Each flight log entry usually
represents a launch or test day, and describes the
events that took place.
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Day 8 - Windy and
Wet
Jordan on its way to our highest altitude.
X-21 ready on the launch pad. Our first 2
bottle rocket.
...and its takeoff.
You can still see the vapour inside the
bottle after landing.
Brotanek II as it re-enters the lower
atmosphere.
Jordan taking off from this high angle view.
The damage it sustained upon impact. You can
see the bottle buckled near the nosecone.
Parachute packed with foam providing a
spring mechanism to pop off the nosecone.
Plenty of standing water on the oval made it
convenient to refuel.
Brotanek II safely back down. Parachutes
increase the survivability rate of rockets.
Jordan taking off with only air in it. No
Water was used.
Spek on its return.
Packing the parachute into the nosecone. The
nosecone is hanging next to the rocket.
Added weight at on the bottom of the rocket
...not a good idea.
Parachute failed to open and the rocket
crashed through a tree.
Date:
5th August 2006 10:30am - 12pm
Location:
Denzil Joyce Oval. (launch site #4) Where exactly is that? Click the
above link to see a Google Earth
place mark. What is
Google Earth?
Conditions:
Overcast, occasional shower, quite a fresh
wind, ground saturated with standing water.
Rockets:
Name
Capacity
Notes
Little Man II
1.25
L
Equipped with whistles. This one
goes pretty high. Main bottle was
replaced since the last flight day.
Spek
2
L
An older rocket now equipped
with a parachute.
Jordan
1.25
L
A new lightweight rocket. Nose
weight added since last launch day.
Currently the highest performing
rocket.
X-21
2 x 1.25
L
New experimental 2 bottle rocket
joined at the base, with a parachute
recovery system
Brotanek II
1.25
L
This rocket has also been around
for a while. For this launch event
it has a new main bottle, and an
improved parachute deployment
system.
Team Members:
PK and GK.
Number
of launches: 16
The purpose of this launch event was to
test the new X-21 two bottle rocket and
test new parachute deployment systems. It
was a good time to go down to the oval
since there was virtually no one else there,
however, we believe the bad weather had an
adverse effect on the launches.
Design Note: Foam placed under the nosecone, on
top of the parachute acts as a spring
mechanism to help push the nosecone off.
We vary the amount of foam to make it
easier or harder to push the nosecone off.
Listen to a water launch:
Water.wav
There is a distinctive two pulse sound - one
as the water bursts out, and the second as
the water runs out and the remaining air
bursts out.
The X-21 is our biggest rocket to
date. We didn't use the simulator to
figure out how much water to use, but
just took a guess. We filled it with
about 600ml, whereas we should have used
closer to 750ml. The rocket was quite
unstable near the top of its flight
path, but that's something a good set of
fins will fix. The bottle joint stood up
very well to the pressures and also the
landings.
Both Brotanek II and Spek used a new
wire supported nose cone mechanism, in
order to reliably support the nosecone
during takeoff. We discovered that both
rockets were losing the nosecone too
early into the flight. Video analysis
showed one possible cause of this.
Because the wind was quite strong on the
day, it appeared that after launch the
cross breeze was enough to angle the
rocket slightly sideways. The rocket
tended to point into the crosswind. This
probably caused a shearing force on the
nosecone as the rocket was heading up
and therefore was blown off. I am keen
to try the same design on a calm day. We
modified the nosecone for it to sit
lower on the rocket and that had a
positive effect on the nosecone
performance.
In a moment of insanity, not
following the rules of aerodynamics, we
decided to add a weight to the tail end
of X-21 (3 AA batteries) to make it come
down backwards hoping the parachute
would be released that way. We forgot
about the going upwards part! In the
video it clearly shows the back-flip
that happens when the CG is behind the
CP.
On its second flight Jordan flew
9.01 seconds which according to the
simulator is in the order of 85-90
meters. How do we measure the time so
accurately? We video tape each launch
and then using a video editor we are able
to step frame by frame to find the exact
launch time and the exact landing time.
This was likely to have been the highest
launch to date. Jordan weighs about 92
grams.
