AutoblogGreen

One thing that has got me wondering is: what is the future of electric aircraft?

Currently working toward commercialization, there are no fewer than three techs that promise to 2-3x the current energy density of li-ion batteries (lithium vanadium oxide, siliconscimi nanowires, or barium titanate supercaps), and possibly as much as 8x it. That clearly makes electric vehicles superior to gasoline on every front -- especially operational costs. But what about electricity for propelling aircraft?

Saving aviation fuel is a big deal in terms of cutting costs, as is reducing maintenance, so turboprops, which are already cheaper to operate than jets, would probably convert and become even cheaper to operate. But what about jets? Sure, electricity *could* create the heat that is the fundamental core of a jet's operation, but this is counterproductive; electric engines only would compete with gasoline because they *don't* have to go through the losses that all heat engines have to go through. It'd seriously underperform. I see two ways that electricity could make inroads into jet operation.

1) "Hybrid" jets. Currently, the compressors in jet engines (and really, all components, such as the fuel pumps, aircraft hydraulic pumps, and so on) are driven by the engine itself. Part of the energy of the expanding gasses is lost to drive a small turbine that spins the compressor and powers everything else. Rather, an onboard electric power source could spin the compressor (the compressor itself could effectively become a big electric motor core) and drive all of the pumps; it would do this all very efficiently. In exchange, you'd get more thrust out of a given amount of fuel since no energy is being wasted running a turbine. It'd probably also make the engine a little cheaper to produce and maintain.

2) "Scimitar" turboprops and profans muscle in. Most people are unaware that there are prop planes that can go as fast as jets -- ~550 mph for turboprops and >600mph for propfans. These planes use counter-rotating props whose propellers are designed to operate at supersonic speeds; they're "scimitar" shaped, mimicking the wing shape that supersonic jets use to minimize problems with shocks. They also use a dozen or more blades per engine so the engine can operate at lower RPM. Like ordinary turboprops, the driving of the propellers could be efficiently converted to electricity. Scimitar designs are currently supposedly cheaper to operate than jets, but they're very noisy, and that's limited their use. Turboprops could eliminate fuel use altogether. Propfans are a hybrid of a turboprop and a jet; they get higher speeds than turboprops but use less fuel than jets. So, the big question would be whether noise reduction could manage to make these two techs more competitive via an electric drivetrain.

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Check out this beauty:
http://www.lange-flugzeugbau.com/htm/english/products/antares_20e/propulsion.html

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wouldn't it be a lot more green not to go at all?

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