Japan’s Entry in Flying-Car Race Takes to the Air | Hacker News Reader

Japan’s Entry in Flying-Car Race Takes to the Air

wsj.com

46 pointspsim160 comments

Aren't flying cars called, "helicopters"?

Perhaps a bit too snide, but helicopters can take off and land vertically and can carry roughly as many people as most passenger vehicles. And they're mature technology that has been around for over half a century at this point. The problem of moving people through the air without a runway for takeoff and landing has been solved for 60+ years.

What advantage does this flying car have over a helicopter? It's a quad rotor craft so presumably is mechanically simpler (no swashplate) but at the expense of lower speed and reduced ability to operate in the wind. Also it means a crash if any of the four rotors fail (no autorotation). It can also drive in the road like a car. But on the other hand it looks like it seats just one person, and in an open top vehicle so it'll be uncomfortable in the rain.

Helicopters are already supplemented by cars in most use cases. I don't really see the advantage of a flying car over flying a helicopter to the nearest heliport and driving in a car the rest of the way. The only real advantage is the fact that there is no vehicle change. But that comes at the expense of using a vehicle that makes major sacrifices to both fly and drive on roads.

didn't think about that, great point!

Even before helicopters we had Santos Dumont flying his dirigibles down Paris streets and stopping for coffee. :)

Like dual purpose amphibious vehicles and seaplanes , it's a case of possibly useful for very small niches, and maybe electric power, VTOL and not needing the space a single rotor aircraft takes up creates a niche for this vs other similar concepts. But ultimately the economics of long haul flight, accident rates of GA and regulator intervention have all moved aviation further from the 'flying car' model than powered flight demos from nearly 120 years ago, and not through lack of innovation.

Funny enough, helicopter commuter services used to exist, primarily because they allowed one to avoid surface congestion.

Of course, this is only true as long as the skies remain uncongested from other helicopters. And these services died mostly because fuel costs became too large, and operating helicopters on sky-high helicopters in dense urban environments was very dangerous.

This is true, but also not true. Helicopters are stuck as a concept: large main rotor and tailrotor and also expensive parts and traditional aerospace practices. There are other physical paths, e.g. Osprey, Cheyenne.

But the big thing now is batteries and electronics and brushless motors. It allows flight at a whole new level of cost/safety.

Compare with toy-drones - your point here to me reads like ”there’s nothing new with these quad-rotor drones, we’ve had gas rc helicopters since forever”. And that is similarly wrong as saying these new vtol concepts are just helicopters. Fundamental tech enables the concept of flight to be reinvented using first principles. We know a bit of where this is going in small quads. For manned flight it is still unknown.

Helicopters are "stuck" because they've largely settled into an optimal configuration over the 70 years if experience designing helicopters. Some of the first helicopters had multiple rotors [1], but those were abandoned for good reasons They have a large main rotor because larger rotors provider greater efficiency. The single large rotor also provides the ability to perform autorotation in the event of power failure. Batteries are also bad choices for aircraft since they have very low energy density by unit of mass [2] combined with the fact they don't get lighter as energy is expended like thermochemical fuel.

These are the main reasons why quadro copters largely remain in the realm of drones and toys. These are the use cases where mechanical simplicity of four fixed pitch electric motors shine, and the shortcomings of reduced safety and lifting power aren't big issues (cameras weigh less than people and their families don't sue when they get smashed in a crash). You point out helicopters aerospace practices as a drawback, but in reality those practices emerged to deal with the responsibility and demands of human air transport. What is it going to cost to insure one if these flying cars? How many people's life insurance policies is going to cover rides in these things?

Definitely quadrocopters have made their mark in consumer electronics and even some commercial applications. But I am very dubious that people will be flying in electric multirotor craft.

1. https://en.m.wikipedia.org/wiki/Focke-Wulf_Fw_61

2. https://upload.wikimedia.org/wikipedia/commons/thumb/c/c6/En...

> The single large rotor also provides the ability to perform autorotation in the event of power failure.

That's a nice fantasy but when the SHTF nobody ever seems to be able to pull off an autorotation landing without fatalities. You need enough forward speed and control authority to make it work. An incident when you're at or near hover is unrecoverable.

An incident at or near hover is close to the ground, and so has much better chances of survival.

The issue with multiple rotors is that if one rotor fails the craft immediately pitches over and crashes. The Chinook solves this because the two rotors have a linked shaft. Definitely a quadrocopter becomes unstable with only 3/4 rotors. Maybe the octocopter posted elsewhere in this thread can sustain one failure and still land.

The military might be willing to risk flying people in electric multirotor craft for a few specialized missions such as casualty evacuation.

