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Technology Behind the Lilium Jet
- SkyPuncher 5y agoIf you work at Lilium, you need to make some tweaks to your website. This was an incredibly frustrating experience, to the point that I gave up. * Scroll jacking - looks pretty, impossible to use. * Cookie consent - It's both too large and takes to long to find the right action.
- hagbard_c 5y agoI never saw any cookie prompt since I block cookiebot.com. Things seem to work just as good/bad without it, try blocking that domain and see if it works for you - not just on this site but all others which use these "services".
- ByThyGrace 5y agoIf you're on desktop there is no spacebar hijacking for scrolling, so I switched to that since the article was interesting anyway. But I agree with the sentiment.
- AeZ1E 5y ago[flagged]
- Timothycquinn 5y agoWhat gives you this impression? They have amazing engineers and huge backers. My impression is that they are one of the most likely to succeed in this space.
- AeZ1E 5y agoThey won't be able to deliver on their spec. Not even close. https://www-aerokurier-de.translate.goog/elektroflug/lilium-weitere-experten-unterstuetzen-kritik/?_x_tr_sl=auto&_x_tr_tl=en&_x_tr_hl=en-US https://www-aerokurier-de.translate.goog/elektroflug/lilium-...
- orangepurple 5y agoAfter reading your article I came to one conclusion: RUN, don't walk from Lilium. They are obviously tricking people who don't know a single thing about airplane engines. Lilium responded to the aerokurier article on Monday with an email in which our experts were accused of having set the hover efficiency of the drives far too low with an efficiency of 20 percent. Lilium, on the other hand, claims that values "of 85-95% are the industry standard for turbo fan levels". According to Lilium, this mistake should have been noticed by any industry expert. Lilium is right with regard to the efficiency of turbofan engines viewed in isolation, as they are standard today on all high and fast flying airliners. However: There are no turbo fans installed on the Lilium Jet. They are jacketed propellers driven by electric motors.
- icefox11 5y agoThat is precisely the problem: believing that one can succeed in this space. Flying personal transport is not economical. On a side note, it doesn't matter how brilliant an engineer is if you set impractical goals to him. Neither good engineers not deep pocketed backers could make Theranos real.
- deepnotderp 5y agoAnd why are you so certain that flying personal transport is not economical? Certainly the history of the automobile should show that such statements can look ridiculous in hindsight.
- rmah 5y agoHe's certain because of energy budgets, weight constraints, safety reasons and more. The history of the automobile vs aircraft shows he's right. To move something in the air inherently uses more energy than any sort of ground transport. To make the aircraft more efficient, you have cut weight, which means more exotic (i.e. expensive) materials. The powerplant has to have a higher power:weight ratio (again more expensive). It's more dangerous to be flying, so you need additional safety equipment that ground vehicles don't need. Etc, etc. And if any aviation technologies manages to gain price/performance better than the stuff used for ground transport... it will be adopted by ground transport. Which still leaves air transport more expensive for the reasons listed above and many others. Hell, in WW2, they stuck an aircraft engine into the most common US tank (sherman). Interestingly, sherman tank crews didn't have to worry about falling out of the sky and dying if their engine failed (though they had lots of other worries, of course). Long story short: there is nothing magical about electric motors turning propellers. And battery energy density is utterly horrible vs gasoline/kerosene. Air transport will ALWAYS be more expensive than ground transport. Perhaps someday it will be cheap enough to be common. But personally, I doubt that such a day is anytime soon. Last aside... You can buy a small used two or four seater plane NOW for < $100k. Get a pilots license and you can fly around to your heart's content. General passenger aviation today is not reserved for the ultra rich.
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- karmicthreat 5y agoI don't doubt this concept could ferry people around. But its safety margin is razor thin. 60s reserve? That is barely time for an operator to figure out where to ditch.
- Ancapistani 5y agoIf I'm reading it correctly, they're claiming 60s of reserve at hover. That would translate to roughly 10m of reserve in level flight.
- sokoloff 5y agoOn a windy day or two, I've done multiple go-arounds in a fixed wing aircraft. In low weather, missing an approach to land is also relatively common. "Don't worry, your pilot has 60 seconds of reserve with which to land safely" is terrifying rather than reassuring.
- soonnow 5y agoI have a helipad on the building next to mine. Being that it can get fairly windy and rainy in the tropics, those guys have balls of steel anyway. But those approaches do take more than 60s for sure.
