Advice needed on Y6 motor redundancy

lunarair

Member
Just did a motor failure redundancy test on my newly build Y6. Test 1 failed upper motor with everything went fine, copter in total control. However, in test 2 when I failed one of the lower motors, the copter went into self-spin and unable to be stopped even with full rudder input, resulting in inability to keep orientation if under FPV. Big thumb down.

Here are the links to the two test videos:

Test 1:

Test 2:

Is anybody able to give an explanation and possible solution to this? I wonder if it's the FC I used that caused the phenomenon, as the difference is huge...

Details:
Y6 300mm arm length
1550 carbon props
DJI WKM
 
Last edited by a moderator:

Dewster

Member
It's certainly way better than a quad losing a prop. The flight controller has a lot to do with the performance of the craft staying level and in the air. I had a flat Hexa that lost a prop and crashed. The new firmware update from DJI is designed to spin the craft to compensate for the loss of one rotor/ESC.

I used different sized props on my Y6. I had Graupner 11x4 on the top motors and Graupner 12x5 on the bottom. My craft would gradually lose altitude with both 11s on top and bottom. The bottom props are already working in disturbed air. They are not working as hard as the top props. I had to compensate by changing the length and pitch of the bottom props. The difference in the props were barely noticeable. I would always have to point out the the bottom props were a little longer.
 

Teamflail

Member
Just did a motor failure redundancy test on my newly build Y6. Test 1 failed upper motor with everything went fine, copter in total control. However, in test 2 when I failed one of the lower motors, the copter went into self-spin and unable to be stopped even with full rudder input, resulting in inability to keep orientation if under FPV. Big thumb down.



Is anybody able to give an explanation and possible solution to this? I wonder if it's the FC I used that caused the phenomenon, as the difference is huge...

Details:
Y6 300mm arm length
1550 carbon props
DJI WKM


Just taking a stab here as I have a decent understanding of aerodynamics from the time spent learning to fly. Most likely having the top motor fail is the better situation as the bottom motor can continue to have it's thrust directed downwards with nothing impeding the airflow. However, when the bottom prop fails and the top prop is providing the thrust, the bottom propeller, will be disrupting the thrust of the top propeller. So, when that bottom prop is just sitting there, it is impeding the thrust from the top. I cannot, off the top of my head, think of a way around this unless the props were like a real airplanes and could be 'feathered', or made to have the smallest amount of drag.

Could be something entirely else but that seems to make sense considering the situation. Hope that helps explain.
 

matwelli

Member
its exactly that Teamflail - if the lower motor fails and the prop is allowed to free wheel, it will react to the air from the top prop and act effectively like a solid disc.

the only way around is to stagger the props so that they only partially overlap

this vid dosent show the the bottom prop failing, but does show what i mean about staggered props http://www.youtube.com/watch?v=LTQYSUMvrPM
 

lunarair

Member
To follow up the thread I've managed to do another test with one of the lower motor unplugged and the prop secured in parallel to the boom - sort of 'feathering' the prop to prevent it's aerodynamic drag when it is windmilled by the upper prop.
View attachment 13163View attachment 13164
The end result - No change at all~~~ the Y6 still spins once it gets airborne. Therefore it seems to me that the spinning motion probably not to do with the drag created by the prop disc, but with some other reasons... perhaps a firmware thing?? But how the hell does it differentiates from upper and lower motor failure??

Further to the motor redundancy, I've done a demonstration for an attempt to fly it back to the home position while it's spinning with one lower motor failed. Please enjoy!


Chit
 

Attachments

  • 2.jpg
    2.jpg
    148.8 KB · Views: 306
  • 1.jpg
    1.jpg
    149.7 KB · Views: 296
Last edited by a moderator:

DucktileMedia

Drone Enthusiast
What camera did you film this with? Some really odd stabilization or something going on when it is on the ground. I also found it interesting that the lower motor didnt have enough vacuum on top of it to at least move the immobilized prop a little and start it spinning from the turbulence.

Another bad reality is if you break a prop, often the adjacent props will break too from the pieces flying outward. Had 5 Xaircraft props break at once one time way back when....
 
Last edited by a moderator:

Top