Water Rocket Launch System

During my tenure at VUW I was in a role responsible for promoting the engineering school to potential students who were in their senior years of secondary school.

As an engineer I'm not much of a conventional marketing person, powerpoint slides and laser cut trinkets don't cut it for me. I also started playing with such toys as water rockets at a very early age... Enter the idea of running a challenge where engineering and school students are pitched against each other. Several emails later and my manager was convinced to go with the idea.

Now in it's simplest form a water rocket is nothing more than a bicycle tyre pump, a rubber stopper with a valve stem through it and a softdrink bottle. You fill the bottle say half with water insert the rubber stopper and pump in air.

Partially due to being prone to building silly contraptions that run on air and also due to restrictions imposed by the health and safety department. The idea of a joint pNuke and VUW branded water rocket launch system was conceived.

It had to be pneumatic as we already have a supply of air (the tyre pump) and so there would be no electrics to get wet.
It had to be black... In all seriousness, I build theatre and movie props... Anything not intended to be seen by the audience is matte black.

In the pneumatics stash I have a couple of HiRotor pneumatic actuators... Ridiculously oversized for this job but hey there's no chance of them breaking.

The actuators are sandwiched between two laser cut plywood plates to give the base sufficient rigidity.

Attached to the actuator shafts are plywood arms which support the two bottle retaining collars.

All the plywood components are soaked in watered down polyurethane, allowed to dry before a coat of flat black and a final coat of flat polyurethane.

The two collars lock onto the neck of the PET softdrink bottle above the flange on the neck, this ensures that the bottle is held in place very securely indeed.

The actuators are connected to the tyre pump after the bottle is pumped up. One firm pump is all that's required to pop them open.

 

Getting the air into the bottle proved more than a five minute task...
As the arms hold the neck of the bottle a good 100mm from the top plate, the bung had to be mounted on some form of standoff. Adding to the complexity is that the bottle is filled with air through the bung.
The final solution involved PVC pipe as a standoff, with a bit of trickery....

I set about creating what was in effect a hollow "bolt" with a 1/8th BSP fitting on one end to accept the air inlet.

This was made up from a modified tail fitting which I drilled to the inner diameter of the copper tubing. The hole was then counterbored to suit the outer diameter of the copper tube for a snug fit.

Pipe soldered into place

Drilled to suit the pipe i.d.

Counterbored

The other end of the copper tube has a short length of hollow M6 bolt silver soldered onto the end of it. The threads allow the bung, spacers and PVC pipe to all be clamped into place by one M6 Nyloc nut and washer.

In testing I realised that the arms don't always open together which can sometimes result in interesting launches... One arm releases the before the other, resulting in the bottle flying off at an odd angle. A temporary fix involving a pneumatic flow restrictor connected to the faster actuator was tried with some success. This will be properly remedied in a future version by use of a timing belt or gears between the two shafts.

A number of students, staff, teachers and friends all descended on Izard park in Wadestown to try out the platform and shoot rocket videos.

Kent from Onslow college was kind enough to bring their Casio 1200FPS camera along. Slow motion rocket take off video FTW!!

A really high speed (1200FPS) close up shot of the launch platform:

Last but not least: Some proof that perhaps pigs can fly... Megan's "Pigtoria" on her maiden flight. Trajectory is a little off due to the bottle falling foul of a hair dryer during construction.

Build photos for The rocket Launcher.
Some launch Freeze frames

New Cannon

This creation is a new attachement built to go with the pNuke system of pneumatic mortars. These have been used for such fun as attempting to break the sound barrier and all kinds of effects in Shihad's Sleepeater.

Mike Bailey put me on to The Rock's Perfect Pie challenge... To build the world's greatest pie launcher. The PiNuke was the result....

Usually all pNuke plumbing is 50mm, now I wanted the pies to be shot intact complete with wrapper for effect. This required the new barrel to be approximately 100mm in diameter to fit a Big Ben pie whole.

A length of 100mm steel pipe was sourced along with a 50mm to 100mm bell reducer and a 50mm male BSP fitting.

The parts were Tig welded together in record time (there was only a week available for the competition)

A quick video was shot and edited the next day just in time to enter, turns out frozen pies at speed inflict rather a lot of damage to microwave ovens...



















Fast forward a couple of weeks and I took the cannon away on holiday with me (weird I know) Zac, Jonathan and myself set about launching some nefariously fun projectiles such as fence posts with the cannon.

Fun with a cannon and cameras down on the farm

The cannon was strapped to an unsuspecting tree and much fun ensued... Of note: Dead leaves used as waddings and the flying soft drink bottles.

Breaking the Sound Barrier

Some friends of mine and I decided to have a bit of a farm get away weekend recently. One of the things we decided would be fun while away was break the sound barrier... With a really big cannon.

Some of you may be familiar with the pNuke system of air toys which have featured in videos such as Sleepeater... The cannon used here is a more powerful and scary version with a custom built valve and some other trickery.

Modified deluge valve fitted to the air tank.

Fire deluge valve with a 5/2 3/8th inch pilot valve.

The barrel is a 6m length of 40mm scaffolding pipe coupled to the pNuke via some very big rubber hose and Mikalor super heavy duty hose clamps.

Clamps securing the rubber hose to the steel pipe. 

Rubber hose coupled to the deluge valve.

Unfortunately we were unable to achieve supersonic projectiles, I think this is due to the maximum flow through the valve not being high enough or the interior of the barrel is too rough.


Despite this the result is pretty spectacular...

As usual, Glow Sticks are pretty impressive in the dark:

We made a projectile out of rolled up newspaper and gaffer tape... It promptly disintegrated when launched.

An attempt to fire a lemon resulted in a lemonade mist... No pieces of the lemon were found.

SHIHAD - Sleepeater

When Sam Peacocke approached me about doing some effects for a Shihad music video I had no idea how apt the title was going to turn out :-D

I was given a ten page PDF of how the video was to play out... It required a spinning shaking chair, water cannons, smoke machines and a wind cannon. For me it simply read: Lets make some cool stuff :-)

The pNuke:

This cannon resulted from my initial "more power Igor!" approach to the water cannon idea. The pNuke is a 9kg gas tank fitted with a 2" solenoid sprinkler valve. The tank is pressurised  with an air compressor, activating the valve dumps the tank with quite some violence.

Thanks to: Greg at work for helping me out with the welding and James at Deeco for the valve.

Testing the pNuke with no nozzle:

The water is thrown even further when you fit the pNuke with a nozzle:

The following video shows why we decided to only use the pNuke as a wind machine... It's simply too violent when shooting water:

My Dad being pNuked:

Smoke Ring Cannon:
We did initially want to shoot smoke at everyone in the video... Software glitches filling our tent with smoke made us decide at about 1am on the saturday morning that smoke was a bad idea.



The Gentle Annie Water Guns:
These were used for generating the streams of water than fly behind and into each person as they spin on the chair.

A bank of 3/4" solenoid valves fill a bunch of polypipes with water and then use compressed air to "empty" them in a hurry.


Valve Bank:

The Gentle Annies required two different air supplies in order to achieve the desired effets. The pNuke was also supplied with regulated and filtered compressed air.

Air Supply Manifold:

The Final Result: www.sleepeater.co.nz/

Check back soon :) This is a work in progress...