The military and other rescue service have been evacuating casualties since the 1950s on helicopters. What advantage does this provide over a helicopter? These electric craft have tiny lifting capacity, only 1 or 2 people, as well as much shorter ranges.

The japanese one has dual props in each position, so it can loose one propeller/motor and still fly (unless they are idiots).

Flying cars are interesting because they have the potential to partially make obsolete the natural monopoly of roads. Governments are heavily involved in natural monopolies (possibly for good reason) but I worry that that involvement may crowd out innovative private organizations that would otherwise have the incentive to bypass the natural monopoly. I wonder what other innovations are being stifled in the same way.

As far as flying cars go, they sure are loud. But cars are fairly noisy as well -- in cities the roads are often very close to apartment buildings.

Natural monopolies are physical monopolies. There's literally only so much room on the Earth's surface. So to the extent that anything is being stifled here, it's because two objects can't occupy the same space at once, not because governments have anything to do with it.

And the challenges airplanes face are very physical as well. It's not really the government's fault if no one proves ever capable of making flying cars safe enough for the airspace above cities to be full of them. At some point it's just an intractable engineering challenge and the limits of human ability.

Personally, I'm doubtful that flying cars will ever be a reality in our lifetime, but the only possible way I envision them ever working is if they're 100% autonomous and owned and operated as a fleet.

You run into the natural monopoly of airspace instead.

There's more room up there, but owners of the land beneath and users of other aircraft alike have a vested interest in the skies not being a free-for-all, and sure enough it's government agencies stepping into the air traffic control and regulation breach.

That’s pretty hard if traffic is not confined to roads and journeys don’t need to start at an airport.

> But cars are fairly noisy as well -- in cities the roads are often very close to apartment buildings.

And that’s an actual issue that should be addressed (electric cars are awesome on this point, you also have different road material that can absorb more sound).

Adding more noisy vehicles is making the situation worse.

The comments here are why we don’t have flying cars.

Everyone thinks of every possible negative. Instead of asking why not we should we asking what if. Maybe think of solutions along with the problems you find.

What if we could decrease the force of gravity? That would be a great solution.

Yes reducing mass would be a good general approach.

Or maybe, we don’t have flying cars because there is no need for them? We had a need for a flying box and ended up creating helicopters.

In high dense cities with multiple tall buildings i think there is a market for evtols to serve at least a small single digit percentage of the population. This off course assumes they become cheap enough in the future.

So, what is the attraction, exactly? It doesn't look as fast as a car or any more convenient, at least until cities are redesigned to accommodate these vehicles. I also assume that it is more energy-hungry than a car and I imagine that accidents are bound to be worse than cars for the foreseeable future.

Is it safer to pilot than an helicopter?

eHang is further along. [1] 16 rotors.

Battery energy density seems to be the big remaining problem. Flight times are too short.

[1] https://youtu.be/T_mezyLhvlA

Wow, those are gonna turn someone into ground meat at some point. I'm not sure that having that many propellers at knee and waist level is a good idea. These seem like less safe helicopters?

That's a problem. You don't want anyone anywhere near those things on takeoff and landing. Which is a problem if they use them for package delivery. However, the eHang really does fly, it really does carry people, and it works well enough they sent a reporter for the SCMP up in it. Closest thing to a flying car so far.

This design is basically not safe to use except on controlled access helipads; landing elsewhere is eventually going to turn someone into hamburger meat. It's really not any different from a small helicopter, which have existed for decades. How is this any closer to a flying car? The key aspect of a flying car is that it's safe to drive around on roads and fly around in the air. This thing can't do roads at all, not the driving nor even safely taking off or landing on them.

The rear rotor of a helicopter will occasionally do that also. Although it could be better with a craft that can easily turn on and off in an instant. A helicopter is often accessed by humans when powered up

The difference with the helicopter is that you can approach it safely from almost any angle to board/deboard, just don't approach from the tail, whereas this flying car thing has a ring of death all the way around the outside. And having the option of leaving the thing running has some advantages too.

I'm just not buying that this design solves any problems. At most it miiiight be a cheaper helicopter, but right now, it looks substantially less capable than helicopters too, and it seems like its failure mode is worse (helicopters can survivably land through autorotation even with a full loss of power; N-copters can't). So I'm not really seeing the benefits of this design.

A question I've always had is, how is the decision on how many propellers made? Why 16, and not 4? Or why 1?

The drone-type designs cannot autorotate like a helicopter. They don't have the variable-pitch blade controls a helicopter does. If you lose an engine or prop, you crash uncontrollably unless you have some spare props.

Ah, I see -- so the 4 prop one in the OP article... that is basically a death trap at some point?

It's 8 (two stacked along the same axis in each corner), so there will be some kind of redundancy.

