When I sat down and designed the PAVA PCB I had in mind launching this under a small foil balloon. These are interesting for a number of reasons, firstly you don’t need a NOTAM, secondly under the right conditions they can float. Although alot of these foil pico launches have been done by members of the UKHAS community I decided it was time for me to do one.
Armed with some 36″ Qualatex balloons from Random Engineering I set about making a very small and light payload based on a single AA and the PAVA R7 PCB :
Coming in at 27g the antennas were made from the inside of CAT5 cables. The case was made from a hollowed out piece of insulation with additional thin insulation in close contact with the PCB. See here for further build images :
To fill the balloon I used a piece of thin tube. I’d been advised to aim for a neck lift of about 1g, to measure this I had a piece of blutac 1g heavier than the payload. I was suprised how quickly the balloon filled up and it may have been slightly over filled :
Launch was extremely windy :
I was happy to see it go as it was pulling towards the ground. Once in the air it floated up gently with an average ascent of about 1-1.5 m/s. Now in theory these things should float at about 4500m but PAVA didn’t it carried on upwards unfortunately too high for the balloon to remain intact. All of a sudden PAVA started to fall at an alarming rate.
Normally with Pico’s they are so light the balloon acts like a streamer slowing down the decent, however there was nothing slow with the 12m/s it hit the ground at. Fortunately it appeared to land in a field. About an hour later we started getting telemetry from the payload again, it seemed one of the people who had been tracking, 2E0KPI had decided to and have a look for it.
Despite the dramatic decent PAVA was still transmitting, however with fading light 2E0KPI was unable to locate the payload. He kindly agreed to go back the next day and have another look where he located PAVA, still transmitting, in a field. The reason for the descent rate was clear, the balloon had blown its valve entirely out :
A big thanks to 2E0KPI for locating the payload and to all the trackers. I’ll have another go at this soon. Congratulations to James Coxon M6JCX who launched an ATLAS/PAVA board around the same time. In a good demonstration on how to do it his balloon went on a 34 hour jaunt around the UK !