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Transportation

Why Elon Musk Doesn't Like Flying Cars (yahoo.com) 183

boley1 quotes Business Insider: According to Elon Musk, the main challenges with flying cars are that they'll be noisy and generate lots of wind because of the downward force required to keep them in the air. Plus, there's an anxiety factor. "Let's just say if something is flying over your head...that is not an anxiety-reducing situation," he said. "You don't think to yourself 'Well, I feel better about today. You're thinking 'Is it going to come off and guillotine me as it comes flying past?'"
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Why Elon Musk Doesn't Like Flying Cars

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  • by drinkypoo ( 153816 ) <drink@hyperlogos.org> on Sunday April 30, 2017 @09:43AM (#54328595) Homepage Journal

    He also doesn't like them because his company, The Boring Company, wants to provide a competing transportation solution.

    He also doesn't like them because people will report on that, and then people will talk about his boring company. It's extremely profitable dislike.

    On the other hand, I agree with him. Adding more air traffic is inefficient at best.

    On the third hand, there's probably plenty of places where tunnels won't work. That's not a reason not to build tunnels where they will work, but we still need something which handles those situations. I still like elevated PRT.

    • by Sique ( 173459 )
      If he liked flying cars, no one would holding him back having The Boring Company developing one. I would consider that a moot point.
    • by K. S. Kyosuke ( 729550 ) on Sunday April 30, 2017 @10:31AM (#54328811)
      Also, energy requirements. Ground vehicles are so much better at lower speeds.
      • by Motard ( 1553251 )

        Also, energy requirements. Ground vehicles are so much better at lower speeds.

        Slower speeds are not a plus for any sort of vehicle. Their original brief is to get us places faster.

        • Unless the optimum flying velocity of several hundred kilometers is so high that by the time you reach it, you're already past your destination!
    • by Zemran ( 3101 )
      How many hands do you have?
  • One can hear a helicopter kilometers away. Now imagine having thousands of those in the air all the time. Unbearable unless they first pass a law to surgically make us deaf. Then it's OK.

    • Not so much with the new generations. Local cops got a new 'ghetto bird', sounds like it's 'differential is about to fail' (I'd pull over if my car made that noise), but it's _much_ quieter.

      I think the pilot navigates by eye and uses a local set of intersections as a reference, you can see him find it, then vector to where he's going. Must be an old fart, gotta have GPS.

  • by FudRucker ( 866063 ) on Sunday April 30, 2017 @09:50AM (#54328625)
    they can barely keep out of collisions on the ground, which covers left, right, forward and backwards, if they get the added complications of up and down and crash landings from up high it will only cause more death and destruction on top of the messes the typical driver does already
    • You're right. However, autonomous cars are almost certainly going to happen, albeit after a longer delay than most folks think. Once the problems of navigation in two dimensions are routinely handled by hardware and software, extending the sensors and computer control to three dimensions probably won't be that big a deal.

      I think other issues like safety, maintenance, insurance, security might be a bigger problem than driver skill. Hopefully none of the latter will be needed, otherwise no structure or liv

    • by monkeyxpress ( 4016725 ) on Sunday April 30, 2017 @10:59AM (#54328967)

      The bigger question is why we have to move around so much. Why does ever journey in modern suburban life require driving? I live in a city, and can walk to restaurants, walk to work, walk to the supermarket. I accept this is not for everyone, but suburban life sits at the other end, where getting a pint of milk requires driving. Add in congestion and parking issues and it is like a real-life rube-goldberg machine for living.

      Stop this obsession with single use planning zones, and the need for humans to turn up in person everywhere and much of these problems can be fixed. It's not like we fixed the time it takes to deliver mail by having a fleet of hypersonic aircraft that can deliver letters anywhere in the world in less than an hour. We just used different technological solutions instead and got far better results. Similarly, the solution to traffic congestion is to stop this ridiculous need for the inhabitants of a city to shuffle back and forth between two areas everyday. The original argument for single use planning was that it would improve quality of life. It evidently does not, because the highest real estate prices now are for quality housing in dense urban areas where people can walk around their local communities.

