time in my life (3/4
a year ago) it also exploded. There was 5 bar on it and i was in the kitchen
(sort of closed room). I did wear eye protection but no ear protection. I
had an annoying
peeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee-
eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeep
in my ears for 2 days. I also had a headache that night. I never ever had
a real headache so it was a revelation for me. When I guppy a rocket now
I use eye and ear protection but since that rocket I have never had a bottle
explode.
The bottle that exploded was all rimpled and bent in a strange angles. There
was no shrapnel coming of it but I guess the whole rocket was heated. There
was nothing wrong with my hands which held the bottle. Just the very loud
bang and an adrenaline thrill!! :-)
Use eye and ear protection if you are close to a pressurized bottle (during production or launch)
Launching person almost hit by a rocket from 110 m
from
u.hornstein
During the last GOLLUMP 4f rocket rise phase I checked unnecessarily
the stop watch "with one eye only", to see, if I had started it right. The
rocket was as fast as before, when looking back I could not find it again
in the sky. OK, I thought, no problem, the watch was started right, and I
still can take the total time if I listen to the "Thud" on impact. This was
easy then, because impact was less than TWO METRES to my left, myself standing
40m away from the launcher! The "Thud" was loud, and consequently I was a
bit frightened! But still I got the time measurement of the total flight.
It came down from around 110 m. Speed may have been around 120 km/h. Ouch!
Make sure all spectators keep watching the rockets in flight. Position spectators upwind of launch position.
Concentrate while launching - use the right program
You mean like the Ariane 5 launch that suffered a safety detonation because they loaded a Ariane 4 flight control program into its computer, and forgot the Ariane 5 had a different flight envelope. They also found out that at the low flight angle, the program produced a "divide by zero" error. It then used the backup machine to come up with the same result. Now if both computers are rendered useless like that, the first computer reboots! First action in the reboot - flare the SRB nozzles outwards to their limits to test the gimballing before launch.......
$2,000 of damage and a "anti-ballistics" law
From: "John H. Boyd" <jhboyd"at"sprint.xx>
Did I have a $$%^^&&* day at work a few weeks ago..... NO!
Do I feel a need to "feel superior" ...... NO!
Now ask if I get fed up with people not thinking things through ahead of time? YES!!!
I found I was reading the same partially processed thoughts I heard from the twit who caused me well over 40 hours of aggravation in the last few weeks dealing with politicians, police and lawyers. This "rocket scientist" didn't consider the consequences of his actions when launching a water rocket in a public park up here. It went unstable and was the direct cause of a single car accident. Fortunately, the driver came away with a shaken ego. The car has over $2,000 of damage after it rammed a telephone pole......... it could have resulted in a fatality. The guy thought nothing dangerous could happen.......
The result of this foolish flight attempt was that the City of Calgary has passed an emergency "anti-ballistics" law banning, among other things, archery, model rocketry, and water rocketry. As someone who has worked closely with school boards and the Ontario Ministry of Education for over 20 years encouraging the use of model rocketry and water rocketry in the science curriculum, I am pissed! We Canadians have spent the last 10 getting a reasonable set of High Power regulations in place here in Canada. I get very angry when some yahoo sends the work myself and others have been doing sent back a good decade or two. As part of the Canadian Association of Rocketry, I can tell you we have been discussing having to regulate water rocketry through a safety code to get the law repealed. Problem is, other jurisdictions will likely copy Calgary's lead and pass their own versions. I do not like seeing all the hard work my friends and I have invested in this hobby to get rid o f regulations be poured down the sewer drain.
Ladies and gentleman, my point was, and still is, THINK about what you are doing and saying. Yes, NASA has lots of wonderful work on drag and aerodynamics ................ most of which is totally useless for us! Aerodynamic scaling up or down is a black art at the best of times.
(...) If you do not know if the model is stable through testing, it is a dangerous rocket and should be flown in isolation from everyone not directly connected with the launch. If you don't know how, get a copy of Stine's Handbook and find out how to do it.
I know many on the list think that water rocketry is a "harmless" diversion that can be a good way to cool off on a hot day. It can be if you treat it with a little respect.
Please be careful and think before each launch. Remember, models can be replaced. Lives can't.
