NEC shows ‘flying car’ hovering steadily for minute
apnews.com
apnews.com
Someone recently flew a jet-powered "hoverboard" across the English channel.[2] That thing is powered by several large model aircraft jet engines. It's much like the Hiller Flying Platform of 1954.[3]
If you like strange VTOL craft, many of them are in the Hiller Aviation Museum in San Carlos, CA.
Also check out the famous AvroCar flying saucer.[4] The US National Archives has uploaded the declassified videos to YouTube. The first video, before the first flight, was classified SECRET. The second video, after the first flight, was only CONFIDENTIAL. The third and final video was UNCLASSIFIED, because it didn't work. The thing was sent to what is now NASA Ames to see if it was good for anything. The video shows it bumping around a meter or two off the ground, pretending to be a hovercraft. The original goal was a supersonic VTOL aircraft. Not even close. The U.S. Army canned the project in favor of the Huey helicopter, which actually worked.
[1] https://www.youtube.com/watch?v=B7Hm-rmLQcU [2] https://www.cnn.com/videos/world/2019/08/04/french-inventor-... [3] https://www.youtube.com/watch?v=ANBeuGcZHBA [4] https://www.fourmilab.ch/documents/army_saucer/
The Volocopter (with 18 rotors above instead of 8 below) looks like a much more reasonable and fault tolerant concept (that has actually had manned flights for years).
EDIT to add: lazy journalists - "World’s First Passenger Drone Unveiled In China" in 2018, while the Volocopter had its first manned flight in 2016 [1] and been flying around in Dubai 2017 [2]... Ignorance is excusable, but not doing even a cursory internet check isn't really.
The eHang 184 is truly a horrendous design in my opinion, and I am puzzled why it is seriously reported about.
Hard to find authoritative statements on it. There is a thread on aviationexchange where some say that an underslung helicopter is actually more stable than a conventional one, but I haven’t been able to verify this.
With a multicopter, the situation might be different still.
And stopped for a refuel half-way.
The car shown in OP is one motor/esc/prop failure away from killing whoever is inside it.
That is no redundancy. With only four booms, it only takes a single boom failure (electrical or mechanical) to crash. And with co-axial counter-rotating props, a prop failure will almost certainly cascade to its partner - so again, you really only have four props.
There is almost no survivable failure mode with that design.
All those 8x parts are much more likely to fail than the boom. How would the boom even fail mechanically if it's just a solid holding mechanical part that is well-built and tested? Would it just break off? Because of what? If so, in any regular normal airplane or a helicopter there are many other similar parts which are usually not redundant. This must be due to the fact that such solid parts fail very rarely, and perhaps more importantly, can be somewhat easily tested on the ground to check their structural integrity. Motors, ESCs, etc can fail due to many other reasons and are sometimes harder to test properly, there is much more risk in them.
So yes there is redundancy.
This configuration of props is called coax, and is specifically less effective than just putting 4 motors of higher power and bigger props. If there were no gains in reliability, no one would build drones like this, because they would just be less efficient and fly for less time. There is basically no other advantage in this setup than their better reliability due to redundancy.
>And with co-axial counter-rotating props, a prop failure will almost certainly cascade to its partner
Do you have a source for that?
If a prop breaks, it will likely fly off onto sides due to centrifugal forces, not on the vertical axis into the other prop. Additionally if a bottom prop breaks, there is already a downward flow of air from the top prop, which will act as additional downward force on those breakaway parts which will force them to fly off downwards, not upwards into the remaining prop.
You have to consider specific failure modes. You might have an object strike, like a bird. You might lose sealing and get water in somewhere, frying anything electronic inside. You might have a loose bolt, a fatigued bracket, or a frayed wire. When you start considering scenarios rather than parts lists, it becomes clear that consolidating things together spatially costs you most of the advantage of redundancy.
This is especially true in the case of props. In point of fact, if a prop breaks the net force is upwards, because that's the direction it was pushing in when it failed. However it's basically irrelevant - unless you perfectly and flawlessly detach the blades symmetrically with explosive bolts, with impeccable timing such that no detached blade hits the airframe, so much energy is released with a moving-part failure that anything in the vicinity is pretty well destroyed. Experience you might have with normal-sized drones is not applicable if you scale it up even a little - big props make a big mess, and you're lucky if the airframe survives at all. You certainly won't be able to count on that shared pod.
