ArduCopter 3.0.1 has been released and is now available in the Mission Planner,, GitHub and the new Downloads Area.

Warning #1: Compass calibration and reducing interference is far more important than with 2.9.1b

Warning #2: GPS glitches can cause sudden and aggressive position changes while in loiter mode.  You may wish to reduce the Loiter PID P to 0.5 (from 1.0) to reduce aggressiveness (see image below of where this gain can be found in mission planner).

Warning #3: optical flow is not supported but will be back in the next release (AC-3.0.2 or AC-3.1.0).

Warning #4: loiter turns does not maintain altitude.  This bug will be fixed in AC-3.0.2.

Warning #5: This release has only been lightly tested on Traditional Helicopters.

Improvements over 2.9.1b include:

  • Inertial Navigation for Loiter and Auto meaning much more accurate control (Randy,Leonard,JonathanC)
  • 3D navigation controller follows straight lines in all dimensions between waypoints (Leonard,Randy)

         WPNAV_SPEED, WPNAV_SPEED_UP, WPNAV_SPEED_DN, WPNAV_ACCEL allows configuring speeds and acceleration during missions

  • "compassmot" to compensate for interference on compass from the pdb, motors, ESCs and battery.  (Randy,JonathanC) (Set-up video here)
  • Safety improvements:
    • simple Tin Can shaped Geo Fence
    • pre-arm checks to ensure all calibration has been performed before arming (can be disabled by setting ARMING_CHECK to zero).  (video description here)
    • GPS failsafe - switches to LAND if GPS is lost for 5 seconds
    • stability patch improvements to stop rapid climbs in very overpowered or overtuned copters
  • Circle mode improvements including "panorama" when CIRCLE_RADIUS set to zero (Randy,Leonard)
  • SONAR_GAIN parameter added to allow better tuning of sonar surface tracking
  • CH8 auxiliary switch (same features as CH7)
  • works on PX4 (some minor features still not available) (Tridge,PatH)

How to upgrade:

1. Make sure you are using Mission Planner 1.2.59 or newer (get it here)

2. Click on the MissionPlanner's Hardware, Install Firmware screen.  The version numbers should appear as "ArduCopter-3.0.1", then click the appropriate frame icon and it should upgrade as per usual.

3. Reduce the Loiter and Alt Hold PIDs if you have modified them from the defaults.  The modified PID values for the 3DR frame can be seen in the image below.

Note: Nav parameters have been combined with Loiter so do not be concerned if you can't find them.

4. Although not directly related to this release, if you purchased an APM prior to March of 2013, update your PPM encoder to the latest firmware (instructions here).

5. Try out the new version in stabilize mode first, then alt-hold, then loiter and finally RTL and Auto.

Numerous How-To videos are available:

Special Thanks to MarcoDaveC and the large number of testers on the pre-release thread who put their copters at risk during the extended testing period.  Some of their videos can be found hereherehereherehere and here.  Thanks also to MichaelO for the MP changes required for this release.

All feedback welcome.  Please put your questions, comments (good and bad!) below.

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Much of that seems exceedingly unlikely.

My H8 uses two Quattro ESC's, so the chance of having a cascading failure is higher than with independent ESC's.  But I think the risk of all of this is acceptable low.  The failures that are much more likely are prop failures, drive failures (collet slipping on shaft, nut coming lose, etc.), or connector failures.  As I've learned, bearing and C-clip failures are also possible, but still won't typically take out the ESC.

Even if the worst happens, with independent ESC's, I'm quite sure the single ESC will explode, and cutting it's own input, and should not drag down the rest of the system.

Haha, yep.  That was such a great demonstration of how well the system works.  It didn't just lose one prop, it momentarily lost two props as the failed motor/prop stalled an adjacent prop.  That's why it flipped.  And so even though it was upside down, it still managed to right itself.  It looked much worse in person.  After watching the video, I realized that it actually didn't do anything too terrible in the air.  The front-left corner dropped, then it came back up, while simultaneously yawing around until it was facing backwards.

It was then very stable, and I could have flown it back, but I decided to ditch it because I wasn't sure exactly what the situation was and I had a good place to land right where it was.

But it should also be pointed out, it lost 50-70 feet of altitude very fast, and also resultingly was moving quite quickly.  So while it can recover from this situation, that still doesn't make it safe to fly an Octo overhead people.

Yes, one has to be practical. There will never be total redundancy but in my 6 months on multicopters I have had one c-clip, one shaft and one ESC fail. As I will be moving on to more expensive cameras I think an H8 will be a good safety upgrade.

If the copter is well powered and using 2 parallel batteries, it may be possible to power the top set of ESCs from one batt and the lower ones from the other. How would power modules manage if wired in parallel to give the APM a backup supply?

Richard? Have you tried disabling one complete (top or bottom) set of motors? Do you think it would fly if well overpowered or at least keep a stable descent?


Rob is there increased possibility of one motor or prop taking out it's pair more so than a coaxial? How much overlap do you have?

