Whenever I hear air taxi, I think about water bottles and airport security.

I don't want some rich dude flying over my house just because he/she can afford to take a airtaxi from the airport to city center while everyone else uses car or train.

For other use cases they can do what they want. Australian outback perhaps.

But airspace pollution and a potential small airplane crashing down in a city? No way.

> No way.

Wait until you see the motor carriages they claim are going to replace horses one day.

You can recognize that cars are going nowhere and it's best if we embrace this fact in our own ways (either by being a car owner, or working around car-designed cities the way we prefer), but still note that our cities could have been designed better from scratch that doesn't favor cars. Similarly, avoiding the same mistake now for helicopters wouldn't be inconsistent with living with cars.

That seems reasonable, but what is missing (at least in this branch of the debate) is data and counter arguments that will not clearly peter out while the technology matures, if they are even trying to be factual to begin with.

As an example, just on the topic of safety: Why would we assume these machines are relatively dangerous once they reach production? Just because they fly? I know of at least one category of vehicles where on that basis our intuition fails us to this day.

And what happens when they do fail? They are not going to explode randomly or purposefully target the closest building. So what are the chances of all fail-safes failing, and catastrophic outcomes occurring?

Why would we assume whatever this technology eventually enables will be operated by human pilots? I for one would be fairly surprised if that was to happen at any noteworthy scale. Clearly, the interesting part about this prototype is electric flight, not its HID, agreed?

So let's build cool things (electric flight is potentially a cool thing) and then gather actual data about other things it brings (some maybe not so cool), before we "no way" it without any facts on the basis of weak conjecture and personal feelings.

> Why would we assume these machines are relatively dangerous once they reach production? Just because they fly?

I don't have a particularly positive or negative opinion of the technology here, but the one good reason I can see to treat these machines as inherently dangerous is because they take all the kinetic energy of something traveling faster than a car and add the gravitational potential energy of something hundreds of feet off the ground, while not being constrained to a well-defined corridor that you can protect with safety barriers.

When cars meet stationary objects at speed they tend to make a mess. These things are likely to be lighter, but when out of control they'll be going faster, and this thing specifically, when it goes bad, will go bad carrying several hundred kilos of lithium into an uncontrolled energetic event.

If risk is probability times expected outcome, my estimate would be that Lilium comes out worse than driving on both sides of the formula. That's not a reason per se not to do it because, like you say, let's gather data. But the basic physics of the situation is also not something to ignore.

I think there are reasons to be a bit more optimistic about the dangers.

A) The reason that cars crash (crash meaning doing damage in the process of failure) is by a large margin not mechanical failure, but human error. While in this case the technology is still infantile and will, even after a couple of years of testing, certainly be more prone to mechanical failure, I see no real reason to assume that it would ever be permitted for actual inner city usage before it beats a certain range/failure-ratio, because that seems trivial to secure and exactly what regulatory bodies are made for.

B) Let's assume there will be no humans piloting these things in an urban transportation scenario, ever, because that does indeed seem incredibly dangerous and silly. I don't think we as a species have the capacity to manually navigate these things in a 3d space filled with them. I don't see any reason we have to. Let's not do that.

C) If you think about it, physics are impossibly bad for car safety. There is no time to decelerate safely and then also no safe space to evade to. In contrast, in the case of flying thingies however, you have space and time working for you: Even if parts of the machine fail, it definitely has at least an order of magnitude more seconds to manoeuvre to relative safety. Of course, catastrophic failure (big fireball in the sky) can possibly still occur (I assume), but you are not working against physics, which is great, because then all you need is outstanding engineering and appropriate fail safes. Engineers will take that over having to beat physics any day.

I don't want to say that the world might look different in 20 years (probably even more)

Advances in ai, energy storage etc.

But right now, air taxi is just inherently stupid.

We know how to build those things. There is nothing really you need to invent. you just need to build them.

The problem are things like safety, airspace (who owns it), co2, terrorism, airspace Management...

Let's talk air taxi again when we can fly fully electric, are in the right way for climate change and when air control is no longer handled by humans.

A and B are solid, sensible suggestions. Inevitably someone stupid (possibly multiple someones, possibly in positions of power) will ignore them. We can leave that to one side.

