Heaviside can take advantage of slim and low-drag aerodynamic forms that are just not practical on cars

Thursday, May 28th, 2020

Electric vertical takeoff and landing (eVTOL) aircraft can be surprisingly energy-efficient:

Under the EPA’s standard freeway driving test, a 2020 Nissan Leaf Plus uses about 275 Watt-hours per mile when it averages 50 miles per hour. It can comfortably seat four, but its average occupancy is somewhere around 1.6. Thus, the Leaf’s energy consumption is about 171Wh per passenger mile across all trips.

Our current Heaviside prototype uses about 120Wh per passenger mile, and does so at twice the speed of the Leaf: 100 miles per hour (of course, we can fly much faster, if we choose). We can save another 15% of energy because while roads are not straight, flight paths usually are. All together, Heaviside requires 61% as much energy to go a mile.

Why is Heaviside this efficient — doesn’t it take more energy to go faster? Yes, and it makes the high efficiency we’ve achieved even more dramatic. The answer is that Heaviside can take advantage of slim and low-drag aerodynamic forms that are just not practical on cars.

Comments

  1. David Foster says:

    “We can save another 15% of energy because while roads are not straight, flight paths usually are.”

    Flight paths will get a lot less-straight if there are thousands of these vehicles in the air at the same time and the realities of collision avoidance must be considered.

  2. Bob Sykes says:

    As usual, the authors neglect the source of the electricity. In Ohio it is mostly coal.

    During the Clinton administration, the Dept. of Energy developed a procedure for estimating gasoline-equivalent fuel efficiency for electric vehicles that actually took the electricity source into account.

    The typical electric car, Tesla for example, gets an EPA rating of about 95 mpg (gasoline equivalent) but as in the article above that only accounts for the electricity drawn from the battery. The true mileage of electric vehicles is about 35 mpg (gasoline equivalent).

    This is one of the many subtle frauds perpetrated on the public by political activists.

  3. C. Matt says:

    True, but the article claims two standard rooftop solar panels could provide the power for the average (16 mile) commute. Assuming that is true (no mention of how long recharge time is) that would put it back at quite efficient.

    Of course, that also would require a lot of investment in infrastructure. But we are too busy playing in the mid-east sand and destroying our economy over a cold.

  4. Dave says:

    VTOL means freedom from traffic congestion, forever. There is simply no way that people who populate a two-dimensional surface could ever saturate a three-dimensional airspace. We couldn’t maintain one-mile separation between aircraft like today, but with good collision-avoidance software, we wouldn’t have to.

  5. Ezra says:

    Decades ago I remember reading that since the end of WW2 about forty cannot miss prototypes of such VTOL passenger aircraft had been designed and had flown successfully. The last one I remember reading about looked indeed like a flying saucer, could hold pilot and one passenger, had eight fan-duct engines and four computers. Was as I said a cannot-miss. But then nothing more.

    And would not be more difficult to drive than a car. Everyone that piloted a plane knows that flying and driving a car are not the same. Hardly.

  6. TRX says:

    “True, but the article claims two standard rooftop solar panels could provide the power for the average (16 mile) commute.”

    In plain English, that is known as “a damned lie.”

  7. Freddo says:

    Ha, we have been here before: https://www.isegoria.net/2019/10/go-anywhere-and-land-anywhere-quickly-and-quietly/

    In my opinion the requirements of all-weather capability and crash resistance (esp. with human cargo) will favor road transport for a long time. However, with the rapid advances in drone technology and self-driving AI it may already be viable as a rich people toy. Avoiding travel lockdowns in a future quarantine situation (even if only by a couple of hours) may be an interesting sales pitch.

  8. Huey Pierce Long, Jr. says:

    1. Glide

    2. Slope

  9. Lucklucky says:

    “VTOL means freedom from traffic congestion, forever. There is simply no way that people who populate a two-dimensional surface could ever saturate a three-dimensional airspace. We couldn’t maintain one-mile separation between aircraft like today, but with good collision-avoidance software, we wouldn’t have to.”

    In a car you can stay 10m from another vehicle.

  10. Dave says:

    Cars maintain that 10m spacing on a two-dimensional surface, most of which isn’t road. Even if aircraft are required to maintain 100m spacing, we still won’t ever run out of sky.

  11. Peter Whitaker says:

    The biggest limitation of electric aircraft is noise. Any aircraft capable of carrying a person will inevitably be extremely noisy.

  12. Bruce says:

    It looks like a fair weather airplane, which to be fair almost all airplanes are. And I bet it gives off too much radio noise to be useful for sneaky military stuff. But it’s PRETTY and I LOVE IT.

  13. Sam J. says:

    I’m very pro electric cars, planes, whatever because it gives the US energy autonomy and it gives, over time, freedom from energy Oligarchies and combines. Eventually solar will be extremely cheap. It won’t happen overnight but there are several technologies that can vastly reduce the price. There are also carbon based batteries that will also be very cheap. When you have these you will be free of the monopolist structures built up to control you.

  14. Sam J. says:

    TRX says,”…two standard rooftop solar panels could provide the power for the average (16 mile) commute.” In plain English, that is known as “a damned lie.””

    Maybe not. Two panels, 200watts x 12 hours is 2400watt/hours and their consumption is 120Wh per passenger mile. So it’s within reason.

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