3689623614?profile=originalLinus Penzlien and Andrew Tridgell have been picking over the log files from the recent stratospheric test flight of our Vulture 2 spaceplane's avionics, and the verdict is largely positive.3689623593?profile=original


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:


Tridge notes: 

"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.

E-mail me when people leave their comments –

You need to be a member of diydrones to add comments!

Join diydrones


  • I was under the impression that most off the shelf GPS units do not work at this altitude, but obviously this is not the case. Do companies (like ublox) put any firmware restrictions so they do not operate at certain altitudes/velocties???

  • No comms on this flight - just logging data on the SD card.

  • Moderator

    Was it using a 3DR radio for comms??

  • Hi -

    Yes, space blanket works, but we're more concerned about electronics overheating at altitude. The internal temperature isn't much of an issue, if the batteries can handle it.

  • I've wondered if lining the case with aluminized mylar as a radiative heat reflector would help. I experimented with an emergency space blanket recently, and its effect was really noticeable in my living room. It's also very, very light.

This reply was deleted.