CHDK/SPARK/CHEAPO Launch – Thu 04/09/14

A couple of weeks ago I launched a few projects I had been working on over the last year or so on a 1200g Pawan latex balloon. These projects included:

The CHDK rig from the conference last year, sending live 600 baud SSDV images encoded straight on the camera. A Navspark based tracker. And A Cheapo Mini flying backup.

I did plan to launch a nasty looking GPS UKHASnet node, but the AVR got stubborn just as we were about to launch and refused to accept any new code.

The launch went off pretty much without a hitch and roughly on schedule, with some much appreciated help from Lewis.


Launch video to be added at some point..

Things seemed to be going according to plan, until SPARK hit about 19KM and decided it had enough. The altitude stopped ascending and the GPS wandered off course, shortly followed by the GLONASS satellites dropping down to 0 and GPS to 3. I posted my results to the navspark forum, but their only theory was that it couldn’t handle the temperature. I’m not exactly sold on this, as it seemed to die at exactly 19km (hey, that could be a coincidence) and the board should feature a TCXO. Perhaps some modes need changing. I will repeat this experiment sooner or later.

Just as the flight started to get interesting, cheapo also decided today was not a good day for HAB. The battery voltage plummeted as the temperature dropped and silence fell. Luckily on the descent things started to warm up, increasing the battery voltage and bringing the tracker back in time to track the landing. I have not seen a lithium battery drop quite this much in voltage before, so I suspect I had a bad cell.

Surprisingly the part I thought most likely to fail actually performed perfectly! The camera sent down SSDV images throughout its flight, with no packets being missed! A great success and a final thank you to Reyalp from CHDK and Phil Heron for their help with the project. The next step will be to implement the whole thing again on a more modern camera with GPS, but I think a well earned break is due first!

SSDV Live Images

The flight photos will appear here at some point, along with the 15gb of gopro footage…


Leave a Reply

Your email address will not be published. Required fields are marked *