Servers by jDrones

SingleCopter & CoaxCopter Support

(Leonard Hall) #81

Hi CM,

Thanks! I have fixed the servo oscillation problem at zero throttle issue I have missed the case when the throttle is zero.

I have made some changes and pushed to master so if you could download that and try again that would be great!!

In the mean time I have uploaded binaries for single copter to:

and coax to:

On the heat of the motors. If people use the same size motor on a single copter as they do on a quad and the copter weight is any more than one quarter of the weight of the original quad the motors will get significantly hotter.


(MadD MacKx) #82


I will also try the new binaries. Im just waiting on some 16" props and 2x 6s 2500mah batteries and I think that will remedy the motor heating issues on my set-up.

Also I want to apologize for my earlier comment lol…after re-reading it I kinda came across as a dick…lol that was not my intention. I meant it as a joke, because @Droner was so much further ahead of us a few years ago lol. Im sorry if I offended anyone. I really appreciate all your help.

I will post the video and logs of my test flights :slight_smile:

(Leonard Hall) #83

No problem Maddmackx,
I thought you were joking but I like to play it safe :slight_smile:

(Christopher Gehrich) #84

I’m excited by the renewed activity to get this system ready to fly. Hope we reach a polished binary soon! :smiley:

(Aj Romelfanger) #85


I’m interested in seeing where we’re at on this, I’ve just downloaded Leonard’s compiled binary for the coax. How is work progressing? Am I right to assume the changes are reflected in the git repository?


(Jacko) #86

@Leonardthall @tridge @rmackay9

Video of Single copter first flight

Here are the results of my tuning single copter code Just a ten-second flight as it was all but night time at the end of the day, but seems all good thus far. Still a bit more tuning but should be easier now we have got single copter airborne.
Thanks to Leonard and all the contributing devs.

(rmackay9) #87

Congrats! looking good!
A bit more tuning is required I think to get rid of the slow oscillation but it’s looking good!

(Christopher Gehrich) #88

I hope to attempt a flight with my relatively heavy (3d printed, not foam board) coax-copter tonight. I’ll post video if get it running.

(Christopher Gehrich) #89

@rmackay9 @Leonardthall @Jacko1

How do I arm without using the GPS? I’ve disabled every GPS setting I can think of and it still blinks blue without spinning the motors. Mission planner says that it is disarmed after I push the arm button and it turns red.

Battery_failsafe = 0
throttle_failsafe = 0
fence = 0
arming_check = -9 (skip gps)

I’m trying to arm in Stabilize or Acro

(rmackay9) #90

My guess is that the circular fence is enabled. If the fence is enabled then it needs the 3d lock to know it’s position (so it can trigger the failsafe if it goes outside the fence).

(Christopher Gehrich) #91


Trouble is that the fence is disabled in the gui and in the parameter list.

fence = 0

(CM) #92

@maddmackx Good to know. After reading your comment I realized my first post was a little tasteless anyway. No hard feeling I hope.

Outstanding. Thank you for the quick replies and fixes to the code. Sorry, it took me a while to respond. I was busy last week and the vehicle did not want to cooperate at all. The BEC and receiver both started shorting out. Then I borked the pixhawk for a bit (main LED off, couldn’t upload code). It’s all fixed up now.

As you have already seen, from Jacko’s flight, the mixing between throttle power and servo throw is now working fine at zero throttle. For some reason my servo moments and corrections for yaw are reversed though. Pitch and roll are fine. I could not find any obvious reason and I’m not sure at what firmware revision this started happening. I could swap the servo connections (top to bottom and left to right) and then reverse the outputs to correct this but I wanted to check before I tried anything so drastic. Have the servo positions been changed since 3.3?

Here are my current servo positions
Out1: Back (Top) fin servo
Out2: Left fin servo
Out3: Front (Bottom) fin servo
Out4: Right fin servo

@Jacko1 That was awesome! It will be a breeze to tune with a first flight like that. Do you have any close up pictures of the copter you can share? Many of the links in this thread are dead.

(Leonard Hall) #93

1 is the 12 o’clock flap,
2 is the 3 o’clock flap,
3 is the 6 o’clock flap,
4 is the 9 o’clock flap,

So it starts at the front and goes clockwise around the copter.

I am not sure what was done in 3.3 but I rewrote the code to be as easy as possible to setup.

Sorry for the confusion!!

(Christopher Gehrich) #94


Are all four flap servos used in both coaxcopter and singlecopter?

Does coaxcopter use differential torque for yaw, or does it rely on the flaps for yaw torque. (this is moot if coax uses only two flap servos)

(Leonard Hall) #95

HI Fragmaster,

All four servo outputs are used in coax but they are in two pairs. So you can choose to use a separate servo for each flap or use two servos and connect the flap pares mechanically.

You will also see that single copter has two motor outputs so you can use a single copter with counter rotating props.

If you built a coax copter using a 4 servo flap setup you could also fly it using single copter.

The difference between single and coax copter is coax copter uses differential torque for yaw while single copter uses the flaps for the yaw torque.

I was thinking of building a 4 servo coax copter so I could test both sets of code.

(Christopher Gehrich) #96

Gan I get a firmware version that’s compatible with the PX4miniAIO? Trying to load the latest firmware to the board gives me a “Error: firmware not suitable for this board”

(Leonard Hall) #97

Hi Fragmaster,
I have not heard of that board and am not aware of it being supported by the project. So it is either fully compatible with pixhawk or it needs custom work that they have not done. I understand the new pixracer sold by hobbyking is the same in that it is only compatible with the software they have preloaded. I think there may be a few manufactures ripping people off.

As I said though, I don’t know anything about that board so I have no idea if they are doing the right things and you just have a strange issue or if they are ripping people off.

Sorry I can’t help!!

(Christopher Gehrich) #98

Strange. It loads regular arducopter just fine. Only singlecopter has an issue. Is PX4 mini not part of the official hardware family?

(Leonard Hall) #99

Hi Fragmaster,

If it loads normal arducopter then it should be ok and should be part of the normal PX4 family. The question is what hardware variant is it?

Ok, it looks like it is based on V1…

I have been trying to compile but I am having trouble. I will have to get back to you.


(Leonard Hall) #100

Hi Fragmaster,

I got the compiler going again. let me know how that goes for you.