Ultralight lithium-sulfur batteries for electric airplanes

Re:Ultralight lithium-sulfur batteries for electric airplanes by Shivetya on Wednesday August 19, 2020 @03:43PM (#24215286)

However you are ignoring that while you can spin the blades more efficiently, however scaling an electric motor to that size may end up with even more weight, you also have to replace the turbojet portion of these motors. So you will need even more engine. That turbo jet is more efficient at speed while the fan is better at lower speed.

In the end we would have slower planes but we will eventually reach a point where we can do it.

Someone can probably explain it better and my understanding is rough and not current; jets were cool when I was kid

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Re:Ultralight lithium-sulfur batteries for electric airplanes by hwillis on Wednesday August 19, 2020 @05:02PM (#24216423)

Your speculation about motors is incorrect; motors are actually more efficient the larger you build them. It's a property of the goodness factor: https://en.wikipedia.org/wiki/Goodness_factor

It is profoundly foolish to compare motors and heat engines on first principles like this, obviously. Still, here's a turbine that handles 30x the power of a jet engine, running a generator that is about the same size as a jet engine: https://www.ge.com/news/sites/default/files/Reports/uploads/...

generator is in the upper left. Obviously not at all optimized for size or weight- there aren't even any magnets in that thing.

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