With C, we're well into "what do the safeties look like" because the assumption that you can manoeuvre at all after something Unexpected And Exciting happens is possibly rash. I don't trust that designs like this one have much unpowered lift or even that much flight control at all in a power-out state. And remember too that the whole point of these things is that they're flying over presumably dense areas. The idea that there will be somewhere safe to manoeuvre to in the seconds you may or may not have is definitely on the optimistic side.

But still, even given all that, a parachute should go a long way to being a workable "emergency stop" equivalent. There are failure states which it doesn't help with (for instance: a birdstrike goes badly enough wrong that a short-circuit starts a lithium fire which, thanks to our parachute, slowly drifts an incendiary path across entire city blocks) but in general I'd expect the benefits to outweigh the risks.

Those aircrafts can be easily fitted with a parachute actually.

The difference is we don't live in the sky. As long as there isn't noise pollution (and electric planes are supposedly a lot quieter), you have to try really hard to create and issue here. Aviation is getting ever more automated and safer.

It’s very energy inefficient to leave the ground.

So is building and maintaining transportation networks of massive proportions on the ground. Somehow that never gets looked at, people just compare the running costs and completely ignore construction and maintenance. Plus the cost of all the deaths it causes, human and non-human. Plus the space it takes up and how it destroys environments. All these are costs.

Planes will not be a solution for all transportation needs, but where it makes sense they're great. A flying bus basically, routes can be very flexibly changed depending on evolving needs.

That's not true.

Public transport is factors more efficient than air travel.

And yes including initial cost.

We build infrastructure to last not to throw it away 5 years later.

You need to understand how much more energy it actually costs to bring a plain up in the air and down again. We talk magnitude more energy than trains.

We can talk about this again in 20 years when solid state batteries are broken through.and sustainable energy sources are the norm.

Air taxi's ate not hard to build on a technical level. We know how to build them.

The motor carriage and its consequences have been a disaster for the human race.

We know much more today than when no one knew what a car is.

And honestly we didn't do a good job. After all climate change is real, lead poisoning was real too.

When a motor carriage loses power, it stops. When a helicopter loses power, it kills people.

When a helicopter loses power it glides, safely, to the ground - assuming it's being flown by a qualified pilot.

https://en.m.wikipedia.org/wiki/Autorotation

And it then glides onto what?

Humans? A uneven roof? A busy road?

And for whom? The rich? People who can afford a few hundred dollars for a quick flight from the airport to the city?

How about no?

I don't know about other parts of the world, but in the UK, helicopters are quite carefully controlled so that they can land safely in such an event.

For example, to fly a helicopter over London requires pilots to fly only over well defined routes - although those with multiple engines are allowed more scope.

That is a fantasy that almost never works out in real life. Autorotation is only feasible with enough forward air speed and control authority. Most helicopter crashes happen outside that narrow zone of survivability. Even if an autorotation is semi-pulled off it's likely to be a hard landing that causes significant injuries.

Wrong. Most helicopter crashes are non-fatal: https://generalaviationnews.com/2021/02/10/fatal-helicopter-...

2020: 94 accidents, 19 fatal accidents, 35 fatalities, 22% decrease in accidents compared to 2019, 36% decrease in accidents compared to 2013

2019: 121 accidents, 24 fatal accidents, 51 fatalities

2018: 122 accidents, 24 fatal accidents, 55 fatalities

2013: 146 accidents, 30 fatal accidents, 62 fatalities

Autorotations are regularly trained (and often taken all the way to touchdown during training). The checkride for private and commercial rotorcraft has a power failure at hover taken all the way to touchdown as part of the standard.

Autorotations are by no means a "gimme", but if every autorotation "likely" caused significant injuries, there wouldn't be enough helicopters or pilots to go around (no pun intended).

Well to be fair those training exercises are probably done in near ideal conditions of altitude, landing zone, forward airspeed, and you know it's coming have studied mentally ahead of time. It's one thing to pull it off during training and another when the engine fails at a random point during a flight in LA/SF/NYC.

Don't you think pilots would tend to try and stay within that "safe autorotation" envelope most of the time while flying? It seems mostly a case of having sufficient altitude and/or speed, similar to what fixed wing pilots try and maintain - a safety margin.

Why would they?

They will probably want to fly across non easy terrain because otherwise you could just use some other means than an expensive helicopter.

Hight perhaps but you will fly across water, woods, power lines, cities.