- aidenn0 5y ago"Simple by design, there are no ailerons..." then goes on to describe a vectored-thrust control scheme consisting of essentially 36 blown elevons. Clearly we mean something very different by the word "simple."
- conradev 5y agoI know very little about aerospace, but from a manufacturing perspective it seems like having a single part or unit that you need to manufacture and test would be simpler but I imagine that this offloads complexity to the flight control software, though – is that what you are referring to?
- GravitasFailure 5y agoMoving to an electric ducted fan instead of an internal combustion engine with a variable pitch propeller definitely simplifies things, though replacing that ICE and prop with 36 ducted fans mounted to elevons seems like you're just swapping one set of complexities for a different set, though gaining complexity through redundancy isn't really the worst thing. My biggest concern with this system is what kind of glide ratio this has in a power loss scenario.
- null0ranje 5y agoMy biggest concern is how you maintain directional control in a power loss scenario.
- GravitasFailure 5y agoThat too. As far as I can tell, this thing has all the control and glide capabilities of a brick. At least the brick has the inherent safety feature of not being mistaken for a passenger aircraft.
- aidenn0 5y agoballistic parachute?
- HPsquared 5y agoInteresting stuff. Haven't heard of the Lilium specifically, but have seen other distributed electric propulsion concepts here and there. DEP is such a nice idea, eliminating a lot of the problems with helicopters/fixed wing aircraft (noise, space requirements etc.) to carve out a new category of aircraft that is perfectly suited to an emerging technology (high energy density batteries). If we ever do get flying cars, they will use distributed electric propulsion.
- dmitrybrant 5y agoOff topic, sorry, but: Why do web designers think that they can provide a better scrolling experience than the default system behavior that the user expects in every other interaction? By the way, hijacking scrolling behavior often breaks other things, such as searching for text in a page. Go ahead, try it, search for a term in that article.
- tommoor 5y agoYea, it's atrocious on this article – makes it unreadable tbh as scrolling muscle memory is completely messed up.
- aidenn0 5y agoI hate scrolljacking too, but to answer your question, overriding the default system behavior in general isn't about providing a better experience but rather a more consistent (from the POV of the designer) experience. The downside of course is that it looks less consistent with other apps and webpages from the user POV.
- fikama 5y agoI just wanted to add that scrolling works normal on mobile. Including searching. It's only loading a bit too long.
- tailspin2019 5y agoI was about to say that it's quite smooth for me on Safari - then I searched for something as per your suggestion and the whole page was vertically offset and effectively broken... oh dear. Edit: The scroll hijacking makes more sense in the context of the home page, which actually uses it to reasonable effect (not endorsing the technique, but the home page is attractive at least). I think the mistake was leaving it on for heavy content pages like the one linked where it adds very little but breaks other basic behaviour.
- skykooler 5y agoIt's quite smooth with a trackpad. With a mouse scroll wheel, it's basically non-functional.
- beaconstudios 5y agowhy are all these new variants of sport aircraft appearing at the moment? There must be something in the water because I've seen so many re-interpretations of the flying car in the past year or two. They look cool in movies but how are they at all a practical method of transportation outside of being toys for the ultra-rich?
- brightball 5y agoI could see these being a more cost effective option than helicopter transport. Especially in island areas.
- qzw 5y agoI think everyone is trying to replicate the Tesla formula where the first Roadster was a toy for the rich, then followed by real products and now $Trillion in market cap. But there are a few steps in there that are probably hard to copy, like being able to sell carbon credits to other manufacturers, federal tax credit for buyers, etc. Oh, and one Elon Musk.
- fh973 5y agoBe aware that you are usually looking at prototypes, not available products. Currently its mostly another set of startups to invest in. They might look attractive to VCs because they're ambitious, require lots of capital, and the technical feasability of a specific approach is complex enough to find merits in. The jury is still out if any of them are actually viable from a technology and economic perspective. Lilium's approach specifically has been publicly critized by aviation experts to not be make sense when looking at the basic physics.
- HPsquared 5y agoElectric cars have increased the availability of mobile electric power systems: experience with batteries, motors, controllers etc in cars is transferable to aircraft. It's "in the air" so to speak. Edit: Also the mass market adoption of small quadcopters; these "distributed electric propulsion" flying car type things are basically the same concept: flight control by altering the speed of an array of propellers. Also a lot of university teaching/research on both of the above.