9 year old girl hit by a rocket from 200 feet
From: "Slack, Ellis G" <SlackEG"at"navair.nayyxxxx>
Chip Slack writes:
c) July 4th , 1999, 3 or 4 hours into launching, 90 psi air only, return flight, 200 feet up, terminal velocity, 3 1/2 oz (100g) rocket, 9 year old girl (neighbor of my cousin in Laguna Niguel), in swimsuit (bare back), sitting cross legged (cradling her rocket - she is next), she sees it coming, and leans forward as it drifts into her, smack! 5 rounded point 2l coke bottle is dented in the inverse shape of a shoulder blade, her skin is not broken, nor is it pink, or swelling, the mother says to quit making such a fuss.....
d) I have suffered more pain and discomfort from bottle failure and the "blast" at launch (a bit of glue in the air stream approaching Mach 1 will cut you!) than any flight impact.
In summary,
1) do not put materials harder than the PET plastic on the rocket. I use a PVC "tail" or empenage(sp?), but paper, plastic cups, straws, string rubberbands, clay, oh yes, chocolate!.. things that have a hard time hurting you at high velocity as described below.
2) "reshaped" bottles and tube rockets, with their higher terminal velocities, just don't tip them with hardened steel nose cones. Although from the effort that goes into these scary projectiles, the "scrunch and bounce" recovery system seems to be a hot topic to avoid (see tumble/unstable or QESC recovery mechanisms in previous mail)
I hope this contribution helps, if not, be aware that I am NOT going to go out of my way to have people/rocket collisions. Nor am I afraid of them.
That's why they are great sport! Educational too, in there somewhere, now where's my labcoat...
Chip
100 gram rocket = 2/3 of the energy of a 38 special Magnum slug !!!
Russell McMahon wrote:
>How dangerous have water rockets proven in practice?
Some rough figuring suggests that the energy available is humungous.
Say 100 gram rocket at 80 metre/second peak velocity
E = 1/2.M.V^2 = 320 Nm.= about 500 ft.lb
This is about 2/3 of the value for a 38 special Magnum slug !!!
OR as E = mgh , for a 1 Kg mass, h = 32 meter !!!
Think about it! The rocket has a much larger surface area than the slug and a nice resilient surface so it would be much more forgiving, but all the same!
Even on landing the energy is significant - about 2 Kg-m for a typical streamlined design lofted to 100m odd.
Bruise in the face
From: "Gordon McDonough" <vapor"at"trailxxxx>
I have been collecting stories for years, now let's see:
I had a student once who, unsupervised, took a 2L bottle at ~30 psi (Friction fit) in the face. He had a good bruise, and was knocked on his derrière, but I suspect mostly by the surprise. It was a learning experience, and he is now a better man for it.
Hand Launches are dangerous
From: "Bruce Berggren" <berggren"at"airmailxxxx>
Matthew Tilyard wrote:
> Does anybody (besides me) launch their rockets by hand?
> I have been doing this with pressures up to 150psi with no problems,
> other than getting a bit wet.
Hopefully this won't come of sounding condescending, but I am concerned for your safety and those of others on this mailing list.
If you're not hydrotesting each bottle (100% full of water) to a significantly higher pressure to verify its strength, I think you need to weigh the fun of hand launching at those pressures against the loss of fingers/eyesight you're very likely to experience soon.
My source of new 2L bottles ALWAYS explode between 110-140 psi. These bottles weren't designed to carry extreme pressures, so there's no guarantee that the next bottle will be as strong as the last. And after a few hard landings, they'll weaken.
And also consider that among the hundreds of members of this group, several will most definatly be younger/less lucky than you. Lets keep hand launching limited to low-pressure launching!
Safety issues at Science Olympiad 2000
From: TXSnapper"at"aolxxxx
<< Water rockets by their nature are HEAVY. Has anyone ever been seriously injured by a water rocket in uncontrolled flight? >>
I am not aware of any injuries. I have discussed this with Jake Winemiller, event coordinator for Science Olympiad. He has run the event for a number of years at national. He has probably launched more rockets around crowds than anyone in the world. I would guess that he launches over 500 to 600 launches a year in competitions. I helped run the event at Spokane this year and we launched around 240 rockets in one day.
At the three nationals that I have attended as a coach I have notice several safety issues that Jake follows.
- No one near the rocket after it is pressurized.
- Launches are typically done in baseball or football fields and only competitors are allowed in the launch area. Spectators are kept some distance back.
- Every competitor must wear safety glasses.
- Jake uses a bull horn to loudly announce each launch and to warn spectators.
- Every launch is proceeded by a warning to be heads up and followed by a count down.