Watch a helicopter take off sometime. It (almost) never lifts into a hover and climbs straight up. Instead, it lifts slightly off the ground and accelerates forward following the recommended takeoff profile.

That’s so the craft can stay in the “autorotation possible” section of the HV diagram as much as possible.

I’m not at all qualified here, but it sounds like autorotation might not be involved in crashes because when autorotation works, there is no crash :P

> That is a fantasy that almost never works out in real life.

Can you quantify this?

> Most helicopter crashes happen outside that narrow zone of survivability.

AFAIK the majority of helicopter crashes are not caused by a loss of engine power, but autorotation is relevant specifically in that context. It's not relevant to helicopters crashing into hills during storms, or hitting wires with the rotor, or anything like that. We're discussing what happens if the engine stops, not all accident scenarios.

> Even if an autorotation is semi-pulled off it's likely to be a hard landing that causes significant injuries.

Yes, but it's better than being dead.

Autorotation generally works just fine. Most helicopter crashes involve things unrelated to possibility of autorotation or not, and sometimes autorotation won't help when you hit something too hard at the end, with all of it happening because client pushed too hard and overworked the crew (I might be quoting a specific crash here...)

Also I suspect the majority of autorotation failures are from using the helicopter for things only a helicopter can do like hovering.

This is why you rarely see them do that, instead they circle - which any small plane could do but the helicopter can hover if needed. It’s just the most dangerous part.

Hovering is the signature helicopter move for laymen, but it's also considerably hard, and "high hover takeoff/landing" is, IIRC, one of the hardest maneuvers (it's been years since I've read the pilot's textbook, though)

There's also a lot of other things that can impact the event - for example, the crash I mentioned involved bad weather, tired crew, and losing both engines at once due to icing. They autorotated and nobody died... but they fell into a forest, landed hard enough to destroy undercarriage, and the first officer survived by accident due to helping get passengers into position when a tree smashed his station.

EDIT: corrected captain to first officer, as visible in this photo: https://static.polityka.pl/_resource/res/path/bc/08/bc086fae... (it's Mi-8, so captain sits on the left, not on the right as is normal in western helicopters)

if a helicopter hovers high in the air it's not dangerous because they have time to turn that height/energy into forward motion. see "dead man's curve" https://en.wikipedia.org/wiki/Helicopter_height%E2%80%93velo...

Yes - at height, they tend to move forwards rather than hovering in one spot to avoid getting stuck in a column of downwards moving air: https://en.wikipedia.org/wiki/Vortex_ring_state

> Autorotation is only feasible with enough forward air speed and control authority.

Control authority yes, but altitude is always a substitute for forward air speed (and is an even better substitute for the eVTOL planes than helicopters).

Most helicopter mishaps start at low altitude.

And you need a place with enough room to land--extremely difficult to find in a city. I really don't like flying single-engine aircraft over large cities.

> Most helicopter crashes happen outside that narrow zone of survivability.

That’s kind of a given, since the successful autorotations do not qualify as crashes.

I guess the question is - can we maintain the standard that is ‘qualified pilot’ as it is today while making it accessible enough for this to scale.

Learning to drive and learning to fly isn’t the same bar today.

And if Lilium think Palo Alto to San Francisco could be $50, they’re gonna need _alot_ of flights to balance their costs.

I think it's safe to assume this class of vehicles (and likely any new class of vehicles from here on out) is not designed to be piloted by a human past its prototype stage.

They do this already. They're called helicopters.

Helicopters are expensive to rent. If Lilium achieves even 10x the cost they've suggested they can reach in the past, they'll be attractive to a customer base who'd never be able to afford regular helicopter rides.

On the one hand, yes.

On the other hand, making it cheap enough that mono-millionaires can do it regularly is going to make a big difference compared to the status quo.

I don't know. The idea that a bunch of people with a couple of millions of dollars in wealth can now zip around above my house (and further alienate themselves from civic reality, even more so than cars do) seems like a pretty bad outcome.

That is essentially how progress begins in every industry. Wealthy people pay for new tech with their vast fortunes, and many times, their lives. Once they work out the kinks and economies of scale take over, the less wealthy enjoy the same tech at higher levels of safety and lower prices.

Yes exactly! I'm traveling business all the time because it's so cheap.

Ah wait let me rephrase this: while more people can fly now economy got shittier than ever.