- djrogers 5y agoThese are som pretty impressive goals. If they can truly achieve a hover state as quiet as 60db, and get the efficiency they've outlined, these could truly change the way we look at short-haul travel. The idea of a 2 hour drive from a small town to the big city being reduced to a 1hr flight (with no airport - yay helipads) is already a market where helicopters are making money. Doing that in even less time, in more comfort (ugh - choppers are loud), and at lower cost per hour/mile will change things dramatically.
- bostonsre 5y agoYea, 60 decibels at 100m would be pretty crazy to achieve.
- avidiax 5y ago60dB @ 100m is 77db @ 15m For comparison, in Washington state, the legal limit for an automotive exhaust is 72db@15m. Still an achievement, but definitely not something you want your neighbor to land at 3 am.
- ananonymoususer 5y agoCan we please use dBa (a measure of absolute sound pressure) rather than dB (a relative term used in many domains)?
- wmf 5y agoObviously aircraft are louder than cars. It seems like this should be compared to a helicopter since it uses the same pads.
- klyrs 5y agoThey should be compared to vehicles that occur in the space that these "air taxis" are meant to take off and land in. If they're relegated to airports, fine, compare to helicopters. If they're meant to take off and land in my neighborhood, compare them to cars.
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- mysterydip 5y ago"The landing gear is fixed and there are no hydraulics." Will this cause issues during landing? I've seen helicopters land and it can be a bumpy/sketchy experience.
- aidenn0 5y agoFixed gear means non-retractable, not necessarily unsprung.
- mysterydip 5y agoI was thinking hydraulics as in shocks, not as in retracting mechanisms. Thanks!
- kensai 5y agoLilium, as I see it, has by far the most secure design of all air carrier designs we have seen recently. And there have been a lot including some really nice! Lilium is the only company going for this distributed propulsion system with so many rotors, adding the the safety of the whole thing. Safety should be paramount! A couple of deadly accidents can literally ground a fleet otherwise. Volocopter also tries a similar approach, but the lack of eVTOL probably makes that bird much slower than the Lilium product.
- fh973 5y agoHowever, Volocopter seems to be further with their product development, while there are serious doubts if the Lilium concept works at all.
- _Microft 5y agoWhat do you mean that their concept might not work at all? They have flown several iterations of their prototypes already but maybe you have something different in mind, e.g. doubts about the possibility to scale the concept up? Here are videos of recent test flights: https://www.youtube.com/watch?v=0idI3sJJKZw https://www.youtube.com/watch?v=0idI3sJJKZw https://www.youtube.com/watch?v=SqMEFdbuzQY https://www.youtube.com/watch?v=SqMEFdbuzQY https://www.youtube.com/watch?v=jqvMXoVZfDw https://www.youtube.com/watch?v=jqvMXoVZfDw
- AeZ1E 5y agoCool, but the event is not unmannedly flying around in a circle for 1 minute but to transport up to 7 people over several hundred miles.
- KentGeek 5y agoFrom those videos, it's difficult to be sure those are full size prototypes and not scale models.
- antoniuschan99 5y agoIt’s all unmanned unfortunately. Still waiting for them to demo at least a dummy payload like Joby did a few months back. Also, Joby, Ehang, and Volocopter are much further ahead in the sense they have done point to point or are building out the factory (same time last year Ehang got hit by being called a scam by Citron, however). From what I read, rumor is the big issue is battery density which is holding Lilium from being viable. We shall see! Also, Joby is most likely the one to look at to track the progress of this air taxi segment since they have just Spac’ed and their aircraft is the most conventional.
- Timothycquinn 5y agoI've been watching this space for quite a long time and this company seems to have the engineering and backing to make it happen. From a safety perspective, this design has a potential for massive redundancy over several other designs being promoted out there. Considering that their marketing is not to desperate, and their releases of footage is slow and stead, I predict that they are very confident in their designs. If I had a few million to throw around, I would definitely be investing in this company.
- martythemaniak 5y agoThey're public and shares are $9, so you can throw any amount of money in them.
- AeZ1E 5y agoCan we make sustainable public transport attractive again - an stop hyping gadgets for the rich?
- mrshadowgoose 5y agoThose are not mutually exclusive endeavors. Please be aware though, that there's always going to be a large population segment that will desire to proceed directly from point A to B in comfort. Unless by "public transport" you're including "government owned autonomous taxis", public transport will never be attractive to that population segment.
