RE: Aston Martin reveals vertical take-off concept
Discussion
Doofus said:
The best way to deal with, and guard against increasing confestion is to invest in the kind of technologies that negate the need to comute in the first place. Of course, that's anathema for an automotive company, but...
Anyway, it's all well and good making it easier to commute into heavily congested cities, but where will they all park?
They won’t need to park. They’ll drop you off at your destination then immediately leave to pick up the next customer (who has booked transport via the app).Anyway, it's all well and good making it easier to commute into heavily congested cities, but where will they all park?
Amanitin said:
CrutyRammers said:
The problem with all of these concepts is the lack of a failsafe. What happens in case of engine failure? Gliding/autorotation all require height, skill and a clear landing zone. We're never going to see traffic flying over cities unless that is solved.
Companies working on these things for real (as opposed to AM) do it through heavy redundancy e.g. 8 separate motor-propeller units, maybe even separate batteries. Safe landing still possible with one failure.The Dangerous Elk said:
Amanitin said:
CrutyRammers said:
The problem with all of these concepts is the lack of a failsafe. What happens in case of engine failure? Gliding/autorotation all require height, skill and a clear landing zone. We're never going to see traffic flying over cities unless that is solved.
Companies working on these things for real (as opposed to AM) do it through heavy redundancy e.g. 8 separate motor-propeller units, maybe even separate batteries. Safe landing still possible with one failure.In terms of this thing though, I can see how it could in theory be done, as you would have multiple units able to produce power (turbines in the text) and then use electrical drive systems to power the props, with a battery bank as the energy store in the middle.
The drive system itself will by definition be more reliable than a piston or turbine engine driving a gearbox. Less moving parts = less chance of failure as long as they are built and maintained to the same standards.
It could work, but the tech is a very long way from being possible, even for manned operations using qualified pilots.
Reminds me of the time (less than a year ago) when AM took the piss out of Dyson after Dyson had announced their EV plans:
Surely, AM are not taking themselves seriously now?
Surely, AM are not taking themselves seriously now?
Edited by tr3a on Monday 16th July 17:23
Edited by tr3a on Monday 16th July 17:33
IforB said:
There's no such thing as a helicopter without a single point of failure. Throw a blade or the gearbox goes pop and you are going in. End of story, no matter how many engines you have.
I've worked in the offshore industry for nearly 40 years (yes I'm an old fart now), I've worked in all the usual places around the globe (commercial diver, or rather ex to be precise 
), and I still go offshore when required. I still remember my first helicopter flight, the chopper looked a bit like this....(and only one pilot)..
Anyhoo, just wanted to agree with IforB, it's why if you hear 'brace brace brace' the only reason for putting your head between your legs is to kiss your ars*hole goodbye
As mentioned, the issue is that aircraft really don't scale well.
For example, today, you can make a very successful small model aircraft powered just by an elastic band, and thanks to the laws of scaling, it will fly.
However, try to make a full sized, 3 people carrying elastic band powered aircraft and see how far you get (literally!)
Today, small battery powered drones (with short flight times) can be made with a high enough power to weight ratio as to enable vertical flight, but those drones cannot be scaled up.
Take the cheapest, simplest 4 seat helicopter you can buy, the Robinson R44. If you've ever been unlucky enough to get in or near one, you'll know they are made out of string and paper, and are incredibly flimsy things. And yet, it still needs a 250 bhp motor to take off (205 bhp at cruise) and requires a massive 210 litres of fuel to get you 300 miles away under the absolutely best case conditions, and carries pilot + 3 people (say 320kg)
210 litres of fuel weighs 160 kg and holds around 7.2 GJ of energy.
A current EV battery using close to state of the art cells has an specific energy density (with support systems (BMS/cooling etc) of around 6.5 kg per kWh, so 7.2 GJ of energy in a current battery would weigh 12.7 tonnes!
Ok, lets say the engine and gearbox and rotor disc in the helicopter only manage around 20% propulsive efficiency (fuel -> thrust) and that some how we make a 100% efficient electric lift system (impossible, esp as losses tend to scale with disc loading, and the design shown has small discs) that means for the same range we now need 5 times less total energy, so that's down to 2.5 tonnes of battery. Hmm, still ain't gonna fly.
So lets cut the range to 50 miles, just enough to fly over a big city, that's a 425kg battery , hmm, still not gonna get off the ground.
So we are left we two options:
1) a just viable short range device for carrying only the pilot in a bare bones type arrangement with zero luxury
or
2) the need to approximately at the very least triple the specific energy density of the battery system, which is extremely close to the fundamental limit of lithium battery energy density (lighter element batteries could have a higher energy density by dint of a lower material density, but they are currently beyond even small scale lab tech today
The other problem is that today, without being able to somehow negate gravity, flying is enormously wasteful in terms of energy. You'd never claim you aircraft was "environmentally friendly" simply because it uses a massive amount of fuel compare to a land based craft that moves on rolling elements (wheels etc) And a helicopter or multi-rotor craft is even worse than a fixed wing aircraft because it has horrendous drag! So, environmentally friendly this new "concept" is not........
