Project Horus High altitude balloon project


A successful launch!

Project Horus was launched at around 2:30pm local time and successfully recovered at around 4:30pm yesterday, reaching a maximum altitude of 29,606m! :D

Payload found!

Our launch was planned for 12:30pm, but was delayed by a couple of hours as assembly turned out to take longer than expected. We were further delayed by an odd GPS issue - none of our modules were able to gain lock for about half an hour. We'd also forgotten our scales, so filling the balloon until it had the right amount of free lift turned into a bit of educated guesswork.

We think this looks good...

We think this looks good...

After much stalling & waiting (unsuccessfully) for GPS lock, we decided to launch without lock, figuring there must be some sort of local source of GPS interference, or bad ephemeris data being broadcast. We tied the balloon to the chute, reflector & payload & let it go...

Ready to launch

Ready to launch

Once the balloon was up, we had a few nervous minutes of waiting for it to gain GPS lock, and then another few minutes waiting for altitude to be correlated. Pretty soon the balloon was indicating that it had lock, but its ascent rate was much higher than we had predicted, meaning our landing predictions would be invalid.

natrium42 was following the launch online and kept us updated on the balloon's progress via #highaltitude, as we were too busy driving, making sure we were decoding telemetry & trying to work out where to go to take note of much of what the balloon was doing.

Soon the balloon had picked up speed and was heading east - 2 of our chase cars headed for the freeway to try & catch up, and Adrian VK5ZSN took an alternate route in his more capable 4wd.


A brief while later, we'd reached Murray Bridge, and were still decoding the balloon OK. We started heading north towards Palmer in anticipation of its flight path, but soon realised that the balloon would likely not be getting much higher, as it had just passed 28km. 1600m and a few minutes later, the balloon popped and started heading back down at 200km/h, owing to the lack of atmosphere to slow it down at this altitude. We turned around south of Tepko and headed back towards Murray Bridge, and let the other cars (both of which had stopped for lunch!) know of the balloon's descent.

As the balloon came below 10km, we realised that the parachute must not be working effectively - it was still falling far too fast. We scrambled to place ourselves in ideal spots - one car atop a hill with a yagi antenna following the balloon down to the ground, another racing towards where we thought the balloon would land.

As the balloon landed, I was about 2-3km away - from this distance I could hear the telemetry signal become very weak, though still audible. Our last fix on the balloon was at about 300m altitude. Given its descent rate, it would have hit the ground 5-10 seconds after this, so we would have no trouble finding it. We confirmed with our third car that they were still decoding the landed payload with the yagi from a few km away, and headed to the landing site - where we found Adrian & Co who'd just sought permission for us to retrieve the payload from the farmer whose paddock we had landed in.

Landed (under the power lines!)

The landing site (under the power lines!)

Despite the hard impact, the payload was in good shape (except for the antenna) & was still transmitting data. After a brief introduction to the local cows, we called it a day and headed home to go over the data & photos captured.

Unfortunately for us, we experienced a lot of condensation on the inside of our payload (or maybe ice outside), which resulted in very blurry photos above about 5-10km. This is something which I'll improve on in future, either by flushing the payload with helium to clear any moisture before launch (thanks Rob), or avoiding the use of glass filters to seal the payload up and allowing the camera lenses to poke out of the sealed interior.

Blurry photos

Blurry photos

Despite the blurry photos (which we'll improve on next time!), we managed to get some good data, and the telemetry systems worked very well in their first real world test. Several amateur radio operators tuned in for the launch & helped us track the balloon, which was great. Our barometric sensor did a great job of calculating the pressure altitude until it reached it zero-value at around 15km. The payload's external temperature was embedded in the polystyrene foam, which prevented it from registering as low as the temperature no doubt reached - something else to work on next time.

A big thanks to all involved for helping this to be a successful launch - esp to Adrian, Alex, Brad, Guy, Alan, Andrew & Holly for coming out on the day and tracking the balloon with me! An interactive map of the balloon's flight path & our chase car routes is available online, and you can also download it to view in Google Earth.

Comments (4) Trackbacks (0)
  1. Sounds like it was a great launch and some minor glitches not withstanding it was an awesome event.
    Hopefully Ill have time to take part in the next one :)

  2. Congratulations on the successful flight I am in the middle of readin gover your web site. Its very interesting. Im researching ballon communicatations systems for a few ideas I have ..

  3. well done guys!
    Are you going to post some more pictures you got while airborne, even if they are a bit blury?
    Cheers and Congratulations again!

  4. Hi Matt,
    Thanks for the kind words the pictures are up on Flickr, Ill put them up on the blog too shortly!

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