- OnlineGladiator 5y ago> Please be aware though, that there's always going to be a large population segment that will desire to proceed directly from point A to B in comfort. How large do you consider this population segment to be?
- sokoloff 5y agoOrder of magnitude as large as the group that commutes by car today.
- deleted 5y ago[deleted]
- mrshadowgoose 5y agoQuite large, certainly a good chunk of the population that currently drives. There's also a segment of the public transit riding population that would prefer personal transit, but do not have the option. People generally prefer to a) be comfortable, and b) proceed directly from point A to B with no interstitial bullshit. You almost never get b) with public transit as commonly realized today.
- Maarten88 5y agoA high-speed train can connect inner cities just as fast as this gimmick jet. It is orders of magnitude more efficient and scalable, and much more safe. A good train could easily be more comfortable, if there is a market for that. Do you think that jet will have dining rooms, sleeping cabins, ample room for luggage? Do you think it will even have a toilet? Just. Build. A. Train.
- Centmo 5y agoI was a core engineer in a different manned eVTOL project, so have spent a lot of time thinking about this technology and watching the space. Lilium raised some eyebrows recently with their SPAC IPO valuation of over $3B, without having released footage of a single manned flight. The prototype is unique and aesthetically appealing, but my engineering mind recoils at the complexity of the design. The variable pitch blades, the adjustable exhaust nozzles, the tilt-wing vectored thrust system, etc. With complexity comes cost, maintenance, and exponentially increasing failure modes. Safety is paramount in aviation, so all flight-critical failure modes require redundant backup systems, which further increase cost and complexity. It's a slippery slope. The eVTOL space is currently seeing a Cambrian explosion of different design concepts, but the first to see economic viability I think will be the simpler ones.
- rayiner 5y agoOne of my senior projects in college was designing a ducted lift fan UAV. One of the things that was apparent from digging through the old research was the monstrous total complexity even of conceptually simple designs that had 1-2 ducted fans embedded in the body or wings. Computers make the complexities of controlling these things tractable, which was a much bigger problem in the 1960s. But even with relatively modern technology e.g. Lockheed has had a hell of a time with the F-35B.
- kwhitefoot 5y agoThat's a very unconvincing video clip on that site. Here's a better one: https://www.youtube.com/watch?v=5ukmS9ZJm40 https://www.youtube.com/watch?v=5ukmS9ZJm40
- Dunedan 5y agoNote that the video you linked doesn't show their latest "demonstrator". Here is a video of their latest one: https://www.youtube.com/watch?v=jqvMXoVZfDw https://www.youtube.com/watch?v=jqvMXoVZfDw
- w0mbat 5y agoI am not at all an expert in this field, but is "jet" the right word? I thought that required combusting fuel and using the flaming exhaust to propel something. This is propellors in tubes. Also this vehicle is about a third of the speed of what most people think of as a "jet plane".
- nickff 5y ago'Jet' has been used to describe many different types of propulsion system. The first jets were what you'd call rocket engines. Then we got 'turbojets' (mostly on aircraft), followed some time later by 'turbofans'. Most confusingly, ducted propellers on submarines are called 'pump-jets'. I would agree with you that this seems better-described as a ducted fan (which the author also says), but this use of 'jet' is not beyond the pale.
- divbzero 5y agoJet propulsion involves ejecting a jet of fluid [1] and does not require combustion of that fluid. [1]: https://en.wikipedia.org/wiki/Jet_propulsion https://en.wikipedia.org/wiki/Jet_propulsion
- Karliss 5y agoThere is also waterjet and jet stream. Not uncommon dictionary of jet is narrow,forceful stream of fluid or the nozzle producing it. Taking that into account difference between jet and propeller in tube is matter of speed and compression. It's just that fuel combustion is one the most practical energy sources including for producing jets of gas.
- dmitrygr 5y ago"fifth evolution of our technology over our six year history" reads: "it still doesn't work, we aren't sure if it can, but need more investor cash" Their rosy projections of how they expect battery systems to magically materialize and double in density over the next few years to make this device actually work are also quite funny.
- rickreynoldssf 5y agoWhat Brilliant Web Designer thought it was a good idea to pulse the text? Are you trying to give me a seizure? SMH WTF
- kevincox 5y agoAnd that 2px per full spin of the scroll wheel ensures I really had time to absorb the content.