Rob how are you liking the Quattro? I've had their page open for weeks, contemplating to get it but I haven't heard of many people using them. Definitely a weight saver and should keep the mag interference at a minimum. Price is right too :)

I did have Andropilot attached on my Samsung during the flight but it was not attached during the testing or playback.  I do not remember seeing it switch back and forth during the actual flight but I will double check the next time I fly.

The "NoH1669" is the radio receiver for the FlySky radio, I have it taped to the underside of the stack the APM board sits on.  

Thanks again for all your help!  Very much appreciated!


Vince, go to the openpilot web site and there is some good discussion on coaxial prop setup and ratios.

Basically the speed of the top prop should be around 97% of the bottom props. Also some of this can be achieved by using different Kv motors s or different size and pitch props.

What seems to me is you aim to build the perfect copter first up. But it might better to just buy yourself a very cheap quad setup and have a play around with this first and do all your learning and crashing on that rather than do this on more expensive setups. . I speak from experiences because my first copter was a X8 with an expensive Droidworx frame and I crashed it a lot at the start.

You can pick up a cheap DJI quad copy frame for around $30 and they are very tough and great to be an experimenter learning rig to test out all you need to do. I have one and I call it my test crash quad. Its a lot of fun and you don't have to worry so much if you crash it. Also good to have later on to test new firmware before putting it onto your more expensive rigs. Just my 2 cents worth of advise for whats it worth.

Rgds John

Some motor manufacturers are using well known big brand bearings. If you can't have the spec from the motor manufacturer, you can have it from the bearing manufacturer. Each bearing has a given life expectancy depending about the load (light, moderate, high) and the rotational speed.

A good way to know if a bearing is ok is to listen it. As soon as a bearing start to make noises, it must be changed because it will fail very fast.

Something to be considered as well is that as soon as you have a crash, you can't trust anymore most sensitive devices on the copter. Bearings are sensitive devices.

So for a professional work it is always better to check and / or change sensitive devices after a crash to keep reliability at the desired level.

It's a common error to think that because our copters are small they do not need the same level of servicing than full scale ones.

Multi-rotors can sometimes have a reliability advantage when a motor fail, but it is not always the case. A propeller can break and stop another motor, or an ESC or motor can become shorted and cause a full power brownout.

And the best is to never have crashes !


Thanks for info John.

Its not first up by a long way .

I have 100s of successful flights on this frame (and its predecessor) and since the brushless gimbal the videos are improving.


Having just taken the UK commercial certificate I would like to use a DSLR and FLIR camera so need more lift and better redundancy.

The DIY frame in the link has been so successful that I would like to use the same vibration isolation, however I may go for a more open construction as its fiddly to install and replace electronic components. I also will concede to having it folding.  

Hi Randy,

Thank you for the reply.
It was also arming when disconnected from the pc.
However I think I found the error.

The default ESC refresh timing is set to 490. On my setup I set it to 400.

After changing this the motors would not spin anymore.
So I refreshed the parameter values and found that the ESC refresh was set to 3954, although I got the message that the values were stored.
I talked to a friend of mine who was having the same issue and he told me that setting the ESC refresh to 398 or 402 works. So I did and indeed it works, this value is stored and the motors are spinning.

I just had my first maiden flight a few minutes ago.
For some strange reason it does not take 400 as a 'valid' the ESC refresh.

When doing my maiden flight I noticed that when using the yaw the quad was also pitching.
Any hint on what this could be related to? I attached my logfile, if you could have a look when you have the time.

There is a spike in the IMU values this is when I tried to enable the althold and it dropped.
From the logs I see that my hover point is around 600 so I already increased the THR_MID to 600 to be in the right zone for althold.



Alex ,

I tried out a 4S as you suggested, but I think I had the Battery FS set to high again. Ive now set it to 13.2 and after doing a full recharge will give it another go and see what the levels drop to under load. Is this about where you have your FS or warning alert set?

It certainly can fly faster using a 4S but would that be the only advantage? A 6000mAh whether a 4S or 3S should have about the same flying time right?

May be in strong wind a 4S might hold better or wander less? I also noticed a bit of a wobble our bounce when trying a quick  maneuver. It might be the extra weight of the battery so might need to lower the PIDs a little.


The spike is gone in this flight. I wonder i it was the camera gimbals readjusting its position when it kicked in the reading from the RC.?

I added some grommets to the APM mounts to try and get the vibration a bit lower. Looks like this has worked for the Y axis, but the X axis hasn't changed at all.    Is X  axis reading left right or front back?

I tried Alt hold again at about 40cm of the ground and it held pretty steady at that high which surprises me considering the amount of wash its sitting in.  Towards the end of this flight I see the sonar and baro separate a bit. Why would that happen?


Is there are facility in APM to set the % of the speed of the top motor vs lower in coaxial setups? This would be a great way to test the best efficiency to fine tune the TB%. Each motor prop combo might require a different %. Just time a loiter or hover in no wind and measure the used mA's.

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