SoylentNews is people
SoylentNews
What's wrong with the prop-powered, drone-style VTOL flying car designs we're seeing all over the place? Ignoring the energy density issues that are holding the entire electric aviation industry back, multirotors are quite noisy, and they have basically no adequate safety systems in place if the power systems fail.
A somewhat mysterious startup called Volerian claims to have a solution for both these points, and it uses a very odd propulsion system we've never run across before.
The system places a large number of flapping wings inside a series of precisely shaped ducts. The wings are driven by cams on a rotating shaft, such that they flap back and forth quickly between the walls of these ducts, much like the tails of fish. A second fixed "stator" wing is mounted further down the ducts "to further increase efficiency," presumably by messing with the swirling pressure vortices created by the flapping wings.
The company claims its furious flappers not only make less noise than a comparable multirotor setup, but that the system is safer as well. In the event of power loss, the wings can be released to flutter against the airstream coming up through the bottom of the vents as the aircraft falls, acting a bit like a parachute. Not to mention, there's no rotating decapitators in the system to worry about.
New Atlas's current issue highlights half a dozen startups that are hoping to make air taxis a reality.
(Score: 2) by Immerman on Tuesday April 14 2020, @09:48PM
Why?
No, seriously, think about it for a minute. Battery tech is big business, and is beginning to advance rapidly. A startup developing new vehicles and propulsion technologies based on where battery tech will be in 10-20 years once your technology is mature is good business sense. There's a risk that the batteries won't be ready yet, and you won't get the range you were designing for - but for now the electric aircraft being designed are mostly novelty toys for the rich, and small short-haul vehicles. Both of which are already seeing adequate (or at least nearly adequate) range from existing batteries. And when much improved batteries become available years from now, these start-ups will be in position with mature technology, while the big players that would normally eat them for breakfast will still be running the same basic fuel-based engines they've been using for many decades already.
Meanwhile synthetic fuels don't actually solve anything. Either you make them compatible with current engines, in which case it's not really relevant to vehicle design, or you have to do a whole lot of new design for a temporary solution that will be obsolete once better batteries are developed.
More importantly - where is the energy coming from? Synthetic fuel is just a storage medium. A thermo-chemical battery if you will. You need to deliver the same amount of total energy to the aircraft either way (actually, about 3x as much with fuel since turning the heat from burning fuel into mechanical energy is terribly inefficient). Even if you're 100% efficient at converting energy to synthetic fuel, you still need to generate the energy - and our grid is nowhere near clean enough yet for that to be much of an improvement. If you're burning 300kWh of coal to generate 300kWh of synthefuel, to deliver 100kWh to the propellors/turbines/whatever-shaft, you haven't actually improved anything.
Electricity also has another big benefit - it's fuel agnostic. If you come up with that great synthefuel - just use a fuel cell and gas tanks instead of a battery - it's only a minor design change, probably consisting mostly of converting uneeded battery space into room for more payload. If you need to use a generator rather than a fuel cell, then you're bringing that terrible inefficiency back into it anyway and may be better off skipping the "electric transmission".
Finally, electricity has one other huge benefit for aircraft even if you're only using an "electric transmission" - you can put the thrust wherever you want, which can boost efficiency and handling immensely. For example, I understand the best place to put engines for various aerodynamic purposes is at the tip of the wings. You can't do that with big, heavy, fuel-burning engines though - the wings have to be made so strong to support them on the ground that you lose all the benefit. The electric motor that delivers the same power though is much smaller and lighter, so that it's no problem at all.