Also we live in 2022, the narrative that rich risk there life's was probably never true (they have test personal) and we have enough capital in our society to do certain things without the money of the rich.

> Also we live in 2022, the narrative that rich risk there life's was probably never true (they have test personal)...

https://en.wikipedia.org/wiki/Amelia_Earhart#Childhood

> Earhart was the daughter of Samuel "Edwin" Stanton Earhart (1867–1930) and Amelia "Amy" (née Otis; 1869–1962).[13] She was born in Atchison, Kansas, in the home of her maternal grandfather, Alfred Gideon Otis (1827–1912), who was a former federal judge, the president of the Atchison Savings Bank and a leading citizen in the town. Amelia was the second child of the marriage after an infant was stillborn in August 1896.[14]

She for one, looks to me to have been wealthy.

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

> and we have enough capital in our society to do certain things without the money of the rich.

Part of the reward for pioneering tech is the taking of the risk and getting the reward while at the end of the day being able to feel a sense of accomplishment having done it largely of your own initiative and cost. The spirit of exploration that existed in early humans, that led to our expansion to the furthest points of the earth, exists today in the form of innovation and invention. While it is enticing of course to create at the behest of government or corporations like was done in Bell Labs or DARPA, there is a severe risk that liabilities and bureaucracy stifle innovation. I cannot imagine a governmental system of incentives that creates an atmosphere quite like the USA had prior to the 1960s that led to innovation, invention, and implementation that we had never seen before, and may never see again.

I wonder how often that's true, or a myth of uber-capitalism - sort of a trickle-down theory for tech. AFAIK, it's often government that pays for new tech, and then once it has a profitable nitch, corporations.

That is true to a large extent today. Sadly, most of the foundations of the tech we have today is based on tech we had developed before governments were involved to level they are today. Cars, trains, engines, CRT, film, computers, telephone, building materials, and much much more, are seemingly only being tweaked. The rapid pace of truly innovative tech has waned. Is this because of government involvement? Is this because our understanding of basic science allowed us to pass some threshold, only to be stymied by the increasing complexity and having to devote more time and material to test the nuances?

Blockchain was supposedly created by a single person. The Federal Reserve Bank of the United States has mentioned creating a digital currency. As they pump more money into that idea and develop some neat tweaks or totally control blockchains, will we look back in 50 years and say, "Look at how much the government did for blockchain." forgetting that it exists in the first place to spite them?

> mono-millionaires

Ah right, moving it from 0.1%-ers to 1%-ers is really going to make a big difference.

Roughly 10% of Americans are millionaires, for reference (though I doubt all of that is liquid).

Sources online show that about 8% of Americans are millionaires, with a significant bump during COVID (probably because of the stock market.) About 10% of households are.

It's hard to find precise qualifications for how they determine that, though. The households figure doesn't include primary residence value (why?), and the individual statistics don't mention liquidity. I suspect that only a small percent of that 8% actually has $1+ million liquid.

Definitely not liquid cash, but assuming that a not insignificant portion of those people are retirees or planning to retire soonish (which is when net worth peaks), I wouldn't be surprised if the percentage of decently liquid assets like stocks and bonds are higher than you might think.

Alright, the actual figure is $1,2M for the 90-percentile household net worth. For the individual that's to be divided by 3 (since there are about 120M households in the U.S.). We are at the 96-percentile for $3M household net worth.

So yeah, 4%-ers then. Really makes a big difference to my point. This is totally gonna change everybody's life. (I.e. those who can afford it, while the majority is scraping by from paycheck to paycheck.)

Owning a house doesn't just allow you to fly business all the time

this comment reminded me of this http://www.temporarilyembarrassedmillionaires.org/

About 10x, right?

Well, _electric_ helicopters or electric helicopter-equivalent-vehicles would be a step forwards, correct?

> They do this already. They're called helicopters.

This is dangerously close to the infamous HN Dropbox critique[1] :-D

And it's likely wrong in the same way.

1. https://news.ycombinator.com/item?id=9224

Past performance is not an indicator of future performance?

Air taxis are really useful in places divided by natural obstacles.

Hop over a fjord, hop over a mountain range. Much cheaper and eco-friendly than building bridges and tunnels everywhere, especially if the population density isn't high.

If population density is not high than it will not be cost efficient for the normal people.im surprised how many people here think that rich people who can afford to fly over a mountain regularly is a good thing.

