Using a DJI 450 FlameWheel Quadcopter with the APM

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Hi, I previously set up a KKX525 with the APM2, but when one of my ESC's started fading, I thought I'd try something a little more upscale.

I have now put together a DJI 450F Flamewheel ARF including DJI motors, Opto ESCs and props from "RC-Drones" at a reasonable $180.00 and am quite happy with it at this point in it's evolution.

If you try this there are a few things you need to know, but no real problems.

Generally follow the downloadable instructions I have provided on the Arducopter Wiki for assembling and setting up and testing a quad copter and in addition see below.

1. If you get the ARF kit, it will come without instructions, but the manual can be downloaded from the DJI website under their FlameWheel support section. It is some help.

2. When you assemble the copter assemble the top board so that the narrow slots are in the front and the back and the wide slots are on each side.

3. Use blue or purple thread lock sparingly on all screws and try to keep it off the plastic. 

4. One of the nifty features of this quad is that the bottom board is also the power distribution board, heat the connection pads adequately to get a good wet bond with the ESC and Battery Wires.

5. You can cover the solder joints with liquid electrical tape or "Glyptol" if you can find it.

6. I tie wrapped each ESC under each arm with 2 tie-wraps front to back through the arm webbing.

7. You will need to add an external switching BEC, the DJI 30 amp Opto ESCs are great optically isolated ESC's but they do not include a built in BEC. I used a Castle 10 amp switcher for about $20.00 you can get cheaper ones from HobbyKing but you should use a switcher, they are much much more efficient. You do not need to cut or remove the ESCs power wire, it doesn't do anything.

8. You do not need to balance or tune the ESCs as shown on the Wiki (in fact you can't they are not programmable).

9. I recommend O-ring suspension mounting of the APM board between 4 standoffs secured at the ends of the long thin slots at the front and back of the top DJI board (assuming you put it in as I described in (2.) above.) Put a machine screw in the top of each standoff and suspend the APM board between them by putting a thin O-ring through each APM corner hole and passing the 2 loops over the top of the screw in each standoff. Size the O-rings so there is little or no APM board movement, they will still provide good vibration isolation. Too much free movement and they will cause handling lag. If you prefer you can mount a fiberglass or plastic board to the standoffs instead and Velcro or double side foam tape the APM board to it. I like the suspension method best though.

10. DJI supplies 2 sets of props, I recommend that for a 3 cell battery you use the longer 10" ones, Only DJI props will fit the self locking oval shaft of the motor unless you do what I did below. The shorter 8" props are for 4 cell use.

11. I didn't like the DJI props although they worked OK. They are light, flexible, noisy and would break easily. So I bored out some very nice GemFan 11" x 4.5 props that I was previously using on my KK to fit the outer diameter of the oval part of the motor shaft (about .31") and because of a thinner hub section I also had to add a washer under each prop. This is a very highly recommended modification, they are quieter, more efficient and will not break at the first unpleasant encounter. These are not the expensive carbon fiber Gemfans but the $2.50 carbon filled ones and they are still great, however looking at Innov8tive's web site I see they now have a 10" x 4.5 version of this prop already hubbed correctly for the DJI motors, buy these, they are a no brainer. My guess is if you use the stock ones you'll need new props soon anyway.

12. When starting the Flamewheel, it arms as per normal (throttle down and to the right) but if you do not spin the props within 10 seconds or so, the DJI Opto ESCs will shut down and you need to disarm (down and to the left) and then rearm again. Anytime you are on the ground longer than 10 seconds without turning the props you will need to rearm. This is not a big deal. You will quickly get used to it and given the capability of these things to shred flesh you will probably come to appreciate it as a worthwhile safety measure.

13. When you are setting up your board with only the USB connected, the ESCs beep continuously, ignore them.

14. When you turn your transmitter on and plug in the FlameWheel's battery, the ESCs should emit a short musical series and be quiet. You are then ready to arm and fly.

I have only covered substantial differences to the normal quadcopter setup procedure, but I highly recommend the Flamewheel 450, it flies quite well with standard PIDs but I will publish PID info later as I tweak it. (See Below).

Although the current stock PID's fly quite adequately, I have found the following changes decreased "twitchiness" and increased stability:

As of 12 / 8 / 2012

Reduce the Angular Rate PIDs P value from .175 stock to .145

Increase the Angular Rate PIDs I value from .010 stock to .030

Reduce the Stabilize PIDs P value from 4.5 stock to 4.0

The above will be revised as I continue to tweak.

Loiter will probably want some tweaking too and I will publish that after I have more extensive experience.

Roll and Pitch inputs are very sensitive so you need a light finger on the control sticks, but once you learn control with them I think you will be happy with them, If not you can probably detune them with the same PID's I am changing above.

I have a friend who has also successfully set up the Flamewheel F550 Hexacopter with larger motors and Graupner props following these procedures with such adaptations as are necessary with a Hex and he is using stock Hex PIDs.

Hope this helps, please feel free to ask questions I will respond as best I can.

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Comments

  • Hi Tony, although I haven't implemented it, I believe that spin on armed feature can be disabled in the Parameter setup section of Mission Planner.

    But it is normally enabled as it is considered a safety feature to have the motors spin slowly when armed.

    When you start raising the throttle the motors should accelerate relatively smoothly as the throttle goes up and you should take off (and hover) at about 50% throttle if everything is set up just right.

    There can be a bit of a raise necessary at the very bottom of the throttle range before any additional prop response is visible due to arm notify spin rate possibly being slightly above minimum throttle setting.

    (Throttle stick has to raise past this point.)

    This is all adjustable including whether the props actually spin at low throttle arm or not, but it is somewhat involved and you need to look at the procedures required on the APMCopter wiki under setup.

    From what you have said, it sounds like your copter is actually behaving like it is supposed to, my suggestion would be to just take off and get used to it in stabilize flying conservatively.

    If there are any PID problems they will identify themselves and you can adjust accordingly.

    Best Regards,

    Gary

  • Forgot to mention Gary. My opinion, The firmware should have a disable/Enable switch in the firmware for the motors activity for arming startup. in case others would like motors not spinning when armed. That switch would make a great extra feature in the mission planner under config settings.

    tony

  • Thank you Gary for your very Fast Response.

    the motors spinning when armed is very good to know. But, how come when it is armed with that firmware, it is like a switch LOW then High. Does not seem to be a slow increase in speed, to high. when at half to full stick. anyway, I have not flown  this quad with this APM board yet. flew it with my Old KK2 board and it flew great!

  • Hi Tony,

    Yes with current firmware, the motors spin at slow speed when you arm to show that it is armed.

    Arm - spin - disarm - stop spin.

    And Thomas, A lot has happened since I first published this, but the above listed PIDs are still a good choice for starting but will vary a bit according to your individual hardware specifications (Motors, props, weight, etc).

    The most important PIDs to modify are the Angular RATE PIDs and the P value is most critical.

    Since this is a symmetrical copter, generally it is best to leave the roll and pitch PIDs locked together (as it is normally).

    Take a look at my QuadcoptersAreFun site the 2 flamewheels build:

    http://quadcoptersarefun.com/2FlamewheelsBuild.html

    and take a look at the DIYdrones APM Copter page on tuning here:

    http://copter.ardupilot.com/wiki/configuration/tuning/

    Best Regards,

    Gary

  • Hello all. has anybody fixed this problem yet? My Rig is a 450 quad with the APM2.6 ArduPilot Mega External Compass APM Flight Controller w/Ublox NEO-6M GPS

    my transmitter is a Turnigy TGY 9X

    My problem is very similiar. when I Arm the APM the motors spin right away. I dont think that the motors are supposed to spin when I arm ths Quad APM. the throttle stick is still down. What setting would I need to adjust to  fix this issue?

  • Anyone figured out the best PID settings for AC 3.0.1? The defaults work pretty well for me, but I continue to struggle with Loiter. Post 'em if you got 'em. Thanks.

  • Gary thank you so much for all the help I got it up and running first time I took off it flew amazingly well.  I could hold it steady in a hover.  I was testing in the garage to keep the wind down and just to make sure nothing went crazy and flew off.  After my second time flying around I took it outside.  I love this APM board and can't wait to try other flight modes besides stabilize.  Marty - I am with you, I found the throttle to be a bit too responsive wasn't sure if I should mess with settings on the APM or adjust on my Turnigy 9X.  Tomorrow is going to be awesome hope the weather holds, I got some flight modes to test

  • Hi Chuck,

    Good luck with that, the online sources have all dried up for the Zeal but maybe a few local shops might still have it, I'd call first.

    From all accounts the Moongel, yes the one in your link is a fine gel too, but I can only personally attest to the Zeal.which is great.

    I think your philosophy is exactly right.

    Way too many people get into this with the idea that I'll get the perfect multicopter that can haul my Panavision Camera around and take professional videos - and I won't ever need to do anything else.

    The result is a multi thousand dollar investment they end up being afraid to fly.

    My little FlameWheels are cheap, versatile, bullet proof development platforms and their personal injury threat level is also appealingly low.

    Eventually I'll invest in a conservative (photo / video copter), but for the time being these little guys are a lot of fun and let me build practical experience safely and cost effectively.

    And the FLIP frame you found is perfect for them too Togher and lighter the only downside is $$.

    Regards, Gary

  • Thanks Gary - me and couple of the guys at the office are looking at The Flip for something to really practice with, the DJI Phantom is too nice to toss around and what I am building is more for simple FPV and AUV type flight - this Quad will be my "try out cool controllers" test case - so I figure there will be some crashing, but not as hardcore as I will likely crash trying to learn acro with the flip.

    Once I printed it out and mounted it on, I noticed I had given it a much longer adjustment ability than I needed.  I am actually going to just have screw holds on it, not the slots, the slots are on the base anyway.  That will allow me to pull in the edge, also I was looking at mounting the receiver on it's side so it sticks out less.

    So you are talking about this stuff as an option: Moongel at Best Buy

    I am going to try to hit up a few hobby shops see if I can maybe score Kyosho Zeal Gel Tape

  • Hi Chuck,

    I really like that "Flip", I'll probably get one of those myself.

    The telemetry radio shouldn't be a problem since the frequencies are so different and problems with it seem to be uncommon.

    I would suggest sticking the GPS in the middle and you can even stick it to the APM case with double sided foam tape.

    It is really important now that 3.0 is out that you mount the APM in a anti-vibration way and the best and simplest solution I have found is Kyosho Zeal Gel Tape, however, noticing that (everybody) is out of it, Moon Gel or Alpha Gel pads will work just as well and Moon Gel is commonly available everywhere.

    You will need to retain the case with a Velcro strap with some "soft" foam (loosely) retained between the strap and the case.

    This should be adequate by itself and is easier to implement than the O-ring suspension method which also requires careful tuning for the ideal O-ring diameter and cross section.

    Don't worry about battery heat, unless you live in the Kalahari desert this is unlikely to be a problem.

    The little shelves looks nice (and useful) I would probably trim it to make it stick out a little less and stick the receiver up on edge to get the weight back towards the center a bit.

    In any case, looks great, you should get a lot of flight time out of it.

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