Toyota Investigating Hovercars

cartechboy writes: Remember back in the day when we all thought we'd be driving flying cars in the future? Well that clearly didn't happen, though it still might in the future. But somewhere inside Toyota there's a team of engineers who think hover cars might be a thing, and apparently there's a project underway at one of Toyota's "most advanced" research and development areas. We aren't talking Jetson's flying car, more like a car that merely hovers "a little bit away" from the road. Probably a few inches, with the aim to reduce road friction. With no wings or ridiculous speed, this is probably no simple process. No one really knows how long Toyota has been working on the idea, or how far along it is. Basically, don't expect flying Priuses any time soon...

Comments

aka

[GoddersUK]

small hovercraft.

this is probably no simple process

Surely the underlying technology required is essentially what's already been developed for hovercraft, which already come in car sized variants. Don't get me wrong, I'm not saying it would be easy to stick a car body on them, develop intuitive controls and stick them on public roads; I'm just not sure the technology is as novel and underdeveloped as the summary makes out.

Re:aka

[CastrTroy]

I'm not sure why a person would want a hovercraft for general use. It's way more efficient to just have car that rolls on wheels. Lifting the entire car off the ground with a cushion of air is terribly inefficient. Not that there aren't any uses at all, but as a general purpose vehicle on public roadways, it seems like a terrible idea.

Re:aka

[Tx]

The trouble with those car-sized hovercraft is the turning and braking profile, which is nowhere near good enough for public roads designed for cars. Now a design something like the Aero-X hoverbike might be able to improve on that - by hovering a bit higher and tilting the entire craft, you could effectively vector a large proportion of the lift airflow for turning force, as opposed to redirecting a bit of the horizontal thrust only with a fin as with conventional hovercraft. Aerofex don't seem to make any such claims about their design though, they seem to be targeting off-road use only, and I guess turning that way might present problems for other road users/pedestrians getting hit by the airflow.

Re: aka

[Viol8]

Given 95% of resistance at motorway speeds is air resistance, not rolling resistance I'm not entirely sure how having a massive fan to create the lift and another to propel the car is going to improve fuel efficiency given how inefficient propellers are to start with.

Re:aka

[91degrees]

Be useful in places where there aren't really roads. Bet the things work great in deserts. In my experience though, steering is a problem. You can't really steer a hovercraft easily. The rudder does hardly anything.

Re:aka

[necro81]

The problem I see with hovercraft (on the same roads as automobiles) is acceleration. The wheels do a lot more for the car than simply supporting the weight - contact with the road surface is absolutely essential for accelerating forward, braking, turning, and keeping the front of the car pointed in the direction of travel. In a hovercraft, you need some alternate mechanism for that - usually pushing with or against the air (i.e., propellers and fans). How does the performance of those alternate means for acceleration compare to rubber on the road? Without a prototype to examine or independent road tests, one cannot say for sure.

Re: aka

[zAPPzAPP]

And no grip whatsoever in curves. Weeeeeee~

Re: aka

[rmdingler]

Yes.

Unless and until technology emerges that makes defying gravity much more efficient, there is no advantage (outside of the WOW factor) for using these vehicles on the highway.

Off-road applications are a different matter.

Re: aka

[Anonymous Coward]

So, basically anything made by an American car company?

Because those have always sucked at cornering.

Re: aka

[Rei]

That's not true. It varies from vehicle to vehicle and between driving profiles, but it's usually 50-75% of the resistance at highway speed coming from aero drag - not 95%. Rolling drag remains a significant loss factor at all speeds.

That said, this doesn't sound to me like the most logical approach to tackle rolling drag - wheels are more efficient than hover as-is in most general-use cases, and I can easily envision a lot more that could be done. For example, you could use very high pressure (120+ psi) tires with a hard, thin central tread, relying on automatic camber to a thick, sticky side tread during accel, braking, cornering, or when traction control kicks in (the additional vibrational load from cruising on high PSI tires could be canceled with, for example, a cable vibration isolation system or active vibration cancellation). Such a system should be able to approach the rolling coefficients of hard steel wheels (a tenth that of traditional car pneumatic tires - effectively rendering rolling losses irrelevant). Heck, if you're going to that extent, it's not much further to go all the way to completely solid wheels (though you'd want foam-core carbon fiber or similar to keep the weight and in particular unsprung mass down, not solid steel) and not even have to deal with tire inflation or puncture risk. So long as you have a way to automatically shift to a thick, sticky tread as needed based on current traction conditions and have a mechanism to soak up the higher vibrational loads to maintain ride quality, you're fine.