Perhaps in 20-50 years when we solved climate change.

Those companies are not trying to just create a cheap and easy to use carplane they want to become rich which needs business viability.

And I don't mind if they solve some niche problems. I mind that they want to fly over my head every 10 minutes.

"rich people who can afford to fly over a mountain regularly"

Look at the rural countryside in places like Norway. I am not talking about rich people primarily, but semi-isolated communities whose older citizens might need specialized healthcare etc.

Also, this was originally a discussion about electric planes, so their effect on climate change is probably neutral-ish.

These kinds of places are also generally suitable for hydropower and geothermal energy which gives considerable amounts of cheap electricity.

>I don't want some rich dude flying over my house just because he/she can afford to take a airtaxi from the airport to city center while everyone else uses car or train.

Why not? He's funding the employment of the air taxi people, plus their technology development, and reducing congestion.

I understand the safety concern, but I don't see how "just because" they can afford it is a reasonable objection.

It's not 'just' a safety concern.

It's the safety concern and it's flying over my head.

There is always a risk/benefit ratio and just because a handful of people want to spend more money so that they can fly faster from the airport to the city center than others is not worth the security implications.

You are aware how much security is involved whenever you fly?

We talk an expensive license, regular flying hours per year (also not cheap), air control, restricted air zones, very regular safety plain checks.

Every single object on a commercial plane for example is tracked, every replacement etc.

Congestion is not solved by small expensive air taxies. If a normal taxi costs x, an airtaxi has to cost 4x and more.

We the people don't need to allow everyone everything just because they have the money into do so.

Like I said, safety concerns are fine, these things should be properly regulated like any aircraft, but if they can be safely regulated then I don't see a problem.

>Congestion is not solved by small expensive air taxies

If you expect a new transport to 'solve congestion' as a requirement for it to be allowed, we're not going to allow anything. Incremental improvements can add up.

I just find these "I can't have it, so you can't either" arguments so short sighted. Lots of technologies start out the domain of the wealthy before achieving scale and mass adoption. Maybe we won't all be mass adopting air taxis, but some of the technologies that come out of these things may well end up in our cars, or houses, or benefiting us indirectly.

Even existing regulated airplanes kill people on the ground every now and then. The risk is small, but I feel like the benefit of transporting ~100 people weighs out the risk much better than transporting ~1.

Fair enough, as I said in my first comment and have re-iterated in my later comment, that's fine. It's a reasonable concern. The safety issue is not really in contention.

My issue is with the argument that simply being wealthy enough (literally 'just because' he is wealthy enough. Check the comment I was replying to.) to do this is by itself reason enough to ban it.

All this redirection back to safety is a smokescreen to distract from the actual issue I'm concerned with.

I say 'not over my head'.

I also say 'do not start polluting the sky's

And ' keep the noise down'

You don't have a lawn?

How would a few rich people flying above the lower ones reduce congestion ... on the ground?

Congestion would be reduced by people using trains and maybe, I would be actually willing to see this as an option, autonomously driving cars.

Funny you mention Australia, back when people worked in offices you could sit down on the banks of the Yarra on a Friday night, and watch chopper after chopper flying the wealthy from their Melbourne offices to their Mornington peninsula weekend homes. There’s already a pretty big rich guys who won’t take the train market.

> airspace pollution

Bit of a fake concern, no?

>potential small airplane crashing down in a city

Is that really much worse than a SUV driving into a building?

Yes it is. A SUV rarly crashes into a building and when it does, it's often possible that humans die.

An airtaxi crashes down from a hight and speed. They will crash into and through your roof or into a street or directly into humans.

Airspace pollution is not a fake concern.

Why would we allow one company to fly over my head and another not?

Either it is so niche that it doesn't add any benefit to our society or it becomes so normal that air space pollution is a real issue.

I'm very very happy when I look into an empty/nearly empty sky.

This is a valid concern.

> Yes it is. A SUV rarly crashes into a building and when it does, it's often possible that humans die.

This is something that happens on a daily basis.

https://www.fox2detroit.com/news/driver-crashes-through-gas-...

https://www.fox35orlando.com/news/car-into-kohls

https://www.cbsnews.com/losangeles/news/vehicle-careens-into...

https://turnto10.com/amp/news/local/massachusetts-wrentham-v...

https://www.nbcmiami.com/news/local/video-shows-suv-crashing...

