Selecting the Right Balloon for Near Space Missions
The Right Size for the Right Mission and Skill Level
Space Balloon Basics and Getting Started
We often call the balloon a “space balloon” or “high altitude balloon” (HAB), but it is technically a “weather balloon” or “sounding balloon.”
High Altitude Science provides a useful explanation of balloon sizes related to their weight:
“Weather balloons are listed by weight in grams and not by physical size. A 350g weather balloon weighs 350g, a 1200g weather balloon weighs 1200g, etc. Weather balloons typically all share the same thickness latex skin, regardless of their ‘size’. The difference in weight between different size balloons comes from the size of the mold the balloon was manufactured on.”
High Altitude Science recommends a balloon as small as 350g for your first launch, while the Global Space Balloon Challenge also recommends using a balloon smaller than 800g.
Balloon Size Calculations and a Note About Manufacturers
HABHUB’s Balloon Burst Calculator is a clear best choice for almost everyone. The inputs and outputs are the ones I would expect most HABers to use for mission planning. Plus, the calculations are open-source available to everyone!
The super-convenient drop-down menu has pre-loaded data for balloons from all the main balloon manufacturers: Kaymont, Hwoyee, and Pawan. You might be able to go to these manufacturer’s websites to buy balloons but it’s not as straightforward as you would expect.
Edge of Space Sciences plans for an ascent rate of 1000 ft/min and this is a good place to start with your calculations. I personally would be interested in making sure that my balloon reached at least 100,000 feet, even if that meant sacrificing some other goal, such as ascent rate. However, be careful that the ascent rate is not too slow or there is a good chance that you will have to drive very far in order to recover your balloon.
Zero Pressure Balloons (ZPBs) for the Ambitious
It is possible to purchase a ZPB or make your own, but this is not a simple process. There was a post on the AMET Purdue website but it seems to have been taken down since I first discovered it.
On the ground, the balloon is partially filled, with enough helium to make it ascend. As it ascends, the pressure decreases so the gas expands until it fills the entire balloon. A hole at the bottom allows extra gas to escape if it goes any higher. At night the gas will cool so the balloon will drop temporarily but ascend again the next day.
If you want to learn more about other types of balloons and their applications you may look up “pilot balloons” and “superpressure balloons.”