DJI vs ... What to do? ...What to do ?

Hi Guys!

THIS is my very first post on DIYDrones, and I am most confused.  This is my story.

I am quite new to this UAV business, and I originally purchased a DJI Phantom (1st generation) from a locally BIG Camera equipment retailer, here in Montreal (LL.Lozeau).  To my knowledge at the time, it was the thing of the moment. I looked on the web, and little that I knew at the time, DJI seemed to be reliable, easy to use and, mostly for me at the time, affordable.

Enthusiastic about this new purchase, I read the provided « instruction sheet », and, I must confess, it was (seemed) most easy to setup and fly.  I did my first flight the next morning, since weather was clever enough to allow me to do so.  Well ... Okay!  Pilot error, I guess, I lost control.  BUT I recovered it, almost intact, a few houses down the block.  Only one Prop Guard was wrecked, but that was fixed rapidly thanks to Super Glue!  And up we go again, and all went well that time.  The same evening, I was flying with my GoPRO, and took some VeRrY ShAkEy PiCtUrEs of the area! ;-)

It was THEN, that I wanted a way to stabilize the HERO3, with, what seemed best at the time, the Zenmuse H3-2D Gimbal ...from DJI, of course.  Costs as much as the Phantom itself, but hey!  A man has to do what a man needs to do!  But that remote control seemed a toy thing, resembling more the one from Fisher Price than one for the real thing.  So I went to purchase a HiTech Aurora 9X Remote Control Unit, along with 4 x 3S 45C Batteries, the big Hyperion 150W charger and the whole kit and caboodle!  The real stuff, I thought!  Well, so far, so good!  I'm in business.  So I had the Gimbal installed, as well as the receiver replaced inside the Phantom.  « Cool!!  Let's try it! »

VERY stable videos!  I was impressed of the results.  Next, I wanted ...telemetry, because I wanted to know my battery voltage remotely!  HPP-22 and HTS-SS, with a HTS-GPS, and HTS-ORPM (Optical RPM Sensor).  OK!  Now I know when to land this thing, before the battery runs out, and if it falls, I'll know where it is!

Then, I wanted to see WHAT was my camera filming in real time, NOT once on the ground (legitimate request, wouldn't you think?)  I then needed a 500mW Video Link from ... Yup!  DJI!  And a link receiver with a screen to see the down linked images!  This is starting to add up $$$!

Now, the ULTIMATE thing would be, ...a Ground Station Control.  WOW!  Completely automatic flight!  That would be way cool!  Only one thing though!  This is a Phantom!  Not a Boing 747!  There is only limited space inside this plastic shell!  I needed the DJI Data Link, AND a DJI Can Hub ...

Hmmm!  What to do?  Well, the Flame Wheel F450 seemed to have plenty of room for all this equipment.  After all, I have the ESCs, the motors, the controller, that should not be to complicated to merge all this stuff to an F450 Frame.

So I did!  Managed to sandwich all the modules, and while we're at it, let's add an FPV camera and transmitter from ... no!  Not DJI!  This time, I wanted a Fat Shark gear!  Simply awesome!  The ultimate FPV, the camera being mounted on 2 servos, for full pan & tilt FPV experience!

Last week, I finally wanted to get this flying wonder a try.  Battery was fully charged, DJI was calibrated to the max, new version software, and all!  I was ready.  Gave it a go in my back yard and ... Well, I was happy it was in my back yard, and not in front of a crowd.  They would've had a very good laugh!  The thing was so heavy, that it raised 5 feet in the air before slowly acting like an elephant with canary wings!  Hehehe!  I had a good laugh my self, because I secretly had my doubts about this baby flying !!

Well, at this time, I see only one solution.  Adding 2 more Props!  So I am in rebuilding my F450 into a DJI Flame Wheel F550 Frame.  Just purchased a top and bottom plate, 2 more Motors and ESCs, and I should be in real business by the end of next week.  At least, I think!

Now I am filled with confusion.  I'm reading all this controversy about DJI and Fly-Aways.  Some are convinced that it's DJI's Naza-M Controller's fault, some others, like Dan Blake and Jamie Peebles (on other Forums), would have tendency to blame the unwanted behavior on the pilot more than the hardware or the software.  Who should I believe?  Should I go with another controller and discard the Naza-M V2 and go towards another manufacturer?

