Quote:
Originally Posted by zeropointbug
- IMO, I don't think that would matter would it? I mean if it's an inrunner of equal power is geared for the same speed, then the torque to the diffs would be the same, as all brushless motors have to the same torque curve (straight line)... and yah, it's too bad that any type of slipper can't be used with a setup like this.
I think there are some major differences between outrunners and inrunners in how they make power. The Gap between the two used to be large when I first got into discussions about this. Those were the days of the two pole inrunners.
The Gap has been closed somewhat with the rising popularity of 4 pole inrunners. (I LOVE 4 pole motors btw)
Ok, Let me explain my thoughts as best I can, this way.
What makes power in an electric motor? Any motor?
It is the repelling/attracting forces of the magnetism. Correct?
How much power we can make depends on the strength of the attracting or opposing magnetism. Correct?
So in the Engineering World for Motors, one would think the bigger/stronger the magnets AND the stronger the electromagnetic field is, then the more overall power is going to be produced.
Bigger is More!? Well yeah. But we only have so much space to work with, right?
This is where I feel the outrunner shines.
Measure the stator on an outrunner. I believe an inrunner would be required to have a rotor almost this big to make the same amount of torque simply because of the obvious leverage advantage.
Now, consider the total mass of the magnets spinning inside the outrunner's can. Think about how large an inrunner's rotor would have to be to contain the same magnet mass.
Then let's add up the poles. A 12 pole motor shaft shifts 30 degrees for every commutation from the ESC. This is where the lower kv comes in, BUT there's a torque multiplier at work here too.
How many degrees does the shaft shift on a 4 pole motor? To be honest, I would have to look it up, but it's alot more.
Long Story Short, the outrunner makes its power at a much lower rpm, but it's still all there. Condensed Power at a much lower rpm. This is what I was calling "Explosive".
Where as, the inrunner makes it's power through it's ramp up (spool up) time, and much higher rpm.
Another thought... I was just moving stuff around on the truck and was tilting the transmission 45 degrees one way and putting the motor centered in the chassis. Now if only I could make it work that way without heavily modifying the chassis to make room for it. If it could be done, then the motor would be centered, trans tilted to the left with steering servo on left as well, with Rx/rx batt on right side, and then twin packs on each side, should be 99% balanced then. Still thinkin on the ideas though.  |
I think what you're doing is great. Please share more and take some pictures.
