Hi Benno,
I was part of a team that sent a balloon up to 37km last year with a HD video camera to film last November's total solar eclipse.
You can read about it here :-
http://joe-cali.com/eclipses/PAST/TSE2012/index_p3.html
You almost certainly will need CASA's permission or at least talk to them and have them tell you that you don't need permission.
Last year, someone in Brisbane released a light balloon using two mobile phones one to transmit position and one to track it. He stupidly put the transmitter in his car and the tracker receiver in the balloon and hence immediately. A CASA safety officer told me they had to divert air traffic around a 500km x 900km corridor stretching from Ipswich to Charleville for about three weeks.
You don't need permission to launch individual unconnected party type (toy store) balloons unless the total number exceeds something like 200. However as soon as you go to payloads, things get much more difficult. The relevant regulation is CASR101 that covers unmanned rockets and aircraft. I have pasted part of it below but you need to download the whole thing.
http://www.casa.gov.au/scripts/nc.dl...D::pc=PC_91039
Pluto's info is correct in concept but inaccurate as he suggested it might be. As you can see from the info below there is no class of balloon being "under 200g."
The classes are
Small balloon <50g
and
Light Balloon 50g - 2kg.
The definitions specifiy the weight is just payload however CASA take the expanded diameter of the balloon into account.
Extract from CASR 101
101.145 Definitions for Subpart - free balloons
(1) For this Subpart:
free balloon means an unmanned balloon that is not
tethered.
(2) There are 4 kinds of free balloon: small balloon, light
balloon, medium balloon and heavy balloon.
(3) In this Subpart:
small balloon means a free balloon that can carry no
more than 50 grams of payload.
(4) In this Subpart:
light balloon means a free balloon that:
(a) is no more than 2 metres in diameter at any time
during its flight; and
(b) can carry no more than 4 kilograms of payload.
(5) In this Subpart:
medium balloon means a free balloon that:
(a) may be more than 2 metres in diameter at some
time in its flight; and
(b) is capable of carrying more than 4 kilograms, but
no more than 6 kilograms, of payload.
However the "light balloon" classification is sort of non-existant.
We calculated that even if you use the lightest 200g latex balloon with a 50g payload and 0.25 cu m of Helium, it will be 0.8m diameter at launch. However, it will expand to greater than the 2m limit for light balloons at altitude thus pushing it into the medium class.
I spent somewhere between 40 - 60 hrs on CASA and Air Services Australia compliance. They were not obstructive but they were tough and it wasn't easy to meet their requirements. At one stage they issued me with a letter stating that they were prepared to consider our balloon a light balloon and as such we didn't need a clearance to launch. Three days later, someone higher up than the safety officer I dealt with decided to revoke the classification and our balloon was reclassified as a medium balloon by virtue of the expansion.
In the end I, in my role as the so-called launch coordinator, had to sign a legal contract that held me personally responsible if we lost the tracking on the balloon and aircraft had to be diverted. This was only sent to me hours before launch, no time to arrange insurance. I took a risk but I signed it because -
a) I had great confidence in the preparation and testing that had gone into the system;
b) The team had put far too much time into it to back down at the final hurdle.
If it had gone really wrong I could have lost my house...everything.
We had an advanced ARPS microbeacon tracking system. Our team had an experienced aerospace engineer with dozens of high altitude scientific launches for NASA, ESA and ROSA behind him and several radio tracking specialists who designed an extremely robust tracking system. Our radio specialists deployed extra digipeaters around Cape York to ensure that the radio signal could not be lost no matter how far it drifted. If you launch in a more populated area, this may not be necessary but you'll have more issues with the balloon being in RPT (regular passenger traffic) airspace.
Good luck with your project, I think it is a very worthwhile endeavor. I would encourage you to consider whether there is an easier way to get publicity for your project. Our flight to shoot an eclipse was a first and yet it didn't get us that much publicity. Sending toys, smart phones up to the stratosphere has been done before. You'll still have to put in the hard yards to get media coverage. You'll expend a great deal of energy and money doing the balloon launch that could probably be better invested in your cause.
best wishes
Joe Cali