      • Shoot, I thought we'd have all figured this out from SimCity. Put a small store on every other corner and your traffic issues go away!

        Seriously, though the places that I've lived where I could walk a half-mile to get anything I need on a daily basis have been delightful. Human-scale living is far better than car-scale, far more interesting, far less stressful, far more healthy and active. Anyone who knocks it probably hasn't tried it.

      • by AmiMoJo ( 196126 )

        Because property prices in cities are often prohibitive. People trade their time for cheaper accommodation.

  • ... it is just a matter of time before someone ships himself instead of 100kg of Amazon purchases.

    My fear would be 16 year old neighbor getting his flying car permit, I see Elon's point. Howeve,r a personal drone that appears to be as safe as some of these self driving cars are on the way to becoming would get people over the fear factor.

    As for the noise, at least it will be short lived, unlike the neighbor's lawn mower that I'm listening to now.

  • The problem (Score:4, Insightful)

    by kbg ( 241421 ) on Sunday April 30, 2017 @10:27AM (#54328793)

    The problem with flying cars is... well they are flying. Which means they are in the air over our heads all the time. When a normal car malfunctions it is only traveling in two dimensial space and on a designated road, which means the damage is minimal given the cirumstances. When a flying car malfunctions he will not only crash into other flying cars in the same two dimensial space he will also fall in the third dimension and on other flying cars below him creating a cascading disaster and they will fall onto buildings, bridges, schools, stadiums e.t.c.

    The only way flying cars will be a reality is that if they are treated exactly like airplanes, with all the pilot training, monitoring and security measures that comes with that or they will have their own "sky roads" which they follow, but in that case the point of flying cars are greatly reduced.

    • Re:The problem (Score:5, Insightful)

      by vtcodger ( 957785 ) on Sunday April 30, 2017 @10:51AM (#54328909)

      More succinctly -- Broken Cars STOP. Broken Aircraft DROP

      • by Rei ( 128717 )

        More succinctly -- Broken Cars STOP. Broken Aircraft DROP

        Tell that to someone whose brakes go out while they're driving.

        • by Rei ( 128717 )

          And more to the point, "broken helicopters" (to pick the closest analogy to many flying car concepts) don't just "drop"; the props autorotate, braking the vehicle on descent.Check it out for yourself [youtu.be].

          • Quads can't, no variable pitch blades.

            Hex or Octo is required to have any redundancy. But for that to work, you have to overbuild all the motors, so it can land, basically, as a quad.

            You could 'emergency mode' the motor controllers, put the motors into high output/low life 'mode' when in emergency landing mode (ref: see 1 million electric truck racing threads), but then you've got an all motors maintenance issue. Weather you overbuild, or switch to 'war power' your putting non-routine stress on a motor

            • by Rei ( 128717 )

              Quads can't, no variable pitch blades.

              And you don't see the solution to that?

              It's really simple. Regulators mandate safety standards so that - in real world conditions - you don't have cars constantly falling out of the sky due to failures or running into buildings. Engineers determine the designs to meet those standards. If they can't, they don't get to sell it.

              • You require swashplates etc on multirotors and you end them. Even making them variable pitch like a modern airplane prop ends them.

                They go from being cheaper and simpler to more expensive and much more complicated.

                Multirotors have to stick with the plan; redundancy. Redundant Array of Inexpensive Impellers.

                More also means smaller cheaper props. Propellers are wear items and aren't cheap.

                If the multirotors props are shrouded, autorotation isn't possible even with variable pitch. Unshrouded props on

        • happened to me in my first car that was 17 years old, I used the parking brake to stop, some of that redundant system magic.

          • happened to me in my first car that was 17 years old, I used the parking brake to stop, some of that redundant system magic.

            According to slashdot logic, that's unpossible as it would definitely have caused your car to spin out or some other such BS, because "the parking brake is not an emergency brake"

            Which is a load of hot cockery, but what can you do? Congrats on not dying.

        • OP didn't quite phrase it right. Broken cars slow down to a stop. Broken aircraft speed up until they hit the ground.