Is that a pretty huge deviation from standard practice? Yeah, by no small amount, it's literally reinventing the wheel. But you know what, it's also a pretty huge deviation to have cars outright hover on the highway. ;)

But yeah, you're right in that rolling losses aren't the *primary* loss mechanism on the highway. A lot more has to be done to tackle aero drag, and that's trickier - not least of which because the optimal shape varies based on speed and things like crosswinds (and the more you optimize your shape, the bigger of an issue this becomes). One of the more clever ideas I've seen - I don't know how it'd play out in the real world, mind you - was Aptera's plan to take a page from Gerald Bull's playbook and fill in the low pressure wake with air ducted in through the cabin. There's also a fair bit of research designed for aircraft (where aero drag is an even bigger issue) that could translate to cars, for example, skin textures or microstructures designed to maintain laminar flow or reduce surface drag. One of the more exotic variants of that which I've seen is a taut film outer-layer over a microscopic layer. The film vibrates in the wind between its ridges, setting up standing waves which separate the laminar flow from the surface, reducing the flow speed in contact with the surface and thus reducing direct surface drag. There've been peer-reviewed papers on it, and one of the researchers founded a company that now makes kits to reskin a variety of small aircraft (not very many thusfar, the skin has to be custom designed for each model). That's of course just one example among many, it's a very active field of research, as even a fraction of a percent reduced aero drag on a commercial airplane results in massive fuel savings.

Honestly, I'll be happy if we can just get people's style preferences to shift away from naturally high-drag forms like those ridiculous oversized front-end things where you can barely see over the hood. I know I'm out of the mainstream, but I love the look of aerodyamics. Real aerodynamics, not counterproductive curvy features that a lot of people think are "aerodynamic" but actually raise your drag. I want my car to look like a wingless plane, a car that cuts through the air like a knife rather than a clobbering oaf shoving it all around as it drives by ("Excuse me air, coming through, excuse me, sorry there!"). I want a rounded front end and a rear end that tapers vertically down with as long of a t

Re:aka

[drinkypoo]

Be useful in places where there aren't really roads. Bet the things work great in deserts.

Only on the flat. You can't cross dunes in a hovercraft. Nor, in fact, can you take any significant grade, nor can you cross any obstacles which very closely approach the size of the gap between the ground and the hard bottom of the craft. Not the skirts, but the hull itself.

Hovercraft have basically one job, high-speed landing craft.

Re: aka

[drinkypoo]

Off-road applications are a different matter.

Yes. A different matter entirely, as in, hovercars will never be useful in off-road applications. Unless, perhaps, they are antigravity vehicles and they are utterly unconcerned about slopes and grades. You cannot take a hovercraft up a grade of any note. Antique steam trains can ascend a steeper grade.

Re:aka

[Ozymandias_KoK]

Gotta have somewhere to put all your eels, you know.

Re:aka

[Rei]

Oh, and just an additional comment, from my past experience in the auto industry: this wasn't an "oops, I wasn't supposed to say that!" remark. The Japanese companies are in general very good at controlling information flow; this was clearly planned for him to say that. But the reason he said it was almost certainly not to prepare people for the coming day of flying cars; it's about perception. It's a major brand positive for an auto maker to be perceived as high tech / cutting edge / innovative, and they want to culture that.

Remember Rick Wagoner, the guy whose tenure at GM made a graph of the company's stock look like a double diamond ski slope? Of all of the things that he could have regretted, he's stated that the number one thing he regrets was axing the EV1 (late 90s electric car) program. The EV1 lost tens of thousands of dollars per unit and there weren't many made so there was major overhead on top of it; but by axing the program to save a little money, they willingly gave up the perception of being a tech innovator, right at the time the Japanese companies were introducing hybrids. Even to people who weren't considering buying a Prius or Insight - aka, the vast majority of consumers - the very perception that Toyota and Honda appeared to be high-tech innovators demonstrably influenced consumer buying decisions.