What is said about learning to fly in Manual Mode worries me, although I fully agree with it!  I've tried that a few times with my AeroSIM RC Simulator, and I crash it within a minute, if not, right at take off !!  I know! I know!  No GPS is used in Manual Mode, and this is the main reason there is no GPS-Glitch related crashes in Manual Mode.  But you need to be a REAL pilot to fly in this mode!  Hehehe!  I practiced in Attitude Mode tonight, and I must confess, it is not easy, although I spent 30 minutes and could maintain a fairly good hover positioning about 90% of the time!  I plan on doing some more practice this week.  Could this help me recover a GPS Glitch situation?  I ask anyone.

Well, here goes my first post.  I hope I was not too long.  I am here for one thing : LEARNING !!  Am I at the right place??  I sure hope so!

I also hope I've posted this one in the right board!  There are so many...

Yours truly,

Daniel.

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    • Hi Gary!

      Thanks for the reply.

      I was (and still am) using 9 inch Carbon Fiber Props (see picture below).  As for more « pull », I decided to stay with the DJI platform, since I'm very satisfied with it, and opt in for the Flame Wheel F550.  I am making sure, while upgrading all my stuff, that all runs on 4S LiPo Cells that will provide my Drone with more boost, but the Cells are much heavier...

      3702501829?profile=original

      Question 1 : Will the 4S Cells allow a higher RPM to the Motors?  I have 2 x 2212/920 KV Motors (original F450) and 4 x ????/??? KV (Original Phantom 1 Motors).  My supplier tell me that the Phantom 1 Motors are the very same as the F450 / F550 Motors, aside from their color.  Could that make sense?

      Question 2 : What is the KV rating?  Like I said, I'm green to this industry.  Some of my questions could seem a bit obvious to you, nonetheless, they are not to me. ;-)

      Pixhawk.  I hear this name often.  Twice today, three times yesterday.  Are they THAT good?  I will « investigate », for I want to possibly rebuild my Phantom, since I have all the original parts, and sell it.  I will then be on the lookout for a new controller.  Will the Pixhawk be compatible with all mi other DJI equipment?  Reading and asking some questions will be my main activity in the DIY Drone Community for the next few weeks, I guess.

      Well, I have much to read and to ask.  I thank you very much for all the valuable info you provided.  I will take a peek at that « http://copter.ardupilot.com » Site.  And I'll look forward to chat with you in the near future.

      Yours truly,

      Daniel.

      • Hi Daniel,

        Going from 3 cell to 4 Cell will increase your existing motors RPM by exactly the difference in number of cells, in this case 33 1/3%.

        Of going the other way from 4 to 3 cell decreases RPM by 25%.

        The KV rating is rpm per volt so for a 1000kv motor at ten volts you have 1000kv x 10volts = 10,000 rpm.

        One thing you should not ever do is mix two different motor types on the same multicopter.

        Even if they are rated the same, the response is not likely to be identical and that WILL cause stability upset.

        Another thing you should also understand is that for multicopters, efficiency directly correlates to prop diameter, basically the bigger the prop, the higher the efficiency.

        There are down sides if you go too big, but unless you go to extremes this is a central point.

        The bigger the prop generally the slower it turns for an equivalent lift and the motors KV rating needs to match this fact.

        Really big props usually correlate to really low KV ratings (100kv for Tiger motors U series but also 28" props).

        You don't want to go there, just trying to give you the basic theory.

        The F550 is an OK frame, but I have a freind with one and it is definitely a little "truck" like in its handling (also with a gimbal and a GoPro).

        He switched to a Hoverthings FLIP FPV Pro (dead cat style) and it fly's like a sports car even with the camera and gimbal.

        The DJI 920kv motors are what I use on my F450, F350 and Flip Sport, but they are very lightly loaded and hover at less than 50% throttle and fly like a sports car.

        No matter what you use you are going to need at least 10" props (the biggest that will fit on an F550) and if you are using the stock DJI motors you will definitely need to switch to 4 cell.

        And that is pretty heavy loading for those relatively inexpensive motors, it is unlikely their bearings will handle that heavy a load for an extended period.

        Really good motors like Tiger Motor and lately KDE cost more than twice what the stock DJI motors cost although there are a number of people who will swear by some less expensive motors.

        As to battery weight, A 4000mah 3 cell battery has roughly the same net energy as a 3000mah 4 cell battery.

        Although you will have shorter flight times with those motors with the 4 cell equivalent battery for a 3 cell due to the fact that those particular DJI motors are noticeably less efficient on 4 cell than they are on 3 cell.

        Go look at the tiger motor website and look at a few of their motors, they publish efficiency ratings for each of them and it is a good way to get a feel for what I am talking about.

        http://www.rctigermotor.com/

        As for the Pixhawk Autopilot, you can find a lot of info on it on the DIYDrones wiki I referenced you to.

