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Ballymacelligott to Taghmon - High Altitude Balloon Photography in Ireland
High altitude weather balloon photography has become increasingly popular over the last couple of years with the advent of relatively cheap photographic and tracking equipment. The phenomenon seems to be particularly prevalent in the US where high schools and colleges regularly have projects relating to such.
There are several reasons why the US is a particularly hospitable climate for the activity, mainly:
Access to cheap helium
Huge landmass where the possibility of landing in the ocean is minimal
To our knowledge very few if anybody has successfully attempted to carry out high altitude weather balloon photography in Ireland. Our aim was to be one of the pioneers in the field and to give others some advice to counteract the particular problems associated with launching on such a small landmass. This is our story.
Having carried out a fair amount of research (well a couple of Google searches one evening when we had nothing better to do) we decided to dive right in.
So we made a quick list of what we wanted to achieve:
Pictures from up high
Keep it simple
Do it at reasonable cost
And a list of what we needed.
Update: Termination Timer and Subsequent Test Flight
Gathering the components
Big Balloon
Sounded straight forward, just get a weather balloon. Well yes and no.
There are loads of sizes available which are graded by mass ranging from 10gm pilot balloons to massive 3000gm ones.
Ok how big do we need it to be? A big enough one to carry the weight of the payload up to an altitude of 20km. We figured we wouldn’t be sending up a DSLR camera, we’d just use a compact so the mass of the payload wouldn’t exceed 1kg.
Without going into messy calculations using the theory of buoyancy we’ll just tell you that a litre of helium will lift 1.113g and a litre of hydrogen will lift 1.202g (well according to Wikipedia anyway)
So roughly a cubic metre of Helium will lift 1kg (See the gas section to see why we used Helium)
A 200gm weather balloon has an inflated capacity of 1 cubic metre.
It’ll lift it but very slowly.
So to go up at a decent rate we decided to get a 500gm balloon with an inflated capacity of 3 cubic metres.
Where to get one of those at reasonable cost? No Irish sites seem to sell them. Ebay didn’t have any for sale. US sites seem to be the only option, so we ordered a 500g one from http://www.scientificsales.com/ for around €60 including delivery.
Gas to fill the balloon
This proved to be the most difficult to source and the most expensive part of the project.
We had 2 options hydrogen and helium.
Helium is an Inert, reasonably safe gas and very expensive. (the helium that we are talking about here is NOT party balloon helium, this is useless as it only contains about 30% helium, the rest is air. Pure Helium is what is need to give the required lifting power
Hydrogen is lighter than helium, cheap and very explosive
Initially we figured we’d go with hydrogen as that was the cheaper option
It’s difficult enough to source either of these gases in Ireland and very few specialist companies stock them.
The only big company we found was BOC gases http://www.boconline.ie/
They were very reluctant to give us hydrogen because of the danger posed using such a flammable substance and the need for flame retardant clothing etc whilst using it.
We tended to agree.
So we went with Helium
To fill the 500gm balloon we needed around 3 cubic metres of Helium
BOC usually only supply Helium to large corporations (Medical device companies and such) and in large quantities and found our request unusual.
The smallest container they were willing to supply was a 9 cubic metre tank.
The cost was truly shocking I have to say, €337 + VAT for the gas, €120 + VAT to rent out a tank. It also required the setting up of an account with BOC to procure it.
Thats around €595 inclusive of VAT.
Camera(s)
With the possibility of losing the camera we wanted to use something cheap and cheerful that would take some decent pictures.
We needed it to be fairly light to keep the payload weight down
So basically we needed a compact digital camera.
We need some way to automate the camera so that it would take pictures on it’s own as obviously we wouldn’t be there to push the shoot button.
You can do this with a pc (with certain software) or an external device like canons Intervalometer/ Timer Remote. Certain cameras have an Intervalometers built and this is definitely the easiest and cheapest option.
Doing some research unearths the superb Canon Hack Development Kit (CHDK) http://chdk.wikia.com/wiki/CHDK
This is software that can be installed on most compact Canon compact camera and includes the ability to run scripts.
