VTOL On Demand Mobility

DWG

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TLDR: "Bristow intends to take up to 100 examples of Eve’s eVTOL aircraft – deliveries are to start in 2026 – alongside pre-orders for 25 of Vertical’s VA-X4 aircraft, plus 25 options."

The article has a picture of a Bristow-branded example of the Eve eVTOL on approach to an oilrig. I really do wonder if any of the current crop have the space and emergency exit potential for a crew of hulking rig workers in survival suits.

OTOH the deal with Vertical strikes me as sensible because it says both sides will set up a working group to collaborate on: "regulatory and airspace; demand, fleet size, spare parts and infrastructure; potential customers; and public acceptance and environmental requirements"
 

DWG

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CATL's Sodium Ion battery is more designed for energy storage; i.e, they claim they can get costs down to the 20-40 USD range per kWh, which, with an estimated 1000 (maybe 2000?) cycle life, gets you to 1.25 cent per kWh storage (assuming 20% charge/discharge inefficiency) as a minimum, with 5 cents being the maximum.
I wanted to pick up on the cycles issue even if this isn't specifically discussing a battery aimed at the eVTOL market. If your battery life is 1000 cycles, and you're recharging three times a day in the eVTOL role, which is certainly a viable estimate, possibly even an underestimate, then you're replacing your battery pack once a year. And the industry would need not just the battery suppliers to handle that, but the battery recyclers to deal with all those piles of no-longer flightworthy batteries.

IOW, it's not just energy density that puts special design demands on eVTOL batteries, it's cycle life as well. And ease of recycling on top.
 

TomcatViP

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The great advantage of battery is that you are trading a gaseous emissions problem for a solid one, something much easier to handle during the recycling process.
But I do agree that there will be a lot of difficulties at the societal level and discontent among users.

Price will soar and peak with speculation ruining your day on an hourly basis for example and recycling effort will probably constitutes a significant part of a new vehicle buy, depending on which type of economy your country is aligned on.
 
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DWG

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IMO most people looking at VTOL on-demand mobility are doing it wrong. Take-off and landing are big problems for this kind of stuff; The better way to do it would be to envision the lifting units as always airborne, but have them carry a passenger compartment which can be landed and recovered trivially. The passenger compartment then can be landed on a sidewalk, or even not landed at all with a ramp off-loading the passenger. This minimizes the infrastructure requirements for pick-up and landing.

If you want to use the sidewalk/footpath to land on, then you're looking at multiple problems.

Firstly the sidewalk in many places just isn't viable, whether because the sidewalk butts right up against buildings - almost inevitable true in downtown areas and frequently true in residential areas, especially older ones - or because the sidewalk comes equipped with a whole range of options for bringing your aircraft down, be those 70' trees, street lights, telephone poles, telephone wires, and in some places, electricity cables.

Nor is the pavement an appropriate area for dropping a pod (or a ramp from a pod). It's difficult for piloted vehicles, and far worse for autonomous ones. You have to check you aren't going to drop it on: people, children, people and children in non-standard formats* - in prams, wheelchairs, on bikes, with bikes (cf the Uber autonomous vehicle trials death in Tempe**), cats, dogs, street furniture, street planting, etc, And just think of the complaints over rental e-scooters being abandoned on the street and multiply that by something the size of a compact family car, especially if you drop it in front of someone's driveway. Even if you recover it immediately you're still going to completely block the footpath for as long as it takes to land, uncouple, wait for everyone to get out, go back for that bag/toddler they've forgotten, figure out how to close the door, recouple and fly away.

If you're envisaging winching down the pod from a high-hover, you then have to consider the effects of crosswinds on the pod, and it's not just how do you put it down on the target, but how do you stop it spinning and making the passengers airsick.