The NHTSA estimates that there are 16000 crashes per year in the US caused by drivers confusing the brake and accelerator pedals. A huge chunk of these do end up with the vehicle inside a building.

https://web.archive.org/web/20161226060428/https://www.nhtsa...

> An airtaxi crashes down from a hight and speed. They will crash into and through your roof or into a street or directly into humans.

The odds of a SUV driving into humans is far greater than the odds of a falling airtaxi hitting anyone.

SUVs end up inside stores every single day because of unintended acceleration on parking lots.

> Why would we allow one company to fly over my head and another not?

What does that even mean?

>Either it is so niche that it doesn't add any benefit to our society or it becomes so normal that air space pollution is a real issue.

The “airspace” is very big 3D space that can simultaneously accommodate thousands of flights over a city before congestion becomes an issue.

Now scale that up to a number which actually makes any difference and your SUV argument falls appart.

And yes it's totally valid as well to not allow it at all if only a handful of other people can benefit from it.

We are the people and I don't care if a rich person wants to do that. My airspace is more important than that one rich person.

> Is that really much worse than a SUV driving into a building?

Yes

Think of it this way. If an SUV drives into your building you can sue and make some money. But if some really rich person crashes their flying gizmo into your building you can sue and make a lot of money!

I can't sue if I've been incinerated by an uncontrolled lithium battery fire.

With more and more SUVs and truck beimg EVs that doesn't change much. Well, eVTOLs will burn longer, not that it matters because a large SUV will burn long enough to not matter to you.

And I'd bet a lot more on the crash safety of aerospace cerrified batteries than those of the automotive sector.

> And I'd bet a lot more on the crash safety of aerospace cerrified batteries than those of the automotive sector.

Why? Aircraft are optimized for weight far more than automobiles. Making airplane batteries safer than car batteries would make them even less energy dense than they already are. Add to that fact that cars have a crumple zone built into them, while an airplane AFAIK does not -- at least not one that matters when it crashes into my house at 100mph.

Furthermore, some Tesla crashing on the freeway on the way to Tahoe is unlikely to start a forest fire. But what about some rich yahoo making the same trip while flying their personal electric plane who crashes in the Oakland hills?

These problems are non trivial particularly because every personal electric plane company wants to scale into the millions.

Neither could you sue if you had been struck and killed by an SUV. The end state of your reasoning is that nobody can ever do anything that involves risk because someone might die and be unable to sue. Sounds like an awful world

Emphasis on "killed." I don't want to be struck by an SUV, but one hitting my apartment at ordinary NYC residential street speeds (at least, pre-COVID) is less likely to kill me than a plane crash.

Risk is a community exercise. You don't (or rather, shouldn't) get to externalize disproportionate risks upon the commons because it makes your life easier.

(An example of such a consideration: what happens when the fire department shows up? They know how to deal with a car accident; are they going to have the presence of mind not to douse a vehicle that looks like a normal personal aircraft in water?)

>but one hitting my apartment at ordinary NYC residential street speeds

Why ordinary speeds? Someone driving into a building is likely to be going significantly faster, perhaps because they confused the brake pedal and accelerator.

Things like this happen all the time https://twitter.com/TempePolice/status/1529914550266368000

You have only that much of momentum from ground in comparison to something already in the air and just falling down.

We currently have a billion cars on the road. Of course we have plenty of accidents.

But that's not a valid comparison.

And perhaps we should also get rid of carsnow your argument is totally invalid

So, are you saying that you think that the worst that happens in car crashes is "someone could sue"?

please don't waste our time.

Why? You’d expect there to be far more people at the street level than on top floors.

And in any case, even if such accidents would be worse, they’d also be vast less common. It’s more difficult to fuck things up in the air, and the level of training required to operate an aircraft is far higher than the level of training required to operate a SUV.

Drivers famously can’t even keep track of which pedal is the brake and which is the throttle https://en.wikipedia.org/wiki/Sudden_unintended_acceleration

So, terminal velocity of a relatively aerodynamic shape (like a bullet falling, or a skydiver who is head down and pulled their arms in) is about 200mph, according to https://en.wikipedia.org/wiki/Terminal_velocity

How many SUVs do you know of that are crashing into houses at 200mph?

