Posted by Guy Reynolds at
kiteweekenders.proboards.com/thread/2387/high-altitude-teddy-drop?page=3Having awoken early Saturday, checked the weather and flight predictions it was obvious that Sunday was going to be a no go so I checked outside to find there was none of the predicted rain, and the wind that had been forecast as >10mph was near enough 0mph. So decision was made to go for a flight and from there things moved fairly rapidly. The flight didn't end up on the tracking site because we were up and done by the time most people were awake and there weren't the receiving stations running when we went.
So was the flight a success or failure? A bit of both from the point of view that I am home with everything (barring the gas and the balloon) it was a great success, however I didn't manage to drop teddy on his own parachute - the release line didn't fully burn through - so from that point of view it was a bit of a failure.
Somethings worked as expected, others didn't:
The transmitter worked but although I could receive, see and hear the telemetry, couldn't decode it a lot of the time. The problem may have been the low cloud but I probably need to use a better aerial with a line amplifier/filter. The transmitter frequency drifted (a known effect of the cold on the module I used) as I was driving and the auto frequencey tracking on the SDR software was not able to keep up with so being on my own I kept having to stop and retune and so by Sudbury I had lost contact completely.
Siobhan's phone battery went flat despite being fully charged before being sealed in the payload so I was left with no backup tracker.
The Teddy tracker work well, I started receiving texts before he landed and he was found exactly where it said he was.
The Payload tracker only started sending texts once I was back at the car. I chose not to use heat packs in the end and teddy's tracker was exposed on his back and the payload tracker was inside all the insulation of the payload. Maybe the payload slowed the tracker warming up.
The data logger was still beeping when I arrived home so functioned for the whole flight and the return home.
Teddycam was off when I found him as were two of the Go-Pros, the third Go-Pro with the battery backpak was still running.
The most nerve racking point was arriving at the predicted landing point at about the time things were supposed to start landing, with no radio signal and no texts. At this point I started worrying about not having filled the balloon enough and it climbing slower and higher and thus travelling further. Then I picked up but could not decode the transmitter signal. From watching and listening to the signal over the past few weeks even though it was feint I knew it was mine. Then a few minutes later and ten minutes later than expected I started getting texts from Teddy. After waiting until the co-ordinates stopped moving I put them in the Sat-Nav and found them to be originating from a point 2.9miles up the road. I regret not putting them in earlier as I could have possibly seen the descent had I been looking in the right direction.
Having driven to the nearest point that I could park I put the Co-ordinates into the Google Maps App only to find that rather than sticking a pointer on the location it puts it on the nearest address. So reverting to the maps linked to from the texts I walked straight to the centre of a cabbage field to be both elated and disappointed to discover the complete payload with teddy intact.
Everything has been cracked open and I am starting to analyse the numbers (z indicates zulu time = UTC = GMT):
Launch time: 06:54:37z
Balloon Burst: 09:04:38z @ 31,311.7 m
Touchdown: 09:34:22z
These figures are somewhat different to the predicted ones:
Duration of Flight: 2hr 25m (Predicted) 2hr 40m (Actual)
Ascent Period: 1hr 40m (Predicted) 2hr 10m (Actual)
Descent Period: 45m (predicted) 30m (Actual)
The differences can be explained by the fact that I inadvertently under filled the balloon leading to a slower ascent rate and ultimately a higher altitude (31,311.7m rather than 30,250m) then because Teddy had a hang up the weight of the payload was heavier causing to descend faster than intended. The chute was designed for 5m/s @ 1000m with a 1.9kg load instead it had a 2.5kg load and was doing 7.9m/s as it went through 1000m. One of the upshots of the altered profile was that all the cameras apart from the GoPro with the battery Backpack shutdown before the burst altitude was reached and come of the hoped for shots were not achieved.
At the moment I am still processing all the data and images so more to come.
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Mike
