DJI S-1000 SPREADING WINGS OCTOCOPTER: DETERMINATION OF ROTOR DOWNWASH SLIPSTREAM SIZE

The DJI S-1000 Spreading Wings octocopter rotor downwash slipstream area of influence was measured in axial climb conditions and in straight level flight. These data were gathered using a simple apparatus of distributed anemometers and a custom made boom affixed to the drone. Straight level flight tests incurred autopilot oscillations that rendered the data gathering and analysis challenging. The best quality data was acquired during the axial climb flight tests. The axial climbs were conducted in calm winds. It was determined that the axial climbs under these conditions displaced the rotor slipstream 9 ± 2.5 cm to the rear of the drone. Its location at the front of the drone closely corresponded to the theoretical value. For straight level flights, the slipstream moved aft of the drone to 81 cm and 84 cm for airspeeds of 3 m/s and 4 m/s respectively. The measured size of individual rotor slipstreams was 15 cm smaller than the theoretical value.