There are two kinds of balloon that you can use:
- Sounding balloons
- Cold Weather balloons
Sounding balloons will typically weigh in at 200 grams to a full kilogram and lift 250 grams of payload. They will also go up to 20 – 30 km.
The cold weather balloons can carry a good kilogram and are made to go to the stratosphere (from 10 to 50 kilometers high where temperatures can be lower than -75 degrees C)
The balloon I used for MSP-1 & MSP-2 was a Kaymont Cold Weather KCI TX1200 balloon. It cost about $105 (shipping included). I now use Hwoyee‘s 1600g balloons from Scientific Sales.
Kaymont’s balloon has a 12 cm long thick neck used to fill the balloon and attach the load lines.
When you manipulate the balloon, I highly recommend that you use latex gloves. It’s not to protect you but to prevent you from damaging the balloon with your nails and your sweat.
Remember: The balloon is very fragile. Find an area that’s very protected from the wind otherwise, it will bounce against you and the ground a lot and may be damaged before even launching it. Because it’s so fragile, you must launch it from somewhere with no possible contact with fences, trees, phone or electric lines.
How much Helium?
To fill the balloon, I highly recommend to use Helium over Hydrogen.
Hydrogen is lighter than Helium but the difference is ridiculous when you think about the risks. Hydrogen is extremely flammable whereas helium is an inert gas. Moreover Helium is easy to obtain and you do not need any special permits if you decide to start transporting several tanks of it around in your truck.
You can find helium tanks at local party stores or welding supply stores.
I found mine at SF Party in San Francisco.
One cubic foot of helium will lift about 28.2 grams. Kaymont recommends a gross lift of 3440g. So I needed 3440/28.2= 122 cf of helium. I took the 244cf tank + a dolly. It cost me $148. Be careful the tank is very heavy.
How to to fill the balloon from the Helium Tank?
Helium tanks from party stores usually come with special regulators for party balloons. It’s not the best thing in our case because the flow rate is low, you need to constantly bend the valve and consequently it slows the filling process down.
The obvious issue is to link the small regulator’s mouth to the 3 cm wide balloon’s neck. You need to build the joint/adaptor yourself.
You need:
- A plastic tube (3 to 6 feet long)
- A 1 inch PVC 90 degrees Elblow
- A 1 inch female PCV tube
- Some scotch tape
To make sure the dimensions are correct, bring with you the balloon and the regulator when you go shopping. You can find the materials at Lowe’s or Home Depot.
The reason you want to a long plastic tube is to be able to inflate the balloon on a clean plastic cover away from everything.
The balloon’s neck is about 3cm (1.2 inch) wide, a 1inch wide PVC tube is large enough to keep it tight. Make sure to secure it with 2 tie wraps and a solid pair of hands.
Since the inflating process can take up to one hour, the person responsible for the balloon can get very tired. The reason you want an Elbow shape is to attach the inflating balloon to something heavy to prevent it to fly away and to measure the lift.
How much Helium is enough?
The tank regulator may or may not have a volume gauge. To measure the balloon’s lift, I found very hard to use a hanging scale. It’s great to weight your payload but absolutely not convenient to measure the lift. The scale is not accurate if there is any wind. It requires at least 2 person and tends to recalibrate itself each time you switch it on.
The best way I found was to attach the regulator joint to a jug of water. Add the desired amount of water to match the lift (3440g -> 3.5 liters). When the balloon is at equilibrium you know you have reached the desired lift.
Remember: It’s always better to have more lift that not enough. (More Lift = Faster ascent rate = Shorter flight time = Fewer problems)
About sealing the balloon, Dave Mullenix has the best instructions: using tie wraps or heavy twine, tie the balloon neck off tightly above the filling adaptor. Remove the joint. Tie the neck again, four to six inches below the first piece of twine. Tie your payload cord to the neck between these two pieces of twine. Now bend the neck over double and tie it again, twice. You will now have the neck of the balloon bent over double, with the payload suspension cord nestled in the bottom of the bend and the whole thing securely tied.
You’re ready to go over your pre flight checklist.
Amazing what you can do yourself with some plastic tube and a bit of Sealing Tape! Great stuff.
I learned a lot from this, thanks! It also helped me with my personal weather balloon project (currently in the drawing board stage). Keep up the nice work!
I was wondering if you had any advice and safety tips on filling a ballon with hydrogen?
Thx.
I wouldn’t recommend to use hydrogen if you don’t have experience with it.
But If I had to, I would start by following the guidelines of the UK High Altitude Society: http://ukhas.org.uk/guides:hydrogen
Hope this helps!
i will send a weather balloon 1600 gr with 2500 kg weigt payload.
is it gonna make a really big diffrence for reaching enoughf ??
thankss
Hi Jack,
Basically a bigger balloon will carry more weight or with the same payload, a bigger balloon will have more room to expend and you will go higher.
A 1600g balloon (filled with the appropriate amount of helium) carrying a 2500g payload should be able to reach around 100,000ft.
Best,
Marc
Thank you very much marc, i have one more question, does 13 inc parachute (from projectaether) can take that much weight> 2300 kg ??
Thank you!
13 inches seems too small. I believe that Project Aether is using 36″ parachutes.
I have been personally using 6 feet parachute from The Rocketman
How much helium would you advise me to use for the Hwoyee‘s 1600g balloon from Scientific Sales.
How to follow altidue ( for example balloon reach 30000 meter) ?
I have spot gps but i can only track..?
Whats your advise?
Thanks!
Hi Michael,
Go to Kaymontballoons.com and check the required lift for a similar size. Based on the lift, you can deduct how much helium you need.
Hope that helps.
Marc
Hi Mickey,
I suggest you read my post “How to track a Near Space Balloon”
Spot messengers do not track altitude. You need another device.
Marc
Hi Marc,
i found this post very helpfull.
I have another project in my mind and think of using a weather balloon to lift it in a height of 15 meters above the ground and light it from inside. The problem is that the weight of the staff i need to light it up is above 5 kg. This means that i can go with a big enough balloon, but is the 1200g enough to lift 5 kg?
Do you have any recommendation?
Thank you in advance!
So you want to use a balloon to lift 5kg up to 15 meters?
I am not an expert. A 1200g balloon seems small, I’d go with 1500g or bigger maybe.
We live in eastern PA, and the U of Wyoming weather balloon predictor said that our project would land in the middle of the Atlantic Ocean if launched today…
What type of weather conditions should we be looking for?
Hot/Cold?
Windy/still/etc?
Thanks,
Mike
Hi Mike,
The less wind you have, the easier it will be to launch your balloon.
Wind conditions change daily, you need to run the prediction tools often to get a general sense of where it’s going to go.
Remember that it’s only a prediction, it will not necessarily follow the predicted flight path.
Run them until you have trajectory that works for you and if not, be ready to travel to a better launch location.
Hi marc
Where can i buy a kaymont balloon? iam outside of US, They dont have a buy option…Before i used scientific but they sent me a cracked balloon, and we were in a very important project, so i cant buy from there..
Thank you!!
Hi Thomas,
You need to call Kaymont to place your order.
I have never had a problem with scientific sales. They sell different brands of high altitude balloons.
I am sure you can find the Hwoyee brand online somewhere else
Hello Marc
Which altimeter do you advise for record the altitude of the balloon? Brand and type?
Thank you!
Hi Jack,
To track the altitude, I have used Byonics GPS4 which is designed to work at altitudes up to 84kms.
Whichever GPS you choose, make sure they operate above 60,000ft. (Most GPS devices do not work above 60,000ft because of ITAR regulations).
Hope this helps.