So having a quick look on Ebay and verifying that that camera was supported by the CHDK developers we purchased a 10mp Canon Powershot A480 with a 4GB SD Card.
It cost around €95 and is a solid camera with decent imaging capability.
As an afterthought we decided it might be cool to have video as well so we bought a small compact keychain video camera from Ebay with an 8GB Micro SD card for around €35.
GPS tracking device
GPS tracking devices have in the last few years become increasingly smaller and cheaper.
Essentially how they work is obtain the GPS coordinates of its current position from the GPS satellite array and relay those to the user via a mobile phone network.
A quick search on www.smazon.co.uk gave us some unbranded Chinese tracking device which we figured would do the job for around €100.
We needed a SIM card so a quick trip to the local O2 store to pick up a pay as you go SIM for €20 including €20 free credit.
The device works by phoning it, hanging up, and it returns the GPS coordinates and current speed via an SMS text message.
The problem with using this method of tracking the payload is the fact that above just 2000m mobile phone coverage rapidly drops and above 4000m the probability of obtaining a signal is practically non existent. This means that the payload will be suffering from “Dark side of the moon” syndrome for most of the journey.
We’d know where is was for a short time after launch and then be flying blind till it dropped back down to mobile phone coverage during the decent.
Parachute
When the balloon bursts they payload will drop rapidly back to earth, to protect it and to minimise the risk of it causing damage on impact a parachute is needed.
So assuming again that the weight of the payload would be around 1kg,
Without going into detail about parachute drag coefficients and air density
A bit of research (Google again) told us that we would need a parachute around 1m in diameter to have it hit the ground at a relatively comfortable 16kph.
To give it the best chance of landing on such a small landmass as Ireland is, we opted for a smaller chute and ergo a faster descent rate. It’d hit the ground harder but we figured the payload could take it.
We picked up a 750mm model rocket recovery parachute on Ebay for around €20.
Payload Box
The payload box is needed for the following reasons:
To hold the camera in position
Protect the cameras and tracker from the elements (210kph winds, temperatures of -60 degrees Celsius in the upper atmosphere)
Protect the camera and tracker from being damaged when it hits the ground (cushion the blow).
Provide a means of easily connecting everything to the balloon and parachute as well as carrying a recovery note should it be found before we had a chance to recover it.
With that in mind we got a sheet of 50mm Styrofoam from a local construction site and manufactured a 200mm cubic box from it.
Cut a few holes and groves in it for the cameras and tracking device and it was ready
The box was jointed together, but to minimise the effects of the extreme temperature the joints were taped up with duct tape
We also taped a recovery note on the box just before launch
Bits and Pieces
We used duct tape to tape up the payload box.
To tie everything together we used heavy duty kite string to minimise the risk of breakage. (Any decent string would have been fine really) We picked it up on Ebay for a few Euro.
Batteries: The keychain camera and the tracking device used rechargeable lithium ion batteries. This is bad as these don’t perform very well at low temperatures, we tried to minimise this problem with the thick insulated walls of the payload. Even so the keychain video camera battery lasted only around 80% of the time it would have lasted in optimal conditions.
The Canon A480 takes regular AA batteries. We used Lithium batteries as they last a lot longer than regular alkaline batteries and are also capable of operating at extremely low temperatures.
Legal Issues
The legalities of launching a weather balloon
Your local airport/ aviation authority will be able to advise you on what you can launch, when you can launch and where you may launch from.
To have the best chance of being cleared to launch by the aviation authority:
Don’t launch in close proximity to an airport
Don’t launch where the balloon may end up being blown over an airport
Keep the payload as small and light as possible, under 1.5kg.
Add radar reflective material around the payload
Do not launch without clearance.
If you are granted clearance by the aviation authority, be sure to follow all their rules and regulations, heed their advice.
Be advised that you will be liable for any damage caused during or by the launch, flight and landing of the craft.