On the video camera I discovered the
lock focus button which prevents the
camera loosing its focus when you are
video taping a tiny dot in the sky. This
proved quite successful. No more
automatic focus for us. This also allows
you to zoom in without the camera having
to hunt for focus.
Little Man II was launched with the
highest pressure to date - 130psi. We
are slowly increasing the pressures to
see the effects on the flight path. We
think the compressor can go up to about
200psi, but at that stage we will use
some form of re-enforcing on the
bottles. The flight time was over 8
seconds. Little Man II weighs in at
145grams, mostly because of the heavy
nosecone.
We fired Jordan with nothing but air
in it to see what happens. The take off
was sure fast, but only reached about
2/3 of what it does with water. The
sound the rocket makes on take off is
also quite different.
When we ran out of water, rather
than going back to the car to get more
we just refuelled from one of the
puddles next to the launcher.
The last flight of the day was the
best because Brotanek II went almost
straight up and the parachute deployed
about a second past apogee. The flight
time was about 17 seconds.
Flight Record
Launch
Rocket
Pressure (PSI)
Notes
1
Jordan
80
Flew quite high and
straight
2
Jordan
110
Flew very high 9.01
seconds. According to the simulator
that is about 85-90 meters.
3
X-21
80
Parachute did not
open, and the rocket was quite
unstable near top. Fell sideways.
4
X-21
100
Parachute did not
open, flew in a big long arc.
5
Spek
110
Parachute opened too
early. Foam under the nosecone was
present.
6
Spek
110
Parachute opened too
early again. No foam under the
nosecone this time.
7
Brotanek II
120
Parachute opened too
early. Foam was present under the
nosecone.
8
Brotanek II
120
Parachute opened too
early, although the rocket flew
higher this time. No foam was
present under the nosecone.
9
X-21
80
Nose cone fell off
due to unstable flight profile, but
chute failed to open as it stayed in
the nosecone.
10
X-21
100
Nose cone fell off
due to unstable flight profile, but
chute failed to open as it stayed in
the nosecone. Again!
11
Little Man II
130
Good flight, and
fairly high. Survived landing fairly
well.
12
Jordan
110
Good flight, good
altitude.
13
Jordan
90
AIR ONLY, this was
to see how it flies without water.
Certainly made a different sound,
and took off pretty quick, although
the altitude looked about 2/3 of
what it did with water.
14
Brotanek II
110
Parachute deployed
too early.
15
Brotanek
II
110
Nosecone was
modified to sit lower on the rocket,
with no foam. This caused the
nosecone not to come off and the
rocket flew quite high and in a big
arc and crashed through a tree on
the way down. The tree probably
saved it from quite a bit of damage.
16
Brotanek II
110
Great flight,
parachute deployed after apogee.
Flight time ~17 seconds.
Notes to self
Bring gumboots when launching at a
flooded oval. Our shoes and socks were
soaked.
Paint the rockets a dark colour so
they can be seen against the sky.
Day 9 - In-flight
Video and Perfect Flights
The tiny solid state video camera is mounted
inside a cardboard sleeve.
Within the sleeve it is surrounded by foam.
When the rocket is to be launched, the start
button is pressed ...
... and the camera is inserted into the
rocket. Here you can see the foam protection.
Sometimes you just have to get wet in order
to get a nice video shot.
Straight up and straight down. You can see
the impact crater at John's foot. The nose cone
remained buried.
A long distance shot of Brotanek II drifting
down.
Date:
13th August 2006 7:30am - 9:15am
Location:
Denzil Joyce Oval. (launch site #4) Where exactly is that? Click the
above link to see a Google Earth
place mark. What is
Google Earth?
Conditions:
Great weather, cloudless sky, mild
temperatures, slight breeze.
Rockets:
Name
Capacity
Notes
Little Man II
1.25
L
Equipped with whistles. This one
goes pretty high. Remained in the
same configuration since last flight
day.
Spek II
2
L
This was the same rocket (Spek)
as the last flight day with the
addition of a digital video camera
module. The parachute was moved
further up the rocket.
Jordan
1.25
L
The same rocket as last flight
day. The rocket remained in the same
configuration.
