APM 2.8 beginner probs and solutions

I spent some frustrating time getting started but this may be useful.
Arducopter 2.8 running v3.2.1
Radio AT9S set to multirotor
GPS module ublox7m

  1. The youtubes by painless 360 are very useful
  2. Unable to arm (indoors, on assembly, props off) . First, in mission planner goto Config - standard param - arm check and turn off the pre arm, save the the change, as you probably won’t get GPS lock indoors. Secondly, I found that I had to reverse the throttle stick function on the AT9S to be able to arm in the lower right stick position.
  3. Unable to lift off. First I had 4 x Air 2205 2000kv motors and I thought they were not powerful enough so I bought 4Xemax 2213 935KV with 1045 props. Still unable to lift off. The answer is that v3.2.1 comes with THR_MAX set at 80 it should be changed to 1000.
    Now airborn! Hope this helps

Thanks for sharing that and happy you got it all flying, do you have any pics of your build :slight_smile: Also very interesting as I am fairly certian the default value should be 1000, if it was 80 then anyone who ever installed arudcopter firmware will never takeoff.

I do know that sometimes the parameters are not always saved correctly, particularly the THR_MAX parameter sometimes has this bug for some reason, particularly if saving lots of changes at once, so possibly on your APM it got messed up. But its always a good thing to check the THR_MAX value if your copter is not making enough thrust!

It’s the 3D Robotics Aero preset param file which sets this to 80 and as many people have used this as a starting point it has crept in like a ‘virus’
I had the same problem,

Whilst on the subject of APM parameters, I had a nasty last week, first flight of my 550 Hex, 2812 motors, 10x4.5 APM props. It was so overpowered the standard minimum throttle of 130 (THR_MIN,130) would not bring it down :scream: I had to wait for batteries to exhaust fortunately not much damage :slight_smile:
But beware of APM with standard parameters, Beginners need to have some good ‘starting point templates’ for various sizes and configurations. Has anybody got any to share ?
Steve :slight_smile:

When :laughing: I get mine flying right I’ll share the files
I’m using APM-MINI on a HEX550 and a QUAD250
Steve :slight_smile:

Just powered up my 550 hex with APM 2.8 software version 3.4.1., Mission Planner. Upon arming the motors the props spin. I knew they were suppose to, but I didn’t think they were going to spin so fast - just below lift-off speed!

Is there a way I can either eliminate the motor spin on arming, or at least slow the spin speed down?

Yes, The speed they spin can be adjusted by changing the MOT_SPIN_ARMED parameter.
it’s default is 100, reduce for a slow speed or set at 0 for no spin when armed:-


Hope this helps
Steve :slight_smile:

Just a thought, if your current setting is almost at lift-off then you may have problems descending or landing once flying
Choose very carefully this setting and also the parameter THR_MIN

I speak from experience :sob: :cold_sweat:

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Thanks for the info concerning the THR_MIN setting. I will be setting that to zero when I get back to flying - I prefer the props to stay still until I TELL them to rotate - that way fingers don’t get whacked up (I,too, speak from experience on that!).

I also appreciate unmannedtech’s comments about the THR_MAX parameter setting - when I originally powered up with the APM 2.8 version 3.2.1 it seemed the motors didn’t spin up very high - at least not as high as they did with the older APM 2.5 module. I was indoors at the time so I didn’t actually get lift-off, but it seemed they were a little sluggish.
Will have to check that param and set it higher if it is at 80.

Doing major remodeling on our house and drones have slid way down on the priority list lately, but hope to get back to flying soon.

Hi, just a question from a newbee in apm world, i’ve been reading all the commands you can change, (seems a bit like CLI in cleanflight) but where the heck can i pit in all those commands😂 Is there a special cli command window in MP?

There is a CLI, however it works more of like a menu system so there is not way to bulk load values via CLI. You can still setup entirely via CLI commands though if you want

To bulk save/load values to your APM you will need to use the mission planner and you can save/load a .param file which keeps all of the settings in a file that you can load

A quick way is to save your params, edit in notepad (its just a text file), save, then load file back up
works for me :grinning:

Steve :slight_smile: