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165 Comments:
Animats said 11 days ago:

The EHang 184 looks more promising.[1] That has four sets of contra-rotating props, so there's some redundancy. Flight time 23 minutes, so it's a demonstrator, not something useful. Like the others, it's a scaled up quadrotor drone. This concept needs a higher battery energy density to work.

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/

FabHK said 11 days ago:

The eHang 184 looks like a device to decapitate many people quickly, or capping kneecaps while on the ground.

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.

[1] https://www.youtube.com/watch?v=OazFiIhwAEs

[2] https://www.youtube.com/watch?v=ROJ76foyihs

coliveira said 11 days ago:

Propeller airplanes are not different, in fact real accidents happen with these airplanes. This didn't stop such airplanes from being widely used. Given a well controlled situation, vehicles such as the eHang can very well be used.

FabHK said 11 days ago:

Well yes, and airplanes only operate on airfields with generally carefully controlled access, and still those accidents happen. Now, with airplanes there is really no other option, but with a drone one can easily place the rotors above, rather than below, the passenger cabin (which also gives better stability).

The eHang 184 is truly a horrendous design in my opinion, and I am puzzled why it is seriously reported about.

wereHamster said 11 days ago:

> one can easily place the rotors above […] (which also gives better stability).

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

FabHK said 10 days ago:

Very interesting. I’m not sure whether that fallacy applies.

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.

onemoresoop said 11 days ago:

I am horrified by eHang's propellers. Can't they add some sort of guard around them or move them above the cabin? I can't stop thinking that even passengers would run into them frequently when stepping on or off the thing, not to mention loss of control situations..

SideburnsOfDoom said 11 days ago:

> Someone recently flew a jet-powered "hoverboard" across the English channel

And stopped for a refuel half-way.

m4rtink said 11 days ago:

Still looks surprisingly useful even in its current form.

kuzehanka said 11 days ago:

Yeah. If the thing is not at least in an X8 configuration (2 independent motors and props for each edge) with enough thrust to safely land you in X4, it should never have passengers on board.

The car shown in OP is one motor/esc/prop failure away from killing whoever is inside it.

matt-attack said 11 days ago:

Couldn’t the same be said about any helicopter? It’s a single blade. A single failure mode. And they routinely ferry tourists and non-professionals.

dsego said 11 days ago:

Helicopters utilize autorotation for emergency landing.

adrianN said 11 days ago:

And whoever happens to be below it at the time.

said 11 days ago:
[deleted]
dTal said 11 days ago:

>That has four sets of contra-rotating props, so there's some redundancy

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.

Erlich_Bachman said 11 days ago:

I'm pretty sure that it is generally considered a more reliable design in both small drones and such vechicles. Yes, there are 4 booms, but there are 8 ESCs, 8 cable sets, 8 motors, 8 motor holders(they are the ones experiencing most vibrations), 8 props.

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.

dTal said 11 days ago:

My source is bitter experience designing and testing counter-rotating electric ducted fans for distributed propulsion drone applications.

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.

mhandley said 11 days ago:

I would think that the most likely failure mode would be bird ingestion. A large bird would likely break the top prop, and the fragments of that prop+bird would hit the cowel, and then be sucked down through the bottom prop. Not to mention the high forces exerted on the top-prop motor mounting from losing only one blade. I'm not sure whether you want the top prop motor mount to fail at that point to save the airframe, but if so, then you'll get the top motor ingested into the bottom prop too. Unless you can actually prevent large bird ingestion, or design props that can survive it intact, I agree you don't really have any redundancy from co-axial contra-rotating props.

de_Selby said 11 days ago:

If just one wheel fails on a car travelling at 100km/h on a road with oncoming traffic you're very unlikely to survive either.

marcinzm said 11 days ago:

Wheels are pretty solidly mounted to cars with large pieces of metal. Tires do blow out however then you still have some control.

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.

