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, February 26, 2008

Polaron IV Boosted flights

We had a great weekend of flying the Polaron IV rocket with the drop away boosters. The boosters behaved exactly as expected and gave the rocket a nice kick on launch.

The on-board video also turned out great.

The full details of the launch day with lots of pictures and video of the highlights is available here:


Friday, February 22, 2008

Successful Booster Test Flights

In preparation for launching Polaron IV we wanted to make sure that the whole launcher will work with the boosters and the main stage all together. We weren't sure if it would come off the launcher cleanly, or if the boosters would fall off, or how the new guide rail would go.

We built a dummy main stage out of old bottles and an old nose cone that used the nosecone-off-at-apogee technique for deploying a parachute. The main stage only had the bottom 2 L bottle pressurised. And had 1.5L of water in it so virtually no air. We added a little ballast into the nose in the form of a zip-lock bag with water in it.

We had two successful vertical take-offs with the boosters all falling off almost simultaneously on both occasions. The boosters were filled with 1L of water and everything was launched at 100psi.

The dummy main stage weighing in at close to 800 grams was still able to reach ~80-90 meters
The parachute opened on the first flight right at apogee, and failed to open on the second flight.
The dummy main stage was destroyed, but luckily all the bits we needed for the Polaron IV rocket survived. The boosters also survived their tumble recoveries.

We proved to ourselves that this particular launcher and booster concept works, and so we are hoping to get at least one flight out of the Polaron IV rocket on Saturday. There are always things that can go wrong on the day, but we will worry about those when they happen.

We have also finished repairing the Hyperon and J4 rockets, so we will have those as backups on Saturday as well.

Full details of the days events with videos of this booster test will be again published on our main site after the launch day.

Sunday, February 17, 2008

Launcher Completed

We spent most of the day in the workshop again today. We are really pushing hard to get Polaron IV and its launcher ready for the next NSWRA launch day. It is only 6 days away.

We did finish the launcher today, which I am really happy about. It now sports a single 2m launch rail. The rocket will use launch lugs to hold onto the rail. We had to switch to this system since there really isn't room for the 3 guide rails we have been using. We ended up using 2 of the feet and guide rails from our medium launcher to support the new launch rail which really reduced the amount of stuff we had to make. The legs are still usable on the other launcher so the nice part is we have less hardware to carry with us when we take both launchers.

We are now finishing off the rocket and the booster retaining mechanisms on the rocket, and then it should be ready to fly. If there is a nice launch opportunity between now and Saturday we may try the boosters with the dummy main stage at our local park.

Monday, February 11, 2008

Splicing Bottles and Pressure Tests

The weather hasn't been too co-operative this weekend so we spent quite a bit of time in the workshop. We have updated our main site with the latest developments here:

The update includes a video tutorial into how we splice our bottles. It also includes an update on the progress of our Polaron IV rocket, and the Acceleron IIIb booster.

Wednesday, February 06, 2008

Glueing and PCB layout

Splicing and Couplings

This week it's been a bit of a mixed bag. Now that we have the PL Premium glue, we are gluing together pairs of 1.25L bottles. These glued sections have a thread at either end allowing us to join them to other sections. We have 6 made up, and two more will get made today. They will be used in constructing boosters and rockets bodies as well.

To join these together we have also been experimenting with making simple "Tornado" couplings. We are still waiting for the glue to dry before we do a full pressure test. We've made up four of these so far and if they work well, we have the materials to make a lot more. They weigh around 7 grams. The other nice thing about these couplings is that they have a 19mm hole which is about 6 times bigger in cross sectional area than the Robinson couplings we have been making. This leads to better internal efficiencies and also means we can put a long 19mm launch tube through them.

The simulator predicts well improved altitudes for rockets made out of the spliced pairs and the tornado couplings.


We have also been doing repairs to the two crashed rockets from last week. This will require a little more work since the nosecones and deployment systems need to be rebuilt.

PCB Layout for Flight Computer V1.5
As a part of making life easier when doing repairs we have been finalising the PCB layouts for the next iteration of the flight computer. We are going to do a small run of these PCBs and make up a number of the computers so that we can quickly replace them should they become damaged. The board will be about 43mm x 55mm in size or about 30% smaller than what we have been making on the prototype board. It will have dual servo motor outputs making it suitable for single and dual stage rockets. It also has a buzzer for audio feedback of mode changes as well as helping to locate it in tall grass.