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Toyota invests $394m in Joby Aviation's flying taxis

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Re: Toyota invests $394m in Joby Aviation's flying taxis

#81

Post by godelski »

nradov wrote: post #76
godelski wrote: post #55

Earlier quoted context omitted.

> Autonomous flight is quite common. When it is used, there are still human pilots standing by to take over in case anything goes wrong. FTFY. I'm just saying that comparing autonomous flight to autonomous driving isn't fair. Flying is a lot easier for a machine. You already have tons of data streaming in from airports, other planes, and lots of equipment on the vehicle itself.

That's completely wrong. Sure machines can control take off, navigation, and landing as long as everything works. However they are unable to cope with unexpected system failures. A lot of things can go wrong on even the simplest aircraft and it's impossible to anticipate and code for all of them.

There's different levels of autonomy, just to be clear. I'm not saying they are level 5.

Re: Toyota invests $394m in Joby Aviation's flying taxis

#82

Post by godelski »

nradov wrote: post #47
godelski wrote: post #40

Earlier quoted context omitted.

Just an FYI, planes already regularly fly by themselves. Auto landing has even been around since the late 60's.

Yes but there are still trained human pilots monitoring the auto landing systems, ready to abort if anything goes wrong. It general autonomous systems are incapable of coping with unexpected failure modes.

Sorry, to be clear, planes are not level 5. But to also be clear, there are different levels of autonomy. I'm not trying to suggest they are level 5 though.

Re: Toyota invests $394m in Joby Aviation's flying taxis

#83

Post by smattiso »

OnlineGladiator wrote: post #31
smattiso wrote: post #17

Earlier quoted context omitted.

The likelihood of failure is much lower with an eVTOL than a conventional helicopter. Additionally a BRS chute could work with eVTOLs in a way it couldn't with a normal heli.

> The likelihood of failure is much lower with an eVTOL than a conventional helicopter. You're basing this on a myriad of assumptions as eVTOL designs are barely at the prototype stage right now. Helicopters have been in use for decades, so we know how safe they are. If they truly prove to be safer then that's awesome, but based on everything I've seen I don't believe that to be true.

Why don't you believe that to be true? There are a myriad of ways for a combustion powered helicopter to fail. Just look at how many billionaires have been killed in helicopter flights.

Electric motors do not fail as often as combustion engines. Most eVTOL designs have redundancies that don't exist in a normal helicopter. I have flown R22s a handful of times and there were many times where an engine failure would have been disastrous.

Re: Toyota invests $394m in Joby Aviation's flying taxis

#84

Post by malandrew »

seoulmetro wrote: post #44
malandrew wrote: post #20

Earlier quoted context omitted.

You'd be surprised how far 469 heliports go. That's one more than the number of stations the NY Metro has, which is the metro with the most number of stations in the world. Now imagine you could travel as the crow flies between any station in NYC. That's awesome efficiency, and if you still need you can grab an Uber at street level if you're still not close enough. You're also not limited to just those 469 heliports.…

No. Seoul Metro has nearly double that of NYC. I have no idea how you could possibly think NYC has the most in the world. Just think of most Chinese cities, let alone Korea's capital. https://en.wikipedia.org/wiki/Seoul_Metropolitan_Subway

Thanks for the correction. Google failed me when I tried to look up the metro with the most number of stops.

Re: Toyota invests $394m in Joby Aviation's flying taxis

#85

Post by hndamien »

rhinokungfu wrote: post #68
omegabravo wrote: post #41

Earlier quoted context omitted.

On a simplistic level, the energy density of hydrogen is far greater than chemical batteries. Less weight to carry the same amount of energy. This is more complex than I summarised, containing hydrogen effectively being one issue.

True, Hydrogen has a far higher energy density than li-ion batteries (~150x). But that doesn't show the entire picture. To store and use that hydrogen, you also need a very strong tank (cause of the high pressure it has to be stored in a vehicle) and a fuel cell stack to generate electrical energy. Taking the example of Toyota's Mirai, the hydrogen tank weighs 90kg to just store 5kg of Hydrogen (at 700bar). And this…

Skai VTOL claims to fly for 4 hours vs battery powered Ehang which is around 30m - for a hydrogen vs battery real world comparison. So perhaps there is some difference when these scale up. Their tank is made from stainless steel as well, rather than carbon fibre, so it appears that there is room for improvement there too.

https://skai.co/hydrogen-details

Re: Toyota invests $394m in Joby Aviation's flying taxis

#86

Post by seoulsubway »

ta1234567890 wrote: post #51
seoulmetro wrote: post #44

Earlier quoted context omitted.

No. Seoul Metro has nearly double that of NYC. I have no idea how you could possibly think NYC has the most in the world. Just think of most Chinese cities, let alone Korea's capital. https://en.wikipedia.org/wiki/Seoul_Metropolitan_Subway

Also Tokyo, Japan. It's ranked first in the world on subway usage and has 882 railway stations. https://en.m.wikipedia.org/wiki/Tokyo_subway

Actually Tokyo has much less than Seoul. You're counting railway stations, not subway stations. There's a large difference. Though the water is quite muddled, the easiest way is to actually look at the maps of the differing cities.

I was actually very let down by the metro of Tokyo compared to other Asian cities. Probably due to my high expectations.

Re: Toyota invests $394m in Joby Aviation's flying taxis

#87

Post by ngoel36 »

kgilpin wrote: post #32

If an aircraft can’t glide or autorotate then I don’t understand how it can be safe at low altitudes. Because whole plane parachutes (BRS) have a minimum altitude required to open successfully, and that altitude is a lot higher than anyone would care to drop. Airplanes have energy from their forward motion. Helicopters have energy in their rotor blades. This energy can be used to soften a crash landing. Without this…

These are fixed wing, so they glide like airplanes. They will also have a BRS unlike helicopters. Additionally, the elctric rotors are independent, so there is built in redundancy. All of this results in a significantly safer aircraft.

Re: Toyota invests $394m in Joby Aviation's flying taxis

#88

Post by ngoel36 »

OnlineGladiator wrote: post #4
joshribakoff wrote: post #3

Earlier quoted context omitted.

From what I gather most companies in the space plan to land and take off from rooftops. That leaves a lot more options for stations and edges connecting them leading to a denser network than something like a subterranean train which requires dedicated stations with tunnels in between them

In that case, what makes them more useful than helicopters?

They are all-electric, 100x quieter, notably safer, and significantly cheaper by the mile.

Re: Toyota invests $394m in Joby Aviation's flying taxis

#89

Post by ngoel36 »

the_duke wrote: post #2

There are a lot of companies working on "flying taxis". All of those seem to have a large footprint with lots of rotors, meaning they will need dedicated landing/take off zones. This seems to limit their usability a lot, turning them more into a short range point to point helicopter service. Not to mention the noise pollution. Those things are all loud. Combine that with limited speed and range, and I just don't see…

These are 100x quieter than a helicopter, and nearly inaudible overhead. All-electric range is 60 miles at 150mph, which covers the vast majority of popular and congested urban routes.
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