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, April 30, 2009

Launch Report update

We've posted an update from the last launch day on our main website here:

There are a number of photos from the day as well as some more design details of the Acceleron V booster build. We are pretty much now focused on getting the Acceleron booster completed. While we are aiming to have it ready for launch at the next NSWRA launch event, it may likely slip until the next one.

Monday, April 27, 2009


We only flew a couple of smaller water rockets this weekend at the NSWRA launch day event, mostly due to the high wind conditions. A few of the pyro rocketeers lost their rockets somewhere over the adjoining suburb, so we decided to call it quits a little earlier too.

I'm putting together the launch report at the moment which should be available in the next few days. It also includes a progress update on the Acceleron V booster.

We did launch a couple of small pyro rockets with the boys and safely recovered those. During the week we bought a bigger pyro rocket kit from Suburban Rocketry so we are now building it with the boys in between all the other rocket stuff. I can see we'll probably be building a few of these as they are fun to build, but the cost of motors is pretty high when compared to air and water. :)


Sunday, April 19, 2009

Acceleron V modelling

This weekend we spent a bit of time modeling Acceleron V to scale in 3DS Max in order to figure out the spacial relationships of the new release mechanism and the position of the staging mechanism. We now have a clear idea how to build the base support mechanism and what clearances are needed. The images below include the second stage, although the colour scheme will most likely be different.

The length of the second stage has not been determined yet but will be such that the entire two stage rocket is stable in flight.

The rocket is designed to be launched from our drop away booster launcher.

Detail of the release mechanism and the location of the staging pod. The pod contains one of our flight computers and uses a standard 9mm Gardena release mechanism to release the second stage. Depending on the length of the second stage, the pod can be moved further up the rocket.

Fabrication of the booster segments continues, and we now have a materials list for the release mechanism so we can start construction on that as well. The staging pod is already finished. I'll post actual build pictures next time.

We've also been preparing our rockets for the next NSWRA launch day. There are no major new rocket changes although there are some experiments we want to run in getting more stable descent video as well as flying the whistling nozzle. After the last crash the Axion rocket has been rebuilt.

Saturday, April 11, 2009

Acceleron V Redesign

We've been collecting 2L bottles from friends and family over the last couple of months to make up more spliced pairs for the new Acceleron booster. After we had a few leak problems with the last spliced-pair batch we're now trying the sikaflex glue as a sealant in the joint area but PL premium as the main glue that holds the splice together.

Some of the 2L bottles ready for processingBottles cleaned, trimmed and curled ready for sanding.

All up Acceleron V has three segments in the cluster and each segment uses 3 x 2L spliced pairs giving a total volume of almost 33 liters. Up until now we have been using 10mm nozzles on the Acceleron boosters but with the larger volume and larger weight of water we have decided to go with the larger 13mm nozzles we use with our drop away boosters. Including the second stage, the total liftoff weight is now going to be approaching 16 kilos. Switching to the new nozzles would have also meant that we would have to machine new nozzle seats for the old Acceleron launcher.

Instead we decided to adapt the booster launcher to work with the Acceleron rocket. The old Acceleron rocket uses a speargun release mechanism, so we are replacing this with custom made aluminium gardena nozzle mounted on the baseplate that holds the cluster together. This nozzle will fit into the existing Gardena central release head.

Because this launcher's minimum nozzle spacing does not allow the three segments to be up against each other like in the old Acceleron rocket, we are going to separate the cluster segments further from each other. This will require a new baseplate for the cluster. This again will be made from aluminium and reinforced with fiberglass. By separating the cluster segments we will be able to lower the second stage release mechanism pod further down in between the segments allowing the second stage to also sit lower in the booster. This will help partially solve one of the problems we've been having with the old Acceleron rockets, namely the stability of the second stage on the end of the staging mechanism. The length of the Acceleron booster and the location of the staging mechanism prevented us from making the second stage any longer. If the second stage had been much longer there was the danger of snapping the rocket at the staging mechanism during the boost phase. By lowering the second stage between the segments, we can use the segments themselves as guide rails for the second stage. This will allow us to build a second stage around the length of an Axion or Hyperon rocket.

The second stage will be pressurised through the central release head allowing it to use a different pressure to the 1st stage. The Acceleron parachute(s) will now be located in the space between the spliced pairs.

With the second stage supported by the segments, it will also mean that the second stage can have a boat tail for better drag efficiency.