        It has a considerably broader range of features and capabilities than the Naza controller(s), but it does have a bit of a learning curve (you do not need to be a programmer though).

        Hope this helps,

        Gary

  • Hello to u Daniel. hope this message finds u well. Ok to start I have both a naza h and a naza m. both to me seem ok. I have had a few random accidents with the naza m. but I could put them down to maybe flat batteries. But I wouldn't say the naza is perfect by any means. But the same could be said about the APM 2.5. I have had a few crashes with the apm but again I cant explain them. very weird accidents. Thing is who can explain them. could be code errors or just a fluke? But good luck with your hunt. look at the controllers as women who can predict them lol. but seriously who know wot could happen. its a path and only u can decide which way to go........

    • Thank you Austin!  Yes, your message found me all right!  Hehe!

      When I told the Controller / Women similarity joke to my wife, she threw me a dirty look!  I'm not sure why ... !o!

      I'll sure investigate all the avenues prior to purchase another brand of controller.  I believe that Naza is, considering the enormous amount of Controllers DJI has out in the field, and the real fails, still very dependable.  But I promise I'll do my homework well before setting my choice.  Like I said previously, I have LOTS of reading and asking to do in the next few weeks.

      Until then, have a very good end of week, and I hope we keep in touch, because I will sure post my finds and progress with this fine Community.

      Best regards,

      Daniel.

  • I second everything Rob wrote earlier Re: DJI naza.

    As far as your question "Could this help me recover a GPS Glitch situation"? (Learning to fly manual)

     

    Absolutely. The more "automated" you fly, the more your system is prone to error. It's not only GPS. Could be barometer. Could be compass. Could be programming of a bad waypoint. Etc ... Knowing how to "recover" in manual (and usually in split seconds) is a must and will save you a fortune long term. And even in manual, things can go wrong that could piloting sometimes can help with.

    But I'd go further than that.  I may be too extreme for some, but for me, even knowing how to fly well in attitude mode is not enough. I'd say learn to fly "the hard way", with no self leveling. You can do this via simulator, but even better, you can buy a blade nqx for $69 (or equivalent), that can fly both in "stabilized mode" and "acro", or non stabilized. Have at it, learn how to fly it in all orientations, including 45 degrees, do banked turns, figure 8's in all orientations, etc ... Start with self-level, then go with "agility" mode (Acro).  Oh, there's be a learning curve, and you'll crash a lot.

    But here's what you'll get: Split second reflexes, no matter the orientation, no matter the height. You won't need to think and loose previous time, it will have it "wired in". Just like you don't need to think when you turn the wheel on you car or apply the brake when a car gets too close. And you'll get better flying in auto, and more guarantee to recover in Atti. You'll "know" what your fly controller is doing when it banks some. You'll learn to anticipate, and to recover if need be.

    You may think well, that's too much. But I'd bet quite a bit that, sooner or later, it will save your copter. And no matter what, it will  make you  fly better and safer. You'll feel like you are driving a tractor when you know how to drive a Ferrari at high speed. When said tractor goes weird ... well no big deal (-:

    I know quite a number of people who wished they had gone this way. This includes a real good cinematographer who went on to buy an DJI A2,  a really nice octo frame and a Red Epic.  Crashed the bird with the camera  after two weeks ...With the camera, a $60k or so rig all told ...

     

    Cheers.

     

     

    • Wow!  Makes me think!  Hehehe!

      I purchased a « 1Si » Micro Quadcopter, from Heli Max (see included pictures), complete with a micro camera and I think I'll get it out of its box before doing anything else.  And I'll get some practice.  I think it has both modes.  I'll check on the box and in the small owner's manual they provide, to mage sure how to set it up.

      I will try it outside on a very calm day.  After all, crashing is very much a part of learning, and to this day, I have nothing to lose by trying it.  I have an edged backyard, so it can'd really fly very far now, can it?

      Thanks for all the good advices and I'll be sure to follow them.

      Best regards,

      Daniel.

      photo 1.JPG

      photo 2.JPG

  • Hi Daniel,

    I bash DJI a lot, but I'll tell you what I think is the honest truth:

    The DJI Naza is probably not likely to have a real flyaway on you, provided you are actually setting it up and operating it properly.  I'm quite sure that a huge number of "DJI Flyaway" reports, are simply due to user error of one sort or another.  It seems that any time a UAV does not do what was in the user's brain, they say that it was a flyaway.  Maybe the problem was actually between their brain and thumbs, but they call it a flyaway.  It's a tempting and common thing to blame a computer for our failures.  A great example is a report I saw of a flyaway, which turned out to be the case where the system switched to "Atti mode" instead of GPS hold mode, and simply drifted away on the wind because the user didn't know what to do.

