Solar balloons of all sizes have capabilites of flying hundreds of miles. They have reached altitudes of over 50,000 feet, higher than most commercial air traffic!
It doesn't take anything special for a solar balloon to fly so long and high. In fact, anybody can do it. Here I will list some tips & info on releasing solar balloons.
Releasing tips
Check wind. Air should be calm and cool when you release. Temperatures of around 70° F and lower are ideal for quick ascents.
Release early. The more daylight the balloon has, the longer it can fly. The sun usually becomes hot enough to heat the balloon shortly after sunrise.
Use a visible tag. When tagging your balloon, make sure the tag is large and visible. I sometimes use a fluorescent yellow highlighter on the tag for added visiblility. Attach the tag near the mouth of the balloon, preferably by a short length of tether so the tag hangs 6-10" below the mouth.
Securely attach the tag. Make sure you use strong, water-resistant tape to attach your tag. You never know where the balloon may land.
Laminate the tag. Use contact paper or strips of packaging tape to cover both sides of the tag for extra water resistance. Write the information clearly on the tag so it can be read easily if found.
Keep the load light. If you're releasing a small balloon, don't make the tag too heavy. You will want your balloon to ascend quickly and reach a good altitude.
Keep the mouth small. Don't cut an oversized mouth on your balloon - you don't want it losing its air if a gust hits it. Also be sure that enough weight is added to the mouth to keep the balloon upright, but don't add too much weight.
Watch where you release! Don't release balloons near an airport or military base. You should always make sure you are in an ideal area for releasing balloons.
Release Tag
Here, you can download and print a tag to use when you release your balloons.
