There nothing like trying to run before you can walk so I’ve started making a stager so I can have multiple stage water rockets. I’ve first intended to make one using the Air Command Water Rockets design, but I decided I wanted it to work by loss of pressure instead of loss of acceration.
Started out be removing the spring and cutting of the hose grip of a hose connector (b&q value one).
Overflow pipe make a really nice tight fit into where the hose would go. The bottle top make a nice fit into 32mm Waste pipe, which fits fairly well into 40mm waste pipe.
The spring will hold the connector open and the inner tube will inflate gripping the 40mm pipe which will be attached to the connecter to hold it in the close position. There’s a hole drilled into the inner pipe to allow the inner tube to inflate.
I cut the overflow pipe to short so I decided to use it to test the inflation. I used a 2 part epoxy to glue the bottle necks and connector to the overflow pipe after first roughing the surfaces with sand paper.
The ends of the inner tube were glued to the overflow pipe and also wire wrapped to further strengthen the join and some inner tube put over the wire to lessen the chances of it puncturing the inner tube.
The stager grips the tube at 15psi and currently tested up to 25psi.
An alternative design would be to leave the spring out and have rubber bands on the outside pulling the outer tube down. This would be a little easier to make and also be metal free.
This is my new launcher incorporating the lessons I learnt from the my first launcher.
- It can be nailed to the ground so it doesn’t slide when the rope is pulled for launch.
- It’s hinged so the rockets can be attached horizontally then rasied to the vertical for launch.
- It can have several launchers attached.
- It will also have a launch abort so the rocket can be depressurized with out launching.
For pressure leak testing rockets I drilled a 13mm hole in a bottle top which had a smooth inside. Then pulled a car valve through the hole.
I think I need a macro lens.
Objective for the day was to compare the launch of a rocket with and with out fins and a general shake down.
The rocket was just a plain 600ml bottle, launch pressure 45psi.
The fins where attached to the water rocket using rubber bands launch pressure was at 45psi. On the first attempt the fins where left behind at launch.
For the second attempt used more rubber band and doubled them up. This time they stayed on.
The rocket came down in a more control manner, but broke a fin on landing due to glue failure.
The photos are taken from consecutive frames of 20fps video clips of the launches. I aim to improve the photographic record by making the rocket more visible and trying a different choice of background.
My first launcher has a launch mechenism based on the launcher shown on this site. My main objective was to be able to launch a rocket as soon as possible and using an approach of trial and error. The requirements I set for the launcher was for it to be free standing and to be able to launch remotely for safety and to stay dry.
Took the launcher for a test and on uneven ground it was unstable but was still able to launch some bottles. The type of bottle I used in making the launch mechenism seemed to hold pressure ok, but other types the seal leaked. It seems the inside diameter of different types of bottles vary very slightly.
To fix the leak I modifed the launcher by attaching the cable ties to a collar (cut off bottle top) so the lock position can be moved. The collar is prevented from moving by a clamp above it.
Used the adjustable collar to alter the lock position so the bottles have to be pushed on a bit harder and this seems to resolve the leak problem tested up to 45psi. With the new locking position the it requires a pressure of 15 to 30 psi to release.
The water supply failed in the area I lived failed and by the time I realised, everybody else had brought up the supply of still bottled water in our local supermarket. So later at home I was looking at these fizzy water bottles and recalled that a few years back I had seen a programme where they had used a fizzy drink bottle for a rocket using water and compressed air as propulsion. I also as a child won a toy rocket using the same principle which due to a bad landing had broke after not much use to my dismay . So a little time later after using google and discovering all the possibilities I had a new hobby. In the next few posts I will show progress so far.
This site is for me to keep a record of whatever I’m doing in the way of personal projects to keep myself amused. It just happens to be public so sorry if it doesn’t always make sense.