WRT ballistic recovery chutes for the pod, that isn't going to work because these vehicles will spend a high proportion of their time at low-level over towns. The 'chute technology might be able to handle the scenario, but who is going to be under that pod when it comes down? In practice you've just doubled the impact areas. I think it was Zootycoon earlier in the thread who mentioned at least one regulator flat out refuses to allow ballistic recovery chutes to be considered in a safety case.

Adding to all of this is you're stuck in the hover for all the time to uncouple the pod, or waiting for the passengers to unload, and that's a major drain on your battery life.

* I've seen footage of an AI trained to visually recognise people in a scene outlining every person in a crowd, except the ones with strollers or holding hands. I'm 100% certain it would also have ignored wheelchair users and almost as certain it would have had issues with people with mobility aids such as crutches or walkers.

** There's also the recent non-fatal incident during the Paralympics as an example, one of the autonomous Toyota shuttle buses ran down a visually-impaired Japanese paralympian crossing the road at a pedestrian crossing, because not only did the vehicle ignore him, the two safety observers assumed he would see the bus and not cross. *headdesk*
 

Zoo Tycoon

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IOW, it's not just energy density that puts special design demands on eVTOL batteries, it's cycle life as well. And ease of recycling on top.

You need to be best buddies with the supplier of your magical battery; It will be bespoke chemistry, so IP will be a single source, liable to competition disruption from other eVTOL eager to prove they’re better, the eVTOL pax service, indeed industry is dependant on both, i) the worst quality single cell that’s produced within the battery supplier and ii) their ability to deliver on time. The eVTOL supplier, the battery supplier, the operator and owner of the operating ports will need to agree a fair division of the profits.

Then if a better tech emerges do you dump your best buddy? Can this industry withstand the first major supplier getting burned?

Gee this business is insanely risky.
 
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alberchico

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So now Honda throws their hat into the ring. At least they are smart enough to realize that having sufficient range will be a big problem for the foreseeable future and are adopting a hybrid powerplant, which I think is the only practical solution that exists right now for extended range.
 

shedofdread

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Re the Kaman cargo UAV's rotors - a company that's good at little rotors (tail rotors) is likely to want to use little rotors.

From personal experience, when multi- rotor platforms get big compromises have to be made maintain accurate control. I'm not surprised they made the choices they did especially when one considers their competencies ("things that we know work")...
 

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Re the Kaman cargo UAV's rotors - a company that's good at little rotors (tail rotors) is likely to want to use little rotors.

From personal experience, when multi- rotor platforms get big compromises have to be made maintain accurate control. I'm not surprised they made the choices they did especially when one considers their competencies ("things that we know work")...
And that is their selling point - we are not a bunch of hippies/failed Tesla copycats.

Be nice if the marines gave them an order for 20.
 

yasotay

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And that is their selling point - we are not a bunch of hippies/failed Tesla copycats.

Be nice if the marines gave them an order for 20.
... and it's cheap. With a lower probability of integration issues during development. Given the USMC's very positive results with the Kaman KMAX, I would not be surprised to see them get an initial small order like 20 to "Try before you buy."
 
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shedofdread

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I rather hope they do. You don't have to get too imaginative to think of quite a few uses for such a platform - both on land and at sea.

Somewhat annoyingly, I'm aware of a company pitching something really quite similar 11 years ago.... *sighs*
 

Inst

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I wanted to pick up on the cycles issue even if this isn't specifically discussing a battery aimed at the eVTOL market. If your battery life is 1000 cycles, and you're recharging three times a day in the eVTOL role, which is certainly a viable estimate, possibly even an underestimate, then you're replacing your battery pack once a year. And the industry would need not just the battery suppliers to handle that, but the battery recyclers to deal with all those piles of no-longer flightworthy batteries.

IOW, it's not just energy density that puts special design demands on eVTOL batteries, it's cycle life as well. And ease of recycling on top.
So-Ion is probably not a good idea for eVTOL. Even LiFePO4 is probably not a good idea for eVTOL. The energy demands of aircraft are substantially higher than that of a car, and e-taxis already have issues with keeping battery life up. NCA/NCM and solid state are likely the best options for eVTOL, although there are a variety of solid state chemistries that range from the cheap (low density) to the expensive (high-density).

