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Day 15 - Big
Rocket, In-flight video, burst tests and high flights
Rockets flown on this day - left to right:
Clifford, D.Y., Brotanek II, Frankovka, OO, John
John.
Preparing the video camera on the new
rocket.
Our air supply system. SCUBA tank today with
a compressor for backup.
Apogee. You can even see the curvature of
the earth. :) Looking east over Curl Curl
lagoon.
You can see North Head, Manly and South Head
here. Looking south.
Due east, looking at the oval.
Looking straight down. The air command team.
Toilet and shower block near the park.
Dee why head on the horizon.
Frankovka making a great debut.
Frankovka post landing. We don't attach the
nosecone so it doesn't get in the way of the
video.
You can clearly see how the base deformed on
D.Y. after it was pressurised to 130psi.
A close up look at D.Y. coming in for a pin
point landing...
...next to Amanda as she records rocket
flight profile. This is where it landed.
Clifford's high speed return to earth made
sure the parachute did not have to be repacked.
OO on the launch pad. You can see 11bar =
150psi on the gauge.
OO ... just a rocket on a parachute.
On one flight the parachute threaded itself
through the ring fin.
Later we found the source of our fuel
leak...
A busy day flying...rockets, chutes empty
bottles and kids.
Date:
8th October 2006 7:00am - 9:40am
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:
Sunny, light breeze, growing stronger
towards latter part of day. Warm.
Rockets:
Name
Capacity
Notes
D.Y.
2.25
L
A newer rocket with re-enforcing
straps, new ring fin strut design,
new parachute and weighted nosecone.
The rocket remained in the same
configuration.
Clifford
1.5 L
A newer rocket with new ring fin
strut design, a weighted nosecone
with a sharp cardboard cone shape.
John
John
600
mL
An older rocket that survives
most impacts without a parachute.
"OO"
2 x 1.25
L
This is a 2 bottle rocket joined
at the base, with a parachute
recovery system. The rocket remained
in the same configuration since the
last launch day.
Brotanek II
1.25
L
This rocket has also been around
for a while. This rocket remained in
the same configuration since last
time.
Frankovka
4
L
This is a new rocket designed to
carry a video camera and a flight
computer. On this day, it was flown
without the flight computer. It
consists of 2 x 2L bottles.
Team Members:
PK, GK, Paul K, John K and AK.
Number
of launches: 22
Today has been our most successful day
yet. Perfect weather conditions, well
behaved rockets and plenty of air to go
around thanks to the use of a SCUBA tank for
filling. After the launches we went to do
some burst tests on bottles that we are
using so that we know how far we can push
them.
Flight Day Events
First launch of the day was the new 4L
rocket "Frankovka" named after Hana's nickname. The rocket will eventually have
a flight computer but today we wanted to
test fly it and record some parameters about
its flight profile so that we can tailor the
computer to the rocket. The rocket uses a
Robinson coupling to attach the two
bottles together. Both bottles are inverted, so
that all water drains from the top bottle.
Water inevitably gets into the top
bottle when we are filling it.
"OO" also uses the same coupling method
but has the bases of the bottles joined.
The disadvantage is that some water is
always retained in the top bottle's base
"feet".
We put the video camera in so that we
could see what the rocket did from its
perspective. We wanted to see the first
flight in case something happened and we
could not fly it again on the day.
The rocket performed beautifully with the
nosecone separating at apogee, and a great
in-flight video was obtained. Again since
we did not have a laptop with us, that was
the only in-flight video for the day.
This rocket uses 1.24L of water, which
significantly increases the "burn" time.
We repacked its chute and started
filling it. When we got up to launch
pressure of 130psi the rocket noticeably
bent in the middle. This was due to the
bottle deformation under high pressure. The
tape holding the separator band between
the two bottles came loose on one side and
so the rocket bent. There wasn't that much
we could do and so we launched it. The
rocket had a good flight, but arced over,
chute deployed early and broke one of the
two parachute lines. I'm glad I provided a
backup line for just such an emergency.
On two separate occasions one of the
main parachute lines broke. We have been
using a dual line system since last time
we saw a rocket with the camera fly with
the parachute being ripped off on the
way up. Others have used an elastic band
to absorb the shock of a high speed
deployment so I think we will give it a
go. I have been reluctant to do that
because I would think an elastic band
would break easier. I think we may use
the elastic band with a second looser
line for backup.
Rocket flight times especially for
the bigger rockets are getting longer.
The majority of the total flight times
are in the order of 25-30 seconds. One
flight was recorded at 32.88 seconds (Frankovka)
which I believe is our own new record,
but not significant enough to make a
fuss over. Frankovka weighs in at a
hefty 415grams having a single parachute
with a hole in it. We believe if we had
twin chutes with no holes in them like
the previous record setting flight, then
the rocket would be able to break the
record significantly.
We also achieved a personal record
pressure with OO of 150psi. The rocket
goes great at this pressure.
"Clifford" made a copycat flight of
its last flight with a flight time of
9.92 seconds with the parachute again
failing to open.
Ever since reading the instruction
manual for the video camera (not the on
board camera) I have had much more
success in getting the camera to focus
on the tiny dot in the sky. This allowed
me to zoom in on the rocket at high
altitudes. We now have a nice shot of
parachute deployment at around 100
meters.
OO managed to do a self launch
during filling. Again no one was near
the rocket or near the release line.
This is the second time that has
happened and is likely due to not being
properly locked into the launcher. If it
happens one more time I think we will
put some kind of a safety lock on the
launcher. Luckily it was relative low
pressure and went up maybe 10 meters.
The parachute opened and brought it to a
safe landing. There is something to be
said about passive chute deployment. :)
On one of "OO" flights we noticed
that the parachute opened well past
apogee and the rocket remained pointing
down. The rocket is normally suspended
sideways so that it acts as an air brake
too. When we recovered it we noticed
that the chute managed to thread its way
through the ring fin. This could be
considered a hole in one, since the
parachute had to make it all the way
from the nosecone to the tail before
opening.
After the launch day we went to do
pressure tests on PET bottles to see how
much they can really take. For details
see the
Burst Test Results section. As we
approach pressure limits for normal
bottles we will have to start testing
re-enforcement techniques.
With the 22 launches filling mostly
the bigger rockets to around 140psi we
only used 50 bar out of the 8L tank.
This means that with our 10L tank we are
likely to get in a whole month worth of
launches on one refill. The pressure
regulator worked great and filled the
rockets quite quickly. We made sure that
we didn't fill at the full rate as we
wanted to control the pressure
accurately.
Flight Record
Launch
Rocket
Pressure (PSI)
Notes
1
Frankovka
115
Great flight, nice
and straight. Good in-flight video,
with a very eerie sound recorded of
the boost phase. Parachute deployed
at apogee and rocket landed well.
2
Frankovka
130
Good flight, rocket
bent on launch pad. Chute deployed
early breaking one of two main
lines. Rocket landed well.
3
D.Y.
130
Good flight, with
parachute opening just before
apogee. Upon landing it was noticed
that the base of the bottle had
changed shape.
4
D.Y.
130
Great flight,
parachute opened at apogee, landed 1
meter from AK.
5
OO
130
Perfect flight, good
chute deployment.
6
OO
130
Great flight, chute
just before apogee.
7
OO
150
New high pressure
record. Rocket took of at a slight
angle. Good chute deployment. (750ml
water)
8
Clifford
140
Very high and
straight. Chute failed to open and
as a result rocket sustained a bit
of damage.
9
Brotanek II
140
Short flight,
parachute opened early.
10
OO
150
Very good flight,
parachute opened well past apogee
because it threaded itself through
the ring fin.
11
OO
150
Very good flight
nice and straight. Chute opened at
apogee.
12
OO
?
Self launched while
filling. pressure was fairly low,
20-30psi? as the rocket did not go
far but high enough for the chute to
open and the rocket was saved.
13
Frankovka
130
Repaired bent rocket
with some tape, great flight and
chute opened near apogee.
14
Frankovka
140
Great flight chute
opened near apogee.
15
Frankovka
140
Great flight chute
opened at apogee.
16
Frankovka
140
Great flight chute
opened near apogee.
17
John John
120
Very good flight and
high, nose was bent on impact but
will fly again.
18
OO
150
Very high,
perfect parachute deployment at
apogee. Long drift from the launch
pad.
19
OO
150
Great flight, but
one of the main parachute lines
broke, but the other was sufficient
to hold it.
20
OO
150
Great flight and
landed well next to me filming. The
rocket is looking a little bent from
the higher pressures by the look of
it.
21
Frankovka
140
Very good flight,
perfect chute deployment, but as
wind was starting to pick up it
drifted a long way from the launch
pad. (117 steps)
22
Frankovka
140
Very good flight,
good deployment and long drift again.
Design and Development
The development on the
flight computer has also continued with
most time being dedicated to the flight
software. Version 1.2 is now almost
finished.
The parachute deploy release door
and ejection piston are also mostly
complete now.
Day 16 - A Mixed
Bag
The difference in shape of a standard 2L
Coke Bottle.
1.25 L bottle wrapped with strapping tape.
2L bottle wrapped in Gaffer tape.
Heat shrunk 1.5L bottle down to 1L.
Shot from below with a payload attached on
string.
Rocket at apogee.
Payload - a stuffed kids toy being carried
aloft.
Paul holds the toy in his hands for
lift-off. The rocket only has around 20psi.
Altitude < 10 meters.
A shot of a water rocket from directly
above.
"Cena" taking off ready to put the aquanaut
into orbit. .. well not quite.
Dusk at the launch pad. The sun has already
set.
Flying at dusk makes it hard to see and
video tape.
"Clifford" coming in for a landing. The sun
has already set.
Yes it was quite dark when we packed up.
The front half of the V1.2 flight
computer.
The back half. Motor and gearbox at the top,
with launch detect switch on the bottom.
Top view showing the battery pack separated
so the rocket can be balanced.
New nosecone being developed housing the
flight computer, camera and side ejecting
parachute. The idea is that you can attach this
to any larger 110ml diameter water rocket.
Date:
22nd October 2006 - All day
intermittent
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:
Windy and showers with clearer weather in
the afternoon.
Rockets:
Name
Capacity
Notes
Clifford
1.5 L
An older rocket, fitted with a
new streamlined nosecone for this
day.
"OO"
2 x 1.25
L
This is a 2 bottle rocket joined
at the base, with a parachute
recovery system. The rocket remained
in the same configuration since the
last launch day.
Frankovka II
4.25
L
This is a newer rocket designed
to carry a video camera and a flight
computer. This is a rebuild of the
Frankovka rocket with a new 2.25L
bottle on top and a 30% lighter fin
structure. On this day only the
video camera was fitted.
Team Members:
PK, GK, Paul K, John K.
Number
of launches: 5 + about 8 low pressure
ones in the back yard for kids.
This day was a bit of a mixed bag, with
bottle burst tests, low altitude fun stuff
with kids, and a few serious launches. This
Sunday morning was windy and rainy so we
stayed away from our usual launch site.
Instead we went and tested four more bottles
to see how much pressure they could take. As
we try to build higher performance water
rockets, we need to test new materials and
techniques for their manufacture.
Flight Day Events
We pressure tested a regular 2L Coke bottle, and 3
reinforced bottles of various capacities
to see how they behaved. (See the
Burst Test page for more details on
the tests.)
The most notable test was the 1.25L bottle
wrapped with a single layer of Scotch
3M Strapping tape. The tape contains some
fibre but I'm not sure exactly what it is
(It may be glass).
The effect it had on the bottle was quite
dramatic. There was virtually no
stretching of the bottle and it burst at
250psi. That's not bad considering the
normal burst pressure for these bottles
was around 185psi with quite a bit of
stretching. I think adding a second or
third layer should hold up to around
300psi.
Our next rocket launch pressure target is
the 200psi mark, so the tape should be
quite suitable. At these pressures we are
also likely to start using some kind of a
safety blast shield once we start
pressurising them on the launch pad and
keep the kids well away.
Since we couldn't go down to our local
park, we decided to do a few low altitude
flights at home, tying the rocket down
with a piece of string so it would not
leave the back yard. Well before you knew
it the other end of the string was being
tied to kids' toys and the like. Paul is
about to loose one of his wobbly baby
teeth, and we seriously considered
removing it with a water rocket, but you
know ... he just wouldn't keep still :)
We did manage to get some unique video
shots of the rocket from directly above
and directly below as it launched. Launch
pressures were around 20-30psi.
We tried going down to the park a
number of times during the day when the
weather cleared up, but there were too
many kids playing baseball. Finally at 6
o'clock when they cleared the range we
swooped in. We managed to get 5 launches
in before the sun set, but launching
rockets at twilight had a number of
problems:
It is difficult to see the rocket at
altitude;
The onboard video camera tends to
smear the images in low light; and
The hand held digital video camera had
a hard time staying focused on auto in low
light.
We managed to get one in-flight movie
for the day, but luckily the camera wasn't
on the rocket for its second flight
because the nosecone came off early and
the parachute deployed way too early. With
the big rocket travelling at around
150km/h opening a parachute is not a good
idea. Both main chute strings failed and the
chute drifted slowly down while the rocket
managed to have a relatively high speed
impact. The nose was quite heavily
damaged, so thankfully the camera was not
in it.
This was the first time the nosecone fell
off too early in about 10 flights, so we
are trying to analyse why. I didn't notice
it at the time but inspecting the rocket
at home I noticed that one of the fins was
damaged. If the rocket had launched with a
damaged fin, this certainly could have
caused it to misbehave and have the
nosecone come off earlier.
The 4L rocket (Frankovka) was upgraded
to 4.25L rocket by exchanging the top
bottle with a 2.25L bottle. New
lightweight fins were also constructed. The
old ones use to weigh 115grams until some
economising reduced the weight to 96
grams. A new redesign and materials only
made them weigh 65grams. But it appears
that this was detrimental and as a result
one broke.
The new fins were however more accurately
made and aligned so that the rocket only
rotated 180 degrees before it reached
apogee. This made for much better
in-flight video stability.
After failed parachute releases with
"Clifford" last week, a new very
streamlined nosecone was made and a set of
new nose cone supports. This new
nosecone also
deployed just a tad early, but the
parachute brought the rocket back in one
piece. I believe that this was caused by
insufficiently attached nose cone weight
inside the nose cone. The weight
probably came off during launch and
impacted on the parachute, dislodging it
and the nosecone.
Flight Record
Launch
Rocket
Pressure (PSI)
Notes
1
Frankovka II
120
This was an
in-flight video flight. It was a
good straight flight, and the
parachute opened near apogee, but
the prevailing wind caused it to
drift into some low bushes.
2
Frankovka II
120
Not such a good
flight, towards the end of the power
phase the nosecone fell off and the
parachute deployed, naturally the
parachute ripped off and the rocket
sustained substantial damage. Later
it was noticed that a fin was broken
so we are not sure if this was the
cause of the erratic flight. There
was no camera present so that was
good.
3
Clifford
130
A fairly good
flight, with the nosecone separating
too early. But the parachute held up
well and the rocket made a safe
landing.
4
OO
130
Very good flight
with the parachute deploying near
apogee.
5
OO
130
Also a very good
flight into the night. On this
launch it was almost too dark to see
the rocket. But the parachute
deployed again near apogee.
Design & Development
Version 1.2 of the flight computer is
also going well. The prototype was tested on
a breadboard and now has been constructed
onto a Printed Circuit Board (PCB). The
computer now sports a 7 segment LED display
for showing status and an extra button for
choosing the program you want to run. The
assembly code has also been written and
tested. Version 1.2 of the computer will
only use a timed release of the parachute.
This will be used to test the performance of
the rocket and computer combination. Once
the parachute deployment mechanism is
reliably triggered by the computer, the next
version of the flight computer will be
equipped with an air speed sensor to allow
the computer to record its readings. When
in the data logging mode, the parachute will
be timed to deploy well after apogee, so
that clean air speed data can be gathered
through apogee and beyond. This is something
we would not be able to do with just the
nosecone off at apogee technique we have
been using until now.
Then once sufficient data has been gathered,
the flight computer software will be
tailored to the sensor so that apogee can be
detected using the sensor. We will trial a
couple of different air speed sensors to see
which one works better.
Notes to Self
Solve this parachute line breaking
issue once and for all.
Rocket parts must be built solidly
for higher performance rockets.