Also, what is the relative mass of the electric airplane with a bunch of lithium batteries, versus the SUV?

What parts of the house might be hit by a falling airplane, versus an SUV crashing into the house from the road?

What is the fire risk of a bunch of lithium batteries having fallen out of the sky, versus the SUV crashing into the house?

There's lots of factors to be considered here, but overall I'd say there's a lot more risk of damage, injury, and death with the falling electric airplane than with the SUV.

Why focus on houses? SUVs drive into ground level shops and restaurants every single day. Places which tend to exists at ground level for accessibility reasons, and contain much more people than your average house.

https://www.fox2detroit.com/news/driver-crashes-through-gas-...

https://www.fox35orlando.com/news/car-into-kohls

https://www.cbsnews.com/losangeles/news/vehicle-careens-into...

https://turnto10.com/amp/news/local/massachusetts-wrentham-v...

https://www.nbcmiami.com/news/local/video-shows-suv-crashing...

https://abcnews.go.com/US/dead-hospitalized-car-plows-dc-res...

https://www.gainsberglaw.com/blog/cars-crash-into-buildings-...

I could find thousands of these.

An airplane falling from the sky is far less likely to hit anyone than a car suddenly accelerating into a store because the driver is flooring the accelerator instead of the brake. These incidents are so common that they have an extensive wikipedia article https://en.wikipedia.org/wiki/Sudden_unintended_acceleration

You can find some numbers at https://www.storefrontsafety.org/statistics.html They claim this happens around 60 times a day.

And you think that having the same amount of air taxies in the air that. SUVs on the street would still make the SUVs look bad?

Again at least with streets I know that an SUV will only crash close to streets with an air taxi it could crash everywhere.

Kindergarden? Yes.

Can we protect a kindergarden from an accidental SUV acceleration? Of course we can. Easy.

> And you think that having the same amount of air taxies in the air that. SUVs on the street would still make the SUVs look bad?

Yes of course, per passenger mile SUVs are far more likely to drive into a building than an air taxi is to fall out of the sky.

> Can we protect a kindergarden from an accidental SUV acceleration? Of course we can. Easy.

But we don’t.

It could be any structure, but the probability is that it will be a house or other type of housing. There are a lot more residential buildings than commercial.

> Why?

All of the things that https://news.ycombinator.com/item?id=31719861 wrote, and:

> You’d expect there to be far more people at the street level than on top floors.

There are far more people who live near the sky than live near a large road.

> It’s more difficult to fuck things up in the air,

No, it really isn't? Aircraft driver licencing and training is notoriously much harder, longer than the equivalent motor-car licencing and training. Car drivers don't have to learn about stalls for starters. The training is there because a) it's much harder to do right, there are more ways to go wrong and b) potentially greater impact.

The common failure mode for a car is that it stops moving at the side of the road. The equivalent for an aircraft is that it falls out of the sky onto whatever is below. We are not ready for a lot more of that.

remember this? https://en.wikipedia.org/wiki/2013_Glasgow_helicopter_crash

I always saw cars / roads as the great equaliser in the cities ... I lived in Sydney for a while where there were a couple of traffic snare points that were unavoidable, no matter your position in life. The Sydney Harbour bridge is one that comes to mind. There would be incidents all the time that would briefly close the bridge and you'd have execs in their batmobiles bumper to bumper with sparkies in their ford transits, nowhere to go and nothing to do. There was literally no way short of commandeering a helicopter that would get you over that bridge faster than the next bozo. Unless you wanted to slum it on public transport or a bike.

Re. Australian outback, air taxi already kind of exists in light planes, helis and of course flying doctor.

“There was literally no way…” in a car. But bikes, walking, etc. Bikes are better for cities.

Biking is not slumming it. There are some pretty fancy eBikes out there.

For sure. I cycled my ~16km return route to work almost every day (starting with a killer hill) ... tho must be said cycling in Sydney is not for the faint of heart.

That said, the particular generation of execs I was referring to largely exist in a culture devoid of bicycle commutes :)

> But airspace pollution and a potential small airplane crashing down in a city? No way.

Why is this fine with big planes, but bad with small ones?

It's not. The big plane fly area at airports.is a hard area to life in due to all the noise.

But small air taxies would first of fly much lower, always in the city and if it is cheap enough for all of us, you need more than just one.

