Cansat question

Australian version of the US CANSAT program, designed to engage upper secondary school students in the science of rocketry.

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air.command
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Cansat question

Postby air.command » Mon Jun 23, 2008 7:51 pm

I've been doing a bit of reading lately about some of the CanSat competitions around the world and wanted to ask if there is a CanSat program here in Australia? I did find some information on cansats on the ASRI site, but there wasn't a whole lot to go on. Are there also other programs? Tarp started a thread back in Feb on CanSats, but the thread is locked. There were a couple of other threads on the topic as well. Any updates on the status of this Tarp?

I'd love to get involved in some way. Anyone know where to find out more info or people to contact?

One way I was thinking of helping out would be to build water rockets that could launch a can sat to around 500' so that the experimenters can test their systems end-to-end, adjust them, and perhaps fly them a number of times evaluating their performance, and when the cansat builder is happy, it would be launched on a real pyro rocket to greater altitudes for the actual experiment/competition.

Launching them with water rockets allows multiple launches at a very cheap price, making it more accessible to high-school students as well as providing more confidence to the builder for the actual flights.

If not test flights on water rockets then perhaps assist with electronics and the experiments themselves.
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memberr
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Postby memberr » Tue Jun 24, 2008 8:09 am

As far as i am aware ASRI are the only people currently offering such a service. I would suggest contacting ASRI as there are many ways you can get involved in their small sounding rocket program. ASRI's rocket motors are also very very cool to experience :)

If the payload was intended for a Zuni rocket i do not think a water rocket could properly test it

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Postby air.command » Tue Jun 24, 2008 11:09 am

memberr wrote:As far as i am aware ASRI are the only people currently offering such a service. I would suggest contacting ASRI as there are many ways you can get involved in their small sounding rocket program. ASRI's rocket motors are also very very cool to experience :)

If the payload was intended for a Zuni rocket i do not think a water rocket could properly test it


Cool, I'll try to contact them. Certainly payloads destined for a Zuni are probably a different kettle of fish.

The CanSat's I've seen for some competitions were launched on regular amateur rockets to around 500m-1000m. Really only the lower altitude competitions could benefit from water powered test flights. Some of the things that could be verified on the test flights could be, recovery system deployment, telemetry, sensor deployment, rate of descent measurements, landing survivability and post landing ground operations as some competitions require that as well.

Water rockets can emulate high - G scenarios as well (50-100G), although for a shorter duration than typical pyro rockets.

Really the main advantage would be the savings in pyro motors for the test flights.
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Postby krusty » Tue Jun 24, 2008 11:13 am

What sort of payload (weight) can you lift with a water rocket?

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Postby air.command » Tue Jun 24, 2008 12:04 pm

A lot depends on the launch pressure and volume of the rocket.

I've done preliminary simulations and to get a 350gram CanSat to 570 feet would take a single stage 12.8 liter rocket pressurised to 130psi. (The total dry weight of the rocket including payload and recovery system is 1500grams.) You would use about 3 liters of water.

This is a straight forward rocket to construct requiring no special reinforcing.

The same rocket at the same pressure could lift two 350gram CanSats to 480 feet.

Our big 2 stage 24L cluster rocket weighs over 8Kg at lift off (2Kg of which is the booster dry weight, ~5L of water, and 1Kg second stage including its water)

Simulation results for the CanSat rocket:

Parameters
Bottle Volume: 12800 cc
Diameter: 110 mm
Water Fill: 3278 cc
Launch Pressure : 896 Kpa (130 PSI, 8.84 Bar)
Nozzle diameter: 22.0 mm
Nozzle viscous losses: 0.16
Dry mass: 1500.0 grams
Coefficient of drag: 0.30
Initial Velocity: 0.0 m/s
Launch Tube length: 1200.0 mm
Launch Tube diameter: 22.0 mm

Results
Launch and thrust phase

Thrust at start of launch tube: 319.9N
Left launch tube at: 11.9 m/s after 50ms
Thrust just after launch tube: 615.1N
Initial burn acceleration: 118.9 m/s2 (12.1G)
Average acceleration: 219.3 m/s2 (22.4G)

Burnout
Burnout after: 290 milliseconds
Burnout Velocity: 63.5 m/s (228.7 kmh, 142.2mph)
Burnout Altitude: 8.2 metres (27.0 feet)
Burnout acceleration: 226.5 (23.1G)
Drag force at burnout: 3.6 newton (0.4kgf)
Deceleration due to drag: 0.2G
Speed increase due to air pulse: 14.5m/s

Coast
Drag-free coast 205.8 metres to apogee at 214.1 metres after 6.8 seconds
Actual apogee at 176.60 metres (579.4 feet) after 5.97 seconds

Crashdown
Crashdown speed 53.4 m/s (192.2 kmh, 119.5mph)
Total flight time 12.17 seconds


(a bigger nozzle will give you higher G's)
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spacelaunch
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Postby spacelaunch » Tue Oct 28, 2008 6:09 pm

Just curious- what program do use to sim the water rockets?.
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Postby air.command » Tue Oct 28, 2008 6:36 pm

spacelaunch wrote:Just curious- what program do use to sim the water rockets?.


We mostly use this one:

http://cjh.polyplex.org/rockets/simulation/

It looks simple, but actually the model behind it is quite complex and we have found that when we compare our altimeter data to the simulation results they are usually in fairly close agreement.

The simulator is less accurate for extreme pressures, or extremes of other parameters, but most rockets built by people are well covered by the sim.

The other nice thing it does is that you can give it a range of values for a particular parameter and it will calculate the optimal value for that parameter to achieve the greatest altitude. This is what we use to work out the amount of water to put in the rocket after we build it.

The sim will do multistage as well.
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Postby spacelaunch » Tue Oct 28, 2008 8:53 pm

Cool I have been looking for a good water rocket simulator :) Thanks for the link
Space is only 100km straight up, see you there :)


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