# How do I interpret the specs of a weather balloon?

I'm planning a high-altitude weather balloon project (to around 100000 feet, or 30 km) some time down the line to take video and pictures of near space altitudes and I have some questions I need to ask before doing so:

1. What does the weight of a weather balloon mean such as 150 g, 500 g, 2000 g, etc mean?
2. What diameter of weather balloon do I need? I'm planning to take upto around 1-2 kg of payload consisting of cameras, Arduino, Raspberry Pi, GPS, parachute etc.
• You may get some information here, but these questions are likely to be best answered by the balloon manufacturer. – milancurcic Oct 16 '14 at 16:19

The weight of a balloon determines most of its specifications, though I'm not sure if they are generalized or specific to a manufacturer. Looking at one supplier we can get a feel for what you need. For a 1 kg payload it looks like you'd want a minimum of a 1200g balloon. According to the site linked, this 1200g balloon will have:

• 6.0 ft diameter at launch
• 113 ft$^3$ volume at release
• 320 fpm ascent rate
• 28 ft diameter at burst
• 109,000 ft altitude at burst
• 1190 g free lift

If you need 2kg of payload you'd need to size a bigger balloon. In general your application is not different from the specs of a normal upper-air sounding launch, so you should be able to spec your balloons directly from suppliers of sounding balloons. All of the balloons for a 1-2 kg payload should burst above 100,000 feet so it just a matter of picking a supplier and a balloon sized for your payload (per the manufacturer specifications).

• what a pleasant surprise to see another one of Aviation SE out here! Thanks for the answer! BTW, in this instructable, it appears a 600g balloon was good enough to get p. high with roughly the same payload: instructables.com/id/… – shortstheory Oct 17 '14 at 14:55
• Furthermore, the site seems to say it's OK to go for 600g to get to ~FL 750-900. kaymontballoons.com/Near_Space_Photography.html – shortstheory Oct 17 '14 at 14:57
• And I'm getting a really good deal from an Indian supplier, PAWAN EXPORTS selling 2 600g balloons for Rs 3000 or \$60, so I guess I'll go on that route :) – shortstheory Oct 17 '14 at 14:58
• @shortstheory Good luck and it would be great if you post a comment with a blog/webpage link to the details of your balloon mission - i.e. photos, videos, measurements etc. would be nice to see. Also, if you get any more details/specs from the manufacturer, please post them as an answer here. – milancurcic Oct 17 '14 at 15:42
• @shortstheory No, that is the weight of the balloon – casey Oct 20 '14 at 13:12