Micro-Trak AIO HA with Hanging J-pole - Link

• Operates on 144.39
• Transmits APRS packets with GPS coordinates
• Need to use high altitude version of GPS or you'll get tracking errors introduced
  • The error is intentional and intended to prevent GPS from being put in a missile guidance system.
  • High altitude version has a higher cap for altitude but lower top speed.
• Configure with call sign
• Default packet encoding is mic-e, turn this off for plain text APRS packets
• Hanging antennas are great for balloons while they're in the air.
  • Can get fouled up or caught on stuff during the landing.
  • Hanging antennas don't work very well if it lands on the ground - tend to coil up and end up with a payload sitting on them.

Need two methods of “cutdown” (bringing the balloon down from altitude) to fulfill regulatory requirements by FAA

• Bursting balloon counts as one, so you only need to design one method of cutdown (unless you launch an under-inflated or balloon using a non-conventional material)
• Melting the rope connecting payload to balloon is a common method of cutdown
  • May have trouble generating enough heat to melt through rope
  • Conduction of heat through air is lower at altitude, air is colder, so it takes longer to melt
  • If the rope fuses to the cutdown system then it's not going to work
• Parachute release mechanism

Not as many as you'd think, it's pretty easy for private citizens and groups to launch balloons provided you follow some rules the FAA and FCC have in place

• Notify FAA air traffic controller nearest the site of operation 6 to 24 hours before launch
• Individual payload must be less than 6 pounds
  • You may have multiple payloads hanging from the balloon provided they are under the weight limit
  • The total payload has a maximum weight of 12 pounds
• It is illegal to put a cellphone in a balloon for the purpose of tracking the balloon.
  • Cellphones make poor tracking devices anyway, there's no cell service at altitude. Stick to radio beacons.
• The rope used to connect the payload to the balloon should break when 50 pounds of force is applied.
• You may not launch projectiles or gliders from the balloon.
• Do not operate the balloon over a restricted area.
  • Don't fly over military bases or airport airspace.
• Do not launch a balloon between sunset and sunrise unless it is equipped with lights that are visible for at least 5 miles and have a flash frequency of at least 40, and not more than 100, cycles per minute.
• If your antenna is longer than 50 feet, it needs to either snap with less than 50 pounds of force or be covered in brightly colored streamers visible for 1 mile.
• Weather conditions need to permit the launch.
  • Cloud cover must at any altitude must be less than half the sky.
  • Any altitude under 60,000 feet must have 5 miles of visibility.

There are more rules that apply if your balloon doesn't meet the Title 14 Part 101 §101.1 exemptions, so try to follow them.