KDE direct motors on solo?

[RichWest]

Thats fine Rich. The added 'friction' is absolutely negligible as each bearing is only loaded by half the amount anway as they now share the load. The double front bearing also adds to overall shaft stability and bearing life for the same reason.
In brushless motors, the design usually dictates that a smaller bearing must be used in the front as there is less room for a bearing because it is inside the stator windings.
This is the area of highest bearing load, when the copter is changing direction the prop load is held almost solely by this bearing. The bearing at the other end of the shaft is just there to stabilize the shaft.

With the front bearing having to 'do all the work' a larger bearing is preferable to distribute the load to a larger area, but this is not possible due to size constraints, but there is room along the shaft further into the motor, so a second bearing alongside can be used to share the load.

KDE are really good motors. Its awesome that they are leading the way and make a motor of this size with the double front bearing. They previously had nothing in this motor size. The double front bearing is an absolute bonus and will increase reliability overall.

A better quality motor can overcome the noise and vibes we see in the stock motors (the Tmotor mod) and a double front bearing will extend the life of the motor even further.
The main reason I did the Tmotor mod was for a reliability increase, and noise/vibe reduction. If another level of reliability increase is available I would take it, and the KDE with the double front bearing offers that.

The figures on the spec sheet look very good too. (if they can be believed of course)

If I was to turn back time with the Tmotor change mod, I would seriously consider the KDE motor.
I may still 'evolove' the mod and test these as the efficiency figures look very good too.
From what I see and read (and hear from friends who are industry professionals who swear by KDEs) I like them a lot. (and no, I dont have shares in KDE)

And so it was written.... Wow Roland I didn't expect you to explain, but then I'm glad you did. Does make sense for the points you made. I will have to research further to grasp the idea fully.

I've always understood bearings work best when loaded, the manufactures call it pre-loading. The shaft pulls the inner races to align the balls into the races. This tension removes shaft tolerances and slop from the bearings, it's how bearings are designed to interface.

Unloaded bearings will be noisy and will wear prematurely, since the balls are not locked up into the races. Further you can see signs of improperly compressed bearings by the wear shafts will sustain from an inner race oscillating on the shaft. Manufacture will warn you to not spin up bearings using air, as it will ruin the bearings as they are pitting the races. I'd assume the same in a three bearing setup, at least for one of the bearings.

Interesting conversation, something new to ponder...

 

[RolandS888]

In terms of being able to preload the bearings, having a third bearing doesn't change anything, as the inner races are butted up against each other. If you preload one then the axial preload force is on both inner races. The friction from one extra preloaded bearing of these dimensions is surely next to nothing.
The radial tolerances on these are so small (indeed the bearings are so small and cheap) I'd doubt that it would have any impact at all, certainly not enough to belie the benefit of the extra bearing.

 

[RichWest]

In terms of being able to preload the bearings, having a third bearing doesn't change anything, as the inner races are butted up against each other. If you preload one then the axial preload force is on both inner races. The friction from one extra preloaded bearing of these dimensions is surely next to nothing.
The radial tolerances on these are so small (indeed the bearings are so small and cheap) I'd doubt that it would have any impact at all, certainly not enough to belie the benefit of the extra bearing.

Roger that...I can see what you are saying...interesting. Thank you again for the detailed reply.

 

[SPP]

awesome info ...... thanks Roland

 

[n01kn0ws]

Another thing which I had in mind is that KDE kde motors are able to handle 3 props configuration + they can be folded
A lot of solo owners is concerning about fly time and how to increase it by putting bigger battery or they want to lift better (more heavy) camera.
To meet this probably folded, 3 props configuration will meet their expectations.
Another benefit of folding props is that they will fit in to the backpack after folding, there will be no need to screw/unscrew props every time when you want to fly
If I remember correctly from some podcast, owner of KDE direct mentioned that folding props have better fly characteristics than non-folding props.

But this is just my wondering...
Don't know why KDE and solo don't work together since they are both US based. In my opinion if they are highlighting that money don't go to China but stay in US. Why just make an alliance with another US based company who is advertising similar approach?

 

[Bullflyer]

Someone with Axi motors ?
What do you think about these motors ?
E-SHOP | AXI MODEL MOTORS s. r. o.

 

[RolandS888]

Someone with Axi motors ?
What do you think about these motors ?
E-SHOP | AXI MODEL MOTORS s. r. o.

Off topic here....but,
Yes I have tested these. They are primarily for fixed wing aircraft where motor balance doesnt matter so much. Needless to say they have a lot of vibes.
They dont have a MR motor that suits Solo anyway.

 

[rcglider]

It's all a mater of scale. Larger bearings can take larger loads.

The quality of the bearings are very important. The classification of the bearing determines the MTBF and maintenance. I don't have the specs in front of me, but KDE uses the same class bearings as my company does for building high speed precision spindles that must withstand many thousands of hours of operation in an automotive production environment without failure. The machining of the shaft and outer race housing is important to get the most of the design of the bearing. Some require axial pre-load, others do not, but the radial side load takes a beating. Provided the housing specs are tight and bearings installed per the standard, triple bearings are better, period.

This is part of what sets KDE apart from T-Motor and why I will always choose KDE over T-Motor when endurance is important. Go right to T-Motor's website and they recommend 60 hour bearing replacement on their most common motors. KDE doesn't state where the bearings are sourced from (shame on them if cheaping out), but for their 2814XF-515 motors they use ABEC-7 (ISO class 4) bearings, which are are considered top of the line standard bearings. Only ABEC-9 (ISO class 2) are higher precision. They are sealed (as are ours) and require zero maintenance between recommended replacement.

