17 ms·

The Lilium Jet

124 points by trollied 4y ago

trollied 4y ago
I had this pop up as a recommendation on youtube. Video of a test flight, VTOL: https://www.youtube.com/watch?v=ywJWka1evH8 https://www.youtube.com/watch?v=ywJWka1evH8
- _Microft 4y ago
  The interesting part seems to be happening around 1:20-1:30 minutes into the video. The main wings and canadards (that's the smaller wings at the front) are oriented fully parallel to the direction of flight. The threads indicating the flow of air over the surfaces are no longer moving around and therefore air is moving smoothly over the wings. The aircraft seems to be relying fully on lift provided by the wings instead of the engines. As far as I know they hadn’t achieved that before. The thrust required for level flight with lift provided by wings is said to be ~ 10% of what is required for vertical take-off and landing. https://youtu.be/ywJWka1evH8?t=82 https://youtu.be/ywJWka1evH8?t=82
kybernetikos 4y ago
This is very cool. But it's also spending a lot of novelty points. I thought energy density was still a huge problem, so it seems weird to try to solve the problem of electric planes with acceptable range at the same time as tackling the enormously energy intensive problem of VTOL.
- lordofgibbons 4y ago
  It makes sense why they'd do this. Given current energy density of batteries, electric planes are only useful on very short flights. If you can only operate out of airports (without vtol), the useful range of the airplane will be significantly reduced
  - kybernetikos 4y ago
    Great point. Reading a little more https://lilium.com/newsroom-detail/technology-behind-the-lilium-jet https://lilium.com/newsroom-detail/technology-behind-the-lil... you're exactly right, and the same thinking drives the requirement of low noise and the ability to utilise helipads.
    - nradov 4y ago
      There aren't many helipads either. Outside of regular airports, only a few urban areas have any helipads available for commercial use. More can potentially be built but that requires large open areas free of obstructions. Adding helipads to existing building roofs is generally impractical due to weight and safety issues.
      - RC_ITR 4y ago
        >large open areas free of obstructions. https://www.beaconhealthsystem.org/beacon-medical-transport/landing-zone-preparation-and-safety/ https://www.beaconhealthsystem.org/beacon-medical-transport/... You need roughly a football field of clear flat land for human-piloted helicopters. In the US at least, that's nothing. It's comparable to one quarter of a clover-leaf offramp.
        nradov 4y ago
        It's not nothing. In the affluent areas where passengers would potentially be willing to pay for air taxi service there aren't many large vacant lots left. So not impossible, but it's hard to see how the economics would work. Medical transport helicopters have somewhat greater freedom to land in random places like roads and fields when necessary to pick up emergency patients. But that only works because police are on the ground to secure the area. And local residents don't complain about the noise from a single emergency flight. Those situations don't apply to air taxis.
        RC_ITR 4y ago
- tlb 4y ago
  Those are related. Part of what makes engine-powered VTOL difficult is the engines. The V-22 Osprey has two propellors and two engines, but in order to handle an engine failure, there's a complicated driveshaft and gear arrangement across the middle of the aircraft to send power from the working engine to the other propellor. I don't know that anyone has seriously tried more than 2 engines for a VTOL system. Electric power allows you to have lots of small fans, a few of which can fail without disaster. Also, throttling turbines up and down fast enough to stabilize an aircraft doesn't seem to work well.
  - scarier 4y ago
    There are a number of VTOL aircraft that have used multiple engines. The Yak-38 used two lift engines and one lift-cruise engine, the VJ101 used four lift-cruise engines and two lift engines, and the Do 31 used two lift-cruise engines and eight(!) lift engines. Out of these, only the Yak-38 was remotely successful, and not nearly as much as the single-engined Hawker Siddeley Harrier (and its derivatives). There are plenty of ways to stabilize an aircraft without relying on pure engine thrust, and turbofan aircraft have some advantages here. The distributed electric propulsion systems do have awesome redundancy, but they have significant losses in efficiency compared to fewer, larger props, which really isn't what you want in an aircraft with severe energy density limitations. I'm curious to see what the production Lillium's payload, range, and power margin end up being.