Cthulhu_ said 11 days ago:

If it falls off that axle is only dropping 20cm though, instead of however high this thing flies. Plus, wheels are a lot more solid than props.

dsfyu404ed said 11 days ago:

Actually you're pretty likely to survive as long as you're wearing a seat-belt and don't crash into anything that only hits the upper half of the cabin (like the side of a big truck)

Ntrails said 11 days ago:

A 200km/h head on collision with equivalent modern cars is absolutely survivable. Gravity is pretty potent at getting you moving faster than that, and with extremely uncertain impact point

marcinzm said 11 days ago:

It's actually a 100km/h collision done twice. Each car goes from 100 to 0, not from 200 to 0. There's twice the energy but it's distributed across the two cars so for each one it's equivalent to hitting a stationary wall.

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.

todd8 said 11 days ago:

A 100km/h head-on with a similar car going 100km/h should be similar to a 100km/h head-on collision with a solid concrete wall. However a car traveling at 200km/h has four times the kinetic energy as a car traveling at 100km/h so a collision at that speed is much less likely to be survived than a collision at 100km/h.

dsfyu404ed said 11 days ago:

> However a car traveling at 200km/h has four times the kinetic energy as a car traveling at 100km/h so a collision at that speed is much less likely to be survived than a collision at 100km/h.

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.

randallsquared said 10 days ago:

The kinetic energy of the human is the important part, and higher speed increases that, unlike higher mass of vehicle as you note.

matt-attack said 11 days ago:

Wow you are the first person to point out what I’ve been saying for decades. A car hitting another car at the same speed is indistinguishable from a car hitting an immovable wall.

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.

esotericn said 11 days ago:

Surely the answer there depends on what's in the intersection - whether you want to roll into it or not.

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.

dzdt said 11 days ago:

The brake will increase survivability for you; neutral will increase survivability for the other driver. What hurts you is the sudden acceleration from the impact, and the brake will decrease that. What hurts the other driver is the sudden deceleration of impact; your brake will make that a harder stop for him while being in neutral would make it a bit less of a hard stop.

gamblor956 said 10 days ago:

This is backwards.

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.]

said 11 days ago:
[deleted]
jfindley said 11 days ago:

I know we're veering somewhat off topic here, but I wonder how true this is in practice?

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!

underwater said 11 days ago:

Terminal velocity for a person is around 195kph.

Retric said 11 days ago:

That’s minimum arms out speeds for a human, you can hit 400+kph in a streamlined dive. Failing aircraft can go well past that into ripping of the wings of an aircraft.

cal5k said 11 days ago:

Ballistic parachutes. They've been a safety feature in composite aircraft like the Cirrus SR22 for a long time.

Useless on commercial aircraft, great for small, lightweight personal transportation vehicles.

fooker said 11 days ago:

>There is almost no survivable failure mode with that design.

Parachute?

nradov said 11 days ago:

Parachutes can help, but even with rocket assist there can be a "dead zone": too high for passengers to survive a crash but too low for the parachute to fully deploy. The aircraft also has to be fairly stable for the parachute to deploy successfully; if the aircraft has a sharp pitch or roll speed due to thrust imbalance then the parachute might not work.

tim333 said 11 days ago:

Maybe a modified version of this skyscraper escape system https://i.redd.it/5ltd9qizlh621.gif ?

mrfusion said 11 days ago:

There should be ways to deploy parachutes faster. Maybe with springs or pressurized gas.

Otherwise having large airbags deploy under the vehicle could be another option.

matt-attack said 11 days ago:

A traditional helicopter had no redundancy either. The single motor could fail or a single blade. What’s the difference?

LMYahooTFY said 11 days ago:

I'm a complete layman in aeronautics, but Lilium's prototypes seem to look more promising (over-optimistic?) on paper and make me worry less about decapitation.

https://www.youtube.com/watch?v=bQSDKmVoaIo

seanhunter said 11 days ago:

> Someone recently flew a jet-powered "hoverboard" across the English channel.That thing is powered by several large model aircraft jet engines. It's much like the Hiller Flying Platform of 1954.

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...

mkl said 11 days ago:

That only suggests the earlier version wasn't consumer ready. And people injure themselves with mass produced consumer ready vehicles every day.

