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Day 96 - Polaron G2 and 2-stage flights
Starting to process some 50 2L bottles for
After the bottles are cleaned, they are
shrunk, curled, sanded and spliced with Sikaflex
When cured the spliced pairs are further
spliced into quads.
The following images show the approximate size
comparison between the current Polaron G1 on the
Polaron G2 on the right. The small booster is
the drop away booster we have been using with
our Polaron Rockets.
Only 2 of the 3 boosters are
The sustainer is an approximate size stand-in
for the final design.
Bevelling the edge of a fin on the bevelling
Fiberglassing jigs have now been extended to
hold the longer quads. We are using two servos
to power the rotisserie now.
New sight added to the camera handle for
more accurate tracking.
Here it is shown with a new full HD video
Testing the Mk 3. stager at higher loads.
The booster has a 15mm nozzle. The fluro line is
for remote arming.
Location:Workshop andDoonside, NSW, Australia
Conditions:Warm, Sunny 26 degrees C, very light breeze,
Team Members at Event:
GK, Paul K, John K.
We have now begun work on a set of higher
performance rockets based on the knowledge
we have gained so far. We want to
concentrate on optimizing the rocket as a
whole rather than just the individual
components. This means improving the
aerodynamics and reducing weight, while
increasing capacity as well as higher launch
pressures. We are reviewing all systems to
see where we can make improvements.
We are starting with the Polaron G2
rocket that will be developed in three
separate phases. We are targeting initial
launch pressures of 250psi (17 bar) and so
most of the equipment will need to be
retested/upgraded for these pressures.
The first phase will consist of a 15.9L
single stage rocket. This will use a bigger
nozzle most likely 15 or 16mm. Phase 1 will
test both the rocket systems and ground
equipment to the higher pressures and loads.
In the second phase we will add 3 x
10.6L drop away boosters and extend the
main stage by another 3.15L for a total of
~19L. The nozzle will be reduced for the
main stage to perhaps 9 or even 7mm for a
long sustained burn. Jet foaming will be
used to power the main stage while the
boosters will use larger nozzles and water
This phase will include a set of static
ground thrust tests to measure the thrust
produced by the jet foaming main stage with
different nozzles, to determine which one
will be used in combination with the
Together the three boosters will have
slightly more capacity than the Acceleron V
Phase 3 will be broken into two
Phase 3a - A small
streamlined sustainer will be developed and
tested. The capacity and size of the
sustainer is still yet to be determined.
Phase 3b - The sustainer
will be fitted to the Polaron G2 main stage.
The main stage will be reduced in length and
capacity to accommodate the sustainer. The
main stage nozzle will be increased again
and the main stage will retain the 3 drop away
That's the overall plan over the
coming months but actual time frame is open
as it is dependent on development time
available, launch windows, and resource
allocation. The image below shows the
overall size and design of the G2 rocket.
Click for a larger image
In order to get better efficiency in
terms of volume per length of rocket, we are
making longer sections of pressure
chambers by splicing together two spliced
pairs of bottles, effectively giving us a
5.3L sections that are 110mm wide. We want
to be able to retain the modular nature of
our rockets as it makes it easier to develop
and transport them. The sections are
again connected by tornado couplings.
We are looking at using some 4mm plywood
to make the fins out of for these rockets.
Although a little heavier than the
they are stiffer and can be made more
aerodynamic. Hopefully they will survive the
landing. We are initially going to paint
them in epoxy, but if more
strength is required, they can always be fiberglassed
The jig is made
from a flat piece of wood with a Dremmel
mounted at an angle. A couple of adjustable
guides allow us to get nice clean edges.
I've added a simple sight to the camera
handle we've been using to film the rockets.
At low altitudes it is possible to track the
rocket on the camera screen but, when it
gets too high, it is impossible to see. Now
we can just look through the sight and know
that both the DV as well as the high speed
cameras are pointing at the right place.
used it quite a bit on this NSWRA launch day,
and it worked very well to keep the rocket
mostly centered in the screen at higher
altitudes. The better tracking accuracy
should allow us to zoom in a little more
during the flight.
Flight Day Report
We went to the Doonside launch this week
to do the final test flights of the Mk3.
stager. We wanted to see how it held up to
higher acceleration, and hence higher
compression forces. The Baryon V booster
was fitted with a 15mm nozzle. We also
wanted to test the sustainer fin support
arrangement for the higher accelerations.
The first flight was at 120psi using 2L
of water, which was closer to the optimum
rather than the 800mL used during the Parraweena
launches with smaller nozzles. The rocket
took off visibly faster and the stager
worked great at burnout again and the
sustainer separated cleanly and vertically.
We didn't have a camera or altimeter on
either of the rockets, since we didn't know
if they would survive the higher loads. Both
the booster and sustainer landed well.
On the next set of flights we will need to include
the altimeter and camera.
The second 2-stage launch setup was
identical to the first. We noticed that once the rocket
was pressurised, the sustainer was leaning
over slightly. This may be the result of
bottle stretching, or it may have been that
I put the rocket on the support braces the
wrong way around. Each of the braces is
individually adjustable for each fin. The
flight went well, however, the rocket
tipped over slightly in the direction the
sustainer was leaning, but the short burn
of the booster still kept it going mostly
Staging was clean again and the rocket
went fairly high. Both booster and sustainer
landed without damage. The time from launch
to staging was a mere 0.72 seconds. The
large nozzle is very effective in getting
all that water out quickly. :)
With this launch, that makes 12 / 12
successful Mk3. staging flights since we fixed
the initial issues with the stager.
The last flight of the day was Axion VI
because we had enough spare parts to put it
together on the spot. We flew it in a Jet
Foaming configuration, and used 2L of water
for a longer sustained flight. Because of
the added water, the takeoff was relatively
slow, but because the rocket is fairly long,
it remained stable.
The boys also flew a number of small pyro
rockets. We even entered one into the
altitude competition, though we don't know
the results yet.
Overall it was a very good flight day,
with quite a few people showing up for the
launch. It's always good to see new faces.
Only a short video this week of the three
water rocket flights from the day: