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Flight Log Updates

#184 - More Axion G6

#183 - Axion G6

#182 - Casual Flights

#181 - Acoustic Apogee 2

#180 - Light Shadow

#179 - Stratologger

#178 - Acoustic Apogee 1

#177 - Reefing Chutes

#176 - 10 Years

#175 - NSWRA Events

#174 - Mullaley Launch

#173 - Oobleck Rocket

#172 - Coming Soon

#171 - Measuring Altitude

#170 - How Much Water?

#169 - Windy

#168 - Casual Flights 2

#167 - Casual Flights

#166 - Dark Shadow II

#165 - Liquid Density 2

#164 - Liquid Density 1

#163 - Channel 7 News

#162 - Axion and Polaron

#161 - Fog and Boom

#160 - Chasing Rockets

#159 - Measurement

#158 - Dark Shadow

#157 - Polaron G2

#156 - Foam Flights

#155 - Down The Barrel

#154 - Revisits

#153 - ClearCam

#152 - Mullaley, Axion G2

#151 - Competition Day

#150 - Rocket Salvos

#149 - Glide Fins

#148 - Too Windy

#147 - Descent Rates

#146 - G2 Launcher

#145 - Harness

#144 - Water vs Foam

#143 - Whalan Reserve

#142 - Doonside

#141 - Windy

#1 to #140 (Updates)



Each flight log entry usually represents a launch or test day, and describes the events that took place.
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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.

Click here for video

Looking south toward manly
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... 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.


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".

    Water Rocket in-flight video

    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.


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:
  1. It is difficult to see the rocket at altitude;
  2. The onboard video camera tends to smear the images in low light; and
  3. 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.

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