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#230 - Tajfun 2 L2

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#177 - Reefing Chutes

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#168 - Casual Flights 2

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#163 - Channel 7 News

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#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 132 - Painting the sky with Inverter

Date: 30th March 2013
Doonside, NSW, Australia
 Sunny, light winds < 10km/h early, 25C
Team Members at Event:
 GK, PK, Paul K, Jordan K and John K.

Launch Day

It was a beautiful morning for launching rockets. The skies were clear with only a light breeze.

With the launcher leak fixed from the last Inverter launch, the Inverter rocket was the first off the pad. During the last launch we noticed that the water with food colouring that we poured in first stayed in the lowest spliced-pair, and really didn't want to mix with the water in the upper spliced pairs. We had to squeeze the lowest bottle to pump it around to mix up. The launch tube in the Tornado coupling makes a pinch point with very little cross sectional area for the water to mix. This got us thinking and so we decided to put different colours in each of the spliced pairs to see if we could change the colour of the water stream in flight. We knew that the top two colours would mostly mix by the time they got out, and so we chose blue and yellow for the top two colours so that when they'd mix we would get green.

Pouring in blue

Putting on the air manifold

After 20 minutes the colours
mixed a little

For the first launch we had prepped the rocket and poured in the water but had to wait about 20 minutes to get all pyro rockets launched first. By the time it came to launch this rocket, some of the colours had mixed a little.

We launched this one sooner so very little
mixing took place.

Getting ready for the second flight

We launched the rocket at 120psi, and again it had a nice slow take-off, and then accelerated well. You could see the different colours as it flew but it was fairly quick. The rocket reached an altitude of 395 feet (120m). You can see how the colour changes in the photos below. These are extracted from the video sequence.

Composite of the changing colours

Although the rocket arced over it was very stable on the way up and didn't roll which always makes for good on-board video. During the last Inverter flight we noticed that the rocket rocked sideways under parachute and so we added a couple of stabilising strings to try to keep it level and give a better view. This worked very well. Next time we'll have to put a second camera facing down to get a view of the ground when it is falling under parachute.

On the second flight we got the rocket up in the air within minutes of filling it with different colours and so they hadn't had a chance to mix very much at all. The problem is that as the rocket is pressurised the volume of the lowest bottles increases and water flows between the sections mixing to a certain extent. 

The second flight was very similar to the first, and again you could see the change in colours. It's much more visible though on the slow motion video. The rocket landed again without any problems. I know for sure I forgot to turn on the on-board camera on this flight as there were too many distractions at the time. The rocket reached an altitude of 377 feet (115m)

Here is a video of the changing colours:

Materials Challenge Revisited

For this week's launch we also wanted to revisit the materials challenge from the last launch day to see if we could strengthen the fins to survive the high speed and acceleration. We reused a couple of the rockets from the last attempt and reattached the fins using a different technique. This time we cut little flaps on the fins and cut some slots in the fin can fairing and then alternatively welded the tabs inside and outside the fairing. This way it wasn't only the welds that were holding the fins on. This definitely felt like a much stronger connection.

Newly attached fins

We then swapped the release head over to the Clark cable-tie launcher and put the repaired PETOne rocket on it. At 120psi it was a very fast launch, and this time the fins stayed attached! The rocket went straight up and straight down and landed less than a foot from the launch pad. With a flight time of 8.8 seconds according to the simulator the altitude would have been close to 302 feet (92m). When the rocket hit the ground one of the fins came off again.

We took the second rocket and pressurised it to 130psi. This time the launch must have been even faster as you could hear the fins flutter on the way up. This would have created a lot more drag and as a result the flight time was only 8.4 seconds. All fins stayed attached even after landing. I think for the higher pressures the fins would need to be reinforced or redesigned to withstand the high air speed. We are now satisfied that this challenge is completed. The crumple nose recovery is working well, as all you have to do is pull the neck out and the rocket is ready to fly again.

 Our last launch of the day was the old Axion II. Launched again at 120psi it went up nice and straight and the parachute opened nicely after apogee.

There was also a great turnout at the launch with lots of pyro rockets (around 70) going up on A to H motors which was great to see.

Here is a highlights video from the day:

Flight Details

Launch Details
Rocket   Inverter
Pressure   120psi
Nozzle   16mm
Water   6500mL
Flight Computer   ST II - 6 seconds
Payload   HD Cam #16, AltimeterOne
Altitude / Time   395 feet (120 m) / 33.7 seconds
Notes   Slow boost but accelerated well. Parachute was released after apogee. Good gentle landing. Good on board video and altimeter data.
Rocket   Inverter
Pressure   120psi
Nozzle   16mm
Water   6500mL
Flight Computer   ST II - 6 seconds
Payload   HD Cam #16, AltimeterOne
Altitude / Time   377 feet (115m) / 32 seconds
Notes   Slow boost again but accelerated well. Arced over a little more. No on board video (forgot to turn it on) and good altimeter data.
Rocket   PETOne
Pressure   120 psi
Nozzle   22mm
Water   400mL
Flight Computer   None
Payload   None
Altitude / Time   ? / 8.8 seconds
Notes   Good fast launch, all 3 fins stayed attached and rocket landed less than a foot from the launch pad. One fin was ripped off on landing.
Rocket   PETOne
Pressure   130 psi
Nozzle   22mm
Water   400mL
Flight Computer   None
Payload   None
Altitude / Time   ? / 8.4 seconds
Notes   Good fast launch, there was audible fin flutter but rocket flew nice and straight again. All fins stayed attached post landing.
Rocket   Axion II
Pressure   120psi
Nozzle   9mm
Water   1500mL
Flight Computer   ST II - 5 seconds
Payload   None
Altitude / Time   ? / 22.1 seconds
Notes   Good Launch. Rocket flew nice and straight. Good deployment and good landing.



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