===

You're right about criticism of pods as well. Moreover, a pod system adds substantial drag to the vehicle, reducing battery life. The footprint recovery issue, however, could be handled by having silos of pods at specific locations, and having the VTOL drop the passenger off via the pod, then pick up the pod and drop it at a storage. When the VTOL picks up a passenger, it first picks up the pod and then picks up the passenger.

I also see a more basic issue with design; i.e, most of them are modeled after quadrotor UAVs, as opposed to helicopters. The passenger compartment is on top of the lifting platform, as opposed to on the bottom of the lifting platform, which makes low-footprint passenger embarkment / disembarkment more difficult to execute.

A hybrid solution might be to, first, make the pod integral to the VTOL, but have it mounted below. The VTOL never fully lands, but has an embarkment or disembarkment unit (a slide, perhaps?) that allows the passenger to board or disembark. That would minimize footprint by allowing the VTOL to hover on dropping or picking up the passenger.
 
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Mark Nankivil

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Passengers usually aren't much for walking in the downwash or rotors and the power output while in hover will cut into overall duration.

Still don't see the viability of eVTOL with the present power sources but I guess someone has to be on the bleeding edge of development...

Enjoy the Day! Mark
 

Mark Nankivil

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WRT KMAX, I'm surprised Kargo isn't an intermeshing rotor design.
The KMax and the earlier HH-43, etc. were/are prodigous load carriers but the intermeshing rotors lack crisp precision in operation so for the type of precise flying envisioned, I can see why they went a different route.

I see this and think DJI Mavic Pro XXXXXXL :)

Enjoy the Day! Mark
 

alberchico

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Passengers usually aren't much for walking in the downwash or rotors and the power output while in hover will cut into overall duration.

Still don't see the viability of eVTOL with the present power sources but I guess someone has to be on the bleeding edge of development...

Enjoy the Day! Mark

It appears that Joby is the only eVTOL developed so far that has the proven range and noise profile to be a moderate success. In certain markets like California and New York this aircraft could sell well. Joby recently broke a record flying 150 miles on a single charge. Aviation Week once did a profile on the company where Joby claimed that their secret to getting long range is to aggressively focus on getting the weight of the vehicle as low as possible. The problem that I see are companies like Lilium that are expecting battery tech to improve by the time their models get certified. That is a huge red flag. It tells me that they know their aircraft are unable to meet performance targets and they are crossing their fingers that the battery chemistry issue gets drastically improved soon, which many experts have said is unrealistic.


 
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DWG

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A hybrid solution might be to, first, make the pod integral to the VTOL, but have it mounted below. The VTOL never fully lands, but has an embarkment or disembarkment unit (a slide, perhaps?) that allows the passenger to board or disembark.

Ramps/slides are more complex than people imagine - I'm a wheelchair user so I get to wait for the ramp to be sorted every time I catch a train or bus. Bus ramps (which tend to be automated) are notorious for breaking, train ramps are put in place manually, and for what you would imagine is a simple process is surprisingly fiddly because you do want the ramp locked in place and secure and flat before you take the liability of a passenger setting foot on it. And these are ramps that in general either go down onto a guaranteed flat surface on a station platform, or onto a specially prepared point at a bus-stop.

You aren't going to have a guaranteed level surface to deploy a ramp onto with an eVTOL, unless you restrict it to dedicated landing spots. That introduces trip hazards/liability, and the potential for a lip and an edge that people get their suitcases hung up on (I've twice had train station passenger assistance staff manage to jam the edge of the ramp between my tyre proper and the pushrim - the express crew were not amused!)

And if it's automated, and you don't have clear vision of it, then are you certain you aren't going to drop it on someone's foot, pet, toddler....
 

