ConOps for eVTOLs

Reaper

Reaper

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I am really interested in the whole urban mobility / eVTOL trend and I wonder how this will play out in the future. That is why I am currently looking at the ConOps and next doing a conceptual design loop for an existing eVTOL.

In the whole eVTOL / urban air vehicle discussion, it becomes clear that the Concept of Operation and the requirements, which drive the design, are really open, resulting in a variety of different concepts (multicopter, eVTOL tilt rotors/Wings...) being pursued by different companies. According to Aurora FS / Airbus the decision point for wing/no wing is a range bigger/smaller than 50km.

Now assuming there would be business customers using eVTOLs first, who are able to trade time for money (getting from the airport to the center of a city like a heli shuttle) and then normal people later (maybe using the plane for commuting). With this is mind it looks that a smaller multicopter would make more sense (from using the energy more efficiently) since most of mega cities (Sao Paolo, Mexico city...) only have a maximum diameter of 50km.

What do you think about these assumptions?
 
There is definitely a crossover point in terms of speed/range above which the pure multicopter doesn't make sense.
The L/D effective of multicopters is somewhere between 1 and 2 (!), so you really start spending a lot of energy if you want to go far. Compare to L/D of 10+ achievable by a clean winged configuration (a bit less for dirtier ones).
The other concern is that pure multicopters will not fly with the cabin level, which could turn off passengers.
 
I read in the Uber report, that their design mission is 2x80km (50miles) trips + reserve (2016), which suggests a winged eVTOL. But in their later presentations there is only one case, where you actually have a 80km trip length (Sao Paolo to another city in the same urban area) Most of their use cases are around 40km (25miles Dallas, Dubai, New Delhi) one trip length max. and then it is not so clear anymore how the concept should actually look like. In comparision the current Volocopter has a max. range of 27km (17miles).

@AeroFranz: With cabin level you mean noise and vibrations in the cabin?

graphic from Aurora FS SAE presentation.
 

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I mean the whole cabin has to tilt in order to get the thrust vector of the rotors to point forward. I imagine it could be as much as twenty degrees, which might feel weird for a passenger.

The other problem of multicopters is that you're speed limited, so in a given day you can only fly so many trips. Other configurations may be more expensive, but can fly more trips (get more revenue).
 
You don't have to land with your rotors level (parallel to the ground). Hence no nausea for your passengers that won't have to seat pointed downward.
Obviously, power is lost that way but this is not really a problem with battery powered aircraft (short period of time).
 
I think the major issue may not be the aircraft, but where it lands. Say you want to hop an aerial taxi from Heathrow into the City of London (aka the Square Mile), where is it going to put down? If it can't put down close to your destination, then do you need to call for a ground-based cab on landing? Are you really going to gain vs hopping on Heathrow Express and then the Tube? Landing space is a non-trivial issue in many heavily urbanized areas.

And the idea of Uber, with its hatred of regulations and confrontational attitude to regulators, c.f. TfL's withdrawal of its license to operate in London as not a fit and safe company, being able to negotiate an Air Transport License is rather an amusing one.
 
DWG said:
I think the major issue may not be the aircraft, but where it lands. Say you want to hop an aerial taxi from Heathrow into the City of London (aka the Square Mile), where is it going to put down? If it can't put down close to your destination, then do you need to call for a ground-based cab on landing? Are you really going to gain vs hopping on Heathrow Express and then the Tube? Landing space is a non-trivial issue in many heavily urbanized areas.

And the idea of Uber, with its hatred of regulations and confrontational attitude to regulators, c.f. TfL's withdrawal of its license to operate in London as not a fit and safe company, being able to negotiate an Air Transport License is rather an amusing one.
Click to expand...

Maybe we will see C-Bands in suits fast-roping onto the tops of skyscrapers.
 
One particularly aspect of those design regarding more traditional rotary wings is there low mass. Around a single metric ton, most skyscraper could be turned easily into a landing pad. Have a look around your downtown area. What do you see? Perspectives for a vertical grow in cities economy (imagine shops doubling themselves with rooftop installation, services relocating there etc...). We are on the verge of a radical transformation and that's what will bring money into those projects.
Meanwhile, It's then the time lost waiting for a place in the lift that would count against "fast" train transportation.
 
Look at the tops of existing buildings: water towers, telecoms, aircon, lift infrastructure. And then there's the issue of security, you're making a previously secure entrance into a significant entrance, open to anyone who can tell an Air taxi your address. Then look at existing rooftop pads and the safety regimes they operate under. The fire risk may be reduced, assuming battery powered vehicles, but does that mean you can do away with safety personnel? Do approach paths to each building need defining and certifying? What happens if you have conflicting traffic?

And then there's access, an aerial taxi isn't much use to me if it drops me on the roof and the only way down is stairs when I'm a wheelchair user.

I'm seeing a lot of broad-sweep it'll be great from the air taxi advocates, I'm not seeing a lot of detailed analysis of infrastructure and certification issues. I worked through ground-breaking civil air transportation certification - 777, first FAA certified FBW system, and it takes a lot of work and years of preplanning.
 
"Easily " was indeed rather insulting given the complexity of the subject when going down to the details. Too much internet for me. :)
I am however convinced that this is where we are heading.
 
The regulatory and infrastructure challenges are enormous indeed.
However, can you think of anything more lucrative than this? Is there anything that people hate more than traffic and wasting time? There's so much potential $$$ involved that there's a good chance they'll make it work regardless of how much time and money is required. Probably with limited service at first (like in Dubai, Singapore, and Dallas FW), and progressively building on that.
Just to name a few companies involved in on-demand mobility (and delivery drones, which have the same ATM problem to solve): Airbus, Boeing/Aurora Flight Sciences, Embraer, Pipistrel, Mooney, Bell helicopters, Amazon, Uber, Zee aero (Larry Page), Mercedes-Benz/DHL. I'm not counting the startups because 9/10ths are guaranteed to fail.
My only concern is if there are high-profile accidents that make the public lose confidence in the technology.
 
You won't take the cars away, and high profile death have been part of this technology since its inception.
If its popular (with an appropriate cost), then it will survive such occurrence.
 

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