We can only guess at why they chose to design it this way - personally I think they're a bunch of cowboys who will kill someone the way they're going. I suspect it's because they want to keep the footprint small, and because it's kind of uncool to have to pick your way through a dense ring of props to get to the cockpit (if you look at some of their videos you'll see that they've experimented with non-coaxial x8 configurations in the past). But stacking the props two-by-two like that only costs you reliability.
Props on the other hands can have electrical component failures, wiring failures, engine failure, bird ingestion induced failures, control instrument failures, etc. Remember that each vehicle has four times these components (ie: four times the failure rate) and the failure of any is a crash.
Just a lot more potential things that can fail and cause a catastrophic accident.
That said, based on this video I don't think an actual 200km/h is anywhere near survivable for the average modern car: https://www.youtube.com/watch?v=LmRkPyuet_o
Possibly higher end sports cars with cages and five point harnesses may fare better.
Kinetic energy by itself does not matter one bit when it comes to how damaging a crash will be for the human occupants. People use it as a proxy for acceleration and jerk. Kinetic energy is only actually useful when you're trying to figure out what acceleration and jerk will be if the crash involves multiple moving vehicles or hitting an object that's light enough to move.
Imagine a freight train crashing into an immovable something at low speed. The kinetic energy is going to be higher than almost any car crash but the occupants will be just fine and they have far less crash protection stuff around them than anyone in a car. Alternatively, imagine an occupied small car traveling at some low speed crashing head on into a person who was shot out of a cannon at high enough speed for their kinetic energy to be equal. Both parties are going to decelerate over the same amount of time but the person shot out of the cannon will experience much higher acceleration (and jerk) because their initial velocity was higher.
Intuition wants to think it’s twice as bad.
As an aside can I pose another physics car challenge to you that 100% of people I’ve asked get wrong?
You’re the only car at stop light waiting for the light to turn green. You look up in your rear view mirror and see a car bearing down on you presumably with a distracted driver. You know you’re about to get rear-ended. In that split second do you: A) Let up on the brakes and put the car in Neutral or B) slam in the brake as hard as you can.
The answer may well be c) gun it and hope for the best!
WRT the two cars crashing - I would bear in mind that immovable objects are quite uncommon, most highway barriers are compressible. So whilst you might be strictly correct I'd imagine few people crash into completely stationary objects like bridge supports without crash buffers.
Your car will accelerate suddenly from the impact either way, so you want to increase the time-frame over which the impact forces of the crash are dissipated. If your car is in neutral, then the crash is less severe because only part of the other car hits you before your car starts gets pushed forward, so more of the energy of the impact gets transmuted to accelerating your car and less energy needs to be absorbed by your car's crumple zones.
If you slam on the brakes, you effectively turn your car into a stationary object, and that means you and the other car must absorb the full energy of the collision. At collision speeds where survivability is a concern, this usually means the crumple zones are inadequate to absorb the energy of the collision and so more of it gets passed on to your body.
Ideally, you would want to accelerate your car as much as possible before the impact to minimize the speed differential. Even a 10mph decrease in the differential has a huge impact on survivability.
[Note: bigger cars can survive crashes better because they have more mass they can act as crumple zones to absorb the force of the crash. Older, more rigid cars would frequently survive with limited damage crashes that killed their occupants, at lower average speeds than today, because the cars transmitted more of the impact forces to the occupants. Modern cars are designed to crumple to dissipate impact forces.]
I can't find a lot of testing done at this sort of speed with regular cars. Racing cars and some high-end sports cars are exceptionally strong and allow you to survive a 200 km/h crash - often with only very minor injuries - but I'm really uncertain that this is true for a regular family car. Do you have any further data on this? Given how many regular cars I see driven at this sort of speed when I visit Germany, it'd be interesting to know!
Useless on commercial aircraft, great for small, lightweight personal transportation vehicles.
Parachute?
Otherwise having large airbags deploy under the vehicle could be another option.
