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.

Wednesday, January 28, 2009

V1.6 PCBs have arrived

We received the PCBs yesterday from the manufacturer. I was very impressed with their quality, and breathed a sigh of relief when all the components fit. :) We'll definitely be using this manufacturer again. I was keen to see if the layout design would work but unfortunately we had a blackout and so I had to hold off on soldering the first unit until after dinner.

Breathed another sigh of relief when the FC powered up first go. The software is pretty much done, just doing a few more minor tweaks to the servo timing routines and testing it with a range of servo motors.

The version shown above has the assemtech G-switch soldered in and it's set up for 9V operation. With the battery clip the FC weighs in at 18 grams.

Next up we are going to do some flight tests with them, and I'll replace the V1.5 FC in the FTC rocket with one of these to see how it performs under higher G-loads.

The documentation and manual still needs to be completed, but that is also close to being done.


Monday, January 26, 2009


Last weekend we went out to Doonside with some of the NSWRA rocketeers but only equipped with lawn mowers and brush cutters. All the tall grass is now gone from the launch area so it is a lot nicer to move around and set up. Phil also installed permanent launcher bases which will make setting up much easier and there is less gear to bring each launch day.

While we wait for the new flight computer PCBs to arrive (Apparently they have now been shipped) we have been continuing to build the Acceleron V booster. We have mostly been testing and reinforcing the 2L spliced pairs. The booster uses 9 of them. We splice a pair together and then hydro test it up to about 80 psi. If there are no leaks we then add the neck reinforcing rings and wait a few days for them to dry, before testing again to 130psi. This way if the original splice fails at the 80 psi we don't waste time and bottles reinforcing the necks. The neck reinforcements are necessary as at about 110psi stretch marks begin to appear around the neck of the 2L bottles.

We are making a few spare spliced pairs in case any need replacing. The spare ones can later also be used for the new bigger Polaron boosters. A couple of the pairs are all-sikaflex splices so we are keen to see how they hold up.

I have also had my first go at fiberglassing. I wanted a simple project initially to learn the technique and so decided to make a ring fin that should be able to withstand a bit of punishment during tail-first landings under parachute. It was quite easy to do but I can see I need to pay a bit more attention in getting all the bubbles out and work a bit more at getting the resin in all the way through. But overall I was pretty happy with the results. The ring fin is 37 grams, 0.8mm wall thickness and uses 3 layers of fiberglass matting. It is significantly stiffer than a PET ring.

Here is the ring fin after the first rough sanding. I'll spend a bit more time making it smoother before painting it. The ring fin will be attached with CF struts to the main rocket body.

The next few fiberglass projects will likely to be fin strut attachment supports for the pressure chamber, and reinforced balsa fins. When I get a bit more comfortable working with it, I'll have a go at reinforcing some pressure chambers.


Monday, January 12, 2009

Progress Update

This last week we have been concentrating on getting the FC V1.6 finished. It has taken a little longer to get the PCB designed as we are still learning the Eagle CAD package, but the package is definitely an improvement over what we were using before. We are also using a new PCB manufacturer so some time was spent configuring Eagle's layout tolerance settings specific to their manufacturing process. The boards are currently being made so we hope to have them within a week or so, and then we can start soldering. :) We've also been creating all the documentation that goes with it.

Rocket development otherwise is progressing slowly at the moment as most spare time has gone into building the bigger workshop.


Friday, January 02, 2009

New Year & Recovery Guide

Recovery Guide

Happy 2009 to all! With the busy time of Christmas over we are now back to more full time rocket development. One of the things we have been working on over the past few months has been a water rocket recovery guide.

The recovery guide is intended for rocketeers wanting to add a recovery system to their water rocket. The guide covers the multitude of approaches rocketeers have taken over the years, discusses some common misconceptions and provides links to various websites covering all aspects of recovery.

The current iteration of the guide is here:

This guide will continue to evolve as more systems are documented and as more links are explored. If you have a recovery system you'd like to share that is not on the list please let us know either through the guide's form, email, or comments on this blog, and we'll classify it and add the references to the relevant sections of the guide.

Plans for Air Command in 2009

Some of the things we are planning for the first half of this year:
  • Continue work on the recovery guide.
  • Release V1.6 of the flight computer. The new version has a PCB around 25% smaller than V1.5 and is designed to fit in regular rockets as well as T8 FTC. It is also simpler to set up and use. A small quantity of these will be available for sale. We are aiming to release by end of January.
  • 33L Acceleron V development. We have a lot of pressure testing and reinforcing to do on this rocket and we may need to upgrade the Acceleron launcher for bigger nozzles. We're looking forward to the flights of this one. :)
  • Polaron VI rebuild with larger boosters.
  • Baryon III multi-stage flights - Actually trying to get the second stage separated properly this time. :)
  • Continue with the static testing. We have a number designs we would like to evaluate.
  • Fiberglassing body tubes for stronger and higher pressure rockets.
We look forward to seeing everyone's progress this year.