I am not sure about this in particular. But in general for redundancy to work you need the remaining equipment to be able to support the craft fully. There needs to be enough spare power. And the remaining thrust must be central enough to avoid loss of control. This doesn't work well with even numbers like 2x or 4x.

Also, adding additional rotors/engines could increase the chance of a failure in a particular flight as you have more things that can go wrong. A 2 rotor helicopter is definately not safer than a single bladed one.

https://archive.is/lg4yx

Is it physically/technically possible to have quiet or silent rotors on drones? I can’t imagine flying cars as depicted in the article becomg a thing in cities if they sound like the 2010 FIFA World Cup.

Not really; an airfoil that’s generating lift makes noise. The bigger the airfoil and the slower its moving (relative to the air stream), the less noise it creates. However, you can’t have those characteristics with this kind of aircraft.

Multi-rotor copters like this rely on light and fast props, so that the speed of the prop can be changed quickly. This changing of the prop’s speed creates the tilting and rotational movements shown in the video.

There are means: https://patents.google.com/patent/US20180305004A1/en?oq=2018...

Blade design can also contribute or reduce noise. Fully silent while providing sufficient lift seems impossible...but how long did it take to innovate to the bladeless electric fan?

Isn't the bladeless electric fan just a ducted bladed fan?

No, because "ducted fan" has a very specific meaning in aerodynamics. But yes, a bladeless electric fan isn't actually bladeless, the blades are just hidden inside the fan body.

https://en.wikipedia.org/wiki/Ducted_fan

I don't see how this could ever be feasible for consumers. People still struggle to drive when there are roads, what's going to happen when you add a third dimension to control?

I suspect self-driving is much, much easier when you get up above ground clutter.

I agree.

In two dimensions, a vehicle moving North-South and a vehicle moving East-West have to cross into each other's path at some point, and 2.5D solutions (bridges and flyovers) help but require significant investment in resources that simply isn't possible at every junction.

In three dimensions, this simply isn't the case; we can separate different directions of traffic by height, and provision of dedicated corridors for changing route is merely a matter of making regulation rather than infrastructure.

There's a reason why we've had autopilot on planes for significantly longer than on cars.

The flip side is twofold - to take advantage of said autopilot, you need a pilot’s license, which is significantly harder and more expensive to get than a car license.

Aircraft are also expensive (and come with expensive operating costs like airframe examinations), since their failure mode is a more-or-less controlled “falling out of the sky” - so you want the most resilient parts you can have to skew more towards the “more controlled” end of the spectrum.

There’s also a whole network of human traffic controllers who work 24x7 to accommodate our existing air traffic; more would be required.

Autonomous operation is easier above the ground clutter in terms of navigation and collision avoidance, however dealing with failure modes is more difficult. It's impossible to code for every possible failure so the control system has to be smart enough to adapt to the unexpected in real time.

People are going to be dreaming of flying cars until some other technology comes along that completely obsoletes them.

Or until they hear how loud they are. People underestimate how loud these flying cars are and how much noise pollution can ruin their quality of life. I can't imagine a suburban neighborhood full of these loud flying cars.

Can just see the kids running to the car after soccer practice and mum yelling "BLADES!!"

If multi rotor cars become standard, we will all be wearing ear protection.

What we need is propulsion systems like the Tic Tac spotted by the Nimitz.

Imagine if every one of your neighbours had one or two...

It's the ultimate wonderful if you own one. Terrible when everyone else does. It's like automobiles X 100.

Looks like a worthy competitor of Moller Skycar /s

why is the headline talking about flying car yet I don't see any wheels?

I can't read the article, but if it leads to widespread adoption like the automobile was, I can see this being much worse for society than the car was. Some examples of the sort of things we can see:

- Suburbs times 100. Now, the suburbs would be even less accessible as they wouldn't even be connected by roads. Coincidentally, they could be anywhere, which would spread out utilities and make them even more inefficient as they are now due to sprawl.

- Much, much more expensive, both due to the complexity but due to insurance. Already cars are deadly and destructive, flying cars would lead to all sorts of accidents and property destruction given the difficulty of driving them especially by non-professionals. This too would probably be normalized like automobile destruction is but the actual cost will still exist and need to be subsidized by sky high insurance premiums

- Further destruction of cities. Now, like wide streets and highways that demolished neighborhoods (often black and immigrant communities), we'd see calls for destruction of tall buildings for "the sake of safety" due to the common place destruction discussed earlier. Streets and walkways like sidewalks today would fall into disrepair, trees and monuments would be cut down or removed for safety, and so on.

Then again, I don't think we'd get that far due to climate change, but this is just based on a historical understanding of what happened to the US since the 30's. I can see a much more atomized and disconnected society.

https://www.wsj.com/articles/japans-entry-in-flying-car-race...