Putting the motors in the wheel is bad for a separate reason: Unsprung weight.

Every ounce you have in the hubs that don't float on the suspension reduces certain suspension attributes. You end up with a crappier ride and poor performance.

▲

toss1 3 days ago | parent | next [-]

Exactly this, which is why I'd expect automakers to use the short axles and CV (constant-velocity) joints which are already well-developed technologies for 4-wheel independent suspensions

I see no reason the small motors can't be mounted inboard from the wheels on the underside of the chassis, as are a rear differential or front transaxle in an ICE car.

Having such a small and lightweight power package opens up serious design and performance opportunities. Plus, even without major redesign to take full advantage, every reduction in weight rolls through the system, providing immediate improved acceleration, cornering, & braking or similar performance using smaller tires, brakes etc..

▲

Lio 3 days ago | parent | prev | next [-]

Yes, I agree. I was careful about how I worded this to avoid saying anything about the motors actually being in the wheels for this reason.

Although, I guess at some point in the future if we can get the weight down low enough and the strength of the motor high enough we could replace the existing braking system with a motor for the same weight penalty we already pay.

In an ideal world all the energy from breaking would be used for regen anyway.

I'm not sure how close we are to that but it's an interesting thought experiment thinking about the trade offs we might be able to make in future.

▲

hawk_ 3 days ago | parent [-]

Deceleration requirements are going to be harder than acceleration, one would think so how would you apply full brakes with the same motor?

	▲	DontBreakAlex 3 days ago \| parent [-]
		I mean if your have a 750kw motor for each wheel, then they're probably always spinning when you floor it, so you also have enough torque to fully use your tires for stopping purposes EDIT: Quick maths show that decelerating at 1g (basically what the best sport tires can do) in a 2000kg car at 300kph requires absorbing ~1500kw, so conveniently two of these motors.

▲

duskwuff 3 days ago | parent | prev | next [-]

If the motors are light enough, though, that might be acceptable... especially if they can make an even smaller version for that application. (You probably don't need 750 kW on each wheel - even for a supercar that'd be excessive.)

▲

fragmede 3 days ago | parent [-]

fwiw four of those electric motors is approximately 4,000 hp. You won't get better 0-60 times with that though, at that point, you're limited by the tires' physical limitations. So at best you could get down to a ~2.2 second 0-60 mph time with regular tires, and then after that, you'd need race sticky tires in order to go faster.

Unless you used the motors to power fans instead, then you could use that for downforce and propulsion, and get well belown 2 seconds, theoretically.

F1 cars with fans to run them upsidedown but with remote drivers for their safety maybe?

	▲	ImPostingOnHN 3 days ago \| parent [-]
		Yeah, the potential here reminded me of the McMurtry Spéirling, which uses fans for active downforce, and gets 0-60 in 1.4 seconds. Top Gear Video link: https://www.youtube.com/watch?v=HPZxcfglU2Q

▲

dzhiurgis 3 days ago | parent | prev | next [-]

Maybe fine for non-performance vehicles, especially considering you can remove driveshafts and brakes.

▲

UncleOxidant 3 days ago | parent | prev [-]

But these are 28lbs which isn't a lot to have in the wheel. Considering that this is the 1000 HP version you definitely don't need 1000HP in each wheel, but maybe they could come up with an even lighter 100 to 200HP version?