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 18 - New Rocket, good in-flight video.
The new J4Y rocket. Looks like the rockets are growing faster than John.
Packing up the parachute for the maiden flight.
After several in-field repairs, the J4Y rocket finally takes off.
Frankovka III with a 7mm nozzle takes off at a bit of an angle.
Another shot of Frankovka III going up to see the world from a different perspective.
J4Y' bottom section, the top section blew off on the launch pad.
Frankovka III with 7mm nozzle - that is still the water column!
Our new lathe, this makes it much easier to manufacture rocket parts at home. (Still covered in grease from shipping)
New couplings flown on the new rocket.
Diagram of how the coupling fits together.
Seal cutters made on the lathe. These cut out the exact seals we need from a rubber sheet.
The end of the long tool showing where it slots into the coupling nut. The tool helps tighten the nut in the bottle.
First version of the ground support vehicle. After it was made we discovered it didn't easily fit in the car.... it was modified a little to fit.
Date: 30th November 2006   6:30 - 7:45 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: Overcast, light breeze, temperature ~20 deg C.


Name Capacity Notes
J4Y 3.75 L This is a new rocket made out of three 1.25L bottles. It is our tallest rocket to date. Parachute deployment is achieved using the nose-cone-off-at-apogee technique. Rocket is typically filled with 1.1 liters of water.
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 for the first time. This is a 2 x 2L rocket. Typical fill is 1.25L of water.

Team Members at Launch Event: PK and GK.

Number of launches: 12

This day was a little different from others in that we decided to go fly on a weekday rather than on the weekend. We met up for an early start at 6:30am so we could get a few launches in before work. It was an overcast morning with only a slight breeze. Great day for shooting rockets.

Flight Day Events

  • First on the launch pad was the new rocket J4Y. The J4Y rocket was named after John because it was his 4th birthday on the day the rocket was finished. As we got up to 50psi one of the couplings started leaking. This was a bit disappointing but it was the maiden flight so you would expect a few teething troubles. We launched it anyway, but it only went up about 5 meters before dropping. We found that the problem was actually the plastic bottle cap part of the coupling which appeared a little distorted. This is something that can be easily fixed with a longer thread bottle cap. The other coupling was holding up quite well.
  • While repairs were being made to J4Y, Frankovka III was fuelled up and placed on the launch pad. Today was the first time we launched the flight computer along with the video camera. We purposefully set the deployment delay back to 5.5 seconds so that we could get a nice clean in-flight video of the rocket passing through apogee and a little beyond. It always looks a little scary from the ground when the parachute doesn't open near apogee as we are use to. The video can be seen below. This is probably our best in-flight video to date.

    Water Rocket in-flight video - good 3

     (If the video does not play, try the latest Flash player from Macromedia)
  • We set up J4Y on the launch pad again, but again it leaked. It was looking like we would not be able to make field repairs to it. But we retightened the bottle and tried again. This time as we approached about 90 psi, the cap failed and the top two bottles with the nosecone ripped themselves out of the lower bottle and flew about 10 meters in the air. You can imagine our surprise we haven't had one of these couplings let go like that yet. The lower bottle was fine, still full of water, and the top two were okay as well, so we screwed it back on, thinking that it won't happen again, and we were going to launch it at a lower pressure.
  • Well, at around 70 psi the top blew off again. Arghh!! so what now? Well, you screw it back on, get some glass fiber reinforced tape and you tape the top section to the bottom section so it (hopefully) can't happen again. After we did that we happily launched it 4 more times increasing the pressure by 10 psi each time. The bad coupling managed to hold up to 90psi without leaking. Replacing the cap back in the workshop should solve the problem.
  • On the final flight the rocket went really well, so we are looking forward to pumping it up to 140psi, although I suspect, the park is a little small for this rocket now.
  • We were launching the J4Y rocket with a custom made new 7mm nozzle to get a slower more spectacular lift-off.
  • Later we launched the Frankovka III rocket with the 7mm nozzle a couple of times at 130 psi and got some very impressive slow acceleration high altitude flights.
  • Modifications to the ground support vehicle were made to carry the various bits and pieces to the launch site. We can carry everything now to the launch site in one go.
  • We had to call it a day and head off to work, but an hour of flying was just enough to keep us happy.