  - nradov 4y ago
    There have been a few flying VTOL prototype designs with more than two turbine engines. The extra engines were used for powered lift during takeoff and landing. But that approach turned out to be impractical due to safety, cost, and weight. https://vtol.org/vstol/wheel.htm https://vtol.org/vstol/wheel.htm
  - dingaling 4y ago
    XC-142 tiltwing, four turboprops https://vought.org/products/assets/images/1758_005_o.jpg https://vought.org/products/assets/images/1758_005_o.jpg
- vidarh 4y ago
  "Acceptable" range is short - they're not really trying to compete with planes, but with other modes of transport.
consumer451 4y ago
Wisk[0], backed by Kittyhawk and Boeing seems like they may have a more practical vehicle, and in some ways it is much further along. Flight Chops has a great video[1] showing a bunch of details, including the addition of "Digital Flight Rules" to VFR and IFR. Though I do love Lilium's aircraft, it is definitely more of a sports car. [0] https://wisk.aero https://wisk.aero [1] https://www.youtube.com/watch?v=yrEeCp5xJj8 https://www.youtube.com/watch?v=yrEeCp5xJj8
- googlryas 4y ago
  Why is kittyhawk investing in airplane startups, when they themselves are an airplane startup? Is that just a sign of too much cash to burn with too few ideas? Not that it matters much anymore...
  - addaon 4y ago
    Wisk was spun off from Kitty Hawk when Boeing invested.
- rootusrootus 4y ago
  Sounds like Kittyhawk is shutting down [0]. Is the future of Wisk in question? [0] https://aviationweek.com/business-aviation/kittyhawk-shut-down-wisk-aero-continue https://aviationweek.com/business-aviation/kittyhawk-shut-do...
  - rgmerk 4y ago
    Wisk claims not: https://twitter.com/wiskaero/status/1572677287455358976?s=46&t=qTX7rXKti4XeLNNt4eH5Ig https://twitter.com/wiskaero/status/1572677287455358976?s=46...
6stringmerc 4y ago
This seems viable especially as next generation power storage comes into the fold. Finally using the wings for sustained flight - something that doesn’t take nearly as much energy as getting whatever payload off the ground in the first place.
narrator 4y ago
The hydrogen conversion of the Cessna Caravan seems a little more practical. Hydrogen is bulky, but light. Fuel cells aren't cheap though. However, hydrogen is quick to refuel unlike battery charging. I think the weight to power is better with hydrogen than li-ion and weight is the most important thing for aviation. https://www.militaryaerospace.com/commercial-aerospace/article/14283551/textron-aviation-taps-zeroavia-to-develop-hydrogenelectric-powertrain-for-its-cessna-grand-caravan https://www.militaryaerospace.com/commercial-aerospace/artic...
- joe_the_user 4y ago
  If you can switch battery packs, refueling could be very quick.
  - mikepurvis 4y ago
    And even though they're heavy and bulky, it's much more tractable to install that infrastructure at a few dozen key airports, and also to manage the tracing/ownership of "fleets" of batteries. Battery swapping has repeatedly faceplanted when it comes to cars, but it's a pretty different scope of challenge, and it seems like every major issue is more favourable to aircraft. On the other hand, planes are often on the ground for 2+ hrs between flights anyway, so maybe it could be realistic with enough power delivery capability to just charge a big pack in situ. Certainly simpler to plug in a big umbilical at the gate than having to have another ground vehicle reaching into the belly of the thing.
    - _hypx 4y ago
      Absolutely not. Airplanes have to be aerodynamic, and it would be incredibly challenging to make the entire bottom portion of the plane something that can open up and fit a giant battery. Never mind the weight of the whole system plus battery. The whole idea is absurd and completely impractical.
    - nradov 4y ago
      Batteries power will only be feasible for short-haul flights, and those have much shorter turn around times. Southwest Airlines has it down to 35 minutes. Recharging within that time limit might eventually become feasible but it's going to take some further battery innovations.
cpursley 4y ago
Can we pass a federal law prohibiting scroll-jacking?
- Sophistifunk 4y ago
  Or kickstart a team of black-ops mofos.
- bestest 4y ago
  Absolutely. I closed the tab once I felt being molested by the scrolling mechanism hijack.
polar8 4y ago
Why do electric planes like this one have many smaller motor, as opposed to 1-4 engines like typical planes do?
- pvorb 4y ago
  Perhaps it has to do with being failure-safe?
  - mikepurvis 4y ago
    With a conventional turbofan (or basically gas-anything) the bigger it is the more efficiency gains can be realised. So I'd expect that conventional jets would really ideally have just one engine, and they typically have 2 or 4 for reasons of fault tolerance and isolating noise from the fuselage. None of this applies with electric, particularly a cleansheet design.
  - UncleOxidant 4y ago
    But then they would've been using many smaller ICE or jet engines already to get redundancy. I suspect the reason is that it's easier to get that kind of redundancy with electric motors - they're more compact, lighter weight, less overhead for each.