KineticLensman said 11 days ago:

A post flight interview suggested that the hoverboard requires very high skill levels and leg fitness.

etatoby said 11 days ago:

I personally prefer the Williams X-Jet or "flying pulpit" from the 80s:

https://youtu.be/guc56Kbz5yI

Pity it never went into mass production. We should crowdfund a modern version!

mc32 said 11 days ago:

Looks pretty advanced for 1980s tech. The army passed on it because it didn’t perform better than alternatives they already had.

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.

DonHopkins said 11 days ago:

Ground Level Chemtrail Distribution via Flying Saucer!

satori99 said 11 days ago:

> All of the flying car concepts, which are like drones big enough to hold humans, promise to be better than helicopters. Helicopters are expensive to maintain, noisy to fly and require trained pilots.

They forgot to add helicopters can also auto-gyrate in the event of engine failure.

Quad-copter drones probably just crash.

Aozi said 11 days ago:

>Helicopters are expensive to maintain, noisy to fly and require trained pilots.

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.

FabHK said 11 days ago:

Electric motors with fixed pitch rotors are much simpler mechanically than piston/turbine engines and fully articulated rotor blades.

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.

dgzl said 11 days ago:

>As for the noise, well this isn't exactly quiet....

I remember listening to Elon Musk dismissing flying cars for this reason.

nradov said 11 days ago:

Well he wasn't wrong. Rotorcraft operations are or will be banned in many populated areas for exactly that reason. If they have to move a high volume of air it's going to be extremely noisy no matter what tricks they play with blade shape or whatever.

jfoster said 11 days ago:

He also makes the excellent points that keeping them in the air is very energy intensive and that they pose a risk to those underneath them, in case of failure or something falling off them.

yoz-y said 11 days ago:

I wonder if asymmetric blades like in fans could work and if they would be any good for reducing the noise.

mannykannot said 11 days ago:

There has been a good deal of economic incentive for finding ways to reduce the noise of the fans in turbofans for a long time. the relatively recent introduction of chevrons on the exit end of fan nacelles shows how even minor improvements are pursued. It is unlikely that an opportunity for significant improvement has been overlooked.

fooker said 11 days ago:

Also reduces thrust.

condercet said 11 days ago:

I imagine a ridesharing / uber-like model will be dominant compared to private ownership and personal piloting. But these things are going to be incredibly annoying and disruptive -- the various drone delivery efforts already seem loud and stress-inducing. I imagine airspace restrictions on these are going to become common in the near-ish future.

prawn said 11 days ago:

Most drones can compensate to account for issues. My drone has hit a tree a few times, self-balanced and continued flight. It's flown fine through heavy wind/rain with cracked propellers (that I've replaced after noticing). There's a video out there of someone throwing cushions at, or suspending weights from, a consumer drone and it takes the hits and re-stabilises.

High-end drones have battery redundancy, six props to account for failures, parachute systems, etc.

nosianu said 11 days ago:

Scale matters. Compare a small animal falling and a large animal falling (i.e. compare what happens when they hit the ground). A "drone" large enough to carry a human or two will be much more heavily damaged by an impact that appears to be similar to one that leaves a much smaller drone intact.

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".

Erlich_Bachman said 11 days ago:

> 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.

nosianu said 11 days ago:

> Isn't it much easier because you have place for many more cells

Don't think space (not the biggest issue here as you say), think weight, power and the ratio.

Erlich_Bachman said 11 days ago:

Yes, of course. I was using "space" as a more general term, as in "capacity". Should have been more clear.

prawn said 11 days ago:

Human-scale drones would have much more powerful batteries and room for redundancy. More powerful motors and blades.

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.

jacquesm said 11 days ago:

If you drop a mouse down a mineshaft it will likely have a bit of a jolt on impact, then scurry away looking for some bit of cheese. If you drop a horse down a mineshaft there will be horsebits splattered on a very large area around the point of impact. Noise problems are inherent to fast spinning rotors, gravity is where the real problems are, and redundancy in drones is more along the lines of controlled crashes than emergency landings. I'd be very much worried about the performance of the system if one or more rotors failed to do their job.

