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events that took place.
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Day 141 - Windy
25th January 2014
Location:Doonside, NSW, Australia
Conditions:Partly cloudy, windy 15km/h
with gusts to 25km/h,
Team Members at Event: PK, GK,
Paul K, and John K.
We had two experiments
to try today: Continue with the roll correction flights, and
try the new improved dual thrust configuration, however, it was
quite a windy day so we weren't sure if we were even going to
launch. Normally we don't launch if the wind is over 20km/h, but
the wind was going in the right direction down range and away
from the trees so we decided to launch.
First up was the dual thrust rocket. The set-up was straight
forward and we launched the rocket at 120psi. The take off was
good, and the sustain phase also went well, but due to the wind,
the rocket weather-cocked and flew in an arc rather than
straight up. It still reached 255 feet. It's interesting hearing
the rocket fly because the sustain phase is so quiet.
Filling up for the first flight
of the day
Pressurised to 120psi
Sustain phase continuing
Going higher than the moon
On the second launch the configuration was identical, the
rocket boosted up well, but there was virtually no sustain
phase. The rocket gently flipped over at 99 feet and started heading for
the ground. With the timer delay set for 5 seconds, the rocket
was about 5m above the ground when the parachute started
deploying. Unfortunately the parachute didn't have enough time to
open and the rocket crashed. The nosecone was damaged as was the
top bottle. Luckily all on board electronics survived and even
the deployment mechanism survived. This will be an easy fix.
We are still trying to understand why the rocket did that. At
first we thought there might have been something blocking the
extension tube and hence reducing the thrust, but there was nothing
obvious. The only thing we can conclude is that for some reason
the sustain chamber didn't get fully pressurised. In that case
there may have been an issue with the non-return valve in the
spacer. We took it apart, but couldn't see any obvious cause.
Video prior to launch shows that some air was bubbling through
the water into the sustain chamber, and you could see that water was transferred. If
for some reason the o-ring blocked the non return valve, the air
in the sustainer would have been compressed only by the water
that entered the space. During flight you can see this water
exit but not with any force. It's also possible that there was a
leak in the sustain chamber so that it didn't pressurise
properly. I guess we'll have to try this
again, and make sure the valve is operating correctly.
Almost no thrust during the
Next up were the roll correction flights
continuing from last time. I had reduced the height of the little ramps
on the fins
because on the last flight the rocket rolled too much in the
Just as we approached 110psi, the base of the top bottle
blew out in a pretty spectacular fashion. This was the first
time in the last 7.5 years that we have seen this kind of
failure. This bottle had been used several times before on
various flights without any sign of trouble. It's possible that
some stress fracture had developed over the previous
pressurisation cycles and today was the day when it had enough.
What was unusual about this failure was the low pressure, and
that the bottom blew out where the plastic is quite thick.
Normally these bottles burst around 190psi and burst on the side
where there is greatest stress.
Undamaged deployment mechanism
that was ejected through the
Unusual failure of the top
2nd attempt at roll correction
The result of the CATO was that it hurled the deployment
mechanism through the nosecone fairing, and surprisingly
suffered no damage. Even the corriflute structure was fine. We
only need to replace the top bottle and fairing. All the
electronics, including camera and altimeter that were right
under the bottle survived, the cardboard camera housing was damaged
which will be replaced. The only casualty was a cracked Gardena
nozzle cap caused by the rocket sliding back down the guide rail
and hitting the release head.
So we swapped out the top bottle, and a spare nosecone. This
was the last one we had with us on the day. We flew it without a camera this time. The flight went well and landed
We set the rocket up again but with the cardboard camera
housing damaged, we just taped the camera to
the side so that we could see if the roll was better or not.
Last flight of the day
Lands nose first on the dirt
Time to head home
The launch went well and post flight video showed that the
roll had improved since the last flight. The rocket drifted a
long way down range, and the nosecone managed to hit the
hardened earth road so the fairing also suffered minor damage.
Because of the windy conditions we decided to pack up and call
it a day. Some days are great, and others not so. This
week was our turn to make offerings to the rocket gods.
Here is a highlights video from
On 30th December last year we featured in Discovery Channel's
"You have been warned" series 2, Episode 11. The segment about
our 2-stage Acceleron V rocket turned out quite well, and they did a good
explanation of how the rocket works. I am unable to post
the video here, but it may become available on Discovery
Channel's YouTube channel like some episodes from the series have.
Below are some
screen shots from the segment. Here is the
original video of the rocket.that
the episode was based on.
We have been making lots of good progress on the Polaron G2
rocket. Here are more updates on the
Polaron G2 build log.