The 2019 Geneva International Motor Show has a number of “concept” vehicles. These are vehicles that usually include some cool feature that isn’t really practical — at least today. For example, in the past, concept cars have had adjustable color interior lighting, plug-in hybrid engines, and power windows — all things that would eventually become commonly available. However, today’s advances in computer-generated graphics have meant you can show things you can’t begin to build. Case in point: Goodyear has a video touting the Aero — a solid car tire that doubles as a propeller for your garden variety flying car.
To us, the thing looks more like a science fiction movie trailer than anything remotely practical. Four relatively small wheels with no central hub can flip and provide enough lift to propel a sizeable vehicle skyward. Even more interesting, is to transition modes from ground to flight, the vehicle balances on two wheels while using only two as propellers to generate lift.
In Practice
While we love speculative thinking, this seems like a lot to swallow. Sure, sure, the future could see very high-speed motors and very lightweight vehicles. But it is hard to imagine the Aero spinning fast enough to generate enough lift to loft a person alone. There’s also the inherent safety issues. If you want to see a more plausible flying car, check out the Bell Nexus. below. See the size of those props? Goodyear also says the tires would contain fiber optic sensors to monitor the road and the tire along with an embedded AI processor because — after all — what doesn’t need that?
Ethics and Kickstarter
This is an interesting problem in engineering ethics and reminded us of a lot of various nefarious Kickstarter campaigns. With computer methods, you can mock up all sorts of impossible gadgets. Would you like a cell phone that needs charging once a month for ten minutes? So would we! We just don’t know how to make one. How about a jetpack? Why not? Granted, Goodyear isn’t seeking funding for this tire, so it isn’t quite so bad, but it doesn’t look any more practical than Hackaday announcing our new once-a-month cell phone charger available sometime in the future.
In all fairness, we aren’t exactly a bunch of flying car designers, so maybe there’s something going on here that we don’t understand. We get, too, that this is supposed to be forward-looking and not something to build today. But short of the video’s vehicles having an antigravity device, we don’t think this looks like anything we are going to see in our lifetime. Flying cars, maybe. But not with tiny propeller wheels.
Education
It isn’t just Goodyear. Every six months or so we see a newspaper article about how scientists are about to invent the transporter because quantum teleportation isn’t well understood. We see stories all the time about the next big battery technology that never seems to actually hit the market.
Arthur C. Clarke famously said, “Any sufficiently advanced technology is indistinguishable from magic.” While I think he meant that in terms of cultures colliding, we may be at a time when most people don’t understand our own technology. That may seem hard to believe if you mostly hang out at hacker spaces and surplus electronic stores. But try asking the average person how a cell phone works. Or a microwave oven.
Maybe it is time to start teaching kids a “technology” class to try to develop common sense about how tech works at a high-level. Some of these kids will become business executives, judges, and lawmakers and we’ve all seen what happens when people in those roles don’t understand the technology about which they are making decisions.
This isn’t the first time we’ve railed against flying car concepts. Like videotape, the flying car is one of those things that makes a lot of false starts into the consumer market. Videotape finally hit, but it is taking a lot longer to get the car — um — off the ground.
It’s that lack of basic scientific knowledge that leads (in part) to scares over your cell phone microwaving your brain if you hold it up to your ear, or your smart meter giving you cancer.
A lot of stuff we don’t have is because the economics don’t work. That “education” could keep away the new shiny as much as it would encourage.
to be fair…. smart meteres ARE cancer. from jacking bills up, toninvasion of privacy, to the massive vulnerability they add to our infrastructure. hell, 15 bucks and 5 minutes on github and i can already manipulate the damn thing, no special skills required. on/off switched remotely added to the remote on/off switch. can you immagine what would happen if an exploit (or a bug) shut those all off at once?
The kind that can be remotely shut off also have been known to start fires.
That Bell Nexus looks like it would require MORE space than say a car pad, let alone a garage.
So park it on the roof!
B^)
Insanely bad driver-fault accident stats in all countries and a lot of people who don’t even know what solid lines and the two-second rule mean, but flying cars..
You’re not wrong, but you are poo-pooing on a technology that doesn’t even exist yet. Instead of shooting down a non-existent plane, why don’t you suggest what can be done to remedy the issues you see? We have Tesla and SpaceX both perfecting their autonomous piloting software. Say we apply those techniques to this flying car. Who is going to drive over double lines or hover in a no hovering spot if the driver is a computer following all the rules? Put some more thought in to your comments, brother.
