Redundancy, What's your experience?

S

Sebas600

Member
Hello,

I've got an octo and today the prop-nut of one rotor came lose.:cold:
Well it didn't fall out of the sky like a brick but a smooth landing it wasn't:upset:
Broke one arm (fortunately the octo's so has some left :shame:) and of corse it landed in a puddle of mud, witch is on everything.

Next up, throw away standard AXI nuts and get self locking.

The reason for going for an octo was the redundancy factor.
And I kind of expected the DJI-WKM to correct the lost engine but it did nothing!
I had to pull stick to the max to make the correction myself, but this wasn't enough
Was i expecting to much on this one?
I've seen some video's of an X8 where there is hardly any problem spotted.
To bad the video didn't make it. don't know what went wrong there but the cam does not show the file.

Setup:

Droidworx AD8-HLE
8x Turnigy Plush 40amp
8x AXI 2814/22
DJI-WKM FC
AV200
Futaba 10CAG
R6208SB s-bus controlled

Damages:

1x 410mm carbon boom E 40,-
1x engine mount upper part E 12,-
3-5 hours work/cleaning

making a total of E 52,-

Conclusion:

Use self locking nuts for props.
DJI-WKM doesn't correct itself in case of prop failure.
 


DucktileMedia

DucktileMedia

Drone Enthusiast
interesting. Good to know my hex has a chance if a motor or 2 fails. I think your octo has a setting wrong somewhere. that just seems wrong it would at least try to compensate. My Xaircraft x8 had 2 props fly off mid air and it came down smooth enough to not cause any damage.
 

R

RTRyder

Merlin of Multirotors
The ability to maintain flight after loss of a motor depends on a lot of things, not just the configuration or number of motors. Weight and balance play a big part, is there enough thrust to keep it in the air with 1 less motor? Is it balanced enough that loss of any motor will not be a problem or is one or more motors supporting more weight than the others?

In some cases the flight controller may be the determining factor and that may be the case here, the WKM likes everything to be in balance and working, something like an MK controller can compensate for a major imbalance, at least in the short term.

For the most part an octo ahould be able to continue flying after the loss of a motor, for it not to is a red flag that something isn't quite right. For a hex to continue flying after loss of a motor is more pure luck than anything else, it really is the exception rather than the rule. If you want the most redundancy possible use a Y6 or X8 configuration, that way there will still be lift at each corner if a motor goes out, then the only thing to worry about is a tendency to yaw more due to the loss of a motor but that can be dealt with.

Ken
 

redridinghood

redridinghood

Member
Maybe DJI throttle by wire system provides no retunduncy from a lost motor. I pulled my wkm in favor for a MK on my SkyJib. Maybe someone can test. You need to first power up and hover with all motors then remove a prop and try again to hover.
 

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