I've got a MK hexa xl kit that I've just finished putting together, and it tries to flip on takeoff. I'm running + config with Arducopter 2.1 firmware.
I checked out the motors with the CLI command, calibrated ESC and radio. In APM Planner setup inputs from the radio are correct.
The hand test gives a first problem: the pitch is reversed (pitch stick forward and hexa points back with motor 1 faster) so I set to reverse on the radio. (but the motors command in CLI give me all ok...)
At take-off throttle gently tilts the hexa, with strong throttle gets going right and then almost stabilized in flight with a tendency to always go to the right. Each time, not to miss the exa, I have come down with a crash.
The motors are MK3638 with propellers 13x4.5 CF with payload a GoPro . Lipo 3S
The propellers are too powerful and create instability? For a total weight of about 2.5 kg such propellers are recommended?
In bench tests, in APM Planner status I see with minimal throttle trigger all channels 1-2-3-4-7-8 in 1189 but with more throttle only increase the channels 1-3-8. Is it OK that arducopter run a hexa take off as a tri?
I am a little frustrated because after 4 attempts at flights I broke about a dozen propellers and an arm of the frame.
I run a similar setup in Y6 config. I found flying it on 3s was super difficult, try switching to 4s and re-doing the entire assembly regarding the APM. Another thing, if your comfortable try loading the firmware from Arduino rather than the mission planner. I almost exclusively do it this way since the mission planner always gives me problems.
Thanks basshead but why is better to fly with 4s lipo?
Sounds like the 13x4.5 props is drawing more power than the 3s can provide. You may be getting brown out on the APM power, because all 6 channels should be active and not just 3. Using a 4S with high discharge rating, should help. What's the discharge rating on the batteries that you're using? (The "C" number) You'll need something at least 30C+ to handle
In your setup you must use "APC SlowFly 12x3.8" and 4s lipo for better performance.
Thanks to all
the battery is a 3s lipo with 50C discarge rate (nanotech 6000mAh)
I think it's a software problem because all the engines running and there is not brown out on esc.
Takeoff (simulated without propellers) all engines running with outputs 1189; more throttle,only the engines 1, 3 and 8 increased speed. But if I change manually the tilt, all engines are controlled by apm.
Then I can not explain why the test engine is correct and in flight the pitch is reversed
Leonardo, are you actually using a scope or to measure the ppm output from the APM or are you just going by the logs? Because, the APM will always log what value it's attempting to write. Whether it actually comes out as the correct value and voltage levels at the ESC signal input is a different story.
It still seems to be a power issue to me, since doing the hand tilting test, not all motors are running at max, all the time. I suspect that when you are running all 8 motors, it's just to much drain on that 3s battery
I read the ppm output from APM Planner status and is the APM that write different ppm output for the six motor. At minimum throttle all the motors are the same ppm output (1189) but with little more throttle the ppm output ftom the APM is 1350 only for motors 1, 3 and 8 of the hexa + configuration. The test is without props and the current read with the sensor is about 1,5 A
In outdoor test with props, if i give strong throttle, the hexa takes off very fast but going right.
It's possible that the 13x4,5 props are too powerful for a hexa with only a Gopro as payload ?
Tomorrow i link the videos of two flights
Yes, would be good to see a video.
Ok, now I see, I thought you were saying that the other three motors were not spinning at all. You mean they're just not balanced.. That shoots my brown out theory down. With 1,3,8 turning faster than the other three, you will have a tendency to yaw(spin) to the right. But it doesn't seem that much difference so the yaw should not be that bad.
I'm assuming you calibrated the radio, esc, and centred all the trim on your transmitter? You are in "stabilize" mode and have a magnetometer installed, and waited until GPS lock was finished. (blue flashing light on the GPS is solid)
Yes Ellison, i'm calibrated the radio, the esc and on take off all the trims but throttle are centred. Confirm that i'm in "stabilize"mode , the magnetometer installed and GPS lock.
On take off the hexa don't yaw but roll to te right
Just being complete, did you turn the mag on and set the + configuration in Mission Planner? Without seeing exactly what kind of instability it is from the video, it's really hard to diagnose any further. It could be a software problem or just a tuning issue. I'm sure 2.1 hasn't been testing in all configurations, like hexa, yet.
I rate batteries to how much drained with current over time at a given voltage.
Work is HP.
If your batteries need more power recharge over time maybe they are failing or need to be replaced.