Yesterday a few of the UK Ardupilot group (Malcolm, Dean & I) arrived at a flight field ready to take a look at and test the DJI Innovations WKH on a traditional Heli, this was installed on a Spectra petrol Heli, it was sent out to hold its position in GPS ATTI mode, we filmed the Spectra to show how it got on! Dean had his OctoCopter there so we tried the "point of interest" function on the DJI Wookong M to add a new angle to the video & show the WKH in position hold.
Both the WKH & WKM both performed without fault, the WKH held the traditional Heli in position from the start of the video until the end without pilot intervention!
One the more interesting points about the WKH and the Heli was the level of vibration coming from the engine which was very high frequency, if you have ever flown Nitro / petrol engine planes before you will know how much vibration is produced from these single piston engines. The WKH IMU did not seem to mind any of these vibrations passing through the frame. At the start of the video you will see the IMU is placed within a few cm of the engine.
We also tried the Atti mode and it worked just as well as GPS ATTI, the Heli was very stable and easy to fly in all modes including "manual".