"OO"
2 x 1.25
L
New experimental 2 bottle rocket
joined at the base, with twin parachute
recovery system. This is the first
rocket with flat fins rather than
our typical ring fin. Turned out to
be quite unstable.
Cena
1.25
L
This rocket has also been around
for a while. It remains in the same
configuration since last launch day.
John John
600mL
This is our smallest rocket and
has performed well. It remained in
the same configuration since last
launch day.
Brotanek II
1.25
L
An older rocket that has flown a
number of times. It remained in the
same modified configuration since
the last flight day.
Team Members:
PK, GK, AK, Paul and John.
Number
of launches: 15
This was a great flying day, with the
stars of the show a couple of new rockets.
The first "OO" being a two 1.25 L bottle
rocket with a more conventional stabilising
fin design. The second "Spek II" had a tiny
video camera mounted in lots of foam. This
was also a day of firsts: a) Twin
parachutes; b) conventional flat fins; c)
video camera; and d) highest launch pressure.
Events
The first rocket of the launch pad
was "OO". This is a very good looking
rocket and is even pained. With about
750ml of water and 80psi pressure the
rocket took off but immediately started
turning over, even as it left the launch
pad. Luckily for us it decided to fly
the other way. Video analysis shows that
it was still accelerating when flipped
over and heading towards the ground.
This means that it has quite a severe
stability issue and we believe this is
due to the fins being too far forward on
the rocket, and the amount of water in
it is causing the CG to be quite far
back. We will have to add large fins
quite a way back on this rocket.
The second flight was our first with
a tiny video camera. The camera was
generously contributed by a friend at
work. The camera uses a 8Mb flash memory
module to record up to 30 seconds of
352x288 video. The camera is powered by
a single AAA battery! The frame rate is
quite reasonable and it also records
sound. The camera is housed in a padded
section of the rocket to help it survive
the landing. Instead of making an
elaborate trigger mechanism to start
recording, the camera is housed in a
separate cardboard sleeve that can be
easily inserted and secured in the
rocket. We simply turn it on, push the
record button, insert the sleeve into
the rocket tape it in, and fire it. From
the start of recording to blast off is
between 5-10 seconds, so that leaves
20-25 seconds of in-flight video. The
rocket moves around quite violently and
so the view is quite all over the place,
but this is very typical of small rocket
mounted cameras. At left are a number of
captured frames from the video sequence.
This was our very first video.
For a better in-flight video have a look
at Day 10.
Because we didn't have a laptop with us
to download the video and clear the
memory, we could only launch it once on
the day. We will look at borrowing a
laptop for downloading so we can do more
flights at a time.
The camera is mounted in such a way that
on takeoff it is looking at the horizon.
The parachute string is mounted so that
when the rocket is hanging on the way
down the camera points downward.
The rocket chosen to fly the camera was
the Spek - 2 L rocket because during the
last flight day it had always released
the parachute too early. We wanted to
make sure that the chute will deploy
rather early than not at all. We believe
that the fins are slightly misaligned
and that causes the rocket to tip over
and deploy the parachute. The height
reached by the rocket was around 30
meters. We will give the rocket new,
stiffer and longer fins in order to
stabilise it. We may also anchor the
parachute at two points on the rocket to
try to stabilise it on the way down.
We also chose not to attach the nosecone
so it didn't dangle below the camera.
The nosecone is harmless enough to come
down without a parachute.
Painting the rockets with dark
colours worked well against the blue
sky. sky.
Jordan's one and only one flight on
the day went well until it decided to
fly in a great arc, and with the
performance we get out of it, it flew a
long way straight into the creek. There
were a lot of reeds and so we though the
rocket was lost. But minutes later we
saw it floating in the creek, and a long
branch retrieved it.
On one flight TNT flew a good
flight, the nosecone separated, but the
parachute failed to open, 2 meters above
the ground it finally decided to open
and slowed the rocket down enough to
prevent any damage to the rocket. That
was a close shave.
I forgot to buy a new video tape for
the camera, and only had five minutes
left on the tape from last week.
Switching to long play (LP) mode gave me
an extra couple of minutes, and only
filming the critical shots made the tape
last through the flight day.
Brotanek II flew quite a few flights
and at least 3 of them flew very well.