- Rockets do land in the crowd from time to time, but with the warnings Jake gives, everyone has gotten out of the way up to this point.
- I would guess that rockets are no more dangerous than golf or baseball, where foul balls are regularly landing in the crowds at similar speeds.
- If I could make one safety recommendation, it would be that all rockets have a blunt cone or atleast a radius similar to a ping pong ball. I know that some people are using pointed cones and loading the tips with lead shot epoxy glued into the cone. This type of cone could cause big time safety concerns.
Test bottle landed in the crowd
From: Passerotti, Mike [mike.passerotti"at"honeywellxxxx]
Embarasing moment this past week: At a demo to scouts I lectured on rocket safety and taking care on breezy days. We had a constant mild breeze with occassional gusts. I should've called it off. I launched a 20oz bottle to test the angle of the pad. Plain 20oz bottles tumble great and don't really hurt if they hit your head. I've had them hit me on the head before just to make sure. Good thing I did the test. A gust put that tumbling bottle right back into the crowd of observers. Shift the crowd, shift the launch pad, tilt the pad more and test again. Safe the second launch and on. But I hate landing my test bottle in the crowd. Mental note: test before the crowd shows up. Mental note: in gusty wind conditions launch low pressure and shoot for a target downrange away from the crowd.
How to deal with spectator crowds
From: "Slack, Ellis G" <SlackEG"at"navair.nayyxxxx>
What with spectators crowding around you, probably asking "well - is it gonna work?" or "when you gonna launch?" and the wind gusting, that is very commendable that you had the wherewithall to launch one of your more harmless rockets - I figure that one of my 2L 4oz rockets hitting an unsuspecting citizen on the head would raise a few small lumps and mainly alot of anger. Only if the victim had the bad luck to respond literally to the good-intentioned but wrong warning call of "Heads up" would result in facial damage requiring medical attention. My point? 3 at least.....
1) Would a weather vane / anemometer have helped you? Yes, you have to position it up and out of the ground clutter. I have made a few out of - guess (2 or 3 Liter bottle and fin stock)
2) the more stable and less tumblesome and less beat up rockets seem to go where they are pointed. My launcher assemblies (plywood base, some galvanized pipe and fittings) weigh several pounds apiece and has a 6" long 1/2" allthread adjustment that when combined with pristing unbattered rockets will allow 1 or 2 turns of the adjusting bolt tilting the 18" square plywood base unit to move the impact site about 10 or 15 feet.
3) Does anyone use any verbal signals per protocol for launching? I have tried a few taken from explosives, armored cav (tanks) and enemy artillery in-coming, but I have not settled on any consistent signals. This would be especially important at multiple launcher events. (...) I have tried "ready on the range" statement while pressurizing, 3-2-1 fire , "On the way" immediately after launch and "incoming" if it is suspected that there is someone in the path of descending rocket. Do not say "heads up". someone might heed that warning.
4) Having total control of the area is paramount, that includes the undivided attention of the spectators present. The first launch or 2 you will generally have everyones undivided attention. Yes, you should have already launched within the last 30 minutes, but if not, either send one up that tumbles (like you did, perfect) or angle an arrow-like rocket absurdly away from the spectator crowd, lose it if you must. By the way, you're never going to convince me that the attentive crowd reacted negatively about you using the first launch to give away one of your rockets, right?
Another close brush with death
From: "Slack, Ellis G" <SlackEG"at"navair.nayyxxxx>
One "Doc Holliday" (...) was the one (around 1994 or '95) that slipped a
xxxx mickey into the 5 gallon plastic sparkletts water bottle rocket (Yes
I know he built it, but...) we were launching at an elementary school, for
after school science, with 5th graders, but also in attendance were faculty,
(2-3), staff (principal and vice principal, media, (either a radio station
or one tv station) the executive officer of the base where I am (still) employed.
He and his fellow conspirators, having overheard me MC the spectators to
a state of readiness of anticipating a 50 or 60 foot launch of this 5' tall
monstrosity, (fins like a rand mcnally road atlas, nose cone of a piece of
"D" sized mylar/vellum paper), slipped in the xxxx (the xxxx was for the
nose cone to give the "vaprous" effect) and really stuffed the rubber stopper
in. 60 feet - after all, the rubber stopper had trouble holding back 15 psi
for the 15 minutes it would take to pressurize the bottle through a basket
ball needle. Only this time, as I hastily helped them guide the rocket to
a stable stance on its fins, I was attempting to connect the little levered
air chuck to the needle in the stopper, when
whhhooooossssssssspllllaaaaaaaasssssshhhhhhh - huh? I never got the chuck
on the needle, all that is in front of me is the chuck, and a big muddy hole
in the ground. The shouts of "Incoming" startled me out of my confusion as
I waited for the rocket to return from a 125' or so altitude and tried to
piece together what happened to provide an explanation to the authority-members
of our spectators that was never requested. Lucky for you Doc.
