Our US allies at Edge Research Lab sent up a Pixhawk, GPS/compass unit, digital airspeed sensor, servos and the two battery packs which power the whole rig (see pic at top).
The Pixhawk was in "servo wiggle" mode - a custom LOHAN ArduPilot AUTO mode command (MAV_CMD_NAV_ASCEND_WAIT) which operates the servos every 15 seconds to prevent them freezing as the Vulture 2 ascends to launch altitude. There's more on the Low Orbit Helium Assisted Navigator (LOHAN) custom programming here.
While the external temperature dropped to a teeth-chattering -50°C, it was comparatively tropical 0°C inside the payload box, in line with what we'd expect.
Linus and Tridge have identified some spikes on the servo rail voltage, which may require deployment of a zener diode, and we had the servo rail voltage a tad high at 5.6V:
The data from the airspeed sensor proved entertaining:
"The blue line is the actual airspeed reading, which is apparent airspeed. It was very noisy over a small range. The green line is the true airspeed calculated by TECS during the flight by using the EAS2TAS ratio. The red line is the GPS vertical velocity, which ideally should match the true airspeed.
"The GPS vertical speed and true airspeed do follow the same curve, but are offset by a factor of around 1.5. It would be nice to work out why that is."
Suffice it to say, we're on the case and are planning a second test flight to check out any necessary mods to the system. There's more on the above data and analysis right here.