And if it's not affordable for us, than there is no real reason for us to accept this at all.

And yes the big planes when they travel very high you can not hear them but it's also totally valid to have the discussion about air pollution and sky visual pollution.

But air transport for goods is actually something were we all benefit. Airmail as well.

> a potential small airplane crashing down in a city? No way.

Drones ought to have megaphones that scream DRONE CRASH IMMINENT before impact.

Boy, that would scare the crap out of those Russian T-72 tank drivers just before they die....

> I imagine it all depends on how silent those planes can be.

I agree. I’d say, though, not just how silent, but how pleasant sounding. Aesthetics of sound could make or break this industry.

You either get a chop-chop-chop, or a bzzzt, both incredibly loud. It's not the engine that makes the noise, it's mostly the propeller/rotor. The only advantage of electric VTOLs is easier manufacturing and better control.

> You either get a chop-chop-chop, or a bzzzt

Well, for instance, if they could line up the harmonics to create a missing fundamental (eg with the addition of external sounds), they could make propellers present an artificially lower pitch.

Your solution to them being too loud and annoying is to make them louder and hopefully less annoying?

Yes. It’s possible that louder but less annoying is more viable, wouldn’t you say?

I would say the most viable solution is to not subject hundreds of thousands of people to an incredible amount of noise pollution, so that a couple of playboys get to skip a taxi ride to the airport.

Private-transport helicopters or equivalents have no place in cities. The gain is in no way worth the cost.

To complement that: they are only viable because they are heavily subsidized by the suffering of city dwellers. If you placed the cost of air pollution on the bill, they'd be much more expensive.

Its not just unreasonable because the person flying gets less utility that is otherwise lost. It is also an unfair form of theft.

There is plenty of space to change the number of propellers, total area, and rotational velocity and change the sound profile of the plane.

There is also a lot of space on how you maneuver it on the landing and take-out, so you make less sound when it matters the most.

There is the entire thing about minimizing weight too, that also reduces sound, but it's also not clear how much can be done.

Overall, it's not clear at all how much noise the eVTOL planes will make.

Props need feathers.

do you have any references to back these statements up? I am not an expert but I did read in a hacker News comment that the energy density of gasoline is about 14 (reading that article, its 50) times higher than a "normal" battery.

if that is true (I do not think that he left references either) then I would think that your statements seem less plausible.

a replier who later deleted their comment left a reference saying the energy density is 50 to 1, comparing lithium-ion battery to diesel: https://www.batterypowertips.com/comparing-ev-battery-and-fu...

Combustion aircraft also benefit from the weight reduction as fuel is consumed.

While that’s true, and makes a huge difference for rockets, it only makes a relatively small difference for airplanes. In cruise, most of an airplane’s energy is spent overcoming air resistance to move forward through the air mass (parasitic drag) rather than to create lift (induced drag).

Any idea how reliable electric motors/systems are compared to fossil fuel systems (primarily piston driven as opposed to jets)?

My understanding is that electric motors are generally more reliable than piston engines. I'm not sure how that compares to jets (which are also considered generally more reliable than piston engines). Nearly all modern helicopters are jet powered.

In that niche, why are batteries needed? Couldn't those planes be constructed with gas turbines that generate the necessary electricity?

It's a matter of the weight/power relation. While batteries suck on weight/energy, their weight/power is great.

The lower that relation, the smaller you can make your VTOL vehicles, and the smaller the vehicles, the cheapest and more economical they are on total.

VTOL works fine with turbines, nearly all large helicopters use turbine engines. They don't use the turbines as generators but instead connect both engines to the rotor via a gearbox.

Did the Harrier just get skipped by the rest of the world?

fossil fuel VTOL was cracked in the late 60s.

When talking about practical small plane with relatively acceptable noise levels and fuel efficiency, I don't think Harrier counts as it "being cracked". 125dB at 100 feet from the plane, very limited time it can spend on vertical takeoff while loaded, limited situations (fuel/weight/thrust ratio) in which it can hover at all...If it was cracked, the newer iteration of the "same thing" - F-35B - wouldn't be so complex and take so many billions to develop...

And the Harrier only barely worked at all. For most operational missions, they couldn't really make true vertical take-offs and landings. Instead they usually had to make short ground rolls to get some lift from the wings, or have a carrier ship sail into the wind. And the mishap rate was appalling.