AeroFranz

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For the record, lots of people in the industry think that Joby's 150 mile trip was achieved without pax onboard (obviously) but also the equivalent mass was replaced with a battery in the cabin.
Still very impressive, Joby has done a great job and is at least showing video footage of a fully transitioned vehicle in flight while others flaunt pretty renderings.
 

Fluff

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A hybrid solution might be to, first, make the pod integral to the VTOL, but have it mounted below. The VTOL never fully lands, but has an embarkment or disembarkment unit (a slide, perhaps?) that allows the passenger to board or disembark.

Ramps/slides are more complex than people imagine - I'm a wheelchair user so I get to wait for the ramp to be sorted every time I catch a train or bus. Bus ramps (which tend to be automated) are notorious for breaking, train ramps are put in place manually, and for what you would imagine is a simple process is surprisingly fiddly because you do want the ramp locked in place and secure and flat before you take the liability of a passenger setting foot on it. And these are ramps that in general either go down onto a guaranteed flat surface on a station platform, or onto a specially prepared point at a bus-stop.

You aren't going to have a guaranteed level surface to deploy a ramp onto with an eVTOL, unless you restrict it to dedicated landing spots. That introduces trip hazards/liability, and the potential for a lip and an edge that people get their suitcases hung up on (I've twice had train station passenger assistance staff manage to jam the edge of the ramp between my tyre proper and the pushrim - the express crew were not amused!)

And if it's automated, and you don't have clear vision of it, then are you certain you aren't going to drop it on someone's foot, pet, toddler....
The idea that pods are going to be dropped or similar, 'anywhere' in a city, on the sidewalk/pavement is pie in the sky. - privacy for people in flats, safety, noise, etc etc.

At best the operators might get a license to use space in a public park or similar, for a hefty fee, or rooftops of buildings, if suitable, but again expensive to do, and with a flat worth £1M whats the value of its roof top? This takes you back to the road taxi, or air taxi debate.
 

Fluff

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For the record, lots of people in the industry think that Joby's 150 mile trip was achieved without pax onboard (obviously) but also the equivalent mass was replaced with a battery in the cabin.
Still very impressive, Joby has done a great job and is at least showing video footage of a fully transitioned vehicle in flight while others flaunt pretty renderings.
I think at this stage thats ok, presumably they are also expecting improvements in w/kg, which is reasonable, as the earliest Li-ion cars were upgraded quickly to have more battery power, such as the BMW i3 and Zoe.

I'm wondering if for take off you could use a tethered power cable or even microwave to top up, I suppose a vertical catapult wouldn't be too stylish?
 

shin_getter

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IMO most people looking at VTOL on-demand mobility are doing it wrong. Take-off and landing are big problems for this kind of stuff; you need heliports. The better way to do it would be to envision the lifting units as always airborne, but have them carry a passenger compartment which can be landed and recovered trivially. The passenger compartment then can be landed on a sidewalk, or even not landed at all with a ramp off-loading the passenger. This minimizes the infrastructure requirements for pick-up and landing.
*whispers: jetpacks~

Really though, if VTOL cost structure stacks up, there is a future where architecture and land use get changed in the long term. The tension between "tightly packed" walkability city design and patterns of settlement based on vehicle mobility focused land use would expand far beyond what goes on now. Instead of hub and spoke network of cities due to high throughput land transport infrastructure costs, a point to point 3D transport network would be very different and landing pads simply take less space than roads at the end point.

Personally, I think we are on the cusp of a wave suburbanization that with the wealthy moving out of cities in most advanced economies outside of Asia. Development of remote work and delivery infrastructure, greater class and ethnic tension in cities and devastation of inner cities service business all adds up.

In the fully developed post-VTOL world, everything will be further apart than ever, because now the transport time-cost becomes affordable.

SPRAWL~ YOU HAVEN'T SEEN THE LAST OF IT *shakes fists at urbanists on some other forum that think: "Personal Mechanical Transport Revolution and its consequences have been a disaster for the human" *

It is too bad there is no proper "fly-punk" genre that explores easily accessible flight and its revolutionary impact of culture and life in general, instead old patterns of life gets copy pasted to a world of fantastic technology.
 
