During late January and early February we conducted several test flights to determine the suitability of our airframe setup, and the performance of our custom hardware and AHRS software. We also recorded several of the flights from the ground in addition to the on-board GoPro, as the next Outback Challenge deliverable requires submission of a video in addition to the technical report.
For flights 7 and 8 we used a Scorpion SII-3020-780KV motor (45A max continuous draw) with a 14×6 Aero-Naut folding prop, but when we increased the weight to the full 4.5kg or so it’ll be in the Challenge, that motor wasn’t quite powerful enough for a hand launch. Thus, in subsequent flights we changed to a Scorpion SII-3026-890KV motor with 70A max continuous draw, which can take off from a hand launch with no problems.
After flight 10 ended with an RC range issue triggering failsafe, and the X8 hitting the ground at 130km/h (80km/h of which was downwards), we built the next airframe and repeated the test using a more robust RC antenna configuration.
After flight 11 we were able to confirm our endurance with 3× 4.2Ah 14.4V LiFePO4 batteries is just under an hour in moderate wind conditions, cruising at about 80km/h. This isn’t quite enough for the Outback Challenge, so at this stage we’re planning to switch to conventional lithium-polymer batteries, 3× 5.8Ah 14.8V or thereabouts. They’ll give us a comfortable 80-ish minutes of endurance with negligible extra weight.
The result of all that is we’ve settled on an airframe which we’re confident can meet the requirements of the Challenge, with over an hour endurance at 80km/h and a 25% reserve. Tests under RC control have shown that the X8 can deal with wind up to 30 knots (15m/s), albeit with considerable difficulty; 15 knots is entirely manageable though, and simulation suggests that our control system should have no problems with winds in that range.
We’re now a week or two away from completing bottle drop tests and the first autonomous flight tests, which are the last critical items prior to Deliverable 2 in late April.