For example, today, you can make a very successful small model aircraft powered just by an elastic band, and thanks to the laws of scaling, it will fly.
However, try to make a full sized, 3 people carrying elastic band powered aircraft and see how far you get (literally!)
Today, small battery powered drones (with short flight times) can be made with a high enough power to weight ratio as to enable vertical flight, but those drones cannot be scaled up.
Take the cheapest, simplest 4 seat helicopter you can buy, the Robinson R44. If you've ever been unlucky enough to get in or near one, you'll know they are made out of string and paper, and are incredibly flimsy things. And yet, it still needs a 250 bhp motor to take off (205 bhp at cruise) and requires a massive 210 litres of fuel to get you 300 miles away under the absolutely best case conditions, and carries pilot + 3 people (say 320kg)
210 litres of fuel weighs 160 kg and holds around 7.2 GJ of energy.
A current EV battery using close to state of the art cells has an specific energy density (with support systems (BMS/cooling etc) of around 6.5 kg per kWh, so 7.2 GJ of energy in a current battery would weigh 12.7 tonnes!
Ok, lets say the engine and gearbox and rotor disc in the helicopter only manage around 20% propulsive efficiency (fuel -> thrust) and that some how we make a 100% efficient electric lift system (impossible, esp as losses tend to scale with disc loading, and the design shown has small discs) that means for the same range we now need 5 times less total energy, so that's down to 2.5 tonnes of battery. Hmm, still ain't gonna fly.
So lets cut the range to 50 miles, just enough to fly over a big city, that's a 425kg battery , hmm, still not gonna get off the ground.
So we are left we two options:
1) a just viable short range device for carrying only the pilot in a bare bones type arrangement with zero luxury
or
2) the need to approximately at the very least triple the specific energy density of the battery system, which is extremely close to the fundamental limit of lithium battery energy density (lighter element batteries could have a higher energy density by dint of a lower material density, but they are currently beyond even small scale lab tech today
The other problem is that today, without being able to somehow negate gravity, flying is enormously wasteful in terms of energy. You'd never claim you aircraft was "environmentally friendly" simply because it uses a massive amount of fuel compare to a land based craft that moves on rolling elements (wheels etc) And a helicopter or multi-rotor craft is even worse than a fixed wing aircraft because it has horrendous drag! So, environmentally friendly this new "concept" is not........
"uses a massive amount of fuel compare to a land based craft that moves on rolling elements (wheels etc) And a helicopter or multi-rotor craft is even worse than a fixed wing aircraft because it has horrendous drag! So, environmentally friendly this new "concept" is not........"
Flying is a calculation of the need for speed/cost.
I have always wondered why they cannot make the figures for "Blimp Transport" work.
Flying is a calculation of the need for speed/cost.
I have always wondered why they cannot make the figures for "Blimp Transport" work.
Just to argue with you a little bit Max, the PR stunt is not a helicopter, it is clearly a conventional plane with a central lift fan and front props that can swivel to face forward in conventional flight.
Conventional flight is far more efficient than a helicopter - the Airbus e-Fan crossed the channel and has a battery life of 50 minutes at a speed of 100MPH. We're not that far off being able to build something useable for a single pilot for a short flight duration. Vertical takeoff isn't very efficient though so that would hurt the batteries.
What will make it impossible for the foreseeable future is, as discussed before, the regulatory side of it not the technology.
Conventional flight is far more efficient than a helicopter - the Airbus e-Fan crossed the channel and has a battery life of 50 minutes at a speed of 100MPH. We're not that far off being able to build something useable for a single pilot for a short flight duration. Vertical takeoff isn't very efficient though so that would hurt the batteries.
What will make it impossible for the foreseeable future is, as discussed before, the regulatory side of it not the technology.
Gecko1978 said:
This basically today we could reduce commuting for most service jobs to zero through remote working. City based bank I work for recently closed 2 out of five offices for that very reason only for our director ro decide they wanted all (mostly contracting) staff not to be allowed to work remotely. Its a culture thing thats holding change back. You don't need invotative transport solutuons in say London if 80% of people no longer travel into the office.
I've worked from home for almost 20 years (as an contractor) but one company refused. I asked why and the answer was, in not so many words, "because we don't trust people". When he realised what he'd just said to me he was rather sheepish.Basically, anyone in a senior position with that attitude is judging people by their own lowly standards.
These things will eventually happen and will have an energy consumption equivalent or better than a Tesla on a Wh/mi basis.
I have been doing some calcs on a single-place eVTOL and I think a 100km range at 250km/h at around 650kg MTOW is possible with current technology
On the other hand, I think this AM thing leaves a lot to be desired as a concept.
I have been doing some calcs on a single-place eVTOL and I think a 100km range at 250km/h at around 650kg MTOW is possible with current technology
On the other hand, I think this AM thing leaves a lot to be desired as a concept.
WokkaWokka said:
Aes87 said:
so Aston decided to put its logo on a drone and call it the "vertical take-off concept"
about as attention seeking as Elon Musk's submarine
They haven’t called anyone a paedophile yet to be fair though. about as attention seeking as Elon Musk's submarine
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