Car makers have slick PR teams who survey and carefully try to manipulate the public perceptions about themselves to influence buyer behavior. Expect that the decision to mention this came straight from one of them.

Re: aka

[markhb]

What about off-solid-ground applications, where they are already used? I have an actual use case in mind for a hover vehicle similar to a DUKW, where it could go into hovercraft mode over water that is too shallow to use conventional craft mode, but with a bottom too shallow to use the tires.

However, the on-road applications face another stumbling block: the laws in my US state (and likely most if not all of the others) require all vehicles used on public roads to be exclusively propelled by means of power-driven wheels in physical contact with the pavement. No hovercraft, no strapping a jet turbine to the roof and throwing it in neutral.

Re: aka

[Rei]

It could be (though that would have engineering challenges of its own, and not just noise minimization), but remember that compressing air is a rather lossy process. If you're rapidly dropping the pressure, say from 120psi to 20psi then back, every time you need traction, you're going to lose an awful lot of energy doing so.

Given that increased camber is often a good thing when cornering, and that there's no inherent physical loss mechanism in changing camber, and your required hardware to do so isn't particularly onerous, that's why I mentioned that particular possibility. But overall, that was just an example; the key point is, there's an order of magnitude difference in rolling coefficients between today's car tires and that of rigid wheels**. If you can get rid of all of the compression/flex in your general-use case, and only add it in when you need the additional traction, and make use of a vibration isolation or active cancellation system to maintain ride quality, you could virtually take rolling losses out of the picture.

** - I should clarify that when I say "rigid wheels" perform an order of magnitude better, I don't simply mean "anything non-pneumatic", but rigid to the degree of train wheels or ball bearings. For example, in wheelchairs, pneumatic tires often actually have *lower* rolling losses than "rigid" wheelchair wheels; the latter flex too much and thus lose more energy in the process than their pneumatic equivalents. It's not the use of air that's the problem, it's the repeated bending of material, turning your kinetic energy to heat. To achieve dramatic improvements in rolling coefficients over conventional tires, a rigid wheel needs to offer dramatically less flexure than its equivalent tire as it rotates. But it also has to be lightweight to minimize total mass and in particular unsprung mass. Hence the suggestion of carbon fiber / foam core wheels; I would expect such wheels to be able to meet that kind of spec if built well enough. But who knows without experimentation...

It's also a fair criticism that once you start going for such extreme rolling drag reductions, imperfections in your road surface are going to have an increasingly large impact on your achieved rolling coefficient.

Re: aka

[Rei]

I'm not talking about a long hood so much as a tall hood relative to the rest of the vehicle - the car starts, then suddenly it's nearly as tall as the roof. Example: here's the concept mode for the Chevy Volt. I took one look at it and smacked my head, anyone who knows aerodynamics can see that that thing is going to have the aerodynamics of a rolling brick (spoiler: that's a whopping 0,43 drag coefficient on a supposedly "efficient" car!). Nobody should have been the least bit surprised when it changed dramatically going from concept to production. Yet that concept look is supposed to mimic the look of a "chopped" car (despite not reducing the frontal profile) and thus be "sexy", "muscular-looking" and desireable. It just ruins it for me. I know that I'm weird in being turned off from a car by seeing its awful aerodynamics.

Basically, there's no reason that your "long hood" has to quickly flare to full width/height in the front, then remain relatively constant height up to the windshield. That's highly suboptimal for aerodynamics and achieves nothing in terms of giving you a long distance to decelerate in. The optimal aerodynamic front end is roughly elongated-egg shaped.

Beyond that, you don't need a long hood at all, either, for crash protection, just a long deceleration distance. Hood length and deceleration distance, though related, are not equivalent. One factor, for example, is where the driver / passenger are located inside the vehicle. If you have a highly raked windshield (optimal aerodynamics) then the driver and passenger have to be located a bit further back from the front of the car for headroom reasons, so there's still plenty of room ahead of them to the foremost point on the vehicle. Also at play is how the vehicle deflects force in an accident - whether it crumples straight back or whether the nose rides up during a collision (the latter gives extra deceleration distance). A greater rake on the windshield also decreases the chance of windshield penetration.