It is completely wrong to say bearing load with respect to triple bearings doesn't make a difference. On our spindles we use two matched sets of bearings at each end of the housing for a total of four bearings. The inner races are trapped, and one end the outer races are pre-loaded with a bearing cap while the other end are free. The entire system is dynamically balanced. Triple bearings absolutely increases bearing life and motor performance. Vibration levels are lower, it is quieter and most of all, increases reliability. Whether mounted vertically or horizontally there are side loads on the bearings radially. Increasing and decreasing the prop speed places load on the bearings radially which is why the bearing must be of high quality. On a skateboard, an ABEC 7 (class 4) is overkill, but on precision motors they are a must for high performance operation.

I have 14 KDE motors without one failure. One copter has 180+ hours of operation with no sign of bearing stress. That's why I switched from T-Motors.

 

[SPP]

Now I am drooling on such bearings.
ABEC scale - Wikipedia, the free encyclopedia

What brand of bearing does KDE uses RC ?

Thanks....

EDIT, some readings for those who wants to know more of bearing Class
Bearing Tolerances and Precision Levels | AST Bearings

"While the bearing tolerance classes primarily control boundary dimensions of the rings, it should also be noted that there are features that are critical to the bearings performance and life that are not controlled by the ABEC (or ISO) specifications. These include: internal clearance, surface finish, ball accuracy, torque, noise, cage type, and lubrication. These items should be specified along with the precision class when selecting bearings to ensure optimum life and performance. In many cases, it is one of these features, not precision level, that when specified properly yields the desired performance and or life."

 

[RichWest]

Well from the details it says NMB and/or NSK with 200+ rated hours ABEC-7

https://cdn.shopify.com/s/files/1/0...-a603-de129ad3eb49_2048x2048.jpg?v=1458253702

 

[RolandS888]

I think you are getting the idea now Rich?
Pity the small KDEs werent around when I did the swap to Tmotor, anyway, they are still performing well.
Nice post rcglider...

 

[Jubalr]

My T-motors are performing well and I have more confidence in them than I did the stock. But for the future, I would be interested in the fit for Solo should anyone give it a try.

 

[RichWest]

My T-Motor swap has been great as well, they are performing as I had expected. I've got no regrets, even within this discussion for the KDE.

The KDE's are 0.8mm larger in diameter than stock motors. As it is, the pod frame may not accommodate the larger diameter without a little mod'ing. Both the Sunny-T and T-Motor "snap" into the pod frame. I'll be curious to learn of anyone's efforts for the KDE in Solo.

 

[pyrate]

waiting on the ones from TBS

 

[Maddog]

Yes it is possible for a 'crappy' motor to take out an ESC if the motor is binding up or has locked (prop banged into something) the current will go above (or spike to well above) the amp rating of mosfet that is switching power to the motor, and burn it out.
9 times out of ten (IMO) if the ESC is found to be burnt out after a crash, the motor is responsible for the failure of the ESC,
Usually the ESC is still trying to power the motor while crash or imact is happening, the props is locked and this overloads the ESC and burns it out.
The mosfets used in a well designed ESC usually have a current rating well above what is required for the normal usage. So long as cooling is adequate there is no reason for a mosfet to burn out for no reason.




It will probably fit. It is less than 1mm wider than the T-motor mod detailed elsewhere.
Im sure it could be made to fit.
Triple bearing is a good thing as it will have 2 bearings under the prop, sharing the sideways load.
Larger motors usually have a double bearing at the top of the motor, its good to finally see a smaller motor with that.
Specs show it is not as tall as the Tmotors.
FWIW I like the look of the KDE, I like KDE MR motors in general, but I think that the benefit against a Tmotor motor change in a Solo would be minimal.
Changing to either motor is a step up from the original stock SunnyT motor

Roland, I can certainly see why the ESC would burn up after a crash if the prop was unable to spin.

But what do you think is causing in-flight motor failures to begin with?

I don't know if you can tell from the logs "why" a motor failure occurred or not. After Solo hits the ground, the "evidence" likely will be destroyed if the motor continues to try to turn but the prop is unable to turn for some reason. In that scenario, if you inspect the motor pod and discover the ESC is burned out, can you determine WHEN it burned out? During flight or after ground contact?

 

[n01kn0ws]

Of topic.

Guys you all are correct but to mitigate any risk and to be certain what failed during flying we need to have parachute connected to solo.. When controller discovers any unusual ESC or motor behavior then all motors should be powered down and parachute released.

I'm hoping that 3dr will release parachute very soon!

 

[Maddog]

Of topic.

Guys you all are correct but to mitigate any risk and to be certain what failed during flying we need to have parachute connected to solo.. When controller discovers any unusual ESC or motor behavior then all motors should be powered down and parachute released.

I'm hoping that 3dr will release parachute very soon!

I don't think 3DR will come through on that but maybe someone else will.

 

[Flashy]

Of topic.

I'm hoping that 3dr will release parachute very soon!

Solo drone extends its capabilities with a parachute and 360 degree camera

 

[Maddog]

Somebody posted that parachute here before. Seems having the extra weight on top of Solo made for a very un-fun flight.

 

[SPP]

My T-Motor swap has been great as well, they are performing as I had expected. I've got no regrets, even within this discussion for the KDE.

The KDE's are 0.8mm larger in diameter than stock motors. As it is, the pod frame may not accommodate the larger diameter without a little mod'ing. Both the Sunny-T and T-Motor "snap" into the pod frame. I'll be curious to learn of anyone's efforts for the KDE in Solo.

in 4-5 weeks I shall report back if I can place this KDE motor on Solo motor pod PCB yah