Comment by VLM | Hacker News Reader

Comment by VLM | Hacker News Reader

The key quote from the linked article seems to be "It’s essentially two concentric radial motors bookended by two axial ones."

My question is where's the cooling? You can put more magnetic field and torque into an ever smaller area, always true, but still going to have to dump heat out via some path. And the bigger the path for whatever is cooling, the lower the magnetic flux density and torque. So I'd be interested in hearing how the cooling system works. Its not like their copper is more conductive than everyone elses copper, LOL.

yetihehe suggests drone use, plenty of air movement there.

Some of the quotes in the article sound very aerospace. Everyone is dancing around the concept without saying it, that the main advantage of removing or downsizing the gear train is along the lines of aerospace style "simplicate and add lightness" which is often much more expensive than it sounds. For example, imagine an electric general aviation airplane, you can't have problems man-rating the electric gearbox if your electric Cessna-172 doesn't even HAVE a gearbox between the electric motor and prop. Likewise for EVs, complete elimination of the gearbox would seem to eliminate all gearbox related maintenance and repairs. Honestly, the car manufacturers might not be amused at the concept of selling fewer more reliable cars. (Edited to add, also see car racing entertainment, if you enter an EV in a popular automobile race, you can't drop out of the race due to gearbox failure if you have no gearbox to fail... is that good or bad for ratings?)

Honestly, the car manufacturers might not be amused at the concept of selling fewer more reliable cars

Competition takes care of that problem. If all but one of the carmakers try to avoid selling “fewer more reliable cars” then the remaining carmaker can sell “way more more reliable cars.”

This is what happened when Honda and Toyota came along as the US carmakers were making very unreliable cars.

Competition does not "take care of the problem". There are counteracting forces that act through competition, and competition is inherently only partially restorative. It reduces incentives but does not eliminate them. Companies will only abandon early obsolensence to the point that it is profitable, which depends almost only on the customers naivete.

Worse, that viewpoint ignores the obvious and numerous counterexamples... Everything from apple (semi-reasonably but certainly in their own interest) killing batteries in older phones to outright conspiracy like the lightbulb mafia.

> This is what happened when Honda and Toyota came along as the US carmakers were making very unreliable cars.

You will note that US automakers are still some of the least reliable in the world. Its also ridiculous to suggest that japanese cars outcompete because of reliability. It was cost. It was also power, size, and quality. In fact when the civic took off in the US it was still not that reliable. Toyota and honda didnt get their current reputation until the mid 90s.

Generally speaking, airplane engines avoid gearboxes for reliability reasons.

https://en.wikipedia.org/wiki/Geared_turbofan

Unlike helicopters, where they are used to drive the tail rotor. Even though dual disk helicopters don't need a tail rotor, they still need a gearbox to balance torque between the disks.

A conventional helicopter might not need to drive the tail rotor mechanically in this manner for much longer: https://www.youtube.com/watch?v=jJUgmeSYox4

The aerospace suggestion would also lend itself to battery-powered passenger flight, which is starting to creep into the realm of feasibility.

But the difficult bit is proving and scaling the tech. It looks like they're sensibly starting small, with e-scooters. I'm reminded of Mazda and the Wankel engine somehow; a "unique" topology that remained niche.

> Honestly, the car manufacturers might not be amused at the concept of selling fewer more reliable cars.

I wouldn't worry about it at all. One EVs become truly mainstream, car manufacturers will start removing redundant components and reducing the amount and quality of input materials, until the reliability curve again reaches the shape they desire.

The article does say:

> Furthermore, by using discrete rectangular coils inset into the stator poles, the HET needs 30% less copper than a motor of similar size. The design also eliminates end windings – lengths of copper that lie outside the stator in a typical motor, generating wasted magnetic field and heat.

So it sounds like less heat is part of the secret sauce.

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