It should also be pointed out that such a design also enhances pedestrian safety in a number of respects. The lack of an abrupt flare means a pedestrian is more likely to be hit at an angle and accelerated over a greater length of time (reduced G-forces). The matching rake between the hood and windshield additionally means they're not going to suddenly decelerate at the windshield. To be fair, of course, some pedestrial-safety features, such as low bumpers, run counter to aerodynamics.

As for that SkyTran PRT: Judging from the image on the cover, it looks like a reasonably good shape up front, but the rear end sucks. Contrary to popular misconception, it is *not* good to have a rounded rear end. Once your angle gets too steep, the flow will detach from your vehicle, leaving a low pressure wake. You want to not exceed the critical angle (aka, use a roughly constant taper angle) and prolong the detachment as long as you can (aka, as gentle of a taper as your design parameters allow), and when you can't delay the detachment any more, you want a relatively abrupt cutoff, potentially with a vortex generator to draw down the stream. The actual details vary depending on the situation, and one always needs to do CFD work, but that's a rough "in general" for aerodynamic optimization

Update: I searched more and found some rather different looking PRT images. These are of an excellent aerodynamic form, with an appropriate taper in back (though I personally prefer a vertical taper to a horizontal taper for cars... theirs makes sense for their particular application, however). I'd be willing to wager that their cover image was an early artistic concept, while the latter was something they actually did CFD work on.

Re:aka

[AK Marc]

TFA doesn't claim "hovercraft" That's editorial. What would happen if you found a way to duct air under the tires? Have them lifted 1mm off the ground by a thin layer of air. Part of braking or any other maneuver would be to cut the air, and the tire is then in contact again. The tire still bears 100% of the car weight, but has no contact with the road while under certain cruising conditions.

The "announcement" is overblown from a throw away comment with no detail or follow-up. No official press release, just a comment by an engineer about some of the "cool stuff" they are investigating (not making, not prototyping, just thinking about).

Perhaps the engineer was even flat out wrong. I could claim the same thing he claimed if I worked out a lift system that, as the car approached the road, the lift on the car increased. Then lower the suspension to the point the normal force decreased by 90%. You'd lose 90% of your handling, but that wouldn't matter, as long as you were cruising. And it'd be "cruising" on a cushion of air more than the tires.

Given his statement, I can see 100 different solutions that are all better than "hovercar".

Unless they are looking into powered roadways and mag-lev powered hover cars for freeway cruising, but that'd be massive infrastructure build, and the car would be trivial, once the roads are done.

I get enough flying priuses already.

[nimbius]

call me a fogey but we cant handle flying cars and we certainly cant begin to handle hovering ones either.

Here in america you need look no further than your local road to confirm my assertion. just drive to lunch today and count how many people change lanes without a signal, make an illegal left across two lanes of opposing traffic, run red lights, cut eachother off, and tailgate. We're a fucking mess. On the highways every single vehicle routinely travels 15 miles or more above the speed limit, even though we've had reliable cruise control thats far superior to our own clumsy right foot for more than 3 decades. Drivers are glued to their phones or face down in the texting position for the majority of their commute. We're horrible at looking ahead and predicting when traffic will stop, instead choosing to slam on our brakes and let the other guy do his best to stop. Although every drivers manual reads we should slow down if someone wants to merge into our lane, we instinctually speed up or ignore them. Try an experiment: go the speed limit in the center lane of the highway and see how many furious drivers pound their horns and flash their headlights. Better yet, try driving in the left lane on a road that isnt limited access, a speed limit something around 35mph, and see how many people completely lose their minds despite the fact that what youre doing is entirely legal. And speed? The only time speed factors into any collision in america is when its fatal, and even then its only if the wreckage is catastrophic or the occupant a celebrity. We wrecklessly whip across 3 lanes of traffic and insist on maintaining our lead regardless of how congested the roads are. We categorically ignore speed limits in a construction zone despite a quad-damage boost to any citation received. We race along at all hours of day and in all seasons as if a collision would have no consequences to us, because we're all we think of.

The best innovation in automobiles has been to autonomize them, but compared to things like rail even an autonomous car is laughably inefficient and merely perpetuates a host of systemic and unsustainable problems related to automobiles nonetheleast of which is climate change.

