Each flight log entry usually represents a launch or test day, and describes the events that took place.
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Date:  13th June 2010
Location: Doonside, NSW, Australia
Conditions:  Cool 17C, clear skies >10km/h wind.
Team Members at Event: PK and GK

It has been a while since the last update, but development has been progressing well in the meantime. There were a couple of launch postponements due to adverse weather and hence the delay in our regular updates.

Website Changes

Welcome to our new home, It's kinda roomy in here. :) We have now gone through the full relocation of our main website to a new host where we have 10Gb available up from the old 50Mb. A lot of the larger photos were also located on another server that now have all been moved to the new server.

We've added a search function too, which should make it easier to look for things on our site. With the added room, we'll now include larger images with our regular updates.

Labs Website Extension

Now that we have the new space we have also rolled out the Water Rocket Labs extension we have been working on. Initially it was going to be a separate website, but we have decided to add it as a subsection of this site as it makes it easier to administer. The intention is to add the results of any new experiments to the Labs section and continue with our regular launch reports, construction details, and progress updates here as usual.

If you have data you would like to share with others and have it included in the labs section please let us know.

Williams "Wildfire" Westernationals 2010

Last weekend I took some time off from work and water rockets, and flew over to Perth in Western Australia to attend the Williams "Wildfire" Westernationals. Rocketeers from all over Australia attended. There is only one way to describe it.

Absolutely - freaking - AWESOME!!!

It was a great weekend of high power rocketry. It was fantastic to see an N2000 motor make it's way skyward and the associated noise to go with it. *grin* I witnessed a number of Mach+ flights which were amazing. Congratulations go to all the guys who successfully completed their L1, L2 and L3 certification flights. It was very much evident how much hard work and dedication goes into the sport at this level, and a great bunch of guys as well. Very inspirational stuff.

A huge thank you goes to Scoop, Mel and all those people who helped to organise and cater the event. I had an absolute blast and perhaps will have to take the whole family over next year.

A photo and video thread has been set up on the Forum for Australian Rocketry here: http://ausrocketry.com/forum/viewtopic.php?f=37&t=2189&start=0

I've already posted one video but I'll be putting together a few more from the weekend over the coming weeks.

Right, back to water rockets.....

Polaron G1

Nozzle trouble

A week ago I made up a couple of new 15mm and 16mm nozzles by epoxying long threaded bottle caps into the quick connector adaptors. I aligned the cap with the adaptor and set it on a rotisserie to cure the glue evenly. The cap sat nice and straight in the threaded section.

The day before launch we were going to pressure test these nozzles to make sure they would be able to hold at least 250psi. I screwed the nozzle onto the bottle and noticed that it looked a little off-center. We used the dowel through the nozzle alignment check an noticed that indeed it was off by perhaps 3 or 4 degrees. This was a bit of a surprise and a worry, so we checked the other nozzle and it was off by about the same amount. DANG! ... less than 24 hours to launch and we didn't have a nozzle!

The Polaron G1 is a heavy rocket so a smaller existing nozzle couldn't really be used. Launching a high pressure rocket, with the thrust vector off centerline even by a small amount is asking for trouble. So we proceeded to remove the cap from the adaptor since it was useless in this state. We had to use the Dremmel and lathe to get rid of it and the epoxy.

Next we screwed a new cap onto the end of the rocket, placed the nozzle in the release mechanism on the launch tube and placed the whole rocket on the launch tube as well. This made sure that the adaptor and cap were aligned relative to each other. The mis-alignment was due to a combination of how the cap sits slightly askew when tightened on the bottle (wasn't aware of this previously), and the fact that the adaptor moulding is not very straight either. We could see this easily on the lathe. A part of the moulding was concentric where the o-ring was, but the threaded section was wobbling about the axis.

We used the 24 hour epoxy as it is much stronger than the 5 minute stuff. We then used a heat gun to try to accelerate the cure time, and placed the whole thing in front of the heater to cure, but not hot enough to shrink the bottles.

We were going to have to pressure test the nozzle on the launch pad on launch day. If the glue failed, then the rocket should still launch, but with a much bigger nozzle! When you looked at the nozzle by itself it looked crooked with the cap, but when tightened on the rocket it aligned very well.

Remote Arming

We also added a remote arming system to the flight computer after the vibration failures last time. This consisted of a set of contacts wired in parallel to the ARM button and spring loaded to close automatically. There was a piece of plastic inserted between the contacts and this plastic was tied to another string. After the rocket is pressurised, simply pulling on the string allows the contacts to make a connection arming the computer. The launch detect then works as normal.

