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Day 83 - Flight testing of new splices
Four new 3.15L spliced pairs tested to
These were connected together with 22mm
... with an added payload section,
recovery system and fins to make Polaron VII.
Launched at 130psi on a 15mm nozzle.
Shot from around 490'.
The recovery crew is well trained at
spotting falling objects.
Altimeter data from flight 1
Axion III was filled with around 400 grams
It was launched at close to 100psi because
there was a leak on the pad. Still it was a good
Preparing payload and parachute for flight
The rocket is launched using a 1200mm long
A panorama from flight 2 is assembled from
Polaron VII's Flight 2 altimeter data
Preparing Axion V for a foam flight.
A slow and steady lift off.
Looking back at the launch area.
Parachute opening just prior to apogee.
Second flight went mostly horizontal. You
can see the launch area in the center of the
The high speed deploy bent the rocket in
half. The rest of the rocket survived well.
Distortion of the bottle neck due to too
much heat. (see update)
December 2009(8am - 1:00 pm)
Location:Doonside, NSW, Australia
Conditions:Warm 32C.Light winds,
clear, strong wind in afternoon.
Team Members at Event: PK, GK,
Paul K and John K.
This week we wanted to test fly the new
splices before fitting them to Acceleron V
since we didn't know how they would behave
under real world conditions. Doing a hydro
test only gives you a part of the story.
Acceleration forces during take-off,
parachute deployment and landing all can
affect the spliced pairs. We also wanted to
see how temperature may affect them on a hot
day with the additional heating due to air
compression. Lastly we wanted to see how the
spliced-pairs behave during rapid
depressurisation such as during a launch.
We built a Polaron class rocket (Polaron
VII) using all 4 spliced-pairs giving a
total volume of around 12.5L. The fins were
taped to the rocket body since they were
only temporary for the test flights. Thin
drinking straws were used to improve the
aerodynamics on the leading edge of the
fins. All up about 24 two-litre bottles were
used to build this rocket.
Flight day report
We arrived around 8am at the launch
site. The conditions were almost perfect
with very little wind and clear skies.
We set the Polaron VII rocket up on
the pad. When we use a launch tube we
don't bother with the guide rails, since
the launch tube does a pretty good job
of supporting the rocket.
We pressurised it to 130psi
and launched it with a 15mm nozzle. The
rocket went up very straight and fast
and reached 494' (150m). The parachute
opened right on time and the rocket
Next up was Paul's 2 stage pyro
rocket. The first stage ignited well and
the flight was nice and stable, but
during staging the second stage failed
to light and the rocket nosedived into
the hard ground. Quite a bit of damage
was done to the rocket, but I believe it
is fixable so we will have a go at doing
that over Christmas.
The third flight was again Polaron
VII launched at identical pressure. This
time the rocket went to 506' (154m).
parachute deployment and landing were
good and there was no damage. Not
wanting to risk damaging these spliced
pairs on further flights we retired the
rocket for the day.
The one thing we noticed that some of
the glass strapping tape had a few small
buckles in it. This was most likely
caused during pressurisation and the
bottles and tape stretching somewhat.
We'll remove the stretched tape and
re-tape them. Not all bottles exhibited
For the fourth flight we wanted to
launch a flour rocket since we hadn't
launched one at Doonside before. I fixed
up an old launcher the night before for
this flight because I did not want to
end up with flour sludge all over our
regular launcher. It is not a good idea
to mix flour and water rockets on the
same launcher. Unfortunately the
launcher wasn't properly tested, and
sprung a leak somewhere around 100psi.
We launched the rocket (Axion
III) anyway, though it did not reach
a great height, but high enough to
deploy the parachute and land well.
For the next flight we replaced the
medium launcher's launch tube with the
regular 9mm release head and added the
guide rails. We launched
V at 130 psi with foam. It had a
very nice slow take off but thankfully
it went vertical. We didn't fly an
altimeter on this flight so we don't
know how high it went. The on board
video gave us a good view of the shadow of the foam trail.
The last launch of the day was quite
eventful. We set up Axion V again with
foam, and as we started filling it,
John, who was on the end of the release
string and in his
state of mind gave the string a bit of a
tug. The rocket went up about a foot
still in the launcher and sprayed foam
everywhere. Luckily there wasn't enough
pressure for the rocket to clear the
launcher and so no damage was done.
We refilled the rocket and set it up
again. This time as we almost reached
launch pressure I noticed the
bundled parachute partly sticking out of
the payload bay. This seemed a little
odd, but then I realized the chute had
actually deployed and the guide rail was
keeping it from falling down. I ran over
and re-secured the door and re-armed the
computer. It may have triggered either
due to the vibration of filling, or due
to the buffeting of the strong wind
which had picked up by then. I don't want to
think about what would have happened if had
we launched it with the parachute
All fixed, we launched the rocket, and
despite the long guide rails the now
strong wind (30km/h+) caused the rocket to pitch
over and accelerate down range. The
rocket may have reached perhaps 150 feet
in altitude but flew horizontally for a
lot of the flight. Google Earth tells us
that it landed 260m (850') from the
Although the parachute opened about 5
seconds after launch as it was supposed
to, the rocket had a high horizontal
velocity and the sudden chute opening
caused the rocket to buckle at the
parachute attachment point. The nylon
shroud lines held and the rocket landed
safely. One bottle was buckled which can
be easily replaced. I wonder how much
further the rocket would have flown had
the parachute not opened?
All in all it was a great launch day and
we can now start re-building
Acceleron V with the new spliced-pairs.
There will also be more time to work on
rockets over the Christmas break.
Update: Well having had a close
look at the flour rocket tonight I noticed
flour sprayed on the inside of the the
inter-bottle sleeve. On closer inspection
the o-ring on the Tornado tube had popped
out and leaked. It appears the launcher was
fine. Closer inspection revealed that the
bottle neck and thread had distorted. This
is most likely to have been
heat. Upon pulling apart the Polaron
rocket I noticed two threads on two of the
bottles were also slightly distorted. It was
quite a hot day, with direct sun on the
couplings so I am not surprised that it
happened. I did not have these couplings
protected, but from now on they all will be.
We have attempted to repair these thread
distortions before and it is possible to fix
them by carefully heating the thread with a
heat gun and then shoving a mandrel (broom
stick) inside the neck.
What's more, I found moisture on the
inside of one of the inter-bottle sleeves on
the Polaron rocket. Having pulled the rocket
apart I was quite amazed and embarrassed at
the same time to find one of the tornado
coupling o-rings missing altogether. Despite
that the rocket still managed to fully
pressurise and fly.
flight. Slight fin flutter, good
parachute deploy right near apogee
and the rocket landed well. Good
video and altimeter data.
Pod 2 (Paul's Praetor)
C6-0 first stage C6-5
Altitude / Time
? / ?
First stage ignited
well, and had stable flight, but
during staging 1st stage separated
without igniting motor. Rocket
crashed heavily damaging the
nosecone and upper body tube. Motor
mount came off inside rocket. 1st
stage fin came off. Rocket is
This rocket was
launched in ~30km/h wind. Rocket
pitched over soon after leaving the
launch rail and accelerated
horizontally. Parachute deployed
well but the rocket bent at the
attachment point. Rocket landed
well. One spliced-pair will need to
be replaced. Good on-board video.