Although if you follow all the rules and regulations it is improbable that something bad will happen there is always that possibility.
You launch at you own risk and we take no responsibility from any problems caused by attempting to emulate what we did.
It is possible to take out third party insurance to cover you for the day, but we didn’t inquire as to how much this may cost.
Preparing for Launch
Having gathered all the bits and pieces together we did a quick bit of testing to make sure the cameras and GPS device was operating correctly.
The CHDK software on the Canon A480 allows for the running of scripts written in UBASIC. There are many examples of code on the CHDK website (http://chdk.wikia.com/wiki/CHDK)
We used the ultra intervalometer code from there and it worked perfectly
The gas came in a large cylinder with no way of connecting to it, to fill the balloon, other than a large threaded hole on the tap at the top. We had a quick look around in the local hardware stores for a solution but without success. Eventually we found an old hydraulic hose the local construction site that threaded in nicely. The other end had metal shielding on it which allowed us to clamp on the neck of the balloon with a hose clip.
Organizing a launch date was problematic, with work commitments and the unpredictable Irish weather.
We were looking for a dry day that wouldn’t be completely overcast.
We were launching from Ballymacelligott, a few kilometres east of Tralee in north Kerry. From the observation of weather patterns and prevailing winds we knew that the flight patch would carry the balloon due East.
Therefore to give it the best chance of landing within the country we wanted the wind at ground level to be coming from the south, the southeast preferably.
Launch Day
We ended up launching on the 3rd of February 2011, not ideal as there was a fair amount of cloud cover but at least it was dry and winds were favourable.
We started by hooking up the balloon to the tank and started the filling process. (The tap on the Helium tank regulates how quickly it will fill, and it is advisable to fill it gently and not turn the tap on full blast. It took about 15-20 minutes to fully inflate the balloon)
While it was filling we turned on the GPS tracker, the keychain video camera with fully charged batteries. Switched on the Canon A480, with fresh Lithium batteries and set the script in motion. (We kept it simple and set it up to take a photo every 20s indefinitely, or at least till the battery died or the memory card filled)
We put everything in the payload box, taped it up with duct tape, and stuck a recovery note on the side.
We tied string around the box, tied the box to the strings of the parachute, and the top of the parachute to the filled and tied balloon.
We overfilled the balloon slightly to speed up the accent
After verifying that the GPS tracker was working we let it go at 10am and hoped for the best.
At 11:37am the payload landed. The tracker was acting up and must have landed in a position where it didn’t have GPS coverage but did have cell phone coverage.
After repeatedly pinging it looking for GPS coordinates it did eventually relay it’s location around 8 hours later.
We’re not sure what happened, it may have blown into GPS coverage, or the tracker was faulty, but we didn’t care, it was working now.
It landed about 10km west of Wexford town, for those unfamiliar with the Irish landscape, that’s in the extreme south East corner of the island. I.e.10km from the ocean and oblivion.
We collected it the following morning, it had ended up in field and we had no problem finding it, it was exactly where we had expected to locate it.
The payload box was in perfect condition, undamaged apart from being a little damp on the outside (having rained the night previously). Most of the balloon remains were nearby although curiously had become detached from the box.
Results
The pictures obtained were decent enough (judge for yourself). It’s a pity there was so much cloud coverage and high altitude shots of land were minimal. It was quite blustery and the video which was pointed downwards was quite jerky and only really usable by pausing it to get still images to determine the route the balloon travelled.
We didn’t use altimeters so we don’t know how high it actually reached but from studying the video footage and still images we determined it reached around 20km and the balloon burst about 20km due south of Clonmel town.
Figure 1 Flight Trajectory mapped out in Google Earth
Rough cost:
Balloon = €60
Cameras+Cards = €140
Tracker+SIM = €130
Chute = €20
String+tape etc = €20
Helium = €300*
Total = €670
(*obviously the helium cost a lot more but as regards how much we used for this flight, €300 = around 1/2 of a tank)
Baring in mind that we got everything back in perfect working order, then the only casualties were the balloon and the gas
I.e. around €360 is what we lost.
