From the comments section
" The carbon wrapped stator comes from rockets, let me explain. In rockets we use carbon over pressure vessels to make tanks, these are thin metal tank that are wrapped with thin strip of carbon fiber, these can take pressures of 5000 psi. With the magnets in the motors trying to push away from each other using carbon fiber wrap makes sense so you can hold in the magnets even tighter. If you use a woven cloth then the seam becomes a weak point of failure which would cause the motor to explode, wrapping is the only way they could do it."
" In other words this is rocket science applied to Tesla EV's - again (other one I remember was structural body design) "
Well I'm glad they brought that up so I don't have to! I remember Elon talking about the carbon over-wrapped rotor during the
Plaid delivey event, and clearly there is no other way to make the rotors strong enough to survive 20,000 rpm "
or maybe a bit more", as Elon put it.
Elon also said they had to design and build their own huge custom wrapping machine to spin the carbon fiber thread tightly enough around the rotor. I don't recall offhand, but it's some crazy number like 20 megapascals tension on the carbon fiber required to get that pressure. Elon loves to geek-out!
I laughed a bit when Sandy said he "
didn't like it" and that he would have done it differently, because they had a customer who uses carbon wraps for, what was it, sewing machines? and he likes knitted carbon wraps more because it "
slides on easier". Bah ha ha! Do you think
megapascals slide easy, Sandy?
Its pretty clear that Sandy didn't watch the Plaid reveal event (or might just not have understood the significance of what Elon was saying) But hey, I cut Sandy a huge amount of slack because he clearly gets it about what Tesla is doing with innovation and manufacturing, and he admires good ideas and great engineering. Not a bad style of living.
Cheers!
P.S. Its the rotor that is carbon over-wrapped, not the stator. Stators don't spin, thus don't need to resist centrifugal the forces of high rpm. The rotor in the 3/Y is fine since the even the P model of the car is electronically limited to 163 mph, but with the Plaid S they wanted to hit 200 mph so that's ~20K rpm.