To answer the original question -- for a 6 pole motor, maximum reasonable motor speeds are limited to around 42,000 RPM (25khz commutation frequency.) Above that, timing will start to fade towards neutral.

And you won't want to go any faster than that anyway -- magnetic losses would be terrible at those RPMs.

Patrick,

you are the "Pro" here
Let me kindly ask you, why you suspect this ?

The motor we were talking about is a Tenshock 2240

22mm Rotor diameter 40mm long

I have a 5T = 3100kv

drkdgglr does have the 2240 as well, just 10T = 1560KV

The theard starter is talking about the 2220/6
Same typ of motor, just an 20mm long rotor.

Don't get me wrong ! I love your products and they are always first choice.
Can't wait to get a Mamba XL in my hands;-) to fill up my Castle collection

Generally, when designing a motor, the motor designer tries to maximize torque per amp/turn. The more torque the motor makes per turn, the more copper can be put into the motor per turn.

We are testing a Castle version of a 2622/1Y (28mm can outside diameter, 48mm can length) motor right now -- it's four pole, and 4200Kv with just 1 turn.
It's a 26mm diameter stator, with a 22mm length.

A 1 turn motor crams a TON of copper into the motor per turn -- yielding low resistance and giving high efficiency.

Lots of turns means less space for copper (per turn), and much higher copper losses in the motor (due to high resistance.)

Also, high pole count and high RPM usually don't work well together. Higher commutation speeds means higher iron losses.

The combination of high pole counts, and high turn count, just doesn't seem to make good engineering sense.

A 2 pole lehner 1940/10 also has approx. 1560kv. These are considered as good motors. Does the same rule apply here or are you specifically questioning the 6pole design?

btw, mine runs at 5s=28000rpm

Patrick,

thanks a lot

Yeah, but the Lehner has the advantage of being a 2 pole. This means that the windings are less critical during forming, and generally low losses in the delta connection.

I just don't see the advantage of a 6 pole slotless motor. I haven't seen one (yet) that comes close to the efficiency of a slotted motor (except the Kontronic Tango - -which is a VERY interesting design...)

Slotless motors have some advantages over slotted motors:

1. Slotless motors have more room for copper in the winding.

2. Slotless motors have very low inductance, which means they are easier to start sensorless.

3. Slotless motors have lower iron losses (due to large air-gap.)

4. Tuning Kv is easier (because of the high turns count -- the differences per turn are small.)

5. Tooling for slotless motors is very inexpensive (in the $5000USD range -- vrs around $50,000USD for a slotted motor -- this is why there are so many slotless motors coming from China -- it's cheap and easy to get started in slotless motors.)

6. Because of the large air-gap, much cheaper steel can be used in a slotless motor without a large penalty in efficiency.

and some disadvantages:

1. Slotless motors generate a lot less torque per turn, and as a consequence, have higher resistance than a slotted motor at the same kV.

2. The windings for a slotless are more difficult to form correctly, so the performance of a slotless motor varies more from motor to motor than with slotted motors.

3. The efficiency of a slotless motor is generally lower than a slotted motor of equal weight and kV, in low to medium RPM applications, due to higher copper losses.

In general, slotless motors work well for low pole count, low torque, very high RPM applications. Slotted motors work well for higher pole count, high torque, medium RPM applications.

This is why I question the high pole count, medium RPM, high turn slotless design. I just haven't seen one (yet!) that works well.

That doesn't mean that this motor doesn't work well - - they may have an outstanding motor. I haven't had an opportunity to test one yet (I haven't even seen one yet!) It's just that in my experience, that kind of design is generally lower performance than a slotted design of the same weight and kV.

The motors work really well !

I have a bunch of them here...

Patrick,

i will send my Mamba Monster for repair to you guys soon, i could put a motor in the shippment to your att if you like

How can I tell if the motor is slotted or slotless? (excuse my noobiness)

First one
Slotless Lehner 1950/8

Second one
Slotted TS 2240/6

The plot thickens... That TS 2240/6 is a really odd motor. 9 slots, 6 poles?

bizzaro -- I'm gonna have to do some simulations.

By comparison, a Neu/Castle is 12 slots, 4 poles.

Yes 6 Poles 9 slots
there will be also an 18 Slot 6pol Motor called X802

And also delta connected on the 9 slot motor. I have a hard time believing that that motor would work well. Magnetic simulation shows fairly poor performance -- but I don't have measurements on the stator, so it's hard for me to determine if they are doing something odd in the stator to make it work. Copper and magnetic losses are extremely high in my simulation.

Very odd motor design. I'll have to get one for dyno testing. I just have a hard time believing that it would work well... But I've been wrong before about oddball motor designs before -- sometimes really weird designs actually work well.

We have currently about 6 of those running and they are doing more than well !
Very ESC friendly and

The Test with the CC2200 KV against the 2240/7 same KV running an AE SC8
was a win for the 2240/7 even on 18/46 gearing

in
runtime
temp
power

On MMP

CC 2200
Runtime: ca. 16 min.
ESC ca. 52°
Lipo ca. 41°
Motor ca. 53°

TS 2240/7
Runtime ca. 16 min.
ESC ca. 48°
Lipo ca. 37°
Motor ca. 44°

Lipo Kokam H5 5000 mAh (older one)
Same gearing 16/46

No datalogs yet need to get the Eagle Tree working

We have a very "humpy" track indoor



[YOUTUBE]WjomGqo8uCw[/YOUTUBE]

Again,

i do love Castles products !!! This is not a sales meeting for Tenshock

Well, this type of testing doesn't really say anything - - really need to test on a dynamometer to be sure.


The CC/Neu 1515 motor was designed to have as flat an efficiency curve as possible, and peaks at about 90% efficient. It's possible to get more efficiency from the motor, but at the expense of efficiency "flatness." -- in other words, it's possible to make the efficiency curve PEAK higher at a particular point, but at the expense of efficiency at the extremes of the curve.

It's very likely that the two motors have their efficiency peaks at different places -- which would make one motor have better efficiency in one particular setup, and the other motor have better efficiency in another setup.

I know ! This is just the experience we gained "live"

Same great experience we just gained with the new SCT Sidewinder....