Each flight log entry usually represents a launch or test day, and describes the events that took place.
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This weekend was an excellent day for rockets. We became members of the newly regrouped NSW Rocketry Association (NSWRA) and went to their first launch event this year at Doonside. A number of people worked really hard to get the association back up and running so a big thank you goes to them. There were a great number of rockets, and the smoke and noise was a lot of fun to see. We managed to get 5 launches in on the day.

I will only cover the water rocket flights in this update, information and pictures about pyro rockets from the day are likely to appear on the NSWRA website soon.

It was also good to catch up with Darren and David as well as meeting all the new people from the association and from the Forum for Australian Rocketry. We wish we had more time on the day to talk to everyone, but I am sure there will be more opportunities next time.

Doonside is about 50 minutes away from home, so not bad at all. The launch site is quite overgrown with tall grass and a couple of the guys started clearing it with a whipper sniper. Other than a few rocket eating trees it is a great launch site. We have about a 500m radius of clearance.  On the day we were restricted to 2000', which of course we had no issue with, but some pyro rockets sure were around that altitude.

Events

• We brought J4 IV, Hyperon and Polaron IV to the launch day. For us the main aim for the day was to test Polaron IV as a main stage. Due to its weight, we flew it with a 9mm nozzle and water only. We wanted to test the new payload section with the new FlyCamOne2 camera and the deployment system to get more confidence that it will work when boosted by the Gluon boosters. We did learn a number of important lessons from the test flights. (see below)
• First off the pad was J4 IV. We had flown this rocket a number of times before but unfortunately on this day it misbehaved and pitched over a little after take-off. The parachute failed to deploy for some reason and the rocket bounced heavily. J4 was fitted with the foam nosecone extension so this was a good day to see how effective it was. The payload cover was quite badly mangled, but it was possible to remove the inner section of the payload and virtually everything was intact. The padded nosecone did its job. The servo, flight computer and the whole deployment mechanism survived and all still worked. This will make it much easier to get the rocket back in the air.
  
  We will replace most of the bottles as they buckled on impact.
  
  The altimeter was, however, not that lucky. The LCD screen leaked a little so there is a black blob on the screen, but it still worked and we were able to download the flight data from it. I am not sure if its sensor still works, so we will need to do some tests. As a result we will not be flying altimeters in general, but only when we need to know the altitude for example in new rockets, or record attempts.
  
  As the rocket flew a long way down range it took us a while to find it in the tall grass.
• Hyperon was next and although it spiraled a little the parachute deployed well and we had a good landing. Hyperon's second flight was pretty bad as soon after take-off it pitched sharply over and headed almost parallel to the ground a long way down range. Parachute failed to open and the rocket crashed heavily. The servo survived though, and so no great loss. The flight computer PCB snapped in half (again) and it will get retired now.
• We are not exactly sure what was going on and why the rockets looked a little more unstable in the air than usual, but we are beginning to suspect the black tape we have been using to hold the sections together could be a contributing factor. The black tape is very similar to electrical tape and so quite stretchy. When it heats up in the sun it becomes even softer and the heat that builds up in it is enough to shrink and deform the bottle underneath it. The bottle heat distortion is unlikely to be the cause of the instability but rather the fact that the rocket is flexible because the tape is not providing a good rigid bond. We liked the tape because it would form itself well to the shape and it was visible in the sky.
  
  We are going to switch to a lighter coloured and stronger tape when we rebuild the rockets.
• Then it was time to launch Polaron IV. With the two crashes before we were going to try to minimise the risks with this launch. We added the launcher guide rail extension and filled the rocket up with water only to get maximum speed off the pad.
  
  The take off was slow and graceful and the rocket went straight up. The parachute was deployed right at apogee and there was much rejoicing. The altimeter gave us an altitude of 317 feet (97 meters) which was about 1 meter off what the simulator predicted!
  
  When launched with the boosters we are expecting it to go at least twice that if it keeps going vertically.
  
  From the video footage we can see that the parachute came out right near apogee but, the altimeter data says it didn't fully open until 2 seconds later!
  
  Altimeter data also gives us a descent rate of 4.48m/s for the new parachute.
• The video camera also worked well (almost) and we ended up with good in-flight video. The camera has a number of issues which I will cover in a separate update, but I have read in online forums that a firmware upgrade can fix some of those problems. Other problems I can fix in post production so not really an issue. The 640 x 480 resolution did give us a nice clear image though so we were happy. The long record time also meant we were able to stay away from the rocket while it was pressurized on the pad.
• We lost a fin on the way down as they were only held on with the large rubber bands. One rubber band due to either acceleration or rubbing against the guide rail probably loosened the fin. We found the fin and taped them all on along with the rubber bands for the next launch.
• We flew Polaron IV again at a slightly higher pressure (125psi) and the flight profile was almost identical to the first. The rocket reached 299 feet going mostly vertical and again the parachute deployed on cue and rocket landed well taking video footage all the way.

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• Later at home during video analysis it was obvious from the water plume that the "blow-through" effect was quite severe and it took a while before the water column settled into a nice stream. You could also see that at that point the rocket accelerated significantly. This should not be much of an issue for when we launch it with boosters as Jet foaming will be used with a 7mm nozzle.
• The other minor issue we noticed that the removable part of the payload section had shifted upward about 5 mm. The section is secured against positive G-s but what we forgot to take into account were the negative G's during parachute deployment. The only problem it caused was to move the camera's pivoting head and so we ended up with a little bit of obstruction on the way down. This can be fixed quite easily before the next launch.

Flight Details