While we managed to avoid damaging any aircraft today and brought a 6th plane back to flight status, that's about all for this 3rd day at Oliktok. The first flight showed that the changes made last night solved the pitot/static isssue, but did not keep the autopilot from hanging. By rigging an aircraft with a dedicated RC receiver to control the servos and monitoring the status of the autopilot with the groundstation, we were able to maintain control of the aircraft during all of our flights while testing the autopilot in flight. Multiple test flights showed that the autopilot would run reliably at low altitude and at high altitude, but that around 50m above the ground the autopilot would often hang. It never took place at a flight time consistant across different flights, nor could the problem be replicated on the ground, even in flying mode.
Since the drop out occurs at such a regular altitude, radio interference, especially from the long-range radar on site, seems to be a likely explaination. To hopefully counter this, the entire payload bay, and most of the electronics, had a foil shield applied. A few test flights after dinner showed that the shielding did not work, and that the autopilot still froze up. Unfortunately, this put us almost back at square one.
Luckily, we have a few ideas about antenna placement and telemetry frequency which we look forward to testing tomorrow.
In conclusion, today was generally slow day, but we did manage to get some excellent flight tests and collect plenty of data about the issue.
Visitors on the flight line!
Gijs launching the DataHawk
Nathan and Gijs prepare to launch the DataHawk in the shadow of the suspicious radar dome