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Electric planes

Discussion in 'Electric Vehicles' started by doug, Jun 29, 2008.

  1. daniel

    daniel Active Member

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    I don't think the promoters have thought of that yet. Presumably they'd be subject to the same rules as either helicopters or those ultra-light planes that don't require a pilot's license. Of course, the people promoting them know that the whole thing is a scam to raise money (if you're a small company) or a publicity stunt (if you're a big company) and neither of them really expects to actually sell one any time in the next twenty years.

    Note that they always paint a future where everybody has a "flying car" but they always show pictures of just one flying above the congested traffic. If even 1% of people in a city had them, the air space over the city would be total chaos. On the ground people drive on streets with intersections controlled by traffic lights and stop signs. In the air there are no streets or stop signs.
     
  2. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Well-Known Member

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    The drones taxi companies are really thinking about short trips that avoid congestion, like crossing a river.
     
  3. PhantomX

    PhantomX Member

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    But in order to make business sense, the manufacturer will need to sell sufficient units, and the operators will need to operate high number of flights. Given the small number of people a UAM/drone can transport at any given time, I got to think we'll end up with a very congested space even if it's just a short hop.
     
  4. daniel

    daniel Active Member

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    How does it help people if they take a drone across a river and leave their car behind? Sure, there will be isolated places where your destination is just on the other side, but those will be few and far between. And with the cost of drones and their low capacity, it will still be very expensive to use them.

    We will definitely have drone taxis. They will be for the very rich, as helicopters are now. Maybe a little bit cheaper, but not much.

    Yep. You either have a very low-volume business model, which is expensive because there are so few customers, or you have a high-volume model, which means air-space congestion. Passenger drones are merely an evolution of the helicopter, maybe a little less expensive, but not by much. Congestion is dealt with today by the fact that helicopters have trained, licensed pilots and are directed by Air Traffic Control, the same as fixed-wing aircraft. And by the fact that they are too expensive for ordinary people to own or use them.

    The same will apply to drones: Congestion will be limited by the fact that very few people will be able to afford to own or use them, and they'll have to obey Air Traffic Control, which will mean they'll have to have a trained, licensed pilot or an automated system capable of following commands from Air Traffic Control. Such an automated system does not yet exist, though it might be possible in the future.

    Another thought about drones: A plane that loses power can glide and try to find a place to land. A helicopter that loses power can auto-rotate and try to find a place to land. A drone that loses power falls like a rock.
     
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  5. Brando

    Brando Active Member

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    auto rotate - tiny drones, no not enough weight. Heavy drones person, batteries, electric drone - 500 lbs?? I suspect auto rotate fine.
    If I really cared I'd google for more info - we already have single passenger drones and prototypes of 4-6 passenger.
    Air space is 3D so a lot of space - speeds what ?? 60mph

    enough of my rambling - I'll wait and see - anyone care to research?

    reminder: Sandy Munto already made autonomous plane 2008 - California to Michigan 3 planes flew politicians round trip.
     
  6. daniel

    daniel Active Member

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    It's not the weight, which in fact works against you. It's the physics of the rotor system: A helicopter has very long rotor blades which can provide some lift at relatively slower speed. A drone has much smaller propellers which must turn extremely fast to generate lift. The result is that, no, a drone will not autorotate. A drone will fall like a rock if it loses power. And since they're intended for short-range use over cities, when a drone falls out of the sky it's nearly certain to cause significant damage.

    The fact that the sky is 3D cannot come close to making up for the fact that there are no traffic lanes, stoplights, or any other aids to keep drones from colliding with each other.

    But that's okay, because they'll still be too expensive for any but the very rich. Heck, in the 1960's people were saying we'd all have flying cars by the 1980's. Drones are real. "Drones for everybody" is a fantasy.
     
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  7. evp

    evp Nerd

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    It's much simpler than that. In order to autorotate, the helicopter pilot sets the pitch of the blades negative so that the air passing through them provides energy to keep them rotating.

    Drones have fixed pitch blades. If the motors aren't turning the blades, they just stop. Practically immediately. They have as low rotational inertia as possible, because drones have no control surfaces, so they maneuver by changing the speed of the rotors, and the lighter they are the quicker that happens.
     
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  8. PhantomX

    PhantomX Member

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    And this is why I always wonder how FAA will ever certify passenger drones or any drone that has high kinetic energy. Parachute? Giant airbags like those use on Mars landers?
     
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  9. daniel

    daniel Active Member

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    I love the mental image of passenger drones that inflate huge Mars-lander-style air bags when they lose power, coming down and bouncing around the city. :)
     
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