You want more thought? How about all those people who cut the wire to that buzzer that tells them to buckle up?
Exactly. Some folks would find a workaround so they could still hover in a marked No Hovering spot, or break other rules and kill people. This is why driverless cars will never work…look how many deaths we have had already.
Here in the US we still have guns. So I’d have to say your reasoning does not apply here.
Of course we still have guns here in the US as it is written in the Constitution as the 2nd Amendment. Are you suggesting that we amend the Constitution so citizens have a right to flying cars? I see no reasoning in this idea at all.
Nah I just used the programmer and told the car to not turn that buzzer on…
“If the driver is a computer following all the rules?”
It’s amazing we’ve found the first program that has 0 bugs, no edge cases, and works 100% of the time in the worst possible conditions. The problem he is pointing out doesn’t magically disappear with future magic hand wavey technology. It will always be expected that a human is at minimum capable of interjecting themselves in the loop if the computer goes wrong (as it has with tesla and every other autonomous car system). His point is that humans are bad enough at driving and the physics behind it are relatively simple. By comparison the basics of flight are way more complex (assuming prop based flight and not again hand wavey anti grav magic voodoo). So no we can’t just hand all those complexities off to some future magic computer because people still need to be capable of adjusting to problems if say the computer crashes (pilots of real planes are still expected to do this and it’s why they are in the cockpit in the first place, reference the Hudson river plane incident).
737 MAX 8… Your software can help you or turn against you.
Oh you’re allowed to poop on uninvented technology if it’s this implausible. If perfect autopilot does eventually exist (which in itself is a very sketchy assumption, people don’t respect how insanely hard that problem is and how far away from accomplishing it we really are), it still would never ever be allowed to reach the scale that cars have. No sane government would ever allow hundreds of millions of joe schmoes to privately own flying kinetic weapons like these and park them in garages all across the countryside. No sane civilization would allow such frivolous waste of insane amounts of energy. We’re already facing dire consequences for the amount of energy we use, and sitting on the asphalt is basically free. Literally no magic future technology will beat the energy efficiency of sitting on the ground.
Autopilots can be spoofed. Every product ever made gets hacked by somebody. You could never ignore the security nightmare that is implied by nearly every first-world person owning an aircraft. And it just doesn’t make sense economically or in terms of utility–people basically want them soley because of the cool factor. They’ll almost certainly always exist similarly as they do now: you can buy a helicopter if you’re extremely wealthy, and using it will require very strict oversight and regulation and training. Respectable futurists don’t depend on black swan tech to save their pet concepts. I mean even drones are getting locked down lately because that’s apparently too much to trust the unwashed public with.
You are talking about cost cutting down to consumer level vehicles without the regular maintenance of an aircraft while expect to operate continuously. Now multiply the numbers up by tens of thousands in number. That is before worrying about software bugs, teething pain of new technology, its social implications and human behavior.
What can possibly go wrong?
Right? Good point. Thinking the only problem is driver malice or incompetence that could dubiously be solved with an AI band-aid is way too simplistic. Maintenance alone is a non-starter. Ever take notice of how many cars you see stalled out on the highway? What’s that going to look like in the air? And a massively more powerful and compact engine capable of VTOL flight and landing in a standard parking place is going to need much more extensive maintenance than some crummy Neon or Geo from the 90s–and that’s saying something.
The inspection and oversight required to make sure people aren’t skimping on this hugely expensive maintenance would put us right back where we are now: Want a flying car? Make a ludicrous amount of money somehow and get to da choppa.
Imagine how loud it would be in cities!
So true. It’s quite amazing how nobody seems to get this simple fact… These machines generate A LOT OF NOISE. See how drone makers advertise their products with gentle musics, never letting us to hear the loud and horrible noise generated by their propellers. Like all merchant sthey sell a dream wnich has nothing to do with reality. But Jeff Bezo’s dream to see our cities covered by hundred of drones buzzing over or heads all days long to deliver his parcels is actually a nightmare nobody wants. It about time one mention it.
A network of pneumatic tubes running to/from all addresses would be better or better yet small robots scurrying about like squirrels dropping off and picking up from an autonomous vehicle near-by. :-)
a) This isn’t engineering. This is marketing/PR.
b) The common person never understood technology, even when technology was simple. Go to 1898 and ask the man on the street how a candle works. “It burns, duh”. Well, what’s “burning” if the existence of atoms is as controversial a topic as quantum teleportation is today?