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.

dorusr said 11 days ago:

Maybe they could put an airbag at the underside of the vehicle for when it flies a few meters above the ground

sschueller said 11 days ago:

From what I have read and seen a drone with only 4 props has almost no chance of recovery if one prop fails. This is also why drones for high end expensive video have six or eight props to prevent a catastrophic failure resulting in loss of equipment.

satori99 said 11 days ago:

There are algorithmic solutions to maintaining some semblance of flight with a damaged quad copter, even down to one remaining prop, however it involves spinning the entire air-frame to stay aloft -- which means it is probably not suitable for a human passenger drone

https://newatlas.com/quadcopter-failure-algorithm/30031/

kalleboo said 11 days ago:

One thing I've always wondered is why is it so hard to make a self-flying helicopter? Helicopters already exist, can carry much heavier weights than most multirotors, and have other pro's (like being able to auto-gyrate). Is there some reason we haven't automated the flying of those and are instead going for multirotors?

Or do they exist but just aren't sexy enough to make headlines?

said 11 days ago:
[deleted]
JKCalhoun said 11 days ago:

Almost certainly if the blades cannot vary pitch.

Erlich_Bachman said 11 days ago:

That's why this design is not a quadcopter, it is technically an octocopter.

corodra said 11 days ago:

Flying cars have been functional since the 90s. There are more problems to this concept.

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.

CobrastanJorji said 10 days ago:

I remember C. Why did that stop? Are planes required to fly higher now, or did they get quieter?

Obi_Juan_Kenobi said 10 days ago:

High-bypass turbofans, or just turbofans in general.

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.

corodra said 10 days ago:

Okay, then... am I crazy for noticing jet engines on airliners are significantly larger these days compared to 20 years ago? You did say larger fans. I always thought I was crazy when I noticed planes were quieter until Neil degrades Tyson mentioned it.

travisjungroth said 10 days ago:

You’re not crazy. The engines are bigger and quieter.

tastygreenapple said 10 days ago:

Definitely not crazy, and the engines are getting larger. The 737 MAX issues stem the packaging issues of putting larger engines on an airframe that wasn't really designed for them.

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.

corodra said 10 days ago:

Neil degrades Tyson talked about this on the Joe Rogan show. Jet engines became more efficient and were mandated to be quieter. I'm not sure about altitude because I live near a major airport. Always have lived near airports. The general noise is flat out less.

duderific said 10 days ago:

As far as E, not sure you could do more damage than a box truck would do. If you tried to fly into a crowd somehow you would crash and probably only hurt people within a relatively small radius.

yifanl said 10 days ago:

With big box cars, you can at least set up large concrete barricades to mitigate these on crowds.

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)

corodra said 10 days ago:

I mean, anti air artillery. Lots of fiery death explosions and collateral damage. But we'll live in a world where the Gulf War air raids are the norm.

gamblor956 said 10 days ago:

Bollards and concrete planters can stop a tractor-trailer going 60 mph. Dead stop. They are fully passive defenses. And minimum collateral damage.

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.

corodra said 10 days ago:

Eh? I'm the one who did the ABC list. While yes, I'm in half jest, its partially serious. Because that's what will happen unless there are better safety alternatives.

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

deftnerd said 10 days ago:

Bollards and concrete planters are excellent for stopping a lot of mass going very fast, this is true.

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.

zeeZ said 10 days ago:

Access to more crowds though. Imagine someone crashing into an Oktoberfest tent

corodra said 10 days ago:

Um... should I tell you about a little known event called 9/11?

