[tedsanders]

I think it's very unlikely that airplanes will be battery powered in the medium-term future. The chemical energy stored in hydrogen bonds is just so much denser than the electrical energy stored in concentrated lithium ions.

I know that battery-powered planes have been built, but it just seems so uneconomical to me. Do you have evidence that could persuade me otherwise?

Or perhaps am I misunderstanding? By light aircraft do you mean aircraft less than 100 pounds or something?

[marvin]

In short, I strongly believe that you're incorrect. (Note: I'm talking about general/recreational aviation here). dchichkov mentioned the Antares, which is a high-performance electric self-launch sailplane. In this category, there's also the Pipistrel Taurus G4. Lots of other electrically-powered light aircraft exist, and they are all held back by battery weight, volume and cost.

There is a large number of advantages to electric propulsion vs. combustion engines in aircraft: Much lower maintenance costs, simpler maintenance, higher reliability (in gliders, replacing two-stroke engines with electric motors yields a huge safety advantage), lower fuel cost, simpler operation (less possibility for human error), less noise, lower weight (ex batteries), smaller volume per unit power, higher efficiency, lower purchase cost. The only real disadvantages are low energy density and charging time/infrastructure. At some point in the medium-term future (~5 years) we will hit a point where the benefits obviously outweigh the disadvantages for many use cases. In fact, I think the inflection point has already been hit wrt. the battery tech, it's just that it isn't obvious to anyone who isn't intimately familiar with the progress in battery pack cost development. Give it a couple of years.

Even this list of advantages disregards the fact that the mechanical simplicity of electric motors enable aircraft configurations that haven't been tried at scale, for instance gimballed/swerving variable-geometry ducted-fan propellers, etc. Electric motors are also not dependent on high air pressure to get enough oxygen for efficient combustion. There's just a huge new design space that opens up when you have sufficiently powerful battery storage. Super exciting.

Pay attention to the drone aircraft companies, they are the ones in a position to drive this shift.

[tedsanders]

Thanks for the detailed response! Do you think there's any chance that these electric planes will used for cargo/passengers? (Or do you think they'd mainly fit into the recreation/tourism/short-hop flights? Are there other current/future plane uses that I'm not thinking of?)

[marvin]

I'm agnostic in that regard. Some very smart people (notably, Elon Musk) have said that electric propulsion is the future also for passenger aircraft in the more distant future, but I have not seen any detailed reasoning or numbers to indicate how this would work.

Presumably, there would have to be huge efficiency gains over combustion jet propulsion since the energy density of batteries would in any concievable circumstance be much smaller than hydrocarbon fuels. One possibility would be to fly higher, utilizing the smaller air resistance and the fact that battery-electric propulsion does not have the oxygen limitation with altitude that combustion processes have, but I haven't seen a detailed argument regarding how plausible this is.

If we ever build a "flying car", it will have to be electric and use fixed wings in addition to propellers since this is required for generating energy-efficient lift. In the "short-hop"/low-speed/personal transport category, there will definitely be possibilities.

[dchichkov]

AFAIK electric airplanes have been around for 10 years or so. Antares 20E came out around 2003. And now there are plenty others: http://en.wikipedia.org/wiki/Electric_aircraft#Production_ai...