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.

Tuesday, March 25, 2008

Acceleron IV progress

We spent this weekend working on the Acceleron IV booster getting it back into a working state for next week. We did a pressure test to make sure that everything is still fine, but we found out that the rocket was not holding pressure at all. We pretty quickly discovered that three of the Robinson couplings were missing their seals. Ooops. When we put those back in and everything checked out okay. We must have missed them during preliminary assembly.

We only pressure tested the rocket to ~100psi since the neighbours were out in their back yard, and having had this rocket fail a pressure test in the past, we didn't want to push it. We did have the video camera recording though just in case. The rocket will most likely get launched at 120psi on the day. The rocket theoretically should hold up to around 140psi operational pressure, with a burst pressure of around 180psi.

We hooked up all the electronics and and made sure the staging still worked when the pressure in the rocket dropped. We replaced the sustainer in the test with a small bottle full of water which fired as expected.

We replaced the rubber bands in the staging mechanism as keeping them stretched all this time in storage caused them to deteriorate quite badly. The same went for the wide rubber bands that held the fins on.

The booster segments are now attached with velcro straps which makes it a lot easier to service the segments.

The launcher has also had an upgrade with new longer fill tubes that allow us to use the spliced pairs of bottles on the bottom of each segment.

Some work has also been done on the sustainer. The altimeter has been moved into the space between the bottles which should help protect it. The altimeter is attached to the inter-bottle ring and having its own power supply allows us to swap it between rockets. We still have to re-attach the fins to the sustainer and also mount the new FlyCamOne2 camera to the payload section.

If we get time this week we also want to finish building a reinforced rocket that should be capable of around 180-200psi. It is only a two 1.25L Robinson coupled rocket but we are including the baffle we made a few months back to prevent the blow through effect with this rocket. The higher pressure would only make it worse.

We also made a couple of rocket carriers that help us transport and protect the rockets. They also help prevent the rockets from sagging in warm conditions.

Friday, March 14, 2008

Flight Computer V1.5

Last night I finished soldering up the new board for the latest flight computer. Everything worked as expected which is good, and we will fly it soon.

The large bright LED display allows you to stand back from the rocket while it is pressurised and ensure the correct settings are set. It also has a small buzzer that allows you to hear whether it is armed or not while standing back.

A little more software needs to be written for the flight computer to support the new functionality. The intention is that the code base will be universal enough to be used for regular water rockets, but also for multi-stage, or dual-parachute.

Wednesday, March 12, 2008

Launcher Details in 3D

We spent this weekend documenting our Polaron IV launcher and rocket. We've produced an explanation video of how the launcher works as it is much easier to explain the configuration.

The details are available here:

The update also includes a number of anaglyphs of various parts that you can view in 3D using regular red-blue 3D glasses.

Click on the image to enlarge.
You will need red-blue 3D glasses to see this image properly

Also a quick update on flight computer V1.5 - We received our first PCB this week so we are keen to solder it up and see how it performs. If no changes are required we will get another 9 PCBs made so that we will have total of 10 flight computers ready to go for the up coming experiments.

The new flight software is also progressing and should be finished within the next couple of weeks. Once the flight computer has had a successful couple of test flights, we will publish the full design again, including the PCB layout.


Wednesday, March 05, 2008


After a short break last week to catch up on non-rocket related projects we are back in full swing again.

We ordered some great lightweight ripstop nylon parachute material from the UK this week. It was comparatively cheap at only AUD$32 delivered for 10m x 1m of the stuff. It is a nice orange that should make it easily visible. From the time of order to delivery it only took about 6 days to get here which is pretty fast considering it had to go half way round the world.

We want to make a new lighter parachute to replace the one on the Polaron rocket. The parachute will weigh less than half the weight of the existing one, and also use up about half the space. For the shroud lines we are going to use TigerTail - a very strong light-weight line typically used for making necklaces. It is stranded stainless steel cable coated with nylon. It is very light, doesn't kink, is only 0.3mm thick and has very high tensile strength. This will allow us to make a strong parachute and should pack into a much smaller space.

If this parachute goes well, we will most likely make up more parachutes for the other rockets, including Acceleron.

We have also been doing some more work on flight computer V1.5 and hopefully the prototype should be ready soon. We are getting a number of PCB boards made up so it will take up minimal space and weight. Once finished it will be used on all of our rockets as it is capable of driving two separate servos and has a few more nice features compared to the previous version.

I turned off comments here on blogger (temporarily) due to excessive amount of SPAM last week, so if you would like to ask questions, just visit the main site and go to the contact page.