Conclusions
There are many US sites on the internet that claim to be able to carry out high altitude weather balloon photography for as little as $100.
All I can say is they must be getting the Helium for nothing, use cheap cameras and borrow the tracking device, because there is just no way it can be done in Ireland for anywhere near that price if you have to pay for everything.
Advice to anyone from Ireland who may be thinking of having a go themselves:
Go somewhere else, a big country like the US.
If you are still adamant you want to do it in Ireland, Go as far west as you can, west coast of Galway would be ideal.
Always contact your local airport/ aeronautical authority to obtain clearance before launch (see legal)
Launch on a nice day in the summer, with south easterly winds.
Use a decent tracking device.
Overfill the balloon, so that it will burst quickly (I know you will be sacrificing height but that’s just a concession you will have to make)
Use a slightly undersized parachute to bring it down quickly.
Is it worth doing?
Very much so, really interesting and excellent results can be obtained.
Update: Termination Timer and Subsequent Flight Test
Reflecting back on the original flight a few months later we decided to investigate an easy way to terminate the flight before the balloon drifted too far from it's launch point.
Being in such a small country, it was as much hope as design to have the balloon land in Ireland. As can be seen from the original flight flight we only barely managed to have it parachute to earth in time in optimum conditions.
So researching online revealed a few people who added in a timed mechanism to cut the balloon loose after a specified period of time. From our point of view the equipment they used fairly complex and needlessly expensive. (things ranging from small computers to microprocessor controlled timers). We wanted to keep it simple and cheap.
Nichrome was the most common implement utilized to sever the balloon cord.
Nichrome is a non-magnetic alloy of nickel, chromium, and often iron, usually used as a resistance wire. A common alloy is 80% nickel and 20% chromium, by mass, but there are many others to accommodate various applications. It is silvery-grey in colour, is corrosion-resistant, and has a high melting point of about 1400 °C (2552 °F). Due to its relatively high electrical resistivity and resistance to oxidation at high temperatures, it is widely used in electric heating elements, such as in hair dryers, electricovens, soldering iron, toasters, and even electronic cigarettes. Typically, Nichrome is wound in coils to a certain electrical resistance, and current is passed through to produce heat.
We picked a 5m reel of 32swq for a couple of euro from Ebay. We only needed a length of about 30mm.
The challenge then was to build some kind of electronic circuit that would switch on, after a certain period of time, pass a current through a small coil of Nichrome (wrapped around the balloon cord), which would heat up and burn through the cord releasing the rope.
This rather simplistic layout was problematic as the circuit had to be positioned above the parachute, it would be better to have the circuit in or connected to the payload box.
After some deliberation and a few sketches we came up with a simple solution.
The ring allows the cord to be severed at the top of the payload box. The string then just slides through the ring and hangs loose, releasing the balloon.
The timer switch required a bit of thought, but in the end we came up with a simple wind up kitchen timer (€4 in Tesco), that we hoped to modify to create a switch.
.
A bit of modifying (solder, battery pack (2 AA lithium batteries in series) a few screws) and an empty CD drum box for the housing which would sit on top of the payload box gave this:
Here we just simply wind up the timer and on countdown the 2 screws come into contact, completing the circuit, activating the Nichrome, which cuts the balloon loose.
We tested it in July of 2011.
Weather was terrible unfortunately, but we went ahead anyway as the gas tank was due to be returned and it was a now or never moment.
We used the same setup as the original with this timer contraption strapped to the top of the payload box with one end of the tethering string passed through it.
Set the timer for 35 minutes, launched and waited.
The tracker took a full day before eventually locking on to the GPS signal.
But our setup worked perfectly and we collected it in field North West of the town of Abbeyfeale the following evening. It had traveled only about 30 miles from launch point, though it may have circled back on itself with the wind currents being unpredictable.
It was cloudy and raining so the pictures was unusable for the most part. but the mechanism for termination of the flight early worked flawlessly.
-Two Bored Kerry men
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