
Hunstable Electric Turbine can produce up to 3x the torque of other motors - jchanimal
https://www.autoblog.com/2020/03/08/hunstable-electric-turbine/
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VLM
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?)

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chongli
_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.

~~~
hwillis
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.

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hwillis
Light expert analysis of this motor (it's nothing special and not
manufacturable): [https://www.anttilehikoinen.fi/technology/evaluation-of-
the-...](https://www.anttilehikoinen.fi/technology/evaluation-of-the-linear-
labs-het-motor/)

~~~
rndmio
Having read the article you linked that seems to be a misrepresentative
summary of it.

~~~
murkt
Yep, I've also read the linked article and for me the summary is more like
"HET motor has some interesting ideas, some difficulties, some claims are
incorrect and it's probably a bit difficult to manufacture."

~~~
hwillis
Interesting ideas- _kind_ of, but the interesting ideas are not new.
Dimensionality is one of the oldest formulated motor-related problems. Hybrid
rotors are certainly an active area. The motor is a pretty novel and clever
way to draw all these things together, but it's not the kind of thing to build
a product around.

Some difficulties- these are fundamental issues. They are fundamentally
unsolvable with the suggested architecture. Eg anything that adds cooling back
in will conflict with the rotors or coils.

On manufacturability:

> Flux paths in the teeth seem very much 3-dimensional, which would require
> sintered materials to be used to limit eddy-current losses.

This _really_ belies how much of a fucking nightmare this would be.

First, an unrelated area of development: grain-oriented electrical steels have
30% higher permeability (in one direction) than non-oriented steels. People
are actively looking to ways to orient steel grains into the arches necessary
to make a motor, because even small improvements in permeability can lead to
smaller and more efficient motors. A 30% improvement would be incredible, and
justify a large cost increase since the cost of motors is effectively
determined by the electricity usage.

The permeability of sintered soft materials is at best ~1/10th that of the
electrical steel used in motors. So... thats a huge issue. Its also much more
expensive. Its also mechanically unsuitable for high torque motors, because
it's weak and brittle. It also has much higher losses.

The shape of the stator would also require entirely new technologies to even
make. Die-sintered powders are very precise in two axes- since you're pressing
into a mould, you can rely on near-thousandth repeatable tolerances once you
have accounted for shrinkage after sintering (which can take multiple tries to
get right). That third axis is a real bitch. Powder will never be consistent;
you cant apply hundreds of tonnes of pressing force _and_ be precise to
thousandths of an inch, and even if you can get the force repeatable the
compressability of powders varies too much between batches due to grain shape
and size, temperature, additives, humidity... And even if it was consistent,
you cant design for that. You can only adjust a ten thousand dollar mould
after the fact.

And that z dimension is the most critical, since any asymmetry will cause
uneven forces on the axle bearings. In a normal motor you can trivially be off
by several hundredths of an inch because the axial force is negligible. In
this design a thou will cause a large force imbalance, so each motor will need
to be a precision part. Even variations _inside_ the rotor will cause large
vibrations, so sintering + heat treating will be a nightmare. Not to mention
that the magnets will have to be matched individually, both for size/thickness
and permeability tolerance.

If my boss wanted me to produce this thing, I'd quit.

~~~
murkt
Thanks for a detailed response, it's quite informative and educational.

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JoachimS
Previous discussion on HN:
[https://news.ycombinator.com/item?id=20660403](https://news.ycombinator.com/item?id=20660403)

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justlexi93
The motors are not really taking up a lot of useful space in the car and are
not underpowered by any stretch so this tech needs to be price competitive.
Like Hyundai said batteries are where we need to see advances.

Don't get me wrong it is interesting and I am glad to see advances but I don't
see this as a terribly useful advance today.

~~~
yetihehe
I see it as a BIG advance for small drones. The same torque from smaller
engine where every gram counts is a big win, you can replace that weight with
more battery.

~~~
kragen
What counts there is power density, not torque density, isn't it? Quadcopters
don't typically gear their motors down, instead preferring to pitch the rotors
at shallow angles of attack.

~~~
yetihehe
So, better for racing drones, they will be able to change speed of propellers
faster, they already use higher angles to readuce propeller speed (gyroscopic
effects are killing maneuvring). Shallow angles are better for efficiency.

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yalok
Nice to see Brad making a dent in a completely different domain, after having
had a successful video streaming company.

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TeMPOraL
So I was wondering whether "Hunstable" is some new technical term like
"h-unstable", or some kind of wordplay on "unstable". Turns out it's just the
surname of the creators.

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awefiawejfl
Reminds me of another "revolutionary new motor design" from a few years ago
that promised greater efficiency than any other motor ever built. That one had
an out-of-context praise blurb from an MIT professor, which is clearly better
than an out-of-context praise blurb from a UT professor. At best, this is a
solution in search of a problem. And until it's tested and certified by an
independent party, it's not even that. The whole company reeks of dumb-money
snake oil and I'm putting this in the same category as Juicero.

~~~
londons_explore
Not all new motor design promises are trash though.

The brushless DC outrunner motor, which used to be a niche design due to the
complexity of the control circuits and expense of permanent magnets now seems
to be used in nearly everything new. Most electric cars are moving towards it,
electric bikes, hoverboards and escooters, and it's used in every drone, some
electric powertools, etc.

I think it will be in next-gen trains, and will become the 'standard' motor to
replace current uses of AC synchronous motors in factories, mostly due to its
ability to brake and regen power when stopping, meaning it gets less hot.

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extropy
Call me when they have put it on a dyno next to a Tesla or some other
reasonably efficient EV powertrain.

Until then total snake oil crying for attention.

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mrfusion
Haven’t I heard robotics needs more powerful motors to be viable? At least for
household uses.

~~~
ithkuil
Larger power density also means less weight for the same power.

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jacobush
Still cool if the gearbox can be omitted in car applications.

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Narkov
Do EV's have gearboxes?

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JoachimS
Some do, some don't.

The Koenigsegg hybrid (so not strictly an EV, but can be operated as a pure
EV) famously don't have a gearbox but a single, fixed reduction gear. There is
a hydraulic coupling for the electrical motors to allow slow speeds. At higher
speeds the coupling is mechanically locked to directly connect all engines to
the wheels.

[https://en.wikipedia.org/wiki/Koenigsegg_Regera](https://en.wikipedia.org/wiki/Koenigsegg_Regera)

[https://www.koenigsegg.com/car/regera/](https://www.koenigsegg.com/car/regera/)

~~~
balfirevic
There seems to be some language confusion here. Single speed gearbox is still
called a gearbox.

