Bob Kreutzer's Electric Powered Water Rocket

Clifford's Rocket Pages Home Page
Dean Wheeler made up a very nice hydrolysis cell that I replicated. Here is a picture of the pieces I used. The metal is plain old stainless steel that was laying in the scrap pile. The acrylic is ½" thick because that what was laying in the scrap pile. The plates are sized as per Dean's instructions.
This shows the two outer plates installed in the cell and the remaining slots in the acrylic are shown. This is only one way to make the cell. After replicating Dean's design it is my feeling that it is a very robust design. My opinion is , if you keep the plate size as per his instruction, and the spacing of the plates between ¼" and 3/8" , you will get a nice working cell.
This is the final result. It does not look like all that much, but, it's pretty elegant in its simplicity. The fertilizer bucket is a multifunctional element in this design. It provides the mount for the launch rod, it provides secondary containment for the electrolyte in case of a leaking cell, and it provides some measure of blast containment in case of a catastrophic cell explosion , and finally, it makes a great carrying case and storage container! The rocket is my standard design explained elsewhere. Note the spark gap on top of the launch rod, which is just a slip fit in the plastic flange that is bolted to the top lid of the bucket
A closer look at the reservoir and gas inlet hole. Dean used a 35mm film canister for his reservoir, but, I found this to be easier and stronger. The gas inlet hole is just a straight pin stuck in the ¼" irrigation hose I used. I used hotmelt glue to fasten the hose in the launch rod and when the glue cooled, I removed the straight pin. It was very easy. On my next launch rod I will not cut the slot below the gas inlet hole. It is not needed and, actually can cause the gas to want to vent out the bottom of the bottle. It is better left uncut in my opinion.
I apologize for the focus on this picture. This shows the spark gap I used. It is simply 12 gauge copper wire I got from some Romex scrap. The high tension lead was slipped into some ¼" irrigation tubing for extra insulation value as standard Romex house wiring is not insulated for 30Kv's ! It works just fine and the ground electrode needs no extra insulation , so I did'nt use any ! The electrodes are just hotmelt glued in, simple and easy and cheap.
This shows the entire launching pad in it's stowed position . I used old extension cord for the leads . There is still room for the launch rod to be stowed inside the bucket if so desired for compact storage when not in use. The plumbing and wiring of the launch rod is show here.
The electrolysis cell and ignition coil is viewable here. Note the little amp meter I got out of the scrap pile. It is a nice little feature and usually runs around 4 to 5 amps with the long extension cord I use. What is not visable here is the aquarium air stone I have as a filter/flame arrestor mounted inside the cap of the cell. This too is just hotmelt glued in. It also provides the hose nipple you can see in the cap.
All the pieces are shown here. Take note of the extension cord. It has a cigarette lighter plug for easy use! Notice the brown switch assembly. I can remotely control the operation of the cell and the spark with just a push of a button for a safe distance. I do need to get some better switches though. The scrap pile was'nt too fruitful on this one! But, it is functional and safe.
This poorly focused view shows the electrolysis cell and the level of electrolyte I use. The level is determined by how much power you apply to the cell. This level works well with my long extension cord but foams up too much it I hook it up directly with jumper cables! Once again, Dean's design is quite robust and very "tuneable". I could actually stand to raise the level another ¼" to ½" and get a little faster fill time. At this level , I fill a rocket up in about 40 seconds.
Here it is, ready to plug in and fire off! This configuration will make the rocket very hard to see when it reaches apogee! If I fill it up too much, I can reliably blow the rocket up on the pad. It makes a satisfyingly loud explosion that is always a big hit. As a matter of fact, most demonstration launches usually require the sacrifice of at least one rocket just for fun!
My thanks to Dean Wheeler for all of his help and advice in the construction of this fun little device. My thanks to Cliff, as always , in his gracious hosting of this report. HAVE FUN, BE SAFE !