>In all fairness, we aren’t exactly a bunch of flying car designers, so maybe there’s something going on here that we don’t understand.
Doesn’t take a chef to taste a turd sandwich. In order to take off with two propellers corner-to-corner, the vehicle would have to be perfectly balanced. Otherwise it would simply flip over.
But, like, bicopters are a thing. Combined with ESC and gyros I don’t see why a vehicle of this sort wouldn’t be plausible. I wonder what kind of a parking garage they would need?
Yes, but those are built to be balanced to begin with, and the gyros and ESC only have to deal with the remaining disrepancy.
Think about a car. There’s one person sitting in it. Should they sit on the left, right, or in the middle? Maybe they’re moving inside the car? You got about 100 kg of off-center mass to deal with, and it takes a heck of a gyro to keep the plane level an from veering out of course.
Also, bicopters work because…
http://api.ning.com/files/Sgjg2ZxMofqwSTkrdl85XQoEjYsrgfbDBsMNmbQDFtCa8*LVwrOAAoznzlPyBgfly5GcBYcEB-JiYoZCYO9ueQ__/Nymbus650atBramalea27Aug20112.jpg
(hint: the props are well above the center of gravity)
Nope. Lookup pendulum rocket fallacy. That bicopter flies because it can adjust the thrust angle of the rotors independently, just like an Osprey. The Goodyear car looks like it can do the same thing, if it can drive on the side of the props, it can adjust the angle during flight. It’s going to have terrible efficiency with those little tiny props though.
> That bicopter flies because it can adjust the thrust angle of the rotors independently, just like an Osprey.
I’m pretty sure that the osprey can’t do that.
Nope. In a bicopter, the pendulum rocket fallacy doesn’t apply because the rotors are (should be) free to turn, and they act as gyroscopes so they tend to stay level while the rest of the copter hangs underneath.
Having the center of the gravity lower helps with balancing because all you have to do is keep the rotors level. This isn’t the case for the PR video in the article where the wheel-thrusters are at best at level with the center of gravity, making the whole thing more like the flying beadstead of the Apollo program.
Wade, lets just hope anybody who disagrees with you works not on flying cars.
Steven13, yes the Osprey has cyclic control just like the Chinook.
@Steven13, yes the v-22 does in fact have variable pitch props. It uses them in standard cyclic helicopter mode. Also, I work on them, so… Proof.
They look to have succeeded in designing both a terrible tire and a terrible ducted fan.
The fan would waste a lot of energy around the edge with the tire tread, and the tire would waste a lot of energy driving the fan. Also a fan designed like that would need to spin at a ridiculous speed to lift itself, let alone a car and I can’t imagine the noise with those wonderful serrated square edges.
Totally PR.
From the point of view of electric motor design, an in-wheel motor that is both efficient in driving a wheel, and a high-speed propeller, is technically impossible because it’s a question of the number of poles and the drive frequency, that has to be optimized for impedance(inductance) of the motor coils.
You want torque at low speeds, you need strong magnets, but that decreases the Kv of the motor and stops it from spinning fast. Strong electromagnetics have high inductance, which means they cannot be driven at high frequency because they simply will not pass the current. Pole switching can cheat somewhat, but not by much – you can’t have the same motor operate at two vastly different speed ranges. (0-600 RPM vs. 600 – 6000 RPM)
You could use electromagnets so that you have some control of the field strength. It’ll add more weight, power consumption and bulk.
FYI: Large generators do not use permanent magnets.
Doesn’t solve the problem: in order to generate high magnetic fields with electromagnets, you need more turns of copper windings. You can control the stator windings by controlling the current, but you have to match that with the rotor winding, and one or the other has to carry alternating current to drive the motor, so one of them will experience higher impedance with higher drive frequency.
More specifically, the energy loss in the windings follow the current squared (I^2), so to maintain efficiency you’d rather increase the number of turns in the windings (more inductance/resistance) rather than stuff more current through the coils.
That means, if you have a motor that can turn very fast, it will have abysmal efficiency and ridiculous heat at low RPM. Alternatively, if you have a motor that can directly drive your wheels from 0-65 MPH, it simply won’t turn fast enough to run a thruster fan.
Trying to direct drive in wheel mode (for this configuration) is silly. They should have some gear reduction – may be planetary gears? Marketing/artists aren’t engineers. :P
Also BLDC isn’t the only option. An induction machine (while having a lower efficiency than synchronous machine) is better for getting torque from 0 RPM i.e. from a stand still.