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Inst

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IMO most people looking at VTOL on-demand mobility are doing it wrong. Take-off and landing are big problems for this kind of stuff; you need heliports. The better way to do it would be to envision the lifting units as always airborne, but have them carry a passenger compartment which can be landed and recovered trivially. The passenger compartment then can be landed on a sidewalk, or even not landed at all with a ramp off-loading the passenger. This minimizes the infrastructure requirements for pick-up and landing.
*whispers: jetpacks~

Really though, if VTOL cost structure stacks up, there is a future where architecture and land use get changed in the long term. The tension between "tightly packed" walkability city design and patterns of settlement based on vehicle mobility focused land use would expand far beyond what goes on now. Instead of hub and spoke network of cities due to high throughput land transport infrastructure costs, a point to point 3D transport network would be very different and landing pads simply take less space than roads at the end point.

Personally, I think we are on the cusp of a wave suburbanization that with the wealthy moving out of cities in most advanced economies outside of Asia. Development of remote work and delivery infrastructure, greater class and ethnic tension in cities and devastation of inner cities service business all adds up.

In the fully developed post-VTOL world, everything will be further apart than ever, because now the transport time-cost becomes affordable.

SPRAWL~ YOU HAVEN'T SEEN THE LAST OF IT *shakes fists at urbanists on some other forum that think: "Personal Mechanical Transport Revolution and its consequences have been a disaster for the human" *
There's a more optimistic view. HSR, Maglev, and Vactrain can link up conurbations with cheap and fast inter-city transit, thereby creating megacities and superclusters.

The denser the city, the better its services and so on, if you've lived in megadense conurbs like NYC, Paris, London.
 

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There is a shaping aspect that is selddom discussed: like you said, there will be a factor to reshape blocks in a hub and spoke geometry. But a major rethinking would also have to be done with traditional cities architecture being articulated from ground to higher level when On-demand mobility will reshape this from top to bottom.

The point of entry in an area or a "block" will be the high grounds. You'll then cross commercial area and commuting services on your way down to your employer location or your residence.

I'll try to post a picture of a design to illustrate this.
 
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Zoo Tycoon

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like you said, there will be a factor to reshape blocks in a hub and spoke geometry.

You'll then cross commercial area and commuting services on your way down to your employer location or your residence.

I'll try to post a picture of a design to illustrate thar.

Not the same as you propose, but maybe similar thinking ;-


the city is being built along a single straight line with a transport system running full length along the line. So in theory everyone has easy access to go anywhere within the city, when they want or have a need to. Hence no road network, and the central transport system is emission free.
 

Fluff

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IMO most people looking at VTOL on-demand mobility are doing it wrong. Take-off and landing are big problems for this kind of stuff; you need heliports. The better way to do it would be to envision the lifting units as always airborne, but have them carry a passenger compartment which can be landed and recovered trivially. The passenger compartment then can be landed on a sidewalk, or even not landed at all with a ramp off-loading the passenger. This minimizes the infrastructure requirements for pick-up and landing.
*whispers: jetpacks~

Really though, if VTOL cost structure stacks up, there is a future where architecture and land use get changed in the long term. The tension between "tightly packed" walkability city design and patterns of settlement based on vehicle mobility focused land use would expand far beyond what goes on now. Instead of hub and spoke network of cities due to high throughput land transport infrastructure costs, a point to point 3D transport network would be very different and landing pads simply take less space than roads at the end point.

Personally, I think we are on the cusp of a wave suburbanization that with the wealthy moving out of cities in most advanced economies outside of Asia. Development of remote work and delivery infrastructure, greater class and ethnic tension in cities and devastation of inner cities service business all adds up.

In the fully developed post-VTOL world, everything will be further apart than ever, because now the transport time-cost becomes affordable.