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.

said 10 days ago:
[deleted]
starpilot said 10 days ago:

Which you can already do with existing small helicopters for rent, general aviation airplanes etc. Flying cars aren't a new threat in this respect.

corodra said 10 days ago:

Current pricing and registration are the current barriers to entry, especially training. It's not straightforward easy to fly a helicopter or small airplane. Not crazy difficult. But harder than a ground vehicle. Making it too easy and affordable and making them crazy plentiful in the air so they can't be tracked easily, that's the danger.

olivermarks said 11 days ago:

https://youtu.be/vzm6pvHPSGo IBM decided lotus software was more important than flying cars

sircastor said 11 days ago:

This commercial has stood out on my mind for nearly 2 decades. Probably a combination of Avery Brooks and flying cars, bit it had a lot of memorability to me for someone who used Lotus for 4 months at a job.

CobrastanJorji said 10 days ago:

Their ad attempting to explain the benefits of Linux being open source was spectacular. https://www.youtube.com/watch?v=s7dTjpvakmA

cheez said 11 days ago:

Where did Avery Brooks develop his speech technique...

bitwize said 11 days ago:

(in Jon Lovitz Master Thespian voice) ACTING!

said 11 days ago:
[deleted]
meddlepal said 11 days ago:

It's a pretty good commercial honestly.

olivermarks said 10 days ago:

Saatchi & Saatchi Montreal made the TV spot

swatkat said 11 days ago:

Reminds me of vaporware Moller Skycar[0] and Gyrocopters[1] from yesteryear.

[0] https://moller.com/ [1] https://i.imgur.com/JisWKOR.jpg

ansible said 11 days ago:

Gyrocoptors have been, and still continue to be a thing, for like... 85 years. The design has not been ever marketed as a "flying car" (to my knowledge), though it does have a relatively short takeoff roll compared to conventional aircraft. Search for "autogyro".

dfeojm-zlib said 10 days ago:

I hope people give up on this 1950's-era mythological obsession with trying to realize a cartoon's flying saucer pods because of the potential for energy waste/climate change, public hazards and property damage.

Mathnerd314 said 11 days ago:

Video: https://www.youtube.com/watch?v=cmdilp9LM0E

It rocked back and forth and bounced when it landed, clearly a lot of tuning left.

tqkxzugoaupvwqr said 11 days ago:

The wheels are too narrow. When it landed, it almost tipped over to the side. A little bit of cross-wind and it’s lying on its side.

belgianguy said 11 days ago:

I wouldn't call this a flying car, I would call this a quadcopter with wheels.

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.

erklik said 11 days ago:

> 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.

bobthepanda said 11 days ago:

> air-flight has considerably less environmental variables

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.

enneff said 11 days ago:

Routing is much easier when you can basically go from point A to B directly. Coordination would be required to prevent collisions with other vehicles, but evasion in 3D just means changing to an uncontended altitude. I think the extra dimension actually makes it easier.

benbristow said 11 days ago:

I think you're right.

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.

thombat said 11 days ago:

Large planes fly themselves on planned routes which avoid incursions by other planes by design: the function of air traffic control is to assign the routes such that incursions don't occur. In the event that the onboard collision avoidance system projects that another aircraft will come too close the warns the pilot with a recommended action. There is also a ground proximity warning system which issues warnings about collision with ground/mapped obstacles but again leaves it to the pilot to take the necessary action.

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.

bobthepanda said 10 days ago:

Planes follow flight plans which must be pre-filed before the flight. That doesn't scale for personal travel.

erklik said 10 days ago:

> 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.

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.

nradov said 11 days ago:

Flying from point A to point B while avoiding collisions is relatively straightforward. The really hard part is dealing with in-flight emergencies like mechanical failures or sudden weather changes. It's impossible to predict and program for every failure mode which could happen in the real world. A human ATP rated pilot has enough experience to solve problems in real time but current AI technology is incapable of that.

tsimionescu said 11 days ago:

Air conditions are significantly more complex than road conditions, I would guess - wind direction, temperature differentials, air density may all vary and I imagine they could affect flight characteristics.

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.

excalibur said 11 days ago:

> I wouldn't call this a flying car, I would call this a quadcopter with wheels.