Recently I saw an outrunner type BLDC motor in which the stator can be axially moved to adjust the Kv. With this you can get to higher RPM, while still retaining high torque at low speeds.
“Strong electromagnets have high inductance” is also not true. By using less windings of thicker wire and the same total amount of copper you can have the same magnetic field with much lower inductance. Have a look at a “bitter magnet”. Lots of field, while having a few windings.
Electronics have also advanced to a state where voltage / current conversion is so good it does not matter much (but you’ll still loose a few percent in efficiency)
Yes, but the “bitter magnet” has kilo-amperes of current running through it. The whole point of them is to brute-force as much current through as they can manage by any means of cooling the thing. That’s not practical for a motor that has to fit inside a wheel.
> the tire would waste a lot of energy driving the fan
The video seems to suggest that the fan blades have variable pitch.
LOL
i think my biggest pet peeve about flying cars is the car part. what you really want is personal vtol aircraft. and i think the main holdup there is not technology but regulation. the faa doesnt want to become the new dmv. they just arent setup for that kind of broad scale regulation. the technology isnt really that far off. just look at all the quad copter + lawn chair mashups on youtube.
Yes it is that far off. The energy consumption of hovering is ridiculous, and the infrastructure necessary to handle virtual lanes in the sky just doesn’t exist, not to mention about what to do when some vehicles stray off the designated corridors and may slam into others or just fall out of the sky for other reasons.
It’s not only a regulatory nightmare, it’s a practical clusterfuck.
”quad copter + lawn chair mashups” get a lot of their lift from ground effects.
Things they would need to solve are scalability of air traffic control, battery life, safety, liabilities, noise complains etc.
In some ways the FAA is stuck in the 1970s or even 1960s both in policies and general mind set this is probably the biggest hurdle.
For most people wanting a personal aircraft something along the lines of a roadable light aircraft is probably a better idea than trying to make a car fly.
As for the engine a NASA project suggested using an off the shelf LS family V8 from a Corvette which has a lower MTBF than a 40+ year old Lycomings or Rotax design still using a magneto and carburator.
Don’t need any fancy technology other than synthetic vision and a smart runway and the vehicle can glide if the engines fail though these quadracopter like design can make use of a parachute like a small fixed wing aircraft.
“Any sufficiently advanced technology is indistinguishable from magic.” (A.C. Clarke) and paraphrasing him, in “Unix humor”: “Any sufficiently advanced technology is indistinguishable from a rigged demo”. ;-)
Best regards,
Daniel.
the last one is so true.
https://i.imgur.com/5y86jMW.jpg
*the thing actually flies
but speaking of totally plausible practical things… freestanding counter-rotating exposed rotor blades next to the doors. also while landing – if anyone’s in close proximity of this “air-cab” will get shredded into pieces, unless he’s lying flat on the ground. and this was the top story of one exhibitor at MWC19. oh, and it is of-course self-driving/self-flying. like, what on earth could possibly go wrong here.
That thing looks scary to ride in due to the placement of the rotors.
is there a limit to the blade pitch and RPM of a propeller in air ?
I mean, quadcopter rotors are getting up in to the vicinity of 50,000 RPM but as silicon switching speeds increase can we assume that some day we can have PWM on multi pole rotors up in to the MHz or perhaps GHz or more.
Could future rotors operate so fast that they are silent to our ears and provide thrust we can only only dream of right now?
Simply speed of sound, so no, they won’t be silent at all.
Not sure what you mean there. something spinning at 1500 RPM would create a 1500Hz noise (with harmonics).
I’m sure there is some fluid dynamics equation that will state how fast a propeller can move in air (at sea level) without cavitation etc. But i’m also 100% certain we don’t know everything (yet).
All i’m asking here is could there be advancements in the silicon that can achieve better flight characteristics than is currently obtained and would that be better on the ear than the current quadcopter-flock-of-bees noise that is the current norm
>1500 RPM would create a 1500Hz noise
You keep forgetting that the RPM = Rev. per *MINUTE* There is a factor of 1/60 that you totally missed.
So 1500RPM = 1500/60 = 25 rev per *second* so its fundamental frequency is 25Hz. Not the 1500Hz you claimed.
Human hearing isn’t that sensitive at 25Hz.
50000 RPM is only 50000/60 = 833 revolution per second. So it ‘ll need several orders of magnitudes before speculating about MHz.
Remember the myth buster show on blowing up CD at high RPM? At some point, mechanical limits for current material will be reached i.e. your bearings and prop would disintegrate first. You’ll need beyond military jets turbine level technology to get any usable operating life.
