Water Rockets (What I Have Learned so Far) by Bill Kuhl
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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.
Below are pictures from a park and recreation group, they built the rockets mainly from construction paper which
does not hold up to a high-speed launch, but the kids sure had fun!
For water rockets you need a good quality pump, the pump on the left in the below left picture was a cheap one
and did not hold up. The middle picture shows how the Pitsco AquaPort launcher grips the bottle. Another requirement
will be a method for bringing water to the launch site and pouring it into the rocket.
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.
Parachute recovery is really cool, but it is difficult to get reliable deployment every time, I tried a few methods with
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 in the below left, 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.
I tried many materials for the rocket fins; foam, cardboard from a milk carton, and plastic from cottage cheese lids. The
material needs to be rigid enough and waterproof.
Below are pictures 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
I purchased a rocket from AntiGravityResearch Company. Their rockets use a small hole for a nozzle and all the
parts are held on by rubberbands. A small tube is pushed in the nozzle hole and when you stop pumping, the rocket
launches. The launch speed is slower with this method.
The pictures below are of a rocket I designed using a wind-up timer to push the nose of the rocket off. This can get
rather complicated but it seems to be the most popular method with the more advanced rocketeers. I have only
launched this rocket twice; it worked perfect the first launch and the nose came off too early on the second launch.
Currently I am working on an improved version of this rocket.
Water rockets are really fun and a great way to learn engineering skills. Rockets normally are built from inexpensive
materials and experimenting with new materials is half the fun. I have a video on YouTube which explains what I
have learned in more detail.
New Material Added January 2011
(A) Small rocket with extended foam nose has worked pretty well. Fall-off nose, but when it fails the foam usually
saves the rocket.
(B) Parachute came out perfectly this time.
(C) I must not have folded the parachute properly this time.
(A) I began experimenting with a side-deploy Tomy Timer rocket the end of 2010, not pretty but deployment was
reliable for the most part.
(B) For 2011 a new side-deploy with better mounting of the Tomy Timer.
(A) My plunger Tomy Timer rocket un-damaged on this landing but often the nose did not come off at all.
(B) Close view of plunger mechanism, there is a spring not shown, that pushes the plunger up.
(C) This is what the spring timer looks like, a bad crash landing broke the Tomy Timer open.
New Material 6-10-2011
I came up with a simple water rocket design based on a 24 ounce bottle that was used for two workshops that
had a record number of students despite rainy weather. Fins are blue fan-fold foam and the nose is cut from a
swimming noodle. A dome shape is cut in the foam noodle with a scissors, cover over the hole in the middle
with masking or duct tape.
(A) Completed rocket can be seen in the foreground, everything put together with low-temp hot glue gun.
(B) I cut out 40 sets of fins with hot wire but we needed more so volunteer cut fins with hobby knife.
(C) Waiting in rain to launch, no one wanted to call off the launch.
It helps to put plenty of tape over the foam noodle, in
top image the rocket did not go very high or straight,
covering rocket with tape in bottom image improved height.
Download templates for fins and fin position through this PDF file for the rocket in the above picture.
I just started experimenting with free Tracker video analysis program - read my blog post.
Water Rockets for Kids blog post
Water Rocket Pendulum Parachute Recovery Idea Fail - blog post
Yet Another Water Rocket Parachute Fail - blog post
An Introduction to Water Rockets I - Video on YouTube I created about water rocket experience.
Water Rocket II - my latest water rocket video, experiments in the second year of water rockets .
An Introduction to Water Rockets I (Power Point) - Like the article above with additional pictures.
An Introduction to Water Rockets I (PDF file)
Water Rocket Links from Izzi's Home Page - Water rockets are used as part of a university computer
Water Rocket Resources from National Physical Laboratory Water Rocket Challenge
Water Rocket Forum - an excellent resource for water rocket questions.
Water Rocket @ Leeds - http://www.ast.leeds.ac.uk/~knapp/rockets/Rocket_Home.html another good
UK water rocket resource.
Texas Timers - my source for the timer devices used in parachute deployment, select Plastic Clocks.
Mr. Y Science Guy Water Rockets - http://teacherweb.com/GA/dyerelementaryschool/mryoung/wqr1.aspx
A Very Short Unedited Video of My Side Deploy Timer Rocket added 10-12-2010
Kevin Karplus sent me links to a water rocket launcher he had designed, it releases the rocket when enough pressure has
built-up normally around 30 psi. Instructions in: English PDF and Spanish PDF
321Rockets.com- is a very complete source for Estes solid fuel rockets.