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Day 53 - NSWRA and Polaron IV Main Stage test flights
Polaron IV main stage assembled the night
Detail showing the flight computer with
servo motor. The altimeter is housed in the foam
just below the flight computer
The back side of the payload section. The
parachute is held against the door by the rubber
New FlyCamOne 2 video camera looking back
towards the ground. A protective sleeve extends
over the top of the lens assembly to help
prevent damage on landing.
The nosecone is removable allowing the
rocket to be placed dry on the launch pad and
filled from the top. On the day we did not use
this option. It will be important with the
Hyperon, J4 IV and Polaron IV ready to be
packed up and taken to the launch site.
Turning on the altimeter and flight computer
on J4 IV.
10 seconds later we will be looking for it
in the long grass 1/4 km away.
Hyperon takes to the air.
Setting up Hyperon for its second flight
A good start to the flight, but soon turned
almost 90 degrees and headed down range.
Members and spectators looking on at all the
rocket action of the day.
Some of the pyro rockets flown on the day.
Setting up Polaron IV for its maiden flight.
We added the guide rail extension to give a best
chance at going vertical.
Must remember to:
*Arm flight computer
*Start altimeter logging
What else did I forget? ... oh right ... get
out of the way.
Polaron IV's maiden flight.
Polaron IV making use of an old discarded
Looking back down at the launch site area.
Parachute deployment at apogee. It actually
took another 2 seconds before the chute was
It's that tall grass again. This time we saw
exactly where it landed.
We took turns launching and watching the
Polaron IV gets a second turn at flight.
Here we angled the launcher more into the wind.
And a safe return once more.
Looking back towards Doonside road.
NSWRA group photo.
Date: 26th January 2008
( 8am - 1:30pm )
Slight breeze <10km/h, 25 Degrees C,
partly cloudy. Team Members at
GK, PK, John K, Paul K, Jordan
K, HK, AK, IK + Members of NSWRA and
This weekend was an excellent
day for rockets. We became members of the
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
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.
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
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 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
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
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.
(If the video does not play, try the latest
Flash player from Macromedia)
Later at home during video analysis
it was obvious from the water plume that
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.