Lilium gets $90 million funding to build VTOL flying taxis

[HEXUS]

All electric jet car has 5 seats, VTOL capability, 300km range, and 300km/h top speed.

Read more.

[wazzickle]

The price will end up be a lot more than ground movement, on the one hand because there will be lots of extra regulatory costs to overcome, but also because, if it works as described, it will become a highly desirable mode of transport.

Sign me up.

[philehidiot]

I have some issues here - was that a full size prototype? Is it really a jet? Those are fans and don't look like a jet to me which suggests a level of being "sexed up" but what really worries me is that there are no grey beards at all in that engineering team. Not one. That's a young and enthusiastic team with little experience. To make this kind of thing really work you need a couple of grey beards.

[bitbucket]

I wish we'd stop trying to invent flying cars. We already have them - they're called aircraft.

[Corky34]

Now we just need someone to invent an all electric jet engine.

[Wrinkly]

Hard to tell if full sized. Didn't see a pilot through the canopy. Still, looks fun!

[MatBailie]

A "Jet Engine" is one that simply generates pressurised exhaust. The engines on this compress the intake air and exhaust it as a jet. It's effectively a simplification of a high-pass turbo-fan jet-engine, using batteries to drive the compressor rather than a gas turbine. So, the all-electric jet-engine already exists.

[Valantar]

I wish we'd stop trying to invent flying cars. We already have them - they're called aircraft.

Yup. Also, airborne personal transportation is just silly. It doesn't matter if this is all-electric, it still requires far more energy for the same amount of travel than anything on wheels. What we need is smarter, more efficient personal transportation - something that can actually lure regular people away from using fossil-fueled cars for grocery runs and rush hour commutes. This won't do that, and unless the goal is to replace private 1%-style helicopter commutes, it's not helping in any way.

[wazzickle]

I don't know that that's true. Between the circuitous routes we take on the ground, and traffic and traffic lights, it may well be the case that the two are not that far away. If they can come up with clever ways of recouping some of the potential gravitational energy on the way back down, then you might be looking at a tech that's quicker and better for the environment than regular driving.

[TeePee]

I hope they are ducted fans rather than jets... That sounds like marketing silliness...

[Corky34]

A "Jet Engine" is one that simply generates pressurised exhaust. The engines on this compress the intake air and exhaust it as a jet. It's effectively a simplification of a high-pass turbo-fan jet-engine, using batteries to drive the compressor rather than a gas turbine. So, the all-electric jet-engine already exists.

So in other words there fans, don't get me wrong i understand a high-bypass turbofan gets 60 odd percent of its thrust from that great big hoofing fan at the front but technically that big hoofing fan can only produce such a large percentage of the thrust because of the massive amount of power coming from setting light to the other 40 odd percent.

If that other 40 odd percent is taken away can it still technically be called a "jet engine" and can that 40 odd percent really be replaced with batteries.

[peterb]

So in other words there fans, don't get me wrong i understand a high-bypass turbofan gets 60 odd percent of its thrust from that great big hoofing fan at the front but technically that big hoofing fan can only produce such a large percentage of the thrust because of the massive amount of power coming from setting light to the other 40 odd percent.

If that other 40 odd percent is taken away can it still technically be called a "jet engine" and can that 40 odd percent really be replaced with batteries.

You can look at it two ways.

In fluid dynamic terms it depends what you mean by a jet.

A mass of air forced through a nozzle will increase its velocity, but requires energy to do so. jet engine was originally a reaction engine, the high velocity exhaust gas producing a reaction that propelled the engine and anything attached to it forwards. That gas is generated by a gas turbine. It could be generated by burning fuel in oxygen - which we call a rocket.

If you look at the naming a high bypass fan engine is a turbo-fan, a fan driven by a gas turbine (as a turbo-prop is a propellor driven by a gas turbine either with or without a separate set of turbine blades - although in marine applications, where the power take off turbine is separate from the power generating turbine, the power generating turbine is often referred to as the gas generator)

Is a ducted fan (essentially a high bypass jet engine) a jet or a fan? They are referred to as turbo fans - so I suppose that is the clue, a fan driven by a gas turbine, as the prime mover. If the prime mover is an electric motor, the principle of operation is essentially the same.

