TBS Disco - APM mounting suggestion

3689546700?profile=originalHi guys,
Had a few queries regarding how I mounted my APM (mainly since I get a compassmot of 0%!). Well here it is. This will only work on side exit APM's!
Step 1:
Screw in  4 x 8mm risers in to the bottom plate, and add one sheet of moongel on top of the core (if you have no core, superglue some risers in the spot. Note: yes, that's moon gel stuck into the FPV camera slots.


Step 2:
Glue a 1mm fibre plate on top of the risers & two drops on the moon gel of the core. You can superglue the whole thing in place, but I chose to use 2 screws, for additional security. I use a battery tray plate from a spare set of quadframe legs.

Step 3:
Add you vibe solution. I've use moongel with good success, but I've decided to try out zeal corners (which i why I dismantled it)


Step 4:
Carefully place the APM in place. Take care to ensure nothing it binding; you don't want vibrations transmitted to the APM via the wires. Insert the battery to make sure it does not press the "out" servo leads. Also try and make sure the "in" servo cables don't torque the board too much, but this can be tricky.

Step 5:
Screw it all back together, but take not of the front starboard mount. This is where and how I placed the DJI riser. It's not exactly over the 4 holes - it only uses 2, This moves it outboard a few mm. Not much, but it might be this detail that separates a 0% compassmot from a 1%...

3689546961?profile=originalBUT...THERE'S A MASSIVE PROBLEM...

...take a look at where the USB port is.... You can still reach it with the standard USB cable, by pushing through the port front leg...but it's a really, really tricky, and you are in danger of pulling out a solder!

So find a USB cable with a 90' bend in it. And when you find one...let me know...before the logs fill up and I crash!

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  • Euan,

    Thank you for the info.

    I was already considering of moving the apm more to the front allowing more space to move my battery to the front.


  • I can't say I notice any problems with the flight dynamic - it flies on rails!
    The black rubber thingy is the standard TBS go pro cushion-thingy. Its weight is neglible. I basically fly with the gopro in place all the time, even if I'm not using it. Keep the CoG consistent.
  • Euan,

    I noticed you mounted the APM quite in front of the frame allowing you to slide the battery furhter to the front.

    Doesn't it give a problem since the APM is not quite in the Cog of the frame?

    Another question... The black rubber piece where the 'GoPro' can be placed does it contain any weight used to compensate for the battery in the back?

    I needed to add some weight when I don't mount my GoPro, this is why I'm asking :-)


  • Ahh, just figured out my mistake. I had taken the motor order from the TBS document and hadn't noticed that it is quite different to the arducopter docs. It's quite a pain to get at - or even see the APM when it's mounted on the bottom plate. Feels like it should now - proper maiden flight tomorrow ...
  • Hi Ian ,

    This is the normal disco, and it balances fine with a 4S 4500 or 3s 5000, but I can imagine the problem! Even a small change at the front will affect it.

    I heard that a 6000 might help balance it; but will one fit?
  • Hi Euan,

    Nice clean build. I've just put together my Discovery Pro with the in-built gimbal - which makes it so front heavy that you actually have to hang the battery a long way out the back to achieve the indicated CoG.

    One crazy thing I'm seeing is that the Pro flips (face plant) on takeoff and is very unstable when holding it. I've tried ArduCopter 3.0.1 as well as 2.9.1b. Did you find the same behaviour?

  • Congrats, a very Good and clean looking build.

    My suggestion to solve the USB port problem would come from adafruit.com:

    Cheers k.
  • Just wanted to add that I had a chance to look at my logs and I found ZACCEL at +/- 0.5g (from -5g to -15g) during hovering.  Not awesome but not too bad for just throwing this together without too much care.  Please note that I never left Stabilize mode, and I have no plan to stay with this setup.

  • Literally all I've done is just slap the APM on the top and used a rubber band to hold it down:

    3692825818?profile=originalThis is just temporary...once I get a few more parts I'll be making a better, more permanent solution.

  • Sorry, slow connection, didnt see full image!

    Thank you brian.

    I've found more complicated than other frame to get off all vibration on the disco. I've used moongel inside without success (but ok, maybe i've make something not correct) But with t-motor and perfectly balanced props i hoped for something better.

    Now i hope that my new mount will improve something.

    Ps brian, can you share a photo of your setup with moongel? did you use some ciano to let the moongel stay in place? thanks

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