Unable to Take Off (New Hexarotor Build) Help Please

I am new to PX4 and Y6 drones.
I have been unable to successfully take off.
I have been thru the calibration process many times.
My first impression is that the drone is too heavy, however the ecalc specs that I used to select components states that I should be ok.

The rig I have built includes:

Y6 Frame
PX4 Controller
XRotor 40A ESC (BLHeli_32) - configured in PX4 to use regular PWM not oneshot.
Gartt ML5008 330KV Motors
15Inch Props Pitch 5.5

Attached is a link to the logs of an attempts to take-off and plus the ecalc specs.


Any help much appreciated. I have been having issues with this for 3 months so far.

Just a quick terminology correction, PX4 is software (like Arducopter), your running Arducopter not PX4.

Looking at the logs the controller is asking for full throttle from the escs when you give it full, however there is very little current draw (1.5a your ecalc say this should be nearer 17a) so i would guess you need to calibrate you escs (or your battery monitor is setup incorrectly) Does this very low current draw correspond to what you see, do the props spin slowly and quietly?

Why use PWM when you have BLHeli_32 ESC’s? Let’s see a screen shot of your BLHeli_32 suite config page. Low RPM Power Protect Off?

What battery voltage are you using? 3s, 4s, 6s?

Thanks Peter, I am using a Pixhawk 2 Cube controller.

Based on your comments I have run an Amp check via the multimeter. I have attached the video into the shared drive. At full throttle without the props I am only drawing between .8 and 1.5 amps. Well under what i would have expected.


Hi Mike, I am using a 6s battery.

Hi Dave, I have included the screenshots for BL_Heli32 in the shared files folder. I have turned on DShot. No change.


Unfortunately testing without the props is testing without any load.
I think you have made a mistake in your eCalc, which is common. You have only list 615g without drive. Which means the frame, receiver, flight controller, cables, fpv transmitter, any payload like a camera or gimbal and anything or everything other than the motors and esc’s is only 615g for a 610mm frame. I know a Y tri is going to be lighter than a quad but a tarot 650 quad is 600g for the frame and then I usually end up with a total non-drive weight of 1500g. So if you did not include other items but the frame in your weight then the eCalc calculations are all off.

Also notice that your max power is 350 watts when the motors are designed for a max of 760w.
Building a coaxial is a black art and, although I love eCalc, there are just too many variables for it to do a good job of modeling a coaxial.
Are you using the same size and pitch props on top and bottom?
That’s a problem.
In a coaxial the top prop blankets the bottom. You need the bottom prop smaller than the top or you will have the bottom prop tips sticking out of the stream tube of the top causing the tips to be dragging through slower air. etc etc Article below:

Turn off Low RPM Power Protect. And your log shows MOT_PWM_TYPE still set to 0 so not Dshot unless that’s the log before you set it. Set it to Dshot150.

Hi Mike,

The tests were originally performed with the props on under load.

15x5 props on bottom and 16x4 on top.

The total weight of the frame and all parts is weighed on the scales as: 3.5Kg.

This is less than the All-up Weight of 3849g estimated by ecalc.



Hi Dave,

Turned off Low RPM Power Protect and recalibrated motors to DSHOT 150.

Fantastic. Lift-off. Logs showing a current draw of well over 8 amps at hover. Thanks So Much for the help all.


Having the props on wrong can certain do what you are experiencing. It is so easy to do. Remember in the diagrams that it shows the rotation of the lower prop but the motors are upside down.So the lower motor has to spin in the same direction as the upper motor, if they were sitting on the bench next to each other rightside up, even tho the prop rotates opposite relative to the top prop. The lower prop has to be on it’s motor upside down so the top side of all props is up.

Simple right? :slight_smile:

Great Glen! I suppose you need to calibrate your power module for current. I would expect ~22A at hover with your setup.