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.

Saturday, June 30, 2007

Acceleron III Pod and Flight Computer

This week we finished building V1.4 of the flight computer. It is specifically designed for the Acceleron III booster. The majority of the new flight software has also been written. A few minor changes will still be made to the code, but they are mostly cosmetic. The flight computer now detects the burn-out in the booster to trigger the staging mechanism a short time later. Then after a settable delay the parachute is deployed.

Acceleron III payload pod. (staging mechanism - upper left, long thin tube is the sustainer air supply, the pressure switch is the device with the spring, and the flight computer, actuators are attached to the yellow bulkheads. The parachute is located on the other side of the pod.)

We temporarily mounted the FC into the pod and tested to see how it fits and operates with the staging mechanism. We are quite happy with the overall design and operation. Although it is probably heavier than it needs to be, it is only the first prototype, so a little more weight is acceptable.

The pressure switch (Trevor's TDD) now has a microswitch and is connected by short cable to a connector. This way the unit can be removed from the booster segment for filling with water and then fitted again.

We also manufactured a second 5mm nozzle that has a better fit for the staging mechanism to reduce the amount of wobble the old one had.

We are now pretty much ready to commence full system tests.

Friday, June 29, 2007

MySpace Upgrades

It appears that MySpace is doing some upgrades at the moment, so a number of the videos on our site are not available during this upgrade. Check again later, if there was something you wanted to see.

Sunday, June 24, 2007

Tachyon test flights

We had a sucessful weekend flying the Tachyon sustainer. We wanted to test it as a single stage first to make sure it will perform as expected when it is boosted by Acceleron III.

The full details of the flights can be found here:

A video is included in the update that shows the highlights of the day.

We are now just finishing the Acceleron flight computer (V1.4) and should be ready to do some end to end testing of Acceleron III systems fairly soon. Once all the tests have been successfully completed, the two stage rocket should be ready to fly.

Monday, June 18, 2007

Bad weather

We didn't get a chance to test the sustainer this weekend as it literally rained non-stop the whole weekend, as well as strong winds on Saturday with gusts up to 80km/h. This is the second weekend we haven't been able to launch. :(

We stayed indoors and continued the development. We made good progress with the Acceleron III pod, mounting the servos in it and connecting the staging mechanism to the servo. We did a dry test to see if the servo had enough strength to release the Gardena staging mechanism and it looked good. We also fitted a micro-switch to the TDD so now the flight computer will be able to know when burnout has happened.

We now only really need to finish building the flight computer and making the parachute and the rocket will be ready to go. We will still need to do a few full system tests with staging and parachute deployment before the actual launch.

We also tested the spliced bottle we glued a few weeks back. We pressurised it up to 100psi and it held well. We didn't want to burst test it as there is no guarantee that the next splice will be as strong. We will test these splices to perhaps 20% above operating pressure without destructive testing.

We will make up a number of these spliced pairs (as opposed to sliced pears) and then make our first rocket out of them.


Wednesday, June 13, 2007

Tachyon sustainer and staging mechanism testing

We have updated our website with the latest progress update. There is a video showing the details of the Tachyon parachute deployment mechanism as well as a test of the staging mechanism under pressure.

Update is available here:


We have also added a site index to the website to make it a little easier to find things.

Sunday, June 10, 2007

Tachyon completed

We have finished building the Tachyon sustainer this week, and pressure tested it up to 130 psi.

We wanted to fly it during this long weekend, but due to the heavy storms here in Sydney we were unable to. We had wind gusts of up to 100km/h, huge seas with up to 15m (40 foot) waves and drenching rain. Our local park had quite a bit of standing water on it, so it was unsuitable for launching as well. We will fly it at the next opportunity.

Meanwhile we have been continuing with the staging mechanism on Acceleron III, and plan to continue with it tomorrow.

Monday, June 04, 2007

Tachyon Sustainer Development

This week we concentrated on the Tachyon sustainer. We need to have it built so we can see how it mates to the booster and add the necessary supports. We had our first attempt at gluing the fins directly to the bottle, but found out that PL Premium does not stick to the plastic the fins were made out of. (The glue held great to the PET bottle.) So we connected the fins in a more conventional mechanical manner. The new fin arrangement is removable and does not require to be glued or taped to the bottle.

We also completed the deploy mechanism utilising V1.3.1 of the flight computer. (V1.3.1 includes a software upgrade to drive RC servo motors directly and bypasses the DC motor driver part of the circuit). We are trying a hinged door mechanism for the parachute bay to see how well it works. We wanted to get a more streamlined recovery system compared to the Polaron III rocket. The computer/servo and parachute bay are removable from the rocket skin for easier servicing.

We really need to only manufacture one more aluminium coupling for the inter bottle connection, and then the sustainer should be complete.

We hope to test fly it this weekend to test the deployment system and dynamic stability.