Chip
"Doc Holliday" answered:
Ah, yes! Another close brush with death.
Life is such a rush when you tempt fate to the max.
Lucky for me that turned my head when I set that 5 gallon rocket down. That bad boy launched the second the fins touched ground. My head could have been a satellite! As I have little or no brains it would have been a light payload which would achieve orbit easily.
(The xxxx substance is held back here - after all I don't want to spread potentially dangerous ideas. uh)
Broken hand from hand launches
From: Gary Brown [mailto:garyb"at"ichips.intelxxxx] May 16, 2000
Had an accident though this weekend that's slowing my progress and typing.. got my hand in the way of a water stream that blasted it down against my PVC launcher hard enough to break a bone. Yep I'm in a cast now.. ;-) I've had hundreds of launches w/o any accidents so it can happen to anyone. I'm going to refine my remote launch capability before finishing the recovery system.. be careful folks.
On 31 May 2000 Gary added:
(...) were my thoughts too, when I looked at those hand launching pictures, on the long string for launching. I modified my launcher with a little pulley and nylon string after my accident, er incident. Works great - Not only safer, but you get a better view as well. I'd hate to hear about others getting blasted like I did a few weeks ago. I get my cast off in a week, hopefully.. Keep those body parts out of the rocket thrust - the launch that broke my hand was a 4L rocket ~40% full at 80psi.
One year later, in May 2001, Gary added:
I know many on the list use an Ian cable tie like launch mechanism and some
pull the ring down by hand - don't do it. (see above). I don't want anyone
to go through what I did. It still is hurting one year later...
I use a long rope now and cringe when I see people launch by hand. Extend
your launch rope upwind and keep crowd upwind as well so if the chute doesn't
deploy the rocket will likely be carried downwind away from crowd as it crashes
back to earth. If a kid gets their head above a rocket while pumping it up
and it launches prematurely, it will knock their block off.
Use Safety glasses while machining!
From: "bill roberts" <billyleebob"at"homexxxx>
Please wear safety glasses.
I wear an eye patch due to garage experiments gone bad.
bbob.
High winds are no good for water rockets
From: "Dave Brun" <dbrunsti"at"yahooxxxx>
Just did a few launches this weekend for my nephews and had some fun results. I will post the picts of the bottle tomorrow.
The first two launches went up pretty high and then literally started to fly. It was a very windy day so I do not if that is the reason why it curved over and started gluiding, but is was really cool. The bottle ended up a long way away.
I launched it two more times today for a different nephew and got a little too daring on the second launch and put 110 psi in it. No one saw it go up and so we went inside. About 20 mins later a man from about 6 houses away came to the front door with it. He was real cool about it but he said it came crashing through the trees and landed a few feet from him. He said he thought that a tree limb was coming down. ooooops
PL Premium (Polyurethane glue) is DURABLE on your hands
Bill roberts wrote:
I work as an auto mechanic and have a lot of solvents at my disposal. When I use PL, I do wear my gloves (latex). There have been times that I *just wiped off that last smear with a bare finger*. There doesn't seem to be anything in my arsonal that will clean it from finger tips. You don't even know until the next day and the tell-tail smudge marks you as a WR enthusiast and PL user. How embarrasing. bbob:-)
Tom Benedict answered: On the contrary! It's a mark of pride!
Others wrote:
> Can PLP be removed from fingers without harm ?
> > I have successfully used alcohol to remove the uncured PLP from
my hands,
> > but the stuff is so pervasive that a sufficient amount of alcohol
washing
> > would also really dry out your skin.
> > I wonder about using cornstarch, talc, or some other powder to
help bunch
> > it up and roll it off the skin? Hmmm, maybe a bucket of dry sand.
> >
> > >My best solution to this problem so far includes waiting 3
days and
> > >using sandpaper in the shower. Is there a solvent that will
remove the
> > >glue from the skin and not the other way arround?
> > >bbob
This collection was started on 17.5.01 - the events go several years back.
