Here's the post with my thoughts about the Balloon Launch, sorry it's another long one...
Hi all. Yes, this is true. There are a lot of things to think about and you need to work diligently for a project like this. You need to think ahead and predict everything.
This is definetly true, for anyone interested there's a lot of great material on
https://ukhas.org.uk/ and
http://www.daveakerman.com/?p=1732I had to submit all the papers ( flight approvals) once more as I have cancelled the launch. So the Airport need to be closed( in case of an emergency landing) all the planes need to be redirected to the closest airport- 200 km away.
Have you considered finding a launch site that's not an airport and that's further away from the border, this may make the launch easier (don't have to arrange for the airport to be closed) and gives more chance of not crossing the border (crossing borders isn't necessarily an issue but can make chasing harder). You can potentially also adjust the flight profile by using more gas which will lead to a higher ascent rate and earlier balloon burst. Adjusting the descent rate is also possible but may lead to being less safe (the standard is to aim for 5m/s ascent and descent rates, a faster descent means it has more energy so could cause more damage).
The launch site, my hometown, Iasi, is located 25 km E close to the border with Moldavia and 200 Km N close to Ukraine. So I don't want to start an international mess:)) ( joking). I only have flight approval for Romania and it would be a huge effort to get a flight approval for 2 countries, no to mention about traveling to an unknown terrain and search for a 30cm x30 cm box:)
There are also the regulations for radio-amateur Dual Band Two-Way Radio. I am broadcasting on 144.8 Mhz, using a Baofeng uv-5 so there are different regulations on Ukraine and Moldavia, and again, I don't want to mess arround:)
This is where good tracking comes in, if you're getting good tracking information you know where the balloon is during the whole flight so finding it on the ground should be trivial. With a good camera and lens people here have even managed to photograph balloons when they're at 30km altitude.
APRS, an amateur radio positioning system (which requires a suitable amateur radio license to transmit) isn't bad for this. You may want to consider changing the path and how often you transmit based on altitude. Fewer transmissions and potentially no WIDE settings at altitude (you should be able to reach many igates easily), then add in some suitable WIDE settings and more regular trasnmissions as it gets lower. As noted there is an issue with different requirments in different coutries as to what's allowed (the UK doesn't allow airborne use at all), you often also need a suitable license level to use your license in a different country.
Now for the areas that I can think of that may need consideration to ensure this is a success.
Type of GPS used: In high altitude balloons not all GPS receivers are made equal, some stop working after a few km of altitude, others need special configuration to work properly. The favourite choice tends to be the ublox modules which can work up to 50km however they do need to be configured (if not suitably configured they stop at 12km).
Flight environment: The conditions at altitude can be harsh with low temperatures and little atmosphere. However my concern here is that things could overheat (crazy I know). The biggest issue for electronics is how they can disipate heat, In general this is done by heating the air around and that air being circulated via convection, with a thin atmosphere there's limited convection so the heat builds up around the chip. I think the most popular Pi being used in flights is the Model A due to it's low power requirements. The only other Pi model I'm aware of being flown was the original Model B and that got hot due to the limited convection.
Internet connectivity: This is hard, very hard. The obvious solution would be to use the mobile phone networks, however these are designed for handsets being used 1-2m above the ground. At altitude it just doesn't work, if you got a signal between 1-2km you'd be lucky and i wouldn't expect anything once above 2km. You also may not get anything after landing. Wifi has been tried a few times but really needs specialist equipment (very directional antennas on the ground and ability to point them accurately), special configuration (default settings will limit the distance), and a lot of luck. I'm not sure wifi has been used for more than a few km distance. The last real alternative is one of the satellite modems (e.g. rockblock), they don't give a lot of bandwidth and the charges are high. The only other way you might manage something is through the likes of lora modules which again won't give much bandwidth and will be limtied by power and duty cycle restrictions.
Gas choice: not really a concern but for better green credentials Hydrogen might have been a better choice. Helium is a limited resource and once it's in the atmosphere it's not useable. I beleive it will also escape the atmoshpere and carry on away from the planet.
There are a range of Ballooning communities out there (UKHAS, GSBC, GPSL, ARHAB), if you're going to talk to them it's well worth keeping in touch with the various communities (I became aware of EGC from this being talked about within UKHAS around a month ago but I don't think there's been any discussion since) you may find there are other interested people nearby (there are certainly some enthusiasts around Poland and may well be some from Romania, Hungary and Ukraine).
One thing that's definetly been done right so far is describing it as going to the stratosphere. People often talk to going to space which isn't possible with a gas filled balloon.