Tornado Tubes

Since we have previously only hydrostatically tested the commercial Tornado tubes, we wanted to test fly them to see how they perform in flight. We assembled one rocket (Axion VI) using the Tornado tubes. Because of the sealing and cracking problems when over tightened, we used a couple of soft internal washers to give a better seal. These washers are custom made for our Acceleron rocket nozzles that fit in a bottle cap and have a large hole. They worked well in the Tornado tubes.

Parachute Cam

For the tornado tube test flights we decided to mount a camera in the center of the parachute looking down just to get a different perspective of the rocket in flight. It had nothing to do with the Tornado tubes. We weren't sure if the weight of the camera was going to cause the parachute to deflate, or fail to inflate all together. But what the heck, there was only one way to find out and that was to fly it.

We put two pieces of gaffer tape on either side of the parachute and punched a number of holes through it. We then secured the camera with a couple of pieces of wire twisted at the back.

Launch Day Report

We had two main objectives for this launch. We wanted to test fly the commercial tornado tubes on a proper rocket as well as test fly the fiberglass Polaron G1 that hadn't flown previously due to high wind conditions.

• When we arrived at the launch site the weather was near perfect. We had blue sky and very little wind.
• We set up the launcher to launch the 90mm Axion VI with the long guide rail extensions. The launch was going to be slow so we wanted maximum rail length.
  
  We filled the rocket with water and loaded it onto the launcher but didn't pack the parachute as we needed to turn the camera ON before packing it into the  nosecone. Luckily there was enough room for both the camera and parachute in the side deployment mechanism, though it took a couple of goes to figure out how to fold the parachute with the camera in it.
  
  We used the MD-80 clone camera for the flight as it is only half the weight of the original MD-80.
• The launch was pretty slow at 120psi but the rocket reached good altitude and the parachute opened fine without issues. On the way down we really couldn't see any difference in the shape of the chute which was good.
  
  After landing we downloaded the video to the laptop but it looked all blank. That was disappointing, but the camera had recorded a correct length movie. I was hoping that it was only the laptop that was having issues with a codec, and in checking the video later at home on the PC, to our relief it played fine without trouble.
• Since we didn't know what the issue was with the camera at the time, we swapped it for the original MD-80 for the next flight.
• The second flight was very similar to the first and good video was recorded from inside the parachute. You could tell that the MD-80 has a slightly wider field of view than the clone.
  
  Due to the softness of the material the camera was mounted on, the video is naturally quite shaky. The slow video scan rate also tends to distort the fast moving image giving the impression of a bending rocket and shroud lines.
  
  On the second flight you could see that the parachute at times appeared to move like a jelly fish due to the camera in the middle, but it did not appear to have any bad effects on chute performance.
  
  In any case we were quite happy with the results. The tornado tubes also performed well, so we will be using them in upcoming rockets.
• We then configured the launcher for the Polaron G1 launches. We replaced the 9mm Gardena release head with the 15mm one and a 1.2m launch tube.
• We installed the remote arming string and pinned it down with a brick so it wouldn't accidentally pull away. The arming system worked well and allowed us to arm the rocket from a safe distance after the pressurising stopped.
  
  The advantage with this system was that if the rocket had launched by itself, the arming string would have been pulled out arming the computer, and the launch would be detected shortly afterward so the rocket had every chance of recovering safely.
• The first flight was with 3L of water and a 220psi launch pressure. The rocket went up very straight, and thankfully the epoxied nozzle held. The rocket reached an altitude of 702' (214m) which was lower than what the sims predicted, but the nose on this rocket is fairly blunt and probably had a higher drag at these speeds. The rocket landed well without issues.
• On the second flight we pressurised it to 230psi and again used the remote arming string prior to launch. This time the rocket went to 751' (229m) which was again lower than expected, but it was our highest single stage flight. The rocket again landed well with only slight buckling to one of the fairings because the parachute cord slipped down the rocket and tightened around the unreinforced section as the parachute opened. The pressure vessel was okay.
• The G1 tests were really an evaluation on how these 2L reinforced bottles work in practice, and eventually will be used to replace the Acceleron V booster segments.
• Thanks to David, Craig and Adrienne for helping launch the rockets as our regular launch crew was away visiting friends in the Blue Mountains.

Flight Details