Drone Not Stable

So I am using the APM Board 2.8 with the latest version it can take because it is outdated. I believe it is 3.1. And after completing my build (3508 700kv motors with 40 amp 4-in-1 ESC), I attempted to fly it. Unfortunately, whenever I raised the throttle it would lean one way or another and then when the throttle was raised enough for liftoff it flipped in that direction. I looked on ArduCopters page about troublshooting that issue and I did everything it said. I calibrated again and again both my sensors and my radio and my ESC. I also checked wiring from the ESC to the FC and when I’m just testing which ones move fasted based on what input, it is responding correcty. The only problems I had with the copter were that the battery cells weren’t that balanced and my center of gravity was perfect, but I don’t think that should cause that problem. Any idea on how to fix it?

What type of ESC are you using ?
I use to have this type of problem with my quad , turned out that those cheap shrink wraped red/yellow ESC are terrible . They go out of sync and blow out .
After i changed my ESC with some more modest ones 13$ ESC . The result was much better . The motors spin the same , there is no sync problems .
For my opinion the problem may be your ESC if you are using cheap ones .


Hmm, is there anything else it could be? I have a DALRC 40amp 4 in 1 ESC and I looked online if anyone else was having the same problem and I couldn’t find anyone who was, I found people who had motors not working, but that’s not whats happening in my case.

So here is the list of all my ‘possible’ problems:

  1. APM may not be dead center and may be like at a 1 degree angle (though I calibrated it where it was so myabe it ‘zeroed’ it there)
  2. Propellers are not perfectly balanced
  3. Battery is not balanced
  4. This isn’t a problem as much as it is a deviation but, the wire running from one of the motors is different (same gauge tho) from the other ones.

Anything that it could be?

Do a motor test (REMOVE PROPS) in MP.
Motor A=1, CCW;
Motor B=4, CW;
Motor C=2,.CCW;
Motor D=3, CW:
Can you post a photo of the quad ?

I believe I have the motors wired up right.

Here is the photo: https://photos.app.goo.gl/fEFmRpfata8omZVE8

All you can determine from that photo is the props are turning the right direction. Run the Motor Test as suggested. And to be clear about the Motor test order:
A-Front Right
B-Rear Right
C-Rear Left
D-Front left

If these motors don’t run when you select the A thru D buttons it’s wrong. This is almost always the problem.

Ok, so if doing the motor test doesn’t spin the right motors, it is a problem with the way the signal cables are arranged. But if it does work, it would be a problem with the power each motor is getting, and to fix that would I just have to get a new ESC?

After confirming that the order is right you will probably have to check that the Low RPM Power Protect function in the ESC firmware is turned off. It’s usually turned on by default for higher kV motor use. Unfortunately because you have an obsolete Flight Controller it cannot work as passthru for BLHeliSuite which would allow you to easily change this parameter.

In summary even if you fix a potential motor order problem you will still want to disable this function as 700kV is borderline with it turned on. I would scrap that Flight Controller and replace it with an up to date one. BTW-Arducopter 3.2.1 is the latest version the APM will run not 3.1

So the APM board 2.8 can’t work as a passthru for the ESC firmware? And if not, is their another way to access the settings without getting another flight controller?

No, it can’t. That functionality wasn’t added to Ardupilot until long after that FC became obsolete. Before this was possible with Flight Controllers that will passthru (Pixhawk, many others) I used a cheap Naze32 board running an old version of Betaflight to access ESC’s running BLHeli. But this wouldn’t make any sense for you because for a bit more $$ you can get a Flight Controller that will run the latest Arducopter firmware. There are various cheap “USB Linkers” around that say they will connect with an ESC’s running BLHeli but I’m skeptical that they would actually work.

Ok if I get a Readytosky PX4, would that be fine for a while?

Sure, that will be fine. I have a few of those Pixhawk 2.4.8’s and they all work well.

Out of curiosity (looking at the photo) what is the All-up-weight (incl battery) of that craft. What power (3S, 4S, ?) and what props.

The AUW with the battery is about 2000g more or less. I’m running Garrt 3508 700kv motors with a 40amp ESC and running it all off of a 4S battery (3500mah).

And the props you have on there now?

I have RayCorp 1147 Plastic Props

OK, it looked like a bit of a heavy load but that should fly. Not for long but the thrust to weight isn’t bad.

I may have another idea to get it flying, so you said that given that the motors are placed right with their signal cables, the problem would be configuring the Blheli firmware to turn off the Power Protect function that is used for higher kv motors which I can’t do with my board. And I just happen to have 4 extra 2836 1120kv DYS motors, so what if I put those motors on the drone with the 1147 props and because they are higher kv I wouldnt have to worry about the flashing. Would it work fine with my setup (thrust, wattage, ect.) and would doing that method remove the problem?

Why don’t you confirm the motor order and see if it resolves the problem 1st. As I noted 700kV may be borderline with Low RPM Power Protect meaning it might work. It would be a shame to replace those Garrt motors with those DYS motors but thrust wise it would be OK. However, the flight time would be even less as the efficiency is poor.

Test the motor order. That is almost always the problem when tipping at takeoff