Not sure the Zapata "flyboard" is fully consumer-ready. The inventor lost two fingers flying an earlier version. https://www.core77.com/posts/89748/Franky-Zapata-Crossed-the...
Pity it never went into mass production. We should crowdfund a modern version!
The army might have bought in on this if they had mounted a turret or some offensive weapon system of some sort though, otherwise to them it’s just a toy.
They forgot to add helicopters can also auto-gyrate in the event of engine failure.
Quad-copter drones probably just crash.
This part really puzzles me, I mean I guess they're better than helicopters but all those thing apply to flying cars as well, just to a lesser degree.
Getting some flying cars won't be cheap, maintaining them might be cheaper than a chopper but still not very cheap.
And if you're going to pilot one of these, and carry people around I guarantee you will have to be licensed and trained in piloting one. The regulations won't be as loose as with drones.
As for the noise, well this isn't exactly quiet.... https://youtu.be/cmdilp9LM0E?t=67
Sure it might not be as bad as a helicopter but you also rarely have two dozen helicopters zipping around near ground level. While the whole plan is to have these zipping around everywhere.
Furthermore, with the drones, you have fly by wire, with control inputs translated into manoeuvring in a simple manner, so pilots will require much less skill.
For example, one has to log a certain number of landings in a helicopter. In a Volocopter, you'd literally just slide a button on the control stick up to take off, then slide it down to land, and do that N times, and you've passed that part of the requirements.
I remember listening to Elon Musk dismissing flying cars for this reason.
High-end drones have battery redundancy, six props to account for failures, parachute systems, etc.
A parachute system only helps if you are high enough. Looks like the flying thingys we are talking about here will be close to obstacles a lot and not very high up much of the time given how they are to be used.
Battery redundancy: The scale argument again. This is an order of magnitude harder to achieve on a much larger man-carrying "drone".
Isn't it much easier because you have capacity (weight carrying ability) for many more cells, and the chances too many of them fail is much lower? If you have 3 cells, 1 of them can fail at any given time, and you're left with 66% of power, but if you have 200 cells, and 1 or 2 of them fail, you don't even notice. How do you mean that it's harder? Electric cars certainly don't seem to have any problems with this and their batteries are much more reliable than the ones available for drone usage.
Also with big size/capacity you can easily include additional systems like temperature control which increase reliability because they don't weigh as much in relationship to the whole vechicle.
Don't think space (not the biggest issue here as you say), think weight, power and the ratio.
If a helicopter is doing it with a single main rotor, I'd be surprised if it can't work with a hexacopter and redundancy.
I'd be more worried about noise. A consumer drone is noisy enough, though mostly just noticeable because it's a new thing people are yet to get used to.
Helicopters auto-rotation is not at all comparable to a drone with one or more failed rotors, a helicopter that is autorotating is comparable to a gyrocopter, it will fly relatively well, a drone with one or more failed rotors will not fly well or even at all.
Or do they exist but just aren't sexy enough to make headlines?
https://en.wikipedia.org/wiki/Northrop_Grumman_MQ-8_Fire_Sco...
https://www.engadget.com/2019/07/09/us-navy-mq-8c-fire-scout...
A. Imagine DUIs in widely available flying vehicles.
B. Autopilot is still dogshit. That's the truth.
C. If you're old enough, you'll remember when a commercial airline would be high in the sky and you'd still have to pause talking to someone on the ground. Now, even though they will be quieter, electric and all, but high speed rotors still make noise. Lots of it. Add lots of these in lower altitude. Good bye quiet spaces.
D. Maintaince. Oh my shit, few people properly maintain their ground cars. Wtf do you think is going to happen to a flying car? Difference is, you don't roll to a stop on engine failure. You crash into a home with someone's family in their teaching their toddler to walk.
E. You think those trucks through crowds were bad a while ago? This is borderline democratizing terrorism.
F. Mile per watt is going to be way worse than a car. Itll take way too much energy in comparison. Those power conglomerates are going to want their pound of flesh.
In the early days of jet airliners, you had high-velocity exhaust providing all of the thrust. With turbofans, you have much more thrust coming from low-velocity bypass. This is quieter in itself, but also 'shrouds' the high-velocity exhaust.
As bypass ratios get higher, engines generally get more efficient and quieter. The challenge in doing this is mostly engineering the large fans.
The largest commercial jet engines are actually about as wide as the fuselage of the 737! The first jet engines were less than a meter wide.
With flying cars, you'd never be able to guarantee the safety of any outdoors event (and in either case, it doesn't have to be the result of terrorism, a drunk driver or a midair collision can still cause these problems)
Anti-air artillery is not a reasonable civilian defense system. It's just silly, not in any way relevant to the discussion at hand, and you know it. Stop trolling and move on.
How about remote shut off and control by a gov body? Too expensive and a wonderful vector for remote hacks.
FAA tracking and interception on deviated courses? Holy crap I doubt they can scale fast enough if buying and using flying cars "takes off". See what I did there? Also interception will lead to the same fire ball of death problem.
No fly airspace, which would become nearly every metro and suburb the same day. Thus making the flying car useless.
Unless we do SAMs or antiair, the flying car will be dead in the water. And still would be. It's too large of a premeditated and accidental disaster precursor.
If they're k12 rated. Most bollards are not k12, especially in cities due to shallow dig depths. Even if the bollard or planter themselves are k12. Normally they're never dug deep with supports because contractors are lazy assholes if you don't stand over their shoulder. And those that are k12 are expensive as shit. I actually work in protective design. That, and I think I'm funny so :P
One thing to keep in mind about the threat of "flying car attacks" is that weight requirements of staying in the air generally remove the "mass" part of the equation.
Someone could pack a flying vehicle full of explosives, but explosives that pack a big punch and that are compact & light weight are pretty regulated. Explosives that are easy to acquire tend to have more weight (fuel oil & fertilizer, for example). You could only pack so much in a vehicle before it couldn't take off anymore.
In general, I don't think flying cars would be any more of a risk than light aircraft, which have been around for decades without very many incidents of successful terrorism.
As an example, about a decade ago, and anti-tax nut flew a light aircraft into an office building that housed local IRS offices in Austin. It caused a lot of damage, but not serious structural damage and there were no fatalities other than the pilot.
Let's just add, oh, I don't know, 100 pounds of a fertilizer bomb like the Oklahoma city bomber. He used a lot more, but 100 is still crazy dangerous. Add you have a vehicle that laughes at bollards, gates and fences.
You do know, bad people actually do exist. Trusting tech companies and scifi hopes and dreams really isn't an effective strategy.
It rocked back and forth and bounced when it landed, clearly a lot of tuning left.
While the prospect of having less traffic jams is desirable, the odds of being T-boned from above or below by a distracted pilot become greater than zero.
I think we'll need Type 5-and-then-some AI pilots before any of this becomes a reality in day to day commutes.
Wouldn't AI in flight become much easier to create compared to driving AI on the ground? I mean don't planes already have somewhat of an autopilot.
I have no experience or knowledge on the matter, but common sense seems to indicate that air-flight has considerably less environmental variables and could be significantly easier in most cases.
Does it? Instead of routing in two dimensions you now need to do it in three. You then also need to take into account other actors who are also routing in three dimensions. There are no road delineators in the sky.
There's also the rather obvious safety concern that in the event of a malfunction, an accelerating, out of control thousands-of-pounds mass accelerating forwards becomes an accelerating, out of control thousands-of-pounds mass accelerating forwards and coming down due to gravity.
Planes have had autopilot systems for a while now where they basically fly themselves.
The big tech firms have been struggling to make a fully autonomous no-human-needed driving car for a while now. So many variables to deal with. Watch Tesla videos on YouTube and you'll see them still struggling on certain types/conditions of roads etc.
ATC relies upon surveillance radar that won't provide adequate coverage at low elevations (too many obstructions). ATC is also badly overstretched in busy airspaces coping with existing traffic. Adding a large number of new low-altitude aircraft will require new navigation technology (e.g. coordinating a swarm of vehicles in close proximity, relaying warnings about dangerous wind conditions or uncontrolled vehicles, etc)
Conditions in the air can be more treacherous than on a road: although there are more degrees of freedom the supporting air is also more variable than a road: wind shear and clear air turbulence can be perilous even for large aircraft, icing can quickly cripple aerodynamics, and in the event of failure safely halting can be problematic.