If it look like a duck, quacks like a duck.....

But I take your point about the 40% of thrust being provided directly by the gas turbine, but is that because that is more efficient than trying to harvest that energy in any other way, as it is a product of combustion? In electric drive there is no product of combustion to harvest, al, the energy goes into the fan.

[Valantar]

I don't know that that's true. Between the circuitous routes we take on the ground, and traffic and traffic lights, it may well be the case that the two are not that far away. If they can come up with clever ways of recouping some of the potential gravitational energy on the way back down, then you might be looking at a tech that's quicker and better for the environment than regular driving.

To me, that sounds like a rather naive point of view. After all, air travel is very strictly regulated (and for good reason! It's far riskier than ground travel!), and will only become more so if personal air travel becomes common, as airspace will become more congested and contested. Just as we have roads on the ground, there'll most likely be fixed lanes established for personal air travel as well. Of course, these don't have to account for terrain or buildings (usually), so they can be a bit more direct, but the difference will be negligible. Also, the higher you fly, the more energy you spend on getting up there - energy that is lost, period. Recouping gravitational energy is pretty much impossible, unless you equip your aircraft with gigantic rotors that can safely air-brake an otherwise uncontrolled fall - those tiny turbofans will be utterly unsuitable for the job. If they can't slow the fall, you'd have to spend even more energy by powering the fans to control your descent. Compared to modern electric cars, this is a horrendously inefficient system. I'd wager that it's less efficient than even petrol and diesel cars from the last two decades.

[wazzickle]

To me, that sounds like a rather naive point of view. After all, air travel is very strictly regulated (and for good reason! It's far riskier than ground travel!), and will only become more so if personal air travel becomes common, as airspace will become more congested and contested. Just as we have roads on the ground, there'll most likely be fixed lanes established for personal air travel as well. Of course, these don't have to account for terrain or buildings (usually), so they can be a bit more direct, but the difference will be negligible. Also, the higher you fly, the more energy you spend on getting up there - energy that is lost, period. Recouping gravitational energy is pretty much impossible, unless you equip your aircraft with gigantic rotors that can safely air-brake an otherwise uncontrolled fall - those tiny turbofans will be utterly unsuitable for the job. If they can't slow the fall, you'd have to spend even more energy by powering the fans to control your descent. Compared to modern electric cars, this is a horrendously inefficient system. I'd wager that it's less efficient than even petrol and diesel cars from the last two decades.

Not naive, but hopeful.

I believe the stats bear out the idea that, at least at the moment, and comparing human to human drivers, it's safer in the skies. The congestion will not really be an issue imo as these are all going to be self-driven, i.e. able to optimize every aspect of the journey including for example take-off times such that a good balance between time taken and energy efficiency can be achieved.

[rainman]

Now we just need someone to invent an all electric jet engine.

They already exist. That particular propulsion system is called "Electric Ducted Fan" and it's been around for years, RC hobbyists have been building 200 mph model aircraft with them to great effect for quite some time.

[Corky34]

You can look at it two ways.

And probably many more ways, i think they just want to retain the "jet" part as nervous flyers would probably freak out even more if we told them the only thing keeping them up in the air is a great big ceiling fan and that the wings aren't lifting them into the air but sucking then into the sky.

They already exist. That particular propulsion system is called "Electric Ducted Fan" and it's been around for years, RC hobbyists have been building 200 mph model aircraft with them to great effect for quite some time.

Indeed, although i get the feeling people may have misinterpreted what i was trying to highlight, that IMO there's no such things as an all electric jet engine, that IMO such a thing would be called a ducted fan and that they probably just wanted to retain the "jet" nomenclature so people would feel more comfortable with the concept.