- samstave 5y agoMultiple questions for aerospace folks here: Why are designs with multiple wings no longer developed, not just bi/tri wing planes with wings stacked, but why aren’t their rows of smaller wings, or multiple wings? Do the vortices of the trail of a leading wing fuck up themlift potential on wings behind it? —- We simple golf balls for greater distance through the air, and Wales see an advantage to the barnacles that grow on the leading edge of their flippers which have shown to create eddys behind the tail edge of the flipper which aids in greater vortices and greater propulsion.. Why don’t we dimple wing surfaces? Or plane bodies? Or helicopter blades? What happens when we simulate the leading edge barnacle bumps on the leading edge of a wing, or more aptly, the leading edge of a blade on a helicopter? What software is used to model the airflow over a wings surface, such as solid works… — How much overlap is there between fluid hydro and aero dynamics? (Specifically the observation of the impact to flow/eddy creation over a surface?)
- gfody 5y agoI always loved the look of Burt Rutan's dragonfly, there's a list of issues mostly related to conventional (non-vtol) flying - https://www.nestofdragons.net/weird-airplanes/tandemwings/quickie-and-look-a-likes/disadvantages/ https://www.nestofdragons.net/weird-airplanes/tandemwings/qu...
- thescriptkiddie 5y agoNot only is this company obviously a scam, if their product actually did exist it would be extremely expensive as well as louder and more dangerous than a regular helicopter.
- louwhopley 5y agoQuite a bold statement to make with no substantial backing. If you have any experience with drones or following this air taxi movement, then you’d see many working prototypes out there. This stuff is not so far fetched. For fun, go look at Peter Sripol’s santa sled that he built: https://youtu.be/L-iWUu2HAWQ https://youtu.be/L-iWUu2HAWQ
- twp 5y agoWhat is missing from this blog: Where is the safety margin? i.e. what happens if something goes wrong? Can the aircraft make a safe landing if the motors fail? Do the limited control surfaces give it enough maneuverability to make an emergency landing in a tight field, especially in bad weather? tl;dr great blog, thank you for the technical insight, it sounds like you've designed Lilium for a perfect world. Popular aviation needs to have basic safety margins and there are no safety margins evident here.
- mrfusion 5y agoHow do the engines point down for take off?
- akrymski 5y agoWhy not use hydrogen instead of heavy batteries? Why not use jet engines instead of propellers?
- textcortex 5y agoThere is one fundamental error in this blog; the battery energy density graph. Battery tech does not follow Moore’s law. Batteries are not transistors..
- aj7 5y ago“So, the Lilium aircraft requirements can be summarised as follows… •High seat capacity to achieve attractive unit economics and affordable pricing over time” devolves to “Yes, we are building a 7-Seater!”
- rikeanimer 5y agoThis paper "Electric VTOL Configurations Comparison" [ https://www.mdpi.com/2226-4310/6/3/26/pdf https://www.mdpi.com/2226-4310/6/3/26/pdf ] presents a pretty decent energetic analysis of a few of these eVTOL projects (including Lilium) and is very generous to them. Lilium is vaporware. Ask anyone who has worked in the space. Or just look at it. Or their promotional materials. Ducted fans huh... meh. I don't think they have an interest in people understand how fly-y/hover-y things actually work. I do applaud the investors for their vigorous desire to increase the velocity of money throughout society, it is important econometrically. Somehow I doubt they'll be happy to see their currency shredded by 36 rc brushless motors struggling to thrust an anemic wing into the sky though (before its glorious ~250km/h cruise to destination [of course])--and then ~15s landing hover. What exciting times to fly in.
- theYipster 5y agoNo doubt the whole eVTOL/AAM space will lead to positive and long lasting developments for aviation, but the amount of money chasing specifically the air taxi/uam space (Joby, Lilium, Archer, Volocopter, etc.) is staggering given how utterly nonsensical the business plans and projections are. Right now everyone is in a race to certify. I guarantee that will be the easy part. The whole list of issues this community is not thinking through and addressing dwarfs those that they are. Energy density is just the start. For instance: Power requirements for these business models at scale will require a sudden turnaround and mass embrace of nuclear. Infrastructure build will require government investment and widespread use of eminent domain. City laws and ordinances allowing for uam flight need to be rewritten. I could go on… Btw I am in the industry.