It went straight up and the parachute
opened near or just after apogee. These
flights were around 20 seconds each.
The rocket configuration remained
identical to the last (windy) launch day
where the nosecone was coming off early,
and so our suspicions that the crosswind
had something to do with it is further
supported.
On one of Brotanek II's flight the
nosecone failed to come off, but it
appeared that near apogee the nosecone
tipped over and remained tipped over
causing the rocket to fly at an ever
increasing angle to the ground until it
was gliding almost horizontally and
landed like an aircraft, well not quite,
but enough to prevent the rocket from
being damaged.
We also broke our personal pressure
record a couple of times, first up to
135psi and then 140psi on the last
launch. In both cases they were Brotanek
II (1.25L) bottle.
TNT performed also very well, and
its black colour made it very easy to
see. The parachute almost always
deployed. This is a very good rocket
too.
New nozzles were made that have a
longer thread to hold and seal the
nozzle better against the bottle. These
work quite well with virtually no leaks.
Flight Record
Launch
Rocket
Pressure (PSI)
Notes
1
"OO"
80
Maiden flight.
Flight was very unstable, rocket
flipped as low as a couple of meters
above ground. Twin chutes did not
deploy.
2
Spek II
80
Maiden Flight. This
was our first flight with on board
camera. Parachute deployed early,
but this was expected. Great video
and sound, camera survived landing.
3
TNT
110
Good flight.
Parachute deployed well.
4
TNT
110
Good flight,
nosecone came off after apogee, but
parachute opened only ~2 meters
above ground. Rocket didn't sustain
any damage.
5
Jordan
120
Good flight, but
arced over quite a bit and took a
while to find it floating in the
creek.
6
Brotanek II
120
Very high and
straight up. Parachute failed to
open but nosecone tipped over on the
way down and caused rocket to go
into a glide path and landed almost
horizontally. Did not sustain any
damage.
7
Brotanek II
130
Perfect flight, went
very high and parachute deployed
around apogee, landed well.
8
Brotanek II
130
Perfect flight, went
very high and parachute deployed
around apogee again.
9
Little Man II
120
Nice flight straight
and high. Whistled well also.
10
Cena
120
Good flight and
relatively straight. Had to dig out
rubber nosecone from the impact
sight. Bottle now getting a bit
buckled.
11
Brotanek II
135
Good flight,
parachute deployed after apogee,
rocket travelled in a long arc.
Highest pressure to date.
12
John John
110
Good flight, rocket
spun axially (not designed to do
that) and landed close to the launch
pad.
13
TNT
120
Good flight,
parachute opened just a bit too
early.
14
TNT
130
Good flight, but the
parachute didn't open. Only slight
damage to the rocket but it will fly
again.
15
Brotanek II
140
Great flight, went
very high and the parachute opened
around apogee. This was our highest
pressure yet.
Notes to self
Rocket Maiden flights should be
performed with extra precautions.
Bring a spare video tape.
Day 10 - In-flight
Video and Faulty Nozzles
New improved "OO" with extended tail fin.
Slow take off.
Out of control Little Man II, just above the
tree line heading back for the launchee.
Turning on the video camera inside the
rocket.
Reviewing rocket footage at the scene.
Spek III with video camera taking off. This
is a picture from the camera seen being held on
the in-flight video.
Equipped with whistles. This one
goes pretty high. Remained in the
same configuration since last flight
day - except for a new nozzle.
Spek III
2
L
This was the same rocket (Spek
II)
as the last flight day equipped with
a digital video camera
module. The ring fin was upgraded.
Jordan
1.25
L
The same rocket as last flight
day. The rocket remained in the same
configuration - except for a new
nozzle.
"OO"
2 x 1.25
L
This is a 2 bottle rocket joined
at the base, with twin parachute
recovery system. Since last flight
day the fins have been replaced by a
combination ring fin with flat fins.
This resolved the rockets stability
issues.
Brotanek II
1.25
L
An older rocket that has flown a
number of times. It remained in the
same configuration since
the last flight day.
Team Members:
PK, GK, AK, Paul and John.
Number
of launches: 12
This was a good day for in-flight videos
and testing a new rocket. We brought a
laptop, camping table and camping chairs for
this event. Pretty soon we will need a small
trolley to carry everything.
