Alain JUGE : Contribution on water rockets
Like all human activities, the practice of water rockets is not without risk, and it is good to know the main ones. This is the subject of this page. In all cases, common sense and vigilance are essential. I arbitrarily classified the risks into three categories: risks related to the construction of the rockets, those related to ground tests and finally those related to launches.
The construction of rockets requires the use of tools, such as cutters, and materials, mainly glues, which are not harmless. It is important to avoid accidents to work in order and method, respecting the safety instructions given by the manufacturers.
For the construction of a higher pressure tank, the use of glass or carbon fibers must be done while wearing gloves. very fine fibers can penetrate the skin or eyes and this is very irritating. Worse, the fiberglass or carbon powder, which is made during sanding, is very irritating or even carcinogenic, for the lungs and eyes. So when working with these materials, always protect yourself with gloves, glasses and a mask and work outdoors or in a well-ventilated room.
Likewise, when bonding with polyurethane or cyanoacrilate, wear protective gloves and work outdoors or in a well-ventilated room.
Before launching a brand new rocket, it is good to test its resistance to pressure, so as not to have any unpleasant surprises during the launch. This is especially necessary if the body of this rocket is composed of two assembled bottles.
The major risk is obviously the explosion of the bottle. Such an explosion can be dangerous on the one hand because of the noise which can cause hearing damage and on the other hand because of the projection of sharp plastic debris.
To limit the effects of such explosions, always test your rockets filled with water and keep a respectable distance from the pressurized craft.
This is obviously the most dangerous phase (nothing should be dramatized, however), especially since it often takes place with the public around and there is a sort of atmosphere of celebration and excitement , not very conducive to vigilance and security. See the Beginning page and the "First Launch" topic for the basics of launch security.
First risk , and the most important in terms of the damage it can cause, the fallout of a rocket without a slowing device (whether it is non-existent or not worked). You should know that a very simple rocket made with a 1.5 liter bottle, equipped with fins and a cone made with the upper part of another bottle reaches an altitude of about 50m and falls to the ground at more than 100 km / h. Better not to be below. It is not easy to predict the place of fallout so vigilance is required.
First precaution, only perform launches on sufficiently clear ground where it is possible to check the presence of people (or goods) before carrying out a launch.
Before each launch, warn everyone present to be vigilant during the flight of the machine and invite adults to watch their children. Everyone should stand and watch the rocket continuously until it is on the ground.
Second risk , the explosion of the rocket during pressurization. This can happen if we have not taken the precaution of testing it before (see paragraph above), or if the machine has already made several flights with more or less gentle returns to earth or if it has been damaged. '' any other way (transport, storage, repair, etc ...).
When pressurizing, stay far enough away from the machine and above all keep everyone away from the area as long as a pressurized machine is on the launcher.For high pressure rockets, the person in charge of the inflation must wear ear protection and protective goggles. Also keep the public about fifty meters away.
Third risk , disorder and restlessness. A launch campaign requires bringing a fair amount of equipment to the field ( rockets, pumps, water cans, tools, launcher, etc ...) if there is clutter and commotion around, there is a risk of falling or injury with tools. To illustrate this, I would quote an anecdote: I was doing a launch campaign on a site where there were a lot of people and in particular children (but I will not be taken back). Fortunately, two minor incidents happened to me. The first incident was the unwanted arrival of a soccer ball on one of my rockets (she did not survive her injuries), the second incident could have been more serious, while I had just pressurized a rocket, and that I was going to take the string that I use to release the rocket, a kid, running, got caught feet in that string and of course triggered the launch of the machine. Luckily no one was near the launcher at the time but it could have happened that I was checking that everything was ready for launch, and I could have been hit by the machine taking off ...