Another one bites the dust - FOUND MY PROP - and other news

[robinb]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

Having a look at the joints in closeup.

The yellow wire is not a fracture, its too clean. It looks cut.

Also with greatest of respect the solder joints do look suspect.
The solder has not flowed correctly at high enough temperature.

 

[Palcuz]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

After soldering wires that thin the wires are only as strong (and as brittle) as the solder. Makes sense that the yellow wire parted where it did- at the point where the solder is thinnest as it was traveling up the wire.

When I was soldering those rctimer motor wires it was VERY easy to overheat the tiny strands. They seemed to blacken as the solder melted or very near the same point.

 

[Palcuz]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

Having a look at the joints in closeup.

The yellow wire is not a fracture, its too clean. It looks cut.

Also with greatest of respect the solder joints do look suspect.
The solder has not flowed correctly at high enough temperature.

The black joint looks "cold".

 

[robinb]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

Yes all the joints look cold.

also the yellow has a cut in it.

 

[mede8er]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

Yes all the joints look cold.

also the yellow has a cut in it.

Hmmmm....I wonder how they make stranded wire....do they butt-weld shorter lengths together to make into larger coil lengths?

 

[robinb]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

no its a continuos flow and is cut when the required length reached/ reel is full.

 

[mede8er]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

no its a continuos flow and is cut when the required length reached/ reel is full.

Thanks...can't wrap my head around such a perfectly straight break like that....

 

[robinb]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

The yellow insulator has been pierced by something (see photo) and cut the wire.

 

[RichWest]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

Hmmmm....I wonder how they make stranded wire....do they butt-weld shorter lengths together to make into larger coil lengths?

To answer your question, the spooled winding wires are not spliced from a wire manufacture. Reasons are mechanical, resistance and insulation. Actual stranded wire is spliced, strand to strand, but it's unlikely you'll ever notice a splice since the insulation is formed over the bundle.

The winding wires are actually insulated by a very thin coating. Mechanical removal is required when it is to be terminated. The insulation can be broken in a variety of ways, heat comes to mind and will further the issue. Bending stress or careless handling are the major reasons. Then again you can buy cheap wire that is poorly coated or the copper is of poor quality, never know until it is QC tested.

I did some research on winding brushless motors, there are several methods for terminating the winding wires. First you can gather the strands and terminate to a larger lead wire. Or you can gather the winding wires and then terminate to the end point, obviously heat shrink is applied to the exiting bundled strands. This is from a DIY perspective. From that they caution on pulling the wires to tight, to either cause a gap in the insulation or stress/thin the already fine wire.

I really don't know if any of this information is helpful at all. I think the problem lies in the motor rather than the ESC. Up to this point I think DJI's QC is very poor. Failure rate seems high based on limited feedback from users making it to our forum. Fortunately, those with V3 have a warranty claim, hopefully. Those that upgraded themselves are SOL. Sad all the way around...

 

[burlbark]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

Nope not a cold joint issue. How about metal vibration fatigue along with inadequate wire gauge for the current? Cold joints result in separation or voltage drop, not broken wires.

There is allot to speculate on but there is only one answer. http://forum.dji.com/forum.php?mod=view ... D1&lang=en

 

[gunslinger]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

Nope not a cold joint issue. How about metal vibration fatigue along with inadequate wire gauge for the current? Cold joints result in separation or voltage drop, not broken wires.

There is allot to speculate on but there is only one answer. http://forum.dji.com/forum.php?mod=view ... D1&lang=en

I wasn't aware of that topic... Things are getting interesting here... WTF was DJI thinking???

-slinger

 

[SteveMann]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

Yes all the joints look cold.

also the yellow has a cut in it.

Is this how it came from DJI?
The Red and Black are unacceptable cold joints and the yellow looks like it broke from vibrations.

 

[garrock]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

QUESTION: Is it possible for any of the four ESC's to be electronically driven backwards ???

• 
  There's been a lot of text responses streamed in this report-thread; don't know if this has been raised as an awareness item.

