Comment by jstummbillig | Hacker News Reader

Comment by jstummbillig | Hacker News Reader

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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.

Those aircrafts can be easily fitted with a parachute actually.

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.

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