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  • This video is for test purposes only and shows bank angles and vibration levels during high wind. The various cameras were mounted solidly for that reason. It shows that it is possible to achieve good results without any gimbal at all. But only if the model has really good stability in high wind. Other people were trying to fly that day and were blown over on T/O The footage was shot at 25 fps which is not ideal for Vimeo.

    High thrust velocity and short moment arms is the key to inherent stability. Combine that with fast torque reaction and low weight at the corners and you are on the right road. Everything needs to as close to the center of mass as possible. I think the reason that coax. set-ups were not very good is due to the high inertia. Being able to dial in a PID set-up easily comes from not having any secondary moving mass within the gimbal or it's mounting.

    It may not be what you want to hear and this is just my own opinion but take it for what it is and hopefully it may help you get better results. 

  • I have played around with a few Phantoms including a free one which I won in the Photo comp. I have now modified all of them in different ways keeping the best aspects of the original design. The parts which I consider to be the best are the ESC's which are unsurprisingly tuned to their own motors plus a few similar ones, I ran many motors on my thrust test stand, some such as the HK Multistar 390 KV would not even start on these. I was quite surprised at the performance difference that this motor gave, a motor prop. combination that could produce 15 grams of lift per watt, was totally blown away in terms of stability with another that produced only 10 grams per watt.  The stability of the standard Phantom as delivered is a good yard stick however I wanted to fully get to the bottom of why this seems to work so well.  I had a nice Tarot 650 Quad laying around so I tried a vast number of combinations to see what was working best in terms of flight stabilisation. Without going into the full list of experiments. The results were quite conclusive. We all know that large dia props. are not good for stabilisation even if they are better for endurance when compared to smaller ones and the reason is that is because of the low thrust velocity which needs to be high in relation to the disturbed air around the model. It goes much further than that, You also need to have the moment arm to the center of mass very short as well. Also the moment of inertia must be as low as possible. At the end of the tests the standard Tarot arms had been cut back by about 3.5 ins. The motors were now underslung and the props were 12x6 Eflights cut back to 9.25 dia. The best motors were the white Phantom upgrades from Kopterwox which send this 2.3  kilo cameraship into the air like a homesick angel. The stabilisation is so much better than anything I have tried before including a Phantom. The top quality footage from the PJ810 Sony really needs no Gimbal. Which is a hugh weight saver.  Having got a model so perfectly set-up most of the tried FC's were unable to match the top performing  DJI Naza M V2. It had very little sensitivity to gain setting changes. Just slam the rudder over and it sits there in a perfect rotation about an accurate fixed point and it rides through turbulence like it was still air. 

    The things that In my experience do not work to improve stab. are coaxials  which was not what I was expecting. I did however discover that the smaller prop on top was better that the other way. They are a non starter in my view.  

    My point is that in order to arrive at a point where the FC is able to work at the highest level you must first understand the design criteria that makes up a super stable model without having any guesswork or random components in the mix.  Large models can only have a high thrust velocity if they are very heavy.

  • T3

    I actually have a Phantom 1 which I gutted and bought HK's APM for (on ebay the transmitter, Naza, and GPS nearly repaid the enire copter!).  If I was going for quality, I'd shell out the $200 difference and get 3DR electronics, but I'm trying to make a bargain basement Phantom conversion so HK it is.  I haven't done the conversion yet because I'm busy with school though.

  • Fun indeed, although seems doubtful you'll find much. I got a DJI WKM a week after it came out a few years ago, and it was orders of magnitude betterflight wise  than APM at the time. About as good and comparable to  3.2 now with the just released hybrid mode (but without many APM goodies, of course). So hard to imagine DJI has used  APM code at the time, or now. But who knows, maybe a few inspirations here are there ...

  • @rob as DJI distributes firmware  patches in field for upgrading their units it should not be too hard to unravel the bins into a form I can feed into IDA or radare or vix. and often once things like squash/compression algorithms are dealt with then a simple strings command against the binaries will yield the copyright strings of the various packages involved. Whether its APM or derived from other sources it might be fun to know what the opposition is made of.



  • Actually gpl3 requires you only to publish your changes. But credit must always be given and a link back to the source. If there's no changes, then it would be redundant...
  • for me it s a poor copy

    they doesn t use external compass,it uses old processor and it s not possible apparently to connect telemetrie.......

    so far it s better to buy apm 2.5 clone and fit it on this frame

  • Developer

    > Why hasnt any of the cloners just copied the DJI board and copied the flash ?

    There are some Naza clones made under the iFly and Quanum brands. But at the moment the DJI Naza-M lite controller is so aggressively priced (controller $69, controller + GPS $169) that there is little room for clones to thrive.

  • Why hasnt any of the cloners just copied the DJI board and copied the flash ?

  • Chris, so what does 10000 apm boards for these clones cost?
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