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.

tomcam said 11 days ago:

Has anyone effectively dealt with the noise problem? Vehicles this size would be unacceptable almost anywhere people are present for the noise alone.

inflatableDodo said 11 days ago:

I think the major physics problem that is very hard to fiddle, if you want to achieve the popular sci-fi version of VTOL flying cars aerodynamically, is the requirement that the cross sectional area of downthrust air fits roughly inside something approaching a car's plan view while still having room for occupants and luggage. Purely to hover such a thing, never mind ascend at a reasonable rate, requires airjets that will blow pedestrians cheerfully across a street.

JKCalhoun said 11 days ago:

Never mind the energy needed to consume to do so.

I'm curmudgeony, I say the future is powered bicycles.

benj111 said 11 days ago:

Motorbikes? Or electric bikes?

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.

corodra said 11 days ago:

Theres a Pysch episode where the main character talks about why he has a motorcycle. So he doesn't have to give rides to people. Move furniture. Pick up kids. Etc. He was also a pretty lonely guy. But he said he'd sell it and get a car if the chick he was crushing on in the show, goes out with him.

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.

adrianN said 11 days ago:

Something like the PodRide https://www.youtube.com/watch?v=4lKq1fGtXFM, perhaps a little bit bigger.

benj111 said 11 days ago:

Why did you select the ugliest velomobile to illustrate your point???

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.

inflatableDodo said 11 days ago:

Pedal-powered quadrocopters are obviously the way to go - https://www.youtube.com/watch?v=syJq10EQkog

hanniabu said 11 days ago:

Hell yeah, bicycles with nice thrusters and wings that automatically extend out from drag at certain so that you can glide and coast a bit!

sambroner said 11 days ago:

Would this be a problem if these cars exclusively took off from the top of sky scrapers? If I remember from my time in Nyc, above the 20th floor it’s quite hard to hear even the loudest noises from the street.

Presumably from the ground, it’d be hard to hear one of these taking off on the 30th floor.

semi-extrinsic said 11 days ago:

It severely restricts the potential market if you do this (only travels from one skyscraper to another are supported). For instance you can just completely forget about Washington DC, London and Paris, and many more cities.

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.

vidarh said 11 days ago:

If going by an aim to only land them above 20th floor, then my suburb of London alone is up to 5 buildings over 20 floors, with the highest (not yet complete) at 44, and planning permission given for about half a dozen in the 20-55 floor range given.

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.

pilsetnieks said 11 days ago:

Well, skyscraper to skyscraper (or helipad, or other permitted areas) would be a start. Eventually the tech could catch up - for example, with materials like these - https://phys.org/news/2019-03-acoustic-metamaterial-cancels.... - being developed.

imhoguy said 11 days ago:

Skyscraper cable cars would be less expensive/noisy/power hungry and with more capacity. https://arstechnica.com/science/2013/02/envisioning-the-urba...

vidarh said 11 days ago:

Skyscraper cable cars require them to be near enough to each other, which would limit them to far fewer city centres. London for example has very few skyscrapers, but several parts of town have some and quite a few more have a bunch of 20+ story buildings, but only two areas (City and Docklands) have many buildings like that clustered close enough for cable cars to seem potentially viable by far enough for it to possibly be interesting.

xvilka said 11 days ago:

It reminds me of Canopy from the Alastair Reynolds' Revelation Space book series.

downtide said 11 days ago:

I live rurally near a busy trunk road. I can walk about 1/2 mile away and the road is still in my line of sight, and it is still 'loud' (as in irritating). However, I'm blighted by this road as I'm so close to its proximity. And it disturbs me. However, I did notice when visiting a busy part of town recently that it was a complete aural assualt, and as such, you might hear/perceive less under the cacaphony of much.

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?

ses1984 said 11 days ago:

I would like to know what the measurement of the loudness when you are 1/2 mile away from the road.

downtide said 10 days ago:

The quotes around 'loud' here, is an emphasis on relativeness.

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.

leoedin said 11 days ago:

The Pan Am building in NYC used to have a helipad, but there was a crash [1] and it was removed.

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...

taneq said 11 days ago:

We could solve the skyscraper-to-skyscraper problem much more effectively with a series of ziplines.

benj111 said 11 days ago:

I would guess that would be the pivot for Zipcar.

vkou said 11 days ago:

Helicopters are much louder than street noise.