          Falls start to become fatal from about 50 feet, and are nearly always fatal from above 100 feet. So for flying cars to be reasonably safe, you'd have to limit them to about 50 ft altitude. Factor in uneven terrain, and that altitude ceiling means there's very little advantage to flying cars vs ground-based cars.

          It's also worth pointing out that Musk's Boring idea is the same thing a
        • "Tell that to someone whose brakes go out while they're driving."

          Happens from time to time when master cylinders fail. Mostly people manage to get the vehicle stopped with engine braking and or the parking brake. Or they end up in a low speed collision with something solid like the vehicle in front of them.

          Now having a ball joint fail causing the front wheel to tuck under the car... That's a different story.

          But mostly car engines stop running and the car just sort of coasts to a stop.

      • by Rei ( 128717 )

        Tell that to someone whose brakes go out. And furthermore, broken helicopters don't just drop (helicopters being the closest analogy to a VTOL flying car). The props autorotate [youtu.be]. I'd much rather be in a helicopter that's lost its engine than an airplane.

        • I'd much rather be in a helicopter that's lost its engine than an airplane.

          Sadly, multicopters (where multi > bi) don't autorotate, and the "flying cars" which are about to hit the market are all multicopters.

          I'd rather just be on the ground, so I don't have to worry about whether I will fall out of the sky, unless I'm going someplace across an ocean. Moving quickly on the water is quite inefficient, so far.

  • by RockyMountain ( 12635 ) on Sunday April 30, 2017 @10:50AM (#54328901) Homepage

    I am a major skeptic about the whole flying-car idea. For many reasons, but not the same reasons as Musk.
    Here, I am disagreeing with one of Musk's points out of technical nit-pickery, but I DO agree with his overall conclusion that flying cars are not the right answer to personal transportation.

    I agree they will be noisy. That will never be fully solved. (And expensive and unsafe, but that's off topic.)
    But, Musk's wind objection -- I just don't buy it.

    Yes, aircraft generate lift by displacing air downwards. Some inclined plane (either the wings, or the rotor blades) deflects air downwards, creating an equal and opposite force upwards. So yes, all flying machines "create downward wind". Some do it highly efficiently (at optimum cruising speed, a typical fixed-wing plane or even to a lesser extent a helicopter). Some do it a little less efficiently (a fixed wing plane at very low airspeed), and some do it horribly inefficiently (a helicopter or drone hovering).

    The efficiency is largely a function of the craft's forward speed through the air, for a very basic Newtonian reason. F = ma.

    The upward FORCE (which must counterbalance the aircraft's weight) must be matched by downwards ACCELERATION of some MASS of air. Acceleration is not velocity, it is rate of change of velocity. Therefore, lift comes from the act of imparting new or increased downward velocity on some mass of air. Absolute velocity doesn't help, only increase in velocity. Hold that thought, we'll get back to it.

    An aircraft moving forward horizontally encounters a steady supply of new air that does not yet have any vertical velocity. OTOH, once an aircraft that is hovering, has imparted downward velocity on a column of air, it remains within that accelerated column as it tries to accelerate more mass downwards. The established downward velocity of the air doesn't help, only the acceleration (increase) in downward velocity of some part of that air. To solidify this concept, think of "swimming up a waterfall".

    Hopefully this illustrates why hovering is highly inefficient, and cruising is much more efficient.

    Enter simple economics. Any economically VIABLE system of flying vehicles spends the minimum time hovering and the maximum time cruising. This is the reason helicopters are used only for specialized tasks or by rich people, while fixed wing planes are used for general transportation. While I don't personally believe that flying cars will take off (bad pun semi-intended), if they do, simple economics dictate that they won't spend much time milling around close to their terminals hovering. They will rapidly get a move on along their course. Once they are moving en-route, their "downward wind" is over such a dispersed area that is is essentially immeasurable.

    I don't know what exact means they'll use to transition from takeoff to cruise -- rotors, fixed wings, adjustable wings, whatever -- but they won't be concentrating their "downward wind" in one small place for very long. If one's vision of personal air transportation involves any significant time hovering close to the terminal, then economics dictate that it won't succeed. And downward wind during cruise is simply not a problem.

