“Is it a Dandelion?” a friend asked. Not quite. It’s a High Altitude Balloon (HAB). Specifically, that’s the striking image of our Kaymont 1,200-gram weather balloon bursting 31.8km (over 100,000 feet) above ground at 3:29pm on 11th July 2015. That altitude qualifies as near space and is three times the height that airliners fly at. The image was captured by an upward-facing HD video camera, mounted on a polystyrene payload box suspended 30m below the balloon.
By this point, the helium-filled balloon had carried its 500-gram payload upwards at 6 metres per second for 90 minutes from launch at Churchill College, Cambridge, UK.
The decreasing air pressure meant the latex balloon had now grown 100 times in volume, to almost 9m across (a volume of 360,000 litres, or the capacity of 9 full-size articulated petrol tankers!). The balloon couldn’t expand any further, so it burst, sending the camera payload free-falling earthwards at 160+mph until gradually the air became dense enough for the parachute to slow the fall …
Meanwhile, back on the ground, our family-and-friends chase team had been tracking the position of the payload on a Google map and driving towards the predicted landing site. The real-time tracking was magical, made possible by an Arduino-powered GPS/radio tracker and the help of numerous HAB enthusiasts (including a chap from the Netherlands) receiving the RTTY radio signals from our payload, decoding them and uploading the telemetry data in real-time to the HABHUB tracking website.
Everything went as well as we could have hoped for. Our last-minute choice of large balloon had helped us speed the ascent to shorten the flight and avoid the predictable risk of being blown Eastwards out-to-sea. Others that day weren’t so lucky. The flight was further shortened by a tangled parachute causing a faster-than-predicted descent.
Thankfully the payload had a safe landing in a grassy field (near Occold in Suffolk) and the radio telemetry continued to operate after the landing, giving us GPS co-ordinates to help us pinpoint the location of the landing site.
Recovering the payload and retrieving the footage from the three on-board cameras marked successful completion of my first High Altitude Balloon (HAB) flight. The beautiful balloon burst image was icing on the cake. Mission accomplished!
In future posts I’ll share more details of the project behind the mission, including the GPS radio tracker, the cameras, designing the payload enclosure and planning/preparing the flight.