This blog covers the day to day progress of water rocket development by the Air Command Water Rockets team. It is also a facility for people to provide feedback and ask questions.

Thursday, May 26, 2011

Measuring Bottle Stretch Thrust

Last weekend we did a little experiment to measure the thrust produced as a bottle contracts while depressurising. From earlier experiments we learned that bottles can stretch significantly and we wanted to know how much of this energy is returned during the boost phase. The main idea behind this experiment was to help refine future models of water rocket thrust behaviour. The full experiment writeup is here:

We also compared the thrust produced by stretching alone to the thrust a regular rocket produces.

Monday, May 16, 2011

10 Water Rocket Challenges

Over the last few weeks we’ve been putting together a series of challenges that people can attempt with their water rockets. These challenges are designed much the same way one would collect scout badges when they have achieved certain activities. Each challenge is also designed to address a different aspect of the sport.

For each challenge you achieve you are awarded a patch that you can place on your website, blog or video. There are no judges or approval processes, and patches are purely self-awarded on an honor system when you believe you have achieved the challenge in the spirit it was intended.

You should also be able to attempt all the challenges at your local park, but be warned these challenges are difficult!

Are you up for a challenge? …. Read More....

Tuesday, May 10, 2011

Polaron G2 flight day report

I've uploaded the update from this weekend's NSWRA launch on our main website here:

The update includes photos and video of the Polaron G2 launch. The flight was encouraging for us in order to keep pushing further with the G2 development. Although the 210psi launch pressure was 20% lower than what the rocket was designed for, we decided to at least get a couple of good flights in before increasing the pressure again. Also encouraging is that the simulator results from two different simulators predicted the altitude quite accurately for this flight. This means we can continue to use the simulators to predict the behaviour of this class of rocket.

The G2 in this configuration still has room for improvement on two fronts. Each 10psi increase in pressure beyond the 210psi adds around 50 feet to the altitude. These pressure chambers have been hydro tested to 270psi. The rocket is designed to be extended by a further spliced-quad like we used in the first attempt. This extra spliced quad should add a further 100 feet or so. How the rocket stands up to higher speeds and stresses is unknown at this stage, so more fights will follow.

We also flew a second high pressure rocket on the day - Axion G2 - that is based on the Axion series of rockets. The rocket flew well, but failed to deploy the parachute and crashed. I can see the G2 name is going to get confusing here. The 'G' in the name simply stands for "Glass"-reinforced and the 2 is just the second in the series.

Sunday, May 08, 2011

Polaron G2 - flight

Perfect launch conditions today for the G2 launch. Virtually no wind and mostly blue skies. The G2 had a great flight and the higher power was quite evident from the sound it made. We're putting together the launch day report along with the highlights video, which should be on our website in the next few days.

Friday, May 06, 2011

Servo Timer II - boards

We received the PCBs for the Servo Timer II from the manufacturer yesterday. We decided to use PCBCart this time around as they were well recommended and our experience with them so far has also been very positive.

I soldered up a couple of the timers yesterday to check that I didn't stuff up on the board, but luckily the circuit powered up first go. We are going to continue more flight testing with these in the coming weeks. I'm just in the process of ordering the components for them in bulk quantities, but it will still be some time before they will be available.