If so... then DBS needs a search party to find that missing prop; for the entire Phantom Pilot Community's sake.

If the missing prop is a distance away from the crash site, and the condition of the prop hub is good, then the above statement is a strong candidate.

We need our own NTSB; an Open Collective of flight failure submissions with: a multi-party multi-discipline analysis of field failure report submissions. No Bureaucratic information blocks or Pay Walls.

• 
  
  DBS (Downed Drone 2) Field Report Visual Evidence:
  http://www.phantompilots.com/viewtopic.php?f=27&t=32035&start=40#p293793

 

[locoworks]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

regarding solder joints, a hot high wattage iron is best with the biggest tip you can use to do the job. the joint needs to be made quickly so there is no chance of heat building up in the copper wire strands on the motor wires allowing molten solder to wick its way up the strands inside the insulation and turning a flexible wire into a solid one more prone to fracturing due to vibration. I wonder is it worth epoxying the motor wires onto or near the ESC board so any resonance in the wire isn't felt at the ESC solder connection.

also try and get solder with lead in it, not available in some parts but it runs so much better than lead free eco friendly health and safety stuff.

 

[garrock]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

... the joint needs to be made quickly so there is no chance of heat building up in the copper wire strands on the motor wires allowing molten solder to wick its way up the strands inside the insulation and turning a flexible wire into a solid one more prone to fracturing due to vibration.

excellent advise; the joint becomes more brittle the more solder ingresses into the strands. That is why a terminal crimped joint as been industry practice for so long; while size, weight, and cost influences implementation factors.

However, it's more likely that Mechanical Shock is the brittle solder joint's mode of failure (shock being a very high deceleration impulse).

If that is the case, then Shock could very well have been created during an Air Frame impact event.
But the missing prop appears clean looking as if the prop flew off before impact.

SO.. the original point of failure could have occurred during flight; an electronic control failure; the ESC spun backwards; and while we chase a broken wire as the mishap.


DBS needs a Black Box Search Team to find that missing Prop.

 

[mede8er]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

i"m going up Sat...I'll find that sucker....

 

[DBS]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

Jeeez... Just look a the color wires in DJI's own marketing photo. Sure looks like the wires are insulated with heat sensitive heat-shrink material. If that's a new motor, the insulation should be perfectly symmetrical around the wire. Why in the world would they choose to do that??? Cheaper? Not enough insulated wire available? Has anyone confirmed it's heat-shrink material they are using?

It's because they just extended the wire used to wrap the motor windings long enough to reach and solder to the ESC...

Looks like a set of two are bundled together and heat shrink is slid up to the coil ... There's some markings on the heat shrink that aren't wire gauge markings look more like temperature and diameter.

You can see the two strands here...

 

[arich666]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

Yes all the joints look cold.

also the yellow has a cut in it.

Is this how it came from DJI?
The Red and Black are unacceptable cold joints and the yellow looks like it broke from vibrations.

Someone correct me if I'm wrong, but I think the OP did it himself. I know the other thread, by frank..... was modded by him.

 

[garrock]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

Oh Hell..me eyes did not connect to the two-thick-strand insulated wire !
yeah.. heavily failure prone.

Still. does not account for the missing prop; and if found how that can change the outcome.

 

[burlbark]

Re: Another one bites the dust -UPDATE- found it!! - Page 5

Jeeez... Just look a the color wires in DJI's own marketing photo. Sure looks like the wires are insulated with heat sensitive heat-shrink material. If that's a new motor, the insulation should be perfectly symmetrical around the wire. Why in the world would they choose to do that??? Cheaper? Not enough insulated wire available? Has anyone confirmed it's heat-shrink material they are using?

It's because they just extended the wire used to wrap the motor windings long enough to reach and solder to the ESC...

Looks like a set of two are bundled together and heat shrink is slid up to the coil ... There's some markings on the heat shrink that aren't wire gauge markings look more like temperature and diameter.

You can see the two strands here...

How lovely, solid strand wire in a vibrating platform. Also a thinner gauge far away from the copper mass that would allow it to heatsink... Awesome engineering...