    Just last weekend, I lost a helicopter in a lake, using Arducopter.  It did not do what I wanted it to do at the time, rolled over upside-down and flew into the lake.  This is where many people stop analysing, and blame the complicated system.  However, I could not deny the fact that after looking down at my radio, the switch positions were in Acro mode.  And the telemetry log also indicated I had switched to Acro.  Hmmm...

    Ooops.  I'm quite experienced, but my crash was caused largely by lack of sleep over the past 2 weeks due to stress of getting ready for AVC.  I've never made that mistake before after 3 years of flying.

    Where DJI really suffers is that they make things too easy.  Or they make it look too easy.  They don't help their users understand how the system works.  Everything is obfuscated behind it just works.  People don't have access to logs, or don't have the skills to read those logs and figure out what happened.  They don't make a big deal out of data logs, because well... why would you need logging on a system that never fails and is easy to use?  everything just works.

    Well, you know, stuff happens.

    Figuring out what happened so you can help yourself learn to fly better, or solve your setup problems is a key requirement to grow in this hobby/industry.  Or, in other cases, give the programmers the data they need to fix a bug.  

    Don't get me wrong.  There is plenty of evidence that sometimes DJI systems "just fly away", completely out of control.  I just think it's less likely than some claim.  I only accept video evidence, or testimony from plausible reports.

    You have posted on the right board if you want to get in deep in UAV technology, and actually learn how these things work.

    • Hi Bob!

      Thanks for the VERY useful information you just provided.

      So IF I get this right, DJI does not provide data logs access to their Naza-M Controllers.  Other controllers do?  Like I said previously, I'm quite green to this industry, and would like to learn.

      I am in the process of merging a Phantom's Naza Controller into a new F550 Frame.  My story is on my page, so you know where I came from.  I want to rebuild the Phantom and sell it.  Only, I would be left without a Controller.  Everything I learned so far would be our the window, just like going from Windows to OS X ... PC to Apple.  I know, having done this transition that Apple is more costly and more simple, but is the very best of them two.

      So should I ditch DJI's Naza right away, not even taking a chance, and go with another one right away, or give Naza a fighting chance?

      Yours truly,

      Daniel.

      • I just wanted to chime in as well. I recommend you stick with the NAZA unless you really want to do auto missions and/or troubleshoot a bad flight through logs. I have had both and started with an apm 2.5 but didn't have much time for tuning and setup so sold it and got a NAZA v2 flight controller which perfformed really well. I used it for FPV and aerial video but I got bored of that and am now back and sticking with the awesomeness of the Pixhawk controller. It has what a NAZA has and much more. With the autotune feature you don't have to spend hours trying to get it tuned perfectly. I'm doing 3D mapping by programming patterned missions over an area.

        So if you are happy with the cabability of the NAZA then stick with it. I agree that most fly aways are most likely due inproper setup ... especially the fail safe options. Just last week I had a small crash with my Pixhawk because I was in an auto mission coming in to land and I decided to go into stab mode.... However... I had my throttle stick all the way down (throttle stick down will allow the motors to stop after touchdown when autolanding). Totally my fault but my first instinct was to blame the controller until I saw my throttle stick all the way down.

        Good Luck

        • Thank you John.

          Just today, I went to purchase a piece of UltraWire at my local Hobby Shop, and asked about all the controversy on DJI's Naza Controllers.  The owner of the place sels all kind of controllers so, he could tell me about the pros and cons on DJI Innovations' Controller.

          He told me that given the amount of DJI Drones out there, it is sure that you're bound to hear flyaways.  But if you look some facts, just like you said, most of them are due to pilot error or bad setups/settings.  He flys all kind of planes, copters, drones, and told me not to look at the numbers, but at the percentage of crashes that really involves Naza Controllers faulty operation, this percentage is really minute if not insignificant.

          Of course, I will, in the future, fly auto, and this is the main reason I purchased DJI's Ground Station Data Link module.  But this is not for tomorrow.  I'll learn who to fly in « Attitude Mode » (I call it « Momentum Mode » first.

          Meanwhile, I continue building my Flame Wheel F550 and will dress it up slowly, to make sure I keep the center of gravity at the right place.  After all, I have a lot of modules to add on to this frame one by one.

          Thanks for the reply and encouraging me in my quest for perfection.

          Best regards

          Daniel.

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