2008-07-27
Killarney Heights Space Program
After the Dural meet Peter mentioned he had planned a rocketry meet with his mate from down the road and asked if I'd like to come. Naturally I said yes! Peter's mate has been conducting test launches over the past few months, some of which are documented on Peter's site.
Pete (Peter's mate - I know, confusing), is a lovely bloke with a great family. His youngest daughter had just rolled her ankle in a trampoline accident and didn't come, but Seth his son did.
Pre-launch preparation included charging the telemetry system (camera downlink receiver) battery, and taping the 2.4 GHz camera to the rocket.
Unlike previous experiments this one was to have a parachute recovery system (the highly conspicuous Berocca can atop the D-motor), and would include solid rocket boosters in addition to the main stored-pressure water rocket motor. Flight stability was ensured by a ring-fin arrangement.
Pete's launcher is quite neat, utilising a Gardenia quick-release hose connector hooked up to a length of rope so the launch director doesn't get drenched by the rocket exhaust. This is an excellent safety feature as the Killarney Heights Team have begun using near-boiling water for reaction mass in the hopes of better performance... I have my doubts about this feature myself, I think it just softens the bottle which is already being pushed by the 700 kPa pressurisation.
Quite a crowd collected as we set-up, it seems like the word had gone out to the local kids... As launch time neared so did a rather nasty storm cell. The situation getting positively dangerous with lightening in the area, but the KHSP team pushed on... I suspect I may have been the only one to comprehend how silly it might be to launch a device releasing an ionised trail from an open area towards such a nasty looking cloud-base.
As the rocket was being pressurised and the pyrotechnics armed disaster struck. The water motor seal failed at only a few 10s of kPa launching the rocket prematurely. Fortunately no one was injured, and the rocket airframe was undamaged, but the water motor was in no shape for a retry.
With only seconds to spare the rocket was reconfigured for a pyro-only launch. The two D motors igniting together (something I was also concerned about), and the rocket soaring far above the park, across the road and landing in an adjacent sports oval.
Just as the rocket touched down the heavens opened with freezing sleety rain! Seth and the assembled crowd of spectators took off to recover the rocket, leaving the rest of the team to grab up all the equipment and run for cover. We made it only slightly dampened, and retreated to the KHSP home base for a glass of Red and review of the telemetry. Outside huge falls of snow-like hail pelted down.
The rocket was recovered but took a beating. One of the fin supports was completely snapped, the recovery system tore loose on deployment, leaving the rocket on a ballistic trajectory. Impact with the ground crushed the water motor bottle, but the camera survived unharmed. The parachute and shroud were not recovered.
The premature and pyro-only launches were well documented, all told there were 5 cameras on site: One on the rocket down-linking images to Peter's camcorder, Peter's digital camera, Pete's wife's digital camera placed face-up on the ground near the launcher, his own digital camera and my digital camera. Unfortunately Peter and I turned to watch the approaching storm just as the water motor failed, but it was captured well by the on-board telemetry camera and the launcher camera. For the pyro launch off-axis thrust caused roll rates so high the down-linked video was next to useless, but the ground-based pictures were quite good, except perhaps for losing the rocket into the white background of the overcast sky. The best of the resulting footage was stitched together into a very entertaining movie by Pete and posted on YouTube.
The KHSP team were quite interested to hear I had a Pyrotechnics licence. While I didn't supply pyro for this launch, I'd be happy to be called upon to participate in future launches, and will supply anything I can to further the KHSP team. I was quite impressed that the team was able to get both D-motors igniting at the same time, synchronised ignition is not easy to achieve. I suspect the main water motor is a better way to go, but a pyro based recovery ejection system could be useful, Peter and I discussed remote-control deployment of the parachute or streamers.
Thanks for inviting me guys! I had a lot of fun, it has been ages since I did water rocketry. It is a lot cheaper than pyro motors and quite respectable in its capability. I still enjoyed the smell of black powder reaction products, it has also been a long time since I'd smelt the smoke! Peter's write up is here.
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