Re:I get enough flying priuses already.

[Viol8]

"Try an experiment: go the speed limit in the center lane of the highway and see how many furious drivers pound their horns and flash their headlights"

Yeah , I wonder why that could be. Perhaps because some arrogant ass is blocking the lane when he's supposed to move over if the nearside lane is clear. If you want to play traffic cop go sign up and do the 2 years training, otherwise get out the fecking way.

Re:I get enough flying priuses already.

[JimFive]

Better yet, try driving in the left lane on a road that isnt limited access, a speed limit something around 35mph, and see how many people completely lose their minds despite the fact that what youre doing is entirely legal.

No, it isn't legal. Look up Impeding Traffic. You aren't allowed to impede the normal flow of traffic, even if that traffic is violating the law.
--
JimFive

Re:I get enough flying priuses already.

[drinkypoo]

call me a fogey but we cant handle flying cars and we certainly cant begin to handle hovering ones either.

You might be a fogey, but you're completely correct. I was just driving up the 101 and watching people lane drift and thinking this very thing — people can't handle the cars we have now, they certainly won't be able to handle a vehicle with reduced friction.

Re:I get enough flying priuses already.

[Princeofcups]

So you are saying, it's ok to break the law, as long as everyone are doing it?

When speed limits are designed to be 10MPH lower than what people are expected to drive, then yes. The law makers assume that people will cheat by that much, and set the limits artificially low.

Re:I get enough flying priuses already.

[wjcofkc]

"Try an experiment: go the speed limit in the center lane of the highway and see how many furious drivers pound their horns and flash their headlights"

Yeah , I wonder why that could be. Perhaps because some arrogant ass is blocking the lane when he's supposed to move over if the nearside lane is clear. If you want to play traffic cop go sign up and do the 2 years training, otherwise get out the fecking way.

Yet those same furious drivers will inevitably pass on the right into dense, slower moving traffic, ride someones tail until that driver gets nervous and speeds up enough to let them pass that center lane car only to further pass into the the left lane which was open in the first place. The moral of the story is, once you hit the highway, someone is always an idiot to someone else whether you are actually driving like an idiot or following the letter of the law.

Re:I get enough flying priuses already.

[pr0fessor]

And WTF is up with idiots that slow down 10 - 20 MPH at every green light?

That's my wife, she has been hit by people running red lights while texting twice. I saw it happen to someone else Monday.

The city could make a boat load of money if they had cameras at the traffic lights catching the people running the red lights.

Re:I get enough flying priuses already.

[StormReaver]

No, it isn't legal. Look up Impeding Traffic. You aren't allowed to impede the normal flow of traffic, even if that traffic is violating the law.

Impeding Traffic varies from state to state. In Missouri, for example, drivers in the left lane must move faster than drivers in the right line (assuming both lanes are for the same direction); but only up to and including the speed limit. If the driver in the left lane is at the speed limit, and the driver in the right lane is exceeding the speed limit, the right-lane driver is violating the law while the left-lane driver is obeying the law.

Re:Priuses?

[skovnymfe]

But this isn't Latin. This.. is.. English!

Re:Priuses?

[sanosuke001]

It still sounds ridiculous.

Re:Scrapheap Challenge

[VernonNemitz]

There is a new-ish technology out there for making flying machines, and they can be roughly automobile-sized. Perhaps Toyota should consider teaming up with the inventors....

The future is over?

[asylumx]

Remember back in the day when we all thought we'd be driving flying cars in the future? Well that clearly didn't happen

That's the beautiful thing about the future, it is still (and always will be) ahead of us.

Curtiss-Wright Air Car

[Animats]

The 1960 Curtiss Wright Air Car did this. It's a hovercraft, built to look like a car with bumpers, chrome, two-tone color scheme, and convertible top. Top speed around 38 MPH. 2.5MPG.

Race car design goes in the opposite direction, trying to get as little lift as possible. Some Formula One cars were built with big fans sucking out air from below the vehicle to increase tire contact forces. Worked too well; prohibited by a Formula One rule change.

Re:Priuses?

[rogoshen1]

the Prius is more like the antidote to that particular condition.