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You'd think that since the article is about how this motor is a new record in power density (or rather specific power), it would include the specific power in the article somewhere. You would be wrong, but it does include the information needed to calculate it. The SP260D motor they're talking about has a specific power of 260 kW / 50 kg = 5.2 kW/kg. It's not clear if this includes the weight of the batteries or not.

The article says the usual motor for the Walter Extra 330L is 315 horsepower, which is 234 kW. The "E" in the model number "330LE" apparently refers to the electric version.

To contextualize, motor specific power is actually really important for heavier-than-air flight. The reason Leonardo's helicopter designs wouldn't work is a lack of specific power in the (human) motors he had in mind, more than any aerodynamic reason. (Sufficiently high specific powers can overcome even remarkably poor aerodynamics.) The Wright brothers' main innovations were: a workable system for steering, and a motor with sufficiently high specific power.

The bit about the motor's end shield seems to be describing topological optimization, but the description of the process is somewhat ambiguous. It would be nice to see a picture of the end shield and maybe information about how it's made.

Maybe a less clueless, though even more information-scarce, article is http://www.flyingmag.com/extra-unveils-electric-330le

Other commenters are pointing out that this won't work for long-distance flight. The Flying article I linked above says it will actually only last either 5 minutes or 15–20 minutes (it seems to contradict itself, but maybe I just don't understand it.) So it's adequate for aerobatics only. But it should be better at aerobatics than the standard engine was.

Further links from other comments: https://news.ycombinator.com/item?id=12060954 http://www.gizmag.com/siemens-world-record-electric-motor-ai... https://newshour.online/2016/07/04/world-record-electric-mot...




Speaking of helicopters and specific power and weight and all that, it seems an article of faith that eventually an electromotive tail fan will be lighter than all equivalent reliability mechanical or pneumatic systems. I mean sooner or later as magnet strengths and VFD voltages approach infinity and VFD and motor mass approach zero, at some point the rube goldberg mechanics that make the tail rotor spin will be replaced by a near weightless power cable and electric motor.

You don't need a battery to spin a tail rotor... once the main disk stops spinning there isn't much point in keeping the tail rotor spinning.

A hybrid helicopter is an interesting concept, rather than zero torque the instant the engine dies and hope for good luck WRT autorotation technique, even merely giving the pilot 15 extra seconds of battery thrust would probably save some lives.


Pneumatic hoses are pretty light too, and pneumatic motors are usually a lot lighter and more reliable than electric motors of the same power. But maybe you're saying that this is merely a function of low voltages and weak permanent magnets, and we can expect electric motors to get a lot lighter? I guess that's possible; can you point me at some exemplary modern motors?

I tried to write a thing here about the physics of the situation — saturation flux densities and layer-wound armatures and resistivities and dielectric strengths and so on — but then I realized that I don't actually understand the physics of electric motors well enough to say anything coherent. How are electric motors increasing their specific powers — is it just by higher RPMs, or is it a matter of more poles and/or better materials and geometries? What are the limiting factors?


Drexler gets into electrostatic motor scaling in Nanosystems and presumably his thesis. I have no idea about the kind of designs made today, though.


> The Wright brothers' main innovations were: a workable system for steering, and a motor with sufficiently high specific power.

And an airframe that could work with both of those. Langley, for example, had an engine that weighed about the same as the Wrights', but put out 50 horsepower to their 12. But the Aerodrome collapsed on takeoff, rendering that power useless. The Wrights had a mechanically simpler design that was strong enough to cope with aerodynamic forces.


http://www.flyingmag.com/extra-unveils-electric-330le

I am working on the up left side plane in the picture "EuroSportAircraft" it's a highly efficient aerodynamics, our electrical version manages 1 min flight time for each 1kg/2.2lb battery weight.




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