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OZ HAB

Near Space Project

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parachute

Launch video and data of OZHAB01

Here’s the video of OZHAB01 being launched from Barmedman  NSW as well as other data I have collated so far

Unfortunately I have not yet recovered the payload of OZHAB01 so I am unable to provide any of the on board collected data. However I do have some flight data that was collected via APRS and the RTTY transmitter which gives a good indication of the flight progress.
The APRS was being received by digipeaters around 1000m and continued to have contact until it burst about 31000m. APRS Google Earth KML OZHAB01

aprs-altitude
Elevation Profile
aprs-flight
Flight from Launch until bursting

The RTTY was decoded on my laptop as I chased the balloon and followed the same path as the APRS. I did loose signal a few times as it was climbing to its burst altitude. RAW KML of RTTY Flight for Google Earth

rtty-collected-data-kml

Post Flight thoughts for next time

  • Ensure I pack a highly directional antenna to locate the payload.
    • Something with variable attenuation would be great.
  • Use a weight instead of digital scales to determine correct lift and helium dosage.
    • The digital scales were difficult to read as the wind blew the balloon around, which lead to less helium in the balloon and a slower ascent.
  • Cut balloon away when approaching max altitude to ensure a cleaner descent.
    • As I haven’t recovered payload yet, I don’t know how much balloon was intact and this could have impeded the parachute
  • Don’t forget the tarp next time.
    • Blankets worked , but were too small
  • Improve my APRS decode.
    • APRS was decoding sporadically.
    • I didn’t have an app installed that would upload the APRS data to the web
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Safe Landings

Deciding on a parachute seemed a little harder than I first thought. It needs to be big enough to slow the payload decent so it can be recovered intact. At the same time if its to big the payload will drift a lot further on its decent and potentially take much longer to reach the ground.

Spherachute.com
Spherachute.com

To assist with the parachute decision most manufacturers provide a guide to the decent rate based on the weight of the payload. Some parachutes aim for a decent rate of around 5m/sec. Spherachutes lists it chutes based on the payload weight and other websites provide similar info.

For my project I went for a 48″ or 1.2 metre chute from Spherachutes.

Loops for balloon attachment
Loops for balloon attachment

This seemed to fit the estimated weight of my payload of which was still under construction so I hadn’t determined the final weight. Spherachutes charged a small additional fee to sew some straps at the top of the chute for the balloon to attach to.

48 in. Spherachute
48 in. Spherachute

A similar chute.

Rocketman Chute

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