SPRAWL~ YOU HAVEN'T SEEN THE LAST OF IT *shakes fists at urbanists on some other forum that think: "Personal Mechanical Transport Revolution and its consequences have been a disaster for the human" *

It is too bad there is no proper "fly-punk" genre that explores easily accessible flight and its revolutionary impact of culture and life in general, instead old patterns of life gets copy pasted to a world of fantastic technology.
You may have to come back and argue with my avatar in 100 years time, but really I cant see it. Whatever improvement in batteries, motors will apply equally to cars etc. The romans built roads, we will continue to do so. There are plenty of road layouts in the UK that are 500 years old, with building replaced in a random timeline. VTOL will be for the uber to mid rich, think influencers, and tik tok 'stars'......

Upside down cities etc, are best left with 2000AD.

High speed train/transit will improve, maybe even with some form of capsule swapping, so you dont get out of your pod until you arrive, to be met by a 30 year old Tesla self driver, with E-lon asking you how was your day/come far......
 

shin_getter

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Whenever technology improves, greater fraction of the population become lawyers and ...activists. In many vetocracy environments, the cost of roads approach infinity as reviews, hearings, and land issues can induce death in sane people. If one simply projects historical trends on building things into the future.....

If the economy continues to grow with greater productivity per person, personal aircraft is not unattainable unless too many lawmakers gets into the mix.

Trains and transit are problematic as it gets populated by the zero marginal productivity class whether there is no motivation to police as it is trouble without value. This drove waves of suburbanization already, and it appears that it will do so into the future. The whole point of suburbanization is cost based segregation as other means becomes illegal.
 

DWG

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shakes fists at urbanists on some other forum that think: "Personal Mechanical Transport Revolution and its consequences have been a disaster for the human"

I've yet to come across a pedestrianisation project that adequately addresses the needs of people with limited mobility, and I'm strongly tempted to say that's especially the ones that scatter happy looking wheelchair users through their illustrations. I've talked to some of these people and it's as if researching the practicalities is something that happens to other people. And it's not just the amateurs, it's the NGOs and professionals as well. I've met town planners who've outright denied that planning integrated environments is a thing, despite universal design having been an architectural/planning discipline since the 1960s.

And dragging this back closer to the topic, I think we're seeing a similar phenomenon with urban air mobility. The eVTOL manufacturers are concentrating on the flight phase, they're leaving it to the operators to address how they'll interface with existing society and that's just not happening in a systematic manner, or at all. I can imagine Qatar or the UAE being happy to set up local landing pads in their new-build, constantly being reworked cities, I don't see that working in most countries. If you need a landing pad in central London, then where do you put it? If you can't have a landing pad in central London does your business model work? If you do manage to pick up fares in Central London, then how do you get them to where they want to go if that's scattered in a 150 mile radius all across the South East and the Home Counties? Just how many local landing pads do you need to cover the entire London commuter belt? And if you do suddenly flood the airspace with eVTOLs, who is handling traffic control? Who is keeping them separate from Air Ambulance and Police helicopters operating in that same airspace? Where are all the aviation certified mechanics to maintain them coming from? And who is training those mechanics to work with high-density battery packs? Who is setting the certification standards for those packs?

Aircraft don't exist in majestic isolation, they operate in a system of systems, and I just don't see anyone adequately addressing how eVTOLs will fit into that.
 

DWG

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There are plenty of road layouts in the UK that are 500 years old,

Meh, bloody new towns ;) We're still using a hell of a lot of Roman road-layouts, and some of those will have overlaid existing trackways.
 

DWG

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like you said, there will be a factor to reshape blocks in a hub and spoke geometry.

You'll then cross commercial area and commuting services on your way down to your employer location or your residence.

I'll try to post a picture of a design to illustrate thar.

Not the same as you propose, but maybe similar thinking ;-


the city is being built along a single straight line with a transport system running full length along the line. So in theory everyone has easy access to go anywhere within the city, when they want or have a need to. Hence no road network, and the central transport system is emission free.