NOTE: The still images from the on
board video contain a "ghosting"
artefact.
This is a side effect of the slow image scan
of the tiny camera. This is particularly
evident when the camera is slewing quickly.
We apologise for the low quality of these
images, but to bring you a higher quality
image would require a more expensive camera,
and we are not yet confident that it would
survive more than a handful of landings.
Events
The first off the launch pad was the "OO" rocket.
This was a really beautiful flight
because it took off very slowly and
proceeded to accelerate upward and then
slowly began to arc over. Both
parachutes deployed as expected and the
rocket landed well. Upon video analysis
it was discovered that the spray from
the rocket had an unusual wide spread.
This was most likely to have been caused
by a new nozzle with a new seal. It will
be interesting to try this rocket with
the other nozzles we normally use.
Here is a video of "OO" taking off:
(You may need to update your flash
plug-in)
The second flight of this rocket had
a similar flight profile except that the
chutes failed to open, with one of them
opening about 1 meter above the ground,
but probably did not slow it down
enough. The rocket only suffered minor
damage and will fly again.
We fitted the new nozzle to Jordan
(the rocket that is...) but it went out
of control very early on. It recovered
and then flew at quite a shallow angle
towards our car. It missed it by only a
couple of meters. The car was about 60
meters from the launch pad. At that time
we did not know why Jordan had such an
unusual flight profile since it has
always performed well on take off.
Still not realising that we were
dealing with a bad nozzle. (We only use
a handful of nozzles and switch them
between rockets as needed). We put it on
Little Man II. Little Man II has also
been a very straight flyer, but on take
off it dramatically spun out of control
and nearly hit Paul who was launching
it. On video replay we saw the same
unusual spray pattern.
We thought that was unusual, but who
are we argue? so we set it up for a
second launch to see if the bad launch
was a one off. You guessed it ... same
thing again, but this time it almost hit
me. I have great video footage of the
rocket heading straight for me out of
control, landing next to me.
Luckily we were only doing the
camera flights next with Spek III and it
used a different nozzle and so flew
fine. We managed to make 6 flights in
all with on board camera rolling. We
brought a laptop for downloading the
video after each launch so that we could
clear the camera's memory. The flights
were much more successful than last week
as Spek III was fitted with a larger and
better aligned tail fin. Launch #3 was
particularly good and lasted in the
order of 20 seconds.
Footage from this
flight is available here:
At left are the better still frames from
these flights.
We had to shut up shop as people
started arriving for football practice
at around 9am.
Also on the very last launch the
battery was giving out and so we
couldn't fill the rocket all the way. It
really surprised me because the battery
was fully charged. Later we realised
that we had been filling rockets with
larger capacities and so they took
longer to fill. I probably need to buy a
second backup battery.
Flight Record
Launch
Rocket
Pressure (PSI)
Notes
1
"OO"
100
This was a beautiful
flight, it had very slow take off
and curved over nicely at apogee and
then both chutes deployed well to
bring it to a nice landing.
2
"OO"
120
Another great flight
with the same slow take off. the
parachute opened 1 meter above the
ground, but probably did not slow it
down. Rocket will fly again.
3
Brotanek II
120
Good flight, chute
opened well about 1-2 seconds after
apogee.
4
Little Man II
100
This was a test
flight with more water than normal.
The rocket spun out of control. (Due
to the new nozzle)
5
Little Man II
100
Normal amount of
water, but rocket spun out of
control. (Due to new nozzle)
6
Spek III
110
In-flight video, good
flight.
7
Spek III
110
In-flight video, very
good flight.
8
Spek III
110
In-flight video, ok
flight, parachute deployed early.
9
Jordan
100
Out of control
early, but recovered to fly
horizontally a long distance. (Due
to new nozzle)
10
Spek III
110
In-flight video, ok
flight, parachute deployed early.
11
Spek III
110
In-flight video, ok
flight.
12
Spek III
92
In-flight video, ok
flight, parachute deployed early.
battery ran down.
Notes to self
Rocket Maiden flights should be
performed with extra precautions ...
I really mean it this time.
