Water Rockets (What I Have Learned so Far) by Bill Kuhl http://www.scienceguy.org The idea to try water rockets came to me after helping with a parks and recreation summer camp that was entitled, "Model Airplanes and Rockets". For at least one summer there were no rockets but we built kites instead of rockets, and of course there was little wind. I had built solid fuel rockets as a kid but I knew that would be rather expensive for a large group, so I thought the water rocket idea would be cheap once I purchased a launcher. Some people build their own launchers, but I purchased the better launcher from Pitsco.
At first, I just built rockets that had no recovery system at all, this makes things simple if the rocket survives the crash.
The launch of a water rocket is really fun to watch, within the first few feet all the water has been emptied from the bottle and the rocket can be going over 100 m.p.h.! Safe practices are a must.
For water rockets you need a good quality pump, the pump on the left was a cheap one and did not hold up. The pump on the right has gauge which is necessary.
In this picture you can see the jaws clamping around the bottle.
Some method for carrying and pouring water is needed at the launch site.
Parachute recovery is really cool, but it is difficult to get reliable deployment every time, I tried a few methods with varying success.
Below is what happens when the parachute does not deploy. Sometimes you can fix the rocket but sometimes it is best to try a new rocket and another approach.
What are the problems and how can I fix it, that is what I thought about all the time. In the picture above the fin material was not stiff enough for the size of the rocket and was fluttering in flight. Altitude is greatly reduced when that happens.
Another problem I had was with the parachute lines twisting, using a fishing swivel helped this greatly.
Fins are held on with rubber bands, white tube is a launch guide.
The next few pictures are of a Pitsco Saber rocket I built from a kit. An air chamber that was held squeezed down by vacuum and released slowly when the flap on the rocket came off was used for parachute deployment. This worked well for several launches and then it failed for two launches. It was a simple method for parachute deployment if only it was always reliable.
I taped the bottle when painting to create a water level indicator.