last updated: 21st october 2023 - Day 226 to Day 230 - Various Experiments

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Flight Log Updates

#230 - Tajfun 2 L2

#229 - Mac Uni AON

#228 - Tajfun 2 Elec.

#227 - Zip Line

#226 - DIY Barometer

#225 - Air Pressure Exp.

#224 - Tajfun 2

#221 - Horizon Deploy

#215 - Deployable Boom

#205 - Tall Tripod

#204 - Horizon Deploy

#203 - Thunda 2

#202 - Horizon Launcher

#201 - Flour Rockets

#197 - Dark Shadow II

#196 - Coming Soon

#195 - 3D Printed Rocket

#194 - TP Roll Drop

#193 - Coming Soon

#192 - Stager Tests

#191 - Horizon

#190 - Polaron G3

#189 - Casual Flights

#188 - Skittles Part #2

#187 - Skittles Part #1

#186 - Level 1 HPR

#185 - Liquids in Zero-G

#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

#1 to #160 (Updates)



Each flight log entry usually represents a launch or test day, and describes the events that took place.
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Day 20 - Cluster Development.
Air Command team members present on day 20, sporting their new uniform.
Getting the camera rolling on Frankovka III.
Retrieving the rocket. This picture reminds me of another that I have seen before.
Great shot of the water column and the start of the air pulse from Frankovka III.
J4 powering up to ~130 meters before lawn darting at 160km/h.
The lathe has now produced quite a number of components, for rockets, launchers and necessary tools.
Cluster rocket and launcher under development. Note the spear gun trigger release mechanism.
Cutting out the cluster support frame.
Components of the support frame.
Support frame fitted to test cluster. Note the colour coded lids so that we know which way round it goes.
Launcher base with slot cut out for the trigger release.
Test launcher setup to test release and filling mechanism.
Launching with air only ~15psi.
The cluster is attached by a string so it does't  leave the backyard.
Date: 27th December 2006   8:15 - 9:00 am.

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: Cloudless sky, very light breeze, excellent launch conditions.


Name Capacity Notes
J4 3.75 L This is a newer rocket made out of three 1.25L bottles. Parachute deployment is achieved using the nose-cone-off-at-apogee technique. Rocket is typically filled with 1.1 liters of water. The nosecone was slightly modified from the last day where it was deploying too early.
Frankovka III 4 L This is an older rocket designed to carry a video camera and a flight computer. On this day, it was flown with the camera and the flight computer.
Clifford 1.5 L An old rocket with a ring fin strut design.

Team Members at Launch Event: PK, GK, Paul K and John K.

Number of launches: 5

With all the busy Christmas and holiday rush over we were ready to go fly again. Although the day was short it was still fun. Crashing rockets are always fun to see. We also continued further development on the next still unnamed big cluster rocket (see Design and Development below).

Flight Day Events

  • We flew Frankovka III three times on the day once with a video camera and twice without. We only fly the camera once since we don't usually bring a laptop to the park to download the movie. We have to do that back at home. There is only enough memory on the camera for one flight. The in-flight video was very good and shows a nice panorama of the area.
  • On the first flight the parachute deployed as expected, however, the canopy didn't open and the for a couple of seconds it looked like we were going to need a broom and dust pan to pick up the pieces. But then the canopy opened and the rocket landed well. Perhaps the chute lines were somewhat tangled. On the video you can hear the wind rushing past as the rocket starts accelerating towards the ground.

    Day 20 Inflight video

  • The last flight for the day of Frankovka III was the FC's 16th flight and so far a 100% deployment success.
  • We then launched J4 (renamed from J4Y). On the launch pad we noticed that when the rocket was pressurised the nosecone was a little sticky and didn't want to come off quite as easily as we liked. We tried loosening it by cutting a number of slots around the edges, but it still didn't feel quite right. I managed to convince dad, that when the pressure drops on launch the bottle will shrink and the nose cone will be looser. So we launched it at 130 psi. The rocket went straight up and straight down. I might have mentioned the odd four letter word on the way down. The rocket suffered heavy damage, and it did not fly again on the day.

    J4 Water rocket crash

  • One good thing did come out of it though. Since the parachute didn't open, and with the rocket landing close to the launch pad, it allowed us to calculate the approximate maximum altitude. With a flight time of 10.88 seconds [measured using video frame by frame analysis], and entering all the rocket parameters into the simulator, we get an apogee of around 130 meters (~425 feet). The simulator estimates that the rocket hit with a speed of around 160km/hour (100mph).
  • This week we did not see the sort of pitching over of the rockets like we did last week. We are trying to identify why some of our rockets pitch over significantly just after takeoff.
  • Since J4 was damaged, we flew an older rocket "Clifford". One of the most notable differences with the smaller rockets is how much faster they accelerate off the launch pad compared to the bigger rockets. They also descend a lot slower.

Flight Record

Launch Rocket Pressure (PSI) Notes
1 Frankovka III 130 Flown with a camera, and the computer was set for 4.75 second deploy. Chute tangled on the way down, but opened well above ground. Rocket landed well.
2 Frankovka III 130 Very good straight flight, with deploy set to 4.75 seconds. Good deploy and safe landing.
3 J4Y 130 Very straight flight up, but nosecone failed to separate, and as a result the rocket crashed heavily. Flight time of 10.88 seconds.
4 Clifford ~100 The nozzle seal leaked at around 100psi, so it was launched. The rocket went fairly well, but the parachute opened a little early and the weighted nosecone was ripped off.
5 Frankovka III 130 This was another great flight, with good deploy and landing.

Design and Development

  • As we develop our higher performance single stage rockets, in the background we are experimenting with the next phase of development - multi stage rockets. We are currently designing and building the booster of a two stage rocket.
  • The booster consists of a cluster of 3 segments. A segment is a number of bottles joined together end to end to form a part of the booster. The reason we refer to it as a cluster is because each segment has its own nozzle.
  • The booster release mechanism consists of a single central rod with a slot cut in it that fits into a spear gun release mechanism. The trigger will be remotely activated by a string. We went with a single release point as it simplifies the design and also ensures that all the segments of the booster release simultaneously.
  • Each nozzle of the booster is simply a thin walled aluminium pipe with a flange on the end that holds the seal. The launcher ports have an o-ring in them to seal the nozzle. There is one central port that has air input and two outputs for air to flow to the other ports.
  • Our first test of the setup didn't go quite to plan as the segments are only single bottles and there is no way to equalize the pressure inside them except through the launcher. What ended up happening was as we turned the air on, because the hoses between the ports were all filled with water, as air came to the central port, it started pressurising the bottle, and then a second or so later, the air finally made it to the other bottles. When we turned the air off, we noticed that the central bottle having a slightly higher pressure started emptying all the water by itself into the other bottles. We half expected that that might happen, but it was good to see it in practice.
  • We are now modifying the design to allow only the air to equalize the pressure without transferring the water in each segment. We chose to have the launcher handle the equalising, as it makes booster construction simpler.

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