Flight Record

Launch Rocket Pressure (PSI) Notes
1 J4Y 50 As this rocket reached 50 psi, one of the couplings started leaking, so it was launched. Rocket flew to around 5 meters. Parachute deployed but did not open. No damage was done to the rocket.
2 Frankovka III 120 First flight with both flight computer and on board video. Deploy delay set to 5.5 seconds. Very good flight and good video. Rocket went mostly straight up. Parachute deployed at the correct time.
3 Frankovka III 130 5 Second setting on chute deploy. Very good flight, but the rocket angled a little on take off. Despite the flight away from the launch pad, wind carried it back to a landing 2 meters from the launch pad!
4 J4Y 50 Again leak from the same coupling. Better flight this time about 25m in altitude and a good chute deploy. The rocket used a 9mm nozzle.
5 J4Y 90 After some attempted repairs the top two bottles and nosecone blew off the rocket while pressurising. Flew to around 10 meters. Failed at the leaky coupling. Fitted with 7mm nozzle.
6 J4Y 70 Again the top two bottles blew off at 70 psi.
7 J4Y 60 More repairs, this time the rocket launched properly and with the 7mm nozzle was a good slow take off. Relatively low altitude but reasonable flight with good parachute deploy.
8 J4Y 70 Again 7mm nozzle, angled a little off the launch pad but a good flight and higher than previous. Good deploy.
9 J4Y 80 7mm nozzle, a very good flight with the parachute deploying just before apogee.
10 J4Y 90 7mm nozzle, good straight flight up, highest for the rocket for the day. The parachute deployed a little too early but the rocket landed well.
11 Frankovka III 130 We fitted the 7mm nozzle to this rocket to see how slowly it will take off. The rocket carried no video and the FC was set for 5 second deploy. Rocket angled a little on take off as is quite common for us with a small nozzle, but then flew very straight and very very high, great deploy, drifted down range about 130 meters. landed 1 meter from large tree. Flight time ~ 26 seconds
12 Frankovka III 130 Almost exactly the same flight as #11. The rocket landed about 5 meters from where #11 landed. The slow takeoff and the long acceleration are really fun to watch.

Design and Development

  • As we develop new rockets we often need to manufacture custom parts such as new nozzles or couplings. To make this a whole lot easier and more convenient we decided to buy a small metal-working lathe. Every water rocketeers' workshop should be equipped with one of these. Fortunately dad has known how to use a lathe for most of his life and can churn out accurate parts very quickly. The lathe can cut both imperial and metric threads which is a big bonus.
  • One of the reasons we did not fly last week was because we are upgrading the workshop to accommodate the new toy. We have now made 4 new "Robinson" style couplings for testing. Two of them are made with an 11mm hole and the other two have an 8mm hole. Some photos and a diagram of how the couplings fit together are shown on the left. A slot is cut into the bottom of othe coupling nut to enable a special tool to be used when tightening the coupling in the bottle. We found that a fourth seal between the inner coupling and the bottle cap is not necessary as the cap is soft enough to provide a good seal. We tend to omit it so that the amount of thread available to hold the upper bottle is maximised.
  • The lathe was also used to create seal cutters that enable us to punch seals out of a rubber sheet that are exactly the right size.
  • When testing the 11mm couplings with 1.25L bottles we found that we just could not get a good seal above about 80 psi. The outside diameter of the coupling was just too big for the shape of the bottle. These may work better with slightly larger 2L bottles.
  • The 8mm couplings worked really well and were pressure tested up to 140psi. We don't know how much more they will hold but, we are getting up towards the failure level of the bottles and so we will need to test with re-enforced bottles.
  • We used two of the 8mm couplings on the J4Y rocket.

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