Weather Balloons and HeliKites
Week 3
Balloon Electronics
Both the helikite and the Weather balloon will use similar electronics. Because we are using a balloon we have no need for flight control, all of the electronics are for data collection, imagery and tracking.
We have settled on a Raspberry Pi based tracking and flight computer based on the work done by Dave Akerman called FlexTrak. It’s based on LoRa for communication. Tracking is done via GPS and transmitted to a USB receiver connected to and Android Phone (HAB Explora app) or tablet (HAB PADD app) It should give live telemetry and images the entire flight. We’ll start with a temperature sensor and we need to find a suitable air quality sensor. Imagery will come from a GoPro and a Raspberry Pi camera.
List of components in the payload
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- FlexTrak Flight Computer, 2Mtr APRS Addon Board, FlexTrak is 434.225Mhz
- GoPro Hero3 and Hero3+
- Spot Trace GPS tracker (weather balloon only)
- Broadcast Antenna
Base Station Components
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- LoRaGo OTG Transceiver Dongle
- Laptop or Smartphone
For the helikite we only need the GPS for the altitude and general position info. It’s tied to a string, we know where it is and it’s not going anywhere but up – we just need to know how high. We are more interested in the sensor data and imagery. The weather balloon will needs some additional equipment so we can track it if we lose line of sight. The SpotTrace is a global asset tracker. It will report it’s position anywhere on earth. It will tell us were the balloon has landed but not where it is high in the sky. The APRS (Automatic Packet Reporting System) will help us track it in the sky. The APRS is an amateur radio-based system for real time digital communications of information. Data can include object Global Positioning System coordinates, weather station telemetry, text messages, announcements, queries, and other telemetry. HABBase will show active tracking. HABhub shows balloons in the sky.
Show weather balloon launch
Break out flight computers
Talk tracking
Test equipment
Break out the Helikite equipment and talk launch
Software
Resources
HABhub Balloon Burst Calculator
Balloon Performance Calculator
Launches from around the world
Week 2
Today we are discussing lift and the physics of a tethered balloon. As wind pushes on a balloon the balloon wants to go in the direction of the wind. If the balloon is tethered, the tether acts as an anchor and the balloon-string-anchor combination will point the direction of the wind and the balloon will get pulled towards the anchor. A kite on the other hand produces lift when acted upon by wind. It to will get pulled into the direction of the wind but instead of it getting pulled down by the string, it produces enough lift to keep it up in the air. The more wind the better the lift so instead of getting pulled down, it stays up in wind. A balloon is great with no wind and a kite is great with wind. What happens if we combine a kite an balloon?
Experiment with a balloon and string with wind to see the effect. Do the experiment once with helium and again with air.
Try to attach the two and run the experiment again.
Week 1
Physics of a Weather balloon launch
Balloon is launched with a payload
- GPS
- Radio to communicate position and data.
- Pressure Sensor
- Temperature
- Relative Humidity
- Camera
The balloon travels to about 80,000 ft. At that altitude the pressure in the balloon is too much because of the lack of atmosphere and the balloon bursts. The equipment box falls back to the earth with a parachute to slow the fall. You should be able to track where the balloon lands via gps to retrieve it and the cameras for video.
Fun Videos:
GoPro High Altitude Weather Balloon to 105,000 FT.