- jillesvangurp 5y agoThere's a lot of money floating in this sector for sure. But it's also a potentially huge market that might make it worth the risk. The value proposition is simple: get from A to B quickly at the cost of a few KWH. This plane has a 300KWH battery. That's about 5x a Tesla battery (the big 75KWH ones). The expensive rate for charging a Tesla is about 15$ (give or take). So this, 7 seat plane would cost about 5x that (at the expensive rate, you could get a better rate). 75$. Lets call it 10$ per passenger. And that would be for the maximum range. For short hops, think in terms of a decent coffee at your local coffee shop. Maybe two cups. Just the energy cost of course, there's more cost than that. But that's great value in a world where short 20-40 mile distances in dense urban environments can take an hour+ to travel and where people routinely do that by taxi, uber, or public transport. The premium segment of that is thousands of people paying north of 50$ routinely for relatively long journeys every day. That kind of is the market for this thing. Charge 50-100$ per ride at a cost that is likely closer to 10$. Nice fat margins. The unit price of a single plane is probably going to be around 3 million (initially). So, selling a thousand of those would amount to about 3 billion revenue. Likely prices will come down over time. But basically the first few companies that manage to produce vehicles like this in very modest volume are looking to rake in billions of revenue. The early adopter market is going to be amazingly profitable. The long term market when cost drops, production scales, and the novelty wears off is still going to be quite nice. Fundamentally these machines are not vastly more complicated to build than a premium EV and their energy cost is similarly low. That's why these companies are so hot right now. There will be a lot of companies that fail and a few that might end up printing money. Lilium has a great sales pitch. The only question is whether they can deliver.
- blunte 5y agoI have to wonder about the glide ratio. All those fans will probably create a ton of drag. If for some reason you have a complete power/engine(s) failure, that thing is likely to become a lawn dart. At least with a helicopter you can autorotate if you lose your engine. Unless this plane will get an airframe parachute, I would not fly in it.
- jillesvangurp 5y agoThe glide ratio of an auto-rotating helicopter is not great; not a very hard target aerodynamically. The glide ratio is not going to be great if all 36 engines are out but I'd expect crash landing as a glider it should be totally doable and probably easier than auto rotating a helicopter (nose down to keep the speed up, flare at the right moment). And of course installing some parachutes on it is probably going to be a thing as well. Of course that scenario is not great for either this thing or a helicopter in a dense city.
- PicassoCTs 5y agoLilium and other electric vtol would benefit greatly in my eyes from a cable assisted starting. Just have 500 m of powercord on take-off and once you are over that initial peak you just drop the cable. Not as sci-fi, but alot of kilometers in ex-change.
- louwhopley 5y agoWhat stands out to me about all this eVTOL/air taxi vehicles are that they operate in 3D space instead of 2D like cars. This means, even though more inefficient than cars, you can have more “lanes” to operate in. On roads, you have to have traffic lights and stop streets, traffic itself, and cars driving inconsistent speeds or braking when turning. In the air this can all fall away, so people can live further away from city centres, streets can be left for cycling, and less concrete/asphalt infrastructure is required.
- willyt 5y agoThey could test the market for these in Norway, the Scottish Islands or the Greek Islands. Places where 15 min flights with low passenger numbers over a distance of 50-100km would have a high value compared to a 1-2hr ferry crossing. Wouldn’t need to go anywhere near max range and would still mostly over land not much other air traffic to bump into.
- amelius 5y ago> Lilium’s greatest breakthrough is not accepting that traditional approach to trade-offs but rather getting to first principle understanding of the physics and then systematically innovating and optimising each subsystem in an integrated and coherent manner such that the resulting aircraft achieves all stated performance objectives. You cannot "innovate such that ...", you can only "innovate and hope to achieve ..." There is too much assertiveness in this post.
- ncmncm 5y agoWhat is missing from the presentation is anything about recharging. The reasonable conclusion is they have no good story, there. Most of the profitability of an air transport, when there is any, comes from quick turnaround. Having to wait to charge for an hour eliminates any possibility of that. An alternative is to have removable batteries, so when you land, you drop off dead batteries and slot in charged ones; and charge at the airport. A better design would have an aft liquid-hydrogen tank and fuel cell, instead of batteries, for longer range and much lower mass. LH2 would be produced at the airfield during minimum energy spot prices, and stored underground.
- wiz21c 5y ago> Zero operating emissions Could it be clear to everybody that this thing will require energy and thus will, in a way or another, emit somthing (either CO2 from electricity production or CO2 from the construction of means of electricity production). Besides, why not just invest in trains ? (or lighter alternative if any)