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.

nradov said 11 days ago:

Most skyscrapers don't have a safe space to land on the roof due to weight restrictions, antennas, HVAC equipment, etc. Modifications to allow flight operations would be expensive. Only a few existing skyscrapers have helipads.

smacktoward said 11 days ago:

Forget helicopters, the top of the Empire State Building has a Zeppelin dock: https://www.nytimes.com/2010/09/26/realestate/26scapes.html

kerng said 11 days ago:

Uber's concept showed car ports up on buildings, so flying cars wouldn't be on the ground I guess. In that sense not very different to helicopters and dedicated heliports.

ma2rten said 11 days ago:

I don't understand why this is called a flying car and not a quadcopter. Cars by definition have 4 wheels and drive around.

adrianmonk said 11 days ago:

It is supposed to cover many of the same use cases as a car.

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.

ummwhat said 11 days ago:

Same reason cars were once called horseless carriages

omeid2 said 11 days ago:

Same thing as AI vs Algorithm.

EL_Loco said 11 days ago:

I haven't read much into this, but the Blackfly looks at least as promisin as the competition: https://www.opener.aero/

edit: Forgot to add that it has already flown over 20,000 miles with payload (in about 2k flights)

adrianmonk said 11 days ago:

Same question as always applies: how much energy does it use compared to a car that drives on a road?

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.

FabHK said 11 days ago:

The Uber Elevate white paper answers many of these basic questions [1].

Bottom line:

  Conventional car about  1 mile / kWh
  Electric car about      3 miles / kWh
  Electric VTOL about     2 miles / kWh
[1] https://www.uber.com/elevate.pdf page 81ff
cyknus said 11 days ago:

How much energy does a car use compared to a horse? I get your point and I agree with you, but that is probably not the right question.

xgulfie said 11 days ago:

A flying car, aka "helicopter"

fnord77 said 11 days ago:

Moller's sham skycar managed this feat 15 or 20 years ago.

JustSomeNobody said 11 days ago:

Tethered. Just like the Moller car forever ago.

And you now someone will stand underneath this thing as it's landing and get beheaded. Just saying. If it can happen, it will.

trollied said 11 days ago:

Has anyone thought about downdraught from these if they're ever sold en-masse?

It'll be a complete nightmare for pedestrians.

adrianN said 11 days ago:

And the noise, and the things falling from the sky when they crash.

holoduke said 10 days ago:

In my vision the only challenge we need to overcome is to increase energy density/weight ratio by a factor of 100. Rest of the tech is already there. Letting a car hover for a minute isn't that special. Letting one hover for 3 hours is.

SubiculumCode said 11 days ago:

The only way there will be mass adoption/acceptance of flying cars will be if flight is completely automated. The thought of my neighbor landing on my house is all too vivid.

ht_th said 11 days ago:

Yes, crash landing into people, building, trees, and other traffic is a concern. But automation is not enough, we also need standardization and synchronization, because I am not looking forward to a future where the whole sky above a city is filled with random flying objects everywhere. That would be a mess, particularly around/over low-rise buildings, such as in villages, suburbs, and similar neighborhoods. Flying everywhere you want to go might make sense in either densely populated high-rise cities where you could fly and park your car at height, freeing the ground floors for pedestrians, cyclists, nature, recreation, and so on, or for sparse populated areas where there is no-one to be bothered anyway.

RickJWagner said 11 days ago:

Hovering steadily..... they've got rush-hour scenarios covered!

popeye77 said 11 days ago:

Looks like a cross between drone and rickshaw. I want!

varjag said 11 days ago:

looks like a death wish

693471 said 11 days ago:

Not interested unless they've defied physics and made it silent.

matthewfelgate said 11 days ago:

Stop trying to make flying 'cars' happen.

Erlich_Bachman said 11 days ago:

Why exactly?

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.

Allower said 11 days ago:

We are we still trying to execute on this terrible idea?