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Day 166 - Dark Shadow II and Axion G5
12th September 2015
Location:Mullaley, NSW, Australia
Conditions:Light breeze ~5km/h, sunny
Team Members at Event:GK.
Dark Shadow II
This week NSWRA had its High Power launch at Mullaley.
With dad in Europe, wife at work and the kids at school, I took
a day off from my work and drove
out to give Dark Shadow II an opportunity to stretch its
wings. This is the second airframe we built for
Thunda, but it
never had a chance to fly. Although it is a little longer and
heavier it also has higher capacity. The simulator
predicts that it has similar performance to Dark Shadow I.
The weather was perfect with blue skies, only a slight breeze
and dry underfoot. We launched from another part of the farmer's
property that is a lot more accessible for cars. The location
doesn't get much better than this.
A big thank you goes to the David, Tim, Andrew and Chris who
helped set up and launch the rockets on the day. Also thank you
to Andrew Eltobaji for taking a lot of the photos shown below.
Setting up at the launch site
Dark Shadow II
Dark Shadow II -
Setup was straight forward with the first launch targeted at
500psi ( 34.5 bar ) because that is what
airframe was hydro tested to.
I wanted to get at least one successful launch in before
increasing the pressure. I paused filling at 200psi for around
20 seconds and again at 400psi for 10 seconds to let things cool
down a little, before increasing the pressure to 500psi.
The launch was quick but not quite vertical, though only a few
degrees. Later I found out the reason for that, as there are
yellow paint marks on the rail, and the bottom of the launcher
was pushed into the soft soil. The diagonal rail supports
are attached at the top of the rail so geometry says that if the
bottom of the rail moves down then the rest of the rail will
The rocket flew to 1370 feet ( 417 m )
and drifted down gently about 500m away. The altitude is
an average of the zLog reading (1364 feet) and the AltimeterOne
( 1377 feet ).
Post landing I noticed the camera had been dislodged in the
nosecone, which was my fault because I forgot to tape it into
its foam mount.
Luckily it stayed where it was supposed to for the entire
flight, and it was only the landing that dislodged it. It looks
like the nosecone also hit the payload bay after landing as
there are some pretty good scuff marks on it.
Hearing and eye protection
End of launch tube phase
Boy, it goes quick
1.8L comes out in ~0.1s
1377' feet readout on
Here is the altitude
plot from the zLog altimeter:
Dark Shadow II - Launch #2
After washing the dirt out from the nozzle, it was now time (as
Tim says), "Go hard, or go home". So knowing that the last
launch at Thunda was 640psi, and the sample pressure chamber was
tested to 650psi, we decided to crank it up to
700psi ( 48.3 bar ). The expected
disassembly didn't come and so we let it go. The rocket took
off with visibly more authority than the previous launch and
this time a little more vertical too. This was mostly due to the
fact that we put a support under the launcher. It still got
pushed a good 10cm into the soft soil though, and I expect we
lost a little energy that way. The rocket also had a nice long but
brief contrail as the cold air came out of the nozzle after
burnout. Andrew got a great shot of it. (see below)
With the timer delay set to 11s the rocket flew to
1941 feet ( 591 m ) and gently arced
over before deploying the parachute. The altitude again is an
average of the zLog reading ( 1922 feet ) and the AltimeterOne
reading ( 1961 feet ).
This is now our new personal highest altitude record which we are happy
about. We are getting closer to the 2000' mark. The 60psi
increase raised the altitude around 200 feet compared to Dark
last Thunda launch. I think another 20-30psi could push it over
2000 feet, although I am not sure the airframe could take it. We
must be pretty close to the rocket's pressure limit now. We'll see
where that limit is at the next launch ... :)
Just taking off ..
... and gone
A short time later
Starting water phase
1600N of thrust
You can just see the cars
(lower left corner)
You can see how much the
was pushed into the ground.
The video showed that the rocket has a slow roll compared to the
original airframe that virtually had none. The rocket again
landed about 0.5km away from the launch pad.
Here is the altimeter
plot from the zLog altimeter:
We're happy with how the
deployment mechanism is working under
the high-G loads. The second launch was
around 53G. It's now had 5 successful
Dark Shadow II - 2nd Flight
A combined plot
of the two flights for comparison:
A combined plot of the speed, derived
from the altimeter data:
Axion G5 - Launch
The last launch for the day was Axion G5 with 2.5L of water and
foam. We just used the standard plastic 9mm nozzle for this one.
This was a very nice flight with a long sustained burn. It flew
up to 855 feet ( 260m ) and landed fairly close to the pad. The
roll also wasn't nearly as bad as the last time it flew, and so
the onboard video was reasonable. Rather than swap over to the
LP regulator, we just pressurised it using the direct connection
to the scuba tank like we do with Dark Shadow.
It was then time to pack up and head back to the motel, and back
to Sydney the next day. I didn't get as much video and photos
from this launch, but at least there was less to edit.
Prepping Axion G5
Ready to go with 2.5L of water +
Altitiude 855 feet
Launched at 230psi.
The following is a video
of some of the other NSWRA flights from
the same day.