One of the big things with the pedestrianisation crowd is the '15 minute city', having everything you need to access within a 15 minute walk of your home. Essentially a city of self-contained neighbourhoods/villages, with public transport if you need to go further. Having looked up Neom, I see they're proposing a '5 minute city', which will give them tiny neighbourhoods.

Checking https://en.m.wikipedia.org/wiki/The_Line,_Saudi_Arabia I notice some distinct similarities with urban air mobility as the plans need a completely unrealistic performance from the public transport system and doesn't really address the infrastructure it needs. 20 minutes from one end to the other of a 170km city sounds good, but that needs trains running an average of 510km over the whole distance, and while technically the TGV has beaten that, it was a special run, over specially prepared track, with specially high-powered coaches, didn't count the acceleration segment, and needed another train to run the route in advance to ensure it was clear of anything that might get dragged up by the slipstream. In practice you're talking about doubling your tracks because you'll need a special high speed line, you have to allow for acceleration and deceleration, and just how many people need to travel from one end to the other anyway? The public transport system it actually needs is one that stops at every one of those 5 minute neighbourhoods, so that it's possible to get from any one neighbourhood to any other, and that's going to require frequent acceleration and deceleration that in practice is going to give you something similar to a conventional city metro system. For practicality that's probably going to need to run in parallel with a higher speed rail system for the longer journeys, so even with a linear city you might need a hub station ever 30km or so to let people swap onto a faster long distance service running on a separate, parallel, line.

This is potentially an architecture that might work better with the individual pods that various public transport projects have been proposing for the last 50 years, so that they can either run locally at low speed, or be streamed onto the higher speed long distance lines. But optimising them for running at both speeds is going to be an interesting engineering issue, as is the traffic control system to allow them to switch between lines.
 

Rhinocrates

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There are plenty of road layouts in the UK that are 500 years old,

Meh, bloody new towns ;) We're still using a hell of a lot of Roman road-layouts, and some of those will have overlaid existing trackways.
One I heard a while back: A Briton thinks a hundred miles is a long way, an American thinks a hundred years is a long time.

In Disturbing the Universe, Freeman Dyson recounted a story that's probably apocryphal. The beams in a hall at a Cambridge (or Oxford?) college were starting to look a bit fragile, so the head of the college asked a groundskeeper if he knew of any sufficient large oak trees that could be felled, and he replied, 'Ah yes, I was wondering when you were going to ask about that - about five hundred years ago we planted some.'
 
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DWG

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There are plenty of road layouts in the UK that are 500 years old,

Meh, bloody new towns ;) We're still using a hell of a lot of Roman road-layouts, and some of those will have overlaid existing trackways.
One I heard a while back: A Briton thinks a hundred miles is a long way, an American thinks a hundred years is a long time.

In Disturbing the Universe, Freeman Dyson recounted a story that's probably apocryphal. The beams in a hall at a Cambridge (or Oxford?) college were starting to look a bit fragile, so the head of the college asked a groundskeeper if he knew of any sufficient large oak trees that could be felled, and he replied, 'Ah yes, I was wondering when you were going to ask about that - about five hundred years ago we planted some.'

I've seen statements in a couple of places that the Danish forestry service called the defence ministry in 2007 to let them know their trees were ready.
 

alberchico

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Considering that this industry is in its infancy, developing a cargo drone based on your existing evtol is a smart move. It has low development costs, can be certified more quickly, and has a wide range of civil and military applications.
 

GTX

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coanda

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Cyclogyro concept:
Wow! This could really be huge in the VTOL world if they can make it scale up. Lot less wire strikes, tree strikes, building strikes.
It's going to have some kind of scale limit, due to weight/inertia of moving parts etc. It looks like an interesting technology. Have been following it and was looking forward to seeing it fly - now lets see what it can really do!
 

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