    There will be some localized wind right at the terminals, but if you've ever stood nearby when a helicopter takes off, you know that it is windy very strong but very localized, and does not persist long after the helicopter moves away.

    • And replying to my own post with a slight topic drift. I am also somewhat skeptical (but less so) about Musk's alternatives.

      Boring is a great solution where the cost can be justified, but I'm skeptical of the economies of scale that it's widespread adoption seems to depend upon. And, I'm highly skeptical of the safety proposition -- how do you rescue passengers from a stranded pod in an evacuated underground tube?

      I really want Hyperloop to succeed. I'm just not sure I want to drink all the Kool Aid invol

      • how do you rescue passengers from a stranded pod in an evacuated underground tube?

        TBC is not dependent on hyperloop. You can fill the tunnel however you want. You could just put normal roads in there, or normal rail, or light rail, or a PRT monorail (monorail? monorail!) or a moving walkway or a canal or... use your imagination [youtube.com]. (Personally, I'd imagine away the wheels, and use rail of some sort, whether single or dual. But I imagine the idea is to have dual-mode vehicles that can actually use the network without the sled.)

    • by Rei ( 128717 )

      Congratulations, you have it entirely backwards.

      The maximum efficiency of a prop, in newtons per watt, is 1 / (v_wake + v_freestream), where velocity is in meters per second. The faster you're moving (the freestream velocity), the less thrust you get per watt. Which is why large props are more efficient (more air moved at a lower wake speed), particularly at low speeds, and same for high bypass jet engines.

      Now, in terms of "energy per 100km" or "miles per unit energy", obviously a hover yields "infinite jou

    • Your objection to the annoyance factor of "downward wind" overlooks the fact that if they are an important means of transportation there will be a lot of them, going over every few seconds, and so what for one "flying car" is "widely dispersed" is not when the total traffic is considered.

      Also the argument that "they won't spend much time milling around close to their terminals hovering" is little comfort for anyone anywhere near these terminals, which would need to be in cities to be useful. In fact, withi

  • >> because of the downward force required to keep them in the air

    huh! Author must be living in alternate universe...

    • Why, umm, yes. To keep your machine in the air, it has to exert a downward force on a shitload of air. Newton's Third and all that.

  • so we've had prop and jet propelled flying cars, buses and trucks for over a century. Also spacecraft, which are even scarier when they crash on land

  • They tend to be things like silly-looking airplanes with folding wings, strap-on mini-helicopters, and oversized drone-like craft. Flying cars are what we see in Blade Runner, Back to the Future, The Fifth Element, etc. I.e., devices that meet the following requirements:

    1) Almost completely quiet; at worst, a humming sound.

    2) Able to hover and maneuver effortlessly.

    3) Able to take off and land anywhere effortlessly.

    4) Affordable.

    I would add a fifth requirement:

    5) Fully computer-controlled - most people

  • I remember, quite a while ago, reading in Popular Science magazine about the "Moller Air Car", which was another experimental project that claimed to be on the way to selling people personal flying machines, easy enough to pilot so you basically just used a joystick to tell it which direction to go.

    That idea seems to have crashed and burned, so to speak.

    I think the big challenge with any of these things is going to be getting the FAA to approve their use by the general public. I mean, let's face it. They co

  • "Let's just say if something is flying over your head...that is not an anxiety-reducing situation,"

    However, riding in a narrow, sealed, and windowless capsule inside a sealed steel tunnel whizzing around under ground at nearly the speed of sound is nothing but relaxing, eh Elon?
  • Not until *your* EXPENSIVE insurance pays for a computer-controlled, RADAR-guided anti-aircraft gun to be mounted on my roof, to shoot down the teens, the drunks, the "lost control of my vehicle" seniors, and YOU SLASHDOTTERS who are texting while flying, before you crash into my second floor bedroom.

    • It would make more sense to live in a bunker. If you shoot down an incoming aircraft it just means flaming chunks will be hitting your roof.

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