Balloon, Mark 2 - "Hackathon HAB"

The High Altitude Balloon (HAB) Mk1 project is a collaboration between three Cornell Clubs:

• Amateur Radio Club at Cornell (CARC)
• Cornell's Random Innovative Technologies and Electronics Research Society (CRITERS)
• Cornell Branch of the IEEE

The goal of the project is to engage in a Hackathon day to build a HAB launch vehicle and payload, and on the following day, launch, track, and recover the balloon payload. In doing so, we hope to give Cornell students some exposure to HAM radio as well as supplement their Cornell education with some additional hands-on engineering experience.

We plan to launch a latex weather balloon with a Raspberry Pi and camera payload, transmit images back to ground using SSTV, and track the balloon using APRS. To cover a broad array of interests, we will offer several sub projects such as antenna builds and the various balloon subsystems.

• 12/31 - Survey Sent Out
• 01/05 - Project Green Light
• 01/24 - IEEE, CRITERS, CARC Joint Meeting (5PM)
• 01/27 - HAM Licensing (TCARA)
• Build/Launch Day still TBD

• A confirmed build/launch date
• An alternative launch date if weather doesn't cooperate. Cold's fine, driving in dangerous conditions is not.
• A confirmed list of participants
• A finalized list of sub-projects
• A list of parts for each of those sub projects and at least 50% of the list should be ordered or at least have a firm plan for sourcing those parts for build day.
• A mapping of participants to projects (or at least a 1-2-3 ranking of what project they'd like to work on)
• A list of people committed to taking the HAM licensing exam (again, licenses are NOT required, just icing on the cake). That way we can organize rides and such to 92 Brown Road on 1/27.

• Burst altitude forecast models exist for some documented, but more expensive balloons.
  • Purchase more expensive “well documented” balloon ($70ish) or less predictable one ($25ish)?
  • More expensive balloons offer higher altitude missions. They also require more lifting gas (and expense) and the payload will land farther away. The proposed balloon has a targeted burst at 12,000-15,000 feet if we wish the payload to land within a reasonable driving distance (60-100 miles).
• Do we want to buy offset attenuators and/or inexpensive radios to use with the Yagi antennas?

1. Setup payload for a high altitude balloon based on a Raspberry Pi.
2. Payload uses APRS and CW (Morse Code) for post-flight retrieval.
3. Payload transmit SSTV (Slow Scan TV Images) in flight.
4. Raspberry Pi Camera module to store images on SD card for retrieval after recovery.
5. Payload is packaged in a lightweight insulating container.
6. Payload designed for nichrome cut-down mechanism with balloon burst as a backup.
7. Onboard microcontroller (or Raspberry Pi) drives the nichrome cutdown mechanism.
8. Cutdown is time based, and also potentially distance based, to limit distance from launch.
9. CARC will provide the APRS/CW beacon.

• Parachute size calculator suggests a 36“ parachute for a 500g payload for 4mps descent rate.
• UV5R radio weight includes battery.

• Receive, assemble, display images live.

1. A receiver capable of rendering received SSTV images and storing them.
2. Optionally upload these images to a live web presence during the flight.
3. We can use MMSSTV on Windows to receive images.

• Equipment necessary to monitor and track APRS transmissions from the balloon while in-flight.

1. Vehicles equipped with APRS tracking radios and laptops/mapping.

• Build Yagi antennas for radio direction finding to locate the payload after landing.
• Reference data:
  • DIY: http://makezine.com/projects/homemade-yagi-antenna/
  • COTS: http://www.arrowantennas.com/arrowii/146-437.html

1. Yagi antennas for use in payload recovery.
2. We'll also need
   1. Baofeng UV-5R
   2. SMA to BNC
   3. 3ft BNC Cable

• Build an offset attenuator to go with the Yagi above!

• APRS mapping - payload and foxhunters
• SSTV images

1. Web presence with real-time data collection.
2. APRS data (aprs.fi links?)
3. Chase vehicles
4. SSTV images
5. Other content?

• Finds best resources available for forecasting balloon trajectory.
  • Suggest: http://predict.habhub.org
• Provides recommendation to launch team for initial balloon volume / free lift, based on predictions, to produce a reasonable flight.
• Potentially integrates with real time mission web presence.

As we mount more balloon missions, it would be beneficial to have a fixed doppler station for DF purposes. That way, even with only one mobile bearing we might be able to triangulate. This will also be a useful addition to foxhunts.

There are several kits for building DF dopplers, the most popular of which seems to be the PicoDopp. Other doppler kits are approximately the same cost and complexity, so the total parts bill would be approximately $200.

We can install a 2m and 70cm doppler array on the roof of Barton and put it on the internet for remote usage.

• Kit: http://www.silcom.com/~pelican2/PicoDopp/PICODOPP.htm
• Homebrew:
  • http://members.chello.nl/~w.hofman/pa8w/dopplerRDF.htm
  • http://forums.qrz.com/showthread.php?354837-Autonomous-Doppler-Radio-Direction-Finder
  • http://wiki.spench.net/wiki/SDRDF
  • http://www.eham.net/ehamforum/smf/index.php?topic=81942.0