Well, the 3rd dimension is likely to remain fairly static for most of the trip. I don't see personal flying cars going up and down repeatedly for no reason unless there is an obstacle in the front and once high enough, there shouldn't be many of those.
It's true that you won't encounter pedestrians, and congestion will be much less of a problem initially, but birds are still a major concern.
It looks to me like a quadcopter with a secret weapon. Like Christian Bale's Batmobile could spit out a crazy motorcycle, this looks like it would spit out a bicycle with a stupid trailer.
On second thought, maybe it's more like an RC tricycle with a detachable quadcopter.
I'm curmudgeony, I say the future is powered bicycles.
I must say I'm not that bullish (on bikes and electric bikes). Shopping, hills, rain, children all combine to mean they can't really do 100% of journeys. And human nature will ensure that that big expensive chunk of metal gets used as much as possible to make it worth the cost.
Of course our car powered present doesn't involve 100% car transport so you could still be right, and it's still worth aiming for.
Ps, if that counts as curmudgeonly I certainly have no hope, now get of my lawn.
Kind of proves your point. Bikes in general are awesome. But they're not entirely useful. Cool. But not practical for the masses. But you wont see builders, painters, electricians or plumbers give up their work vans to haul stuff on bikes. No matter how much they would want to. Or people with kids.
I suppose what you're imagining is somewhere between a bike and a car, one step below a Kei car type concept. Yes it does have advantages, you are starting to lose advantages that a bike has, and introduce disadvantages that a car has, so it isn't a free lunch. I had the idea for a speed limited car (30mph ish) some time ago, you could radically reduce weight etc, but the problem is the car crashing into you isn't going to be speed or weight limited, you also do nothing to address the issues of space that cars take up.
Presumably from the ground, it’d be hard to hear one of these taking off on the 30th floor.
And even in cities with skyscrapers, they tend to be clustered in one or two districts, so you can only travel within a very small part of the city.
My feeling about the current push for flying cars and autonomous transport, is that when our grandchildren ask us about it, it will be in the same way as children today ask why they were still playing violins when the Titanic went down.
Lots of parts of London have at least one building that high,and several has buildings quite a bit taller.
Not all of town would be covered, but even just the ability to get to/from a handful of central points that are on the train and tube network would be valuable even if that will prevent them from being as useful as they otherwise could.
Sure,if you only allow that, then it will be a quite severely limiting factor, but places less densely populated are also more likely to have at least some suitable spots where allowing landings on lower buildings will be ok.
And it doesn't need to work everywhere to be worthwhile.
I can hear drones that fly over, but it's not a horrible noise. Much car noise these days seems to come from friction on the road as engines have gotten much quieter. So with that in mind, perhaps in all they'd be quieter, but I can't see an easy way to environmentally muffle the sound, could you invert the sound?
There is a flyover down the valley and sound flies off that. You only recognise silence in the event of road closure. Then momentary bliss is attained through someone elses misery.
Today most western cities have helipads tucked out the way - on the river in London and NYC for instance - for safety. Every time a helicopter falls out the sky and lands on an unfortunate pedestrian, the rules tighten. That's not going to change with drones.
[1]: https://learning.blogs.nytimes.com/2012/05/16/may-16-1977-he...
You may barely hear the street at the 30th floor, but a helicopter flying 300 feet above the ground is going to be incredibly loud.
Also, "car" has many meanings already: passenger car, train (or subway or roller coaster) car, and elevator car. It doesn't seem unreasonable to add another.
edit: Forgot to add that it has already flown over 20,000 miles with payload (in about 2k flights)
The article does mention electric (or hybrid) power, but since electric cars are a thing now, when comparing alternatives it seems like this would not have the lowest energy usage.
Bottom line:
Conventional car about 1 mile / kWh
Electric car about 3 miles / kWh
Electric VTOL about 2 miles / kWh
And you now someone will stand underneath this thing as it's landing and get beheaded. Just saying. If it can happen, it will.
It'll be a complete nightmare for pedestrians.
Everyone knows they will have noise issues and thus cannot be used in tightly populated areas, but there are miriads of other places and usage cases for them.