DJI has what appear to be support people doing some replies to the RCG thread. There are some issues at the moment that will eventually get resolved (I hope) that prevent it from being a good all around APV platform. I have been doing extensive testing and so far have used the WKM on a MK standard quad frame with 925kv motors and 10 x 5 Graupner props on a single 3S 5000 mah pack, the Y6 with Avrotos and 11 x 5 Graupners and now with the Y6 converted to a flat hex. The weight of the test quad configuration is a bit less than 1/2 what the hex it sits on now weighs and the all around performance of the WKM while on the quad was extremely impressive, it wasn't until I moved it to the Y6 and started flying with a GoPro recording that the problems began to show.
The main problem as of right now is the inability of the WKM to maintain a decent level of stability in wind, I have a number of videos I could show to illustrate the point. The big difference I see is the Mk tends to float in the wind and move around but it can still deliver acceptable video if everything is working right. With the WKM the amount of wind hitting the multi induces a wobble the intensity of which varies in direct proportion to the speed of the air hitting it. I have had the hex at tree top level with gusts that made it questionable if it was going to flip or not, that's how bad the wobble was. A large amount of trial and error testing has resulted in settings that provide a lot more stability in the same conditons but still not anything that would be useable video in those conditions even doing post stabilization at the maximum that I can do with software.
The root of the problem it appears is twofold, one the WKM algorithims are optimized for smaller and lighter multis apparently and also optimized to force holding GPS position regardless of conditions and it does that very well at the expense of stability of the platform for AV use. I have found that if I do not use GPS hold along with the latest settings I've tried in windy conditions I can get video that is useable after stabilization though nothing as good as what the WKM can deliver in calm air. That's the part that just boggles my mind, that it can deliver almost flawless, no post processing needed video in calm conditions and totally unuseable video when the wind goes above a couple mph breeze.
The DJI technical contributors on RCG do not seem to have a good grasp of what it takes to do proper APV with a multirotor, they have suggested the problem is reaction time of the motors due to too large of a prop. When following that advice didn't make any difference they then said the props were too small and they needed to be much larger which to me is a direct contradiction of the first advice their suggestion being to use 15 inch props with motors producing 700 grams of thrust. Don't know what they were thinking there but 700 grams of thrust per motor with a 15 inch prop is not only going to have a very slow response time to speed change commands, but itsn't anywhere near the amount of lift required to put a 4 kilo APV multi in the air. The next suggestion was to reduce the weight by at least a kilo! I currently have a GoPro on the frame, if anything the weight is going to increase with a decent camera, so clearly they don't grasp how a real APV multirotor is built and what it takes to fly good equipment.
This is just some of what has been going on. The latest thing that has really ticked off a lot of people, me included, is they are now letting just about anyone become a distributor and have now dropped the price to $200 less than the "introductory" price first set two weeks ago when the first customer units became available. I gave them a lot of crap for that over on RCG, not a way to maintain a happy customer base that's for sure. They also say they are developing their own ESC for use with the WKM that will have a 600hz refresh rate which is technically impossible to do as the PWM frame at 2us cannot fit into anything higher than 500hz and even then its pushing the limits of what is possible.
So the best advice is as Boris has stated, wait until things settle out and then see what direction this is all taking before purchasing anything. It seems that it may require some amount of component change to get large APV craft to be stable in all conditions though at this point they don't really know what those changes should be. They have also said they're going to add some tuning capabilites to the software to make it more friendly to larger and heavier frames but that will come at the expense of the position hold. Seems you can't have both super tight position hold and really good autoleveling with altitude hold unless you're flying a small light frame. We'll see how well that works in a week or two...
Ken