Learn from PC cooling fans – larger diameter prop at slow RPM would be more quiet.
All good points, and yep totally spaced the “per minute” bit.
I guess my original comment was more about increasing the speed of the props past the point they could become silent (actually it was more of a question if that could ever be a thing in the future given the limits of fluid dynamics). There are plenty larger propeller/rotary wing machines out there but i do believe we are wanting smaller and with more lift.
You can turn the propeller faster. The problem is that you won’t get much additional thrust. The additional power will simply be converted in to heat and noise. The limiting factor is the sound barrier.
This is why most general aviation aircraft have propeller speeds limited to approximately 2700 RPM.
Suddenly thinking of Goodyear blimps. They would fly through the air with no Goodyear tires on them. It’s kind of ironic if you ask me. This commercial feels like buggy-whip manufacturers desperately trying to stay relevant when no-one is driving horses any more. In this case few would need tires so they would start making props. More power to them if they want to start selling a new product but I don’t see tires being phased out any time soon. Rolling along is sooo efficient compared to hovering about. Flight is only efficient when moving along quickly or floating in a lighter than air structure.
this happens when marketing department takes over engineering. just throw an “artist rendition” and some soft baritone in british accent and … profit.
i think this is an exceptionally bad habit of exploiting “people who want to believe” – but – hey, it earns us money. sad to see that spread this much though.
From Goodyears video I would think mass transit of any kind would be a better bet in the city shown in its animation. Like the people transport tube from Futurama :^D . And when I see some article saying the word “Concept” my mind now inserts “you will never see it happen, ever” in its place.
lol peoplz, be informed about the more plausible flying transportation system propulsion method:
https://www.nature.com/articles/s41586-018-0707-9
Some things are really only possible in a non-commercial economy… where it won’t matter how much it costs. That leads us to some science fiction mindsets pretty quickly… as no one would ever really build the Enterprise NCC-1701 if it was required to earn its keep *commercially*, I guess it was claimed that they no longer use money in the Star Trek Universe’s federation. (Ignore the Ferengi behind the curtain) Currently, science leads to innovation but then there is a bean counter saying “Nope… you get no money to ‘go all the way’… no matter how great your invention is… we can never make a profit with it.”
In Star Trek, the Humaans don’t use money. The Ferengi aren’t Humaans. Money isn’t banned, Humaans just don’t have any.
…banning money…..that makes about as much sense as warp drives and teleporters. Money is one of humanity’s greatest inventions, right up there with written language and the wheel. It makes it practical for people who have too much of something to trade with others who don’t have enough. Now humanity in all its depravity twists the concept of money by choosing to fall in love with it and being incapable of being satisfied with having enough. Matters never go well when people start loving *THINGS* when they should be loving other *PEOPLE*.
Uh, guys… Isn’t it April first? I think maybe we might be taking this too seriously :)
It would be just fine if you like the idea of living inside a bee hive. :-)
It´s just another rendering. Would you start a highspeed propeller which was bumping over the road a few minutes ago?
It´s something for a computer game cause it looks cool. From an engineering point of view it is total bullshit.
Lets crunch some numbers.
Let’s assume a reference to be “Schubeler DS-215-DIA” – 0.2m/25kg thrust@15kW.
https://www.turbines-rc.com/en/schubeler/2117-schubeler-ds-215-dia-hst-195mm-carbon-edf-ducted-fan-motor.html
Then, from the video, the rotor diameter seems to be ~1m (https://youtu.be/4vbZlzxpr8M?t=179).
Scaling up the diameter (power grows to the ^5), and scaling down the RPM (power drops to the ^3), the new thrust is then 95 kg at 1170 RPM at 22kW.
With a 50kWh battery pack this thing could lift 380kg (200kg battery, 100kg passenger and 70kg structure, incl. rotors).
The hover time would then be 30 minutes.
Pretty reasonable setup. The wheels don’t seem to be necessary at all…
The rule about flying cars is: A flying car will be a pretty bad car, and a pretty bad flyer and there is no way of changing that rule. Its like trying to make a racecar excavator, its possible, but it will be a bad for racing and bad for excavating.
LOL, a run-flat with the walls taken off. Massively in-efficient
I despise futuristic views that have cities without any plants or any green. Those are cities are for rich entrepreneurs and slaves: people who work all day and never relax. Quite a dystopian video.
Let’s start with street-legal hovercraft. Babysteps.