    - jasonwatkinspdx 4y ago
      We do. It wasn't until the 80s that twin engine airliners were certified for long flights. Before then it was 3 or 4 engine only. It took a lot of effort to get jet engines that reliable too. Single vs dual engine helicopter is a big safety distinction. There's heavy lift and military helicopters with 3 engines.
- iijj 4y ago
  It's called Distributed Propulsion, and it theoretically has advantages over normal aircraft propulsion. Presumably using dozens of piston or turbine engines has enough drawbacks to make it not worth it, which is why it hasn't been a thing until electric planes became possible. https://en.wikipedia.org/wiki/Distributed_propulsion https://en.wikipedia.org/wiki/Distributed_propulsion
nharada 4y ago
What kind of range does this specific vehicle get? They've said they're aiming for 300km but that will require density increases to get there, curious what it is now
psadri 4y ago
I always wondered if this could work, that is if it'd be more energy efficient that using fuel/batteries to reach cruising altitude: - use lighter than air balloon to life an aircraft to cruising altitude - transition to powered flight while collapsing the balloon (by compressing the gas into liquid form?). Or maybe detaching from it? - cruise - at destination, glide towards touch down?
- pqdbr 4y ago
  Those are crazy ideas. I love them. Anywhere they have been experimented with before?
  - psadri 4y ago
    Looks like quite a few companies worked on the idea for orbital launches -- lift a rocket with a balloon and then launch from a high altitude.
    - 6stringmerc 4y ago
      There is a lot of talk about horizontal launch for spacecraft - I’m pretty sure steam catapults and aircraft designed to use them could change things as well.
    - Ekaros 4y ago
      Rocketry really isn't about height but speed. And balloons don't actually help so much with that. At least if you want to stay up there once the lift is gone.
      - psadri 4y ago
        Most of a rocket's weight is fuel. Ironically, most of that fuel is needed to lift the rest of the fuel from ground level to some altitude A, then the remaining fuel is used to get to A', and so on. If you could first lift the rocket to a high altitude, you could get away with far less fuel. The smaller mass would mean faster acceleration (think a rocket fired from a jet fighter). note: I'm not a rocket scientist or physicist :-)
zac23or 4y ago
All electric airplane designs today appear to be frauds (like all crypto currency projects), because no one airplane project answers the most important problem: battery power density.
- 6stringmerc 4y ago
  Nope there’s already one flying in England testing for commercial service and its twin is about to get FAA clearance to start testing here as well. It’s an electric aircraft with a hydrogen fuel cell system.
  - zac23or 4y ago
    > hydrogen fuel cell system. It's not a battery.
    - 6stringmerc 4y ago
      Would you consider graphene based next generation power storage a battery or something different? I'm pretty keen on the RC hobby realm and the up and downstream innovations for batteries is still on the uptick I believe. I believe there are some Experimental (by FAA standards) battery based planes flying today, which again, simply is proof of concept to counter the doom and gloom potential outcome. For what it's worth, I felt the same way for years - batteries will never work - but now I'm not so sure.
- J5892 4y ago
  My crypto project is powered by D batteries. I don't know how dense they are, but they're pretty heavy.
  - LightG 4y ago
    Your batteries are my ... my density ... I mean, I mean, my destiny ... (someone will get this).
    - 4y ago
jimbru 4y ago
Does anyone know why you would choose a ducted engine design here? Why not a more traditional propellor?
- chroma 4y ago
  Ducted engines make less noise, which is handy for helipads in cities. They also increase thrust efficiency. If done right, the duct can contain any shrapnel if the fan blades come apart. The disadvantage of a duct is extra weight.
- Sophistifunk 4y ago
  They're chasing the rich-guy helicopter market (think trips to/from/airports) due to the energy density issues of current battery tech, which is going to be much easier without the noise of supersonic blade tips.
z9znz 4y ago
I'm glad people take on crazy projects and push them to some level of completion. That's how we learn and progress overall. Unfortunately for the people who do follow through with unconventional ideas, actually getting a thing to work doesn't necessarily mean (financial) success. In this case, there's really one big benefit at the cost of a lot of negatives. It can VTOL/VSTOL. Most fixed wing airplanes cannot do that. So it can theoretically take off in a parking lot or a helipad or a small field. That's really the only plus as I can tell. The negatives are many compared to a traditional plane. In no particular order: Less efficient cruising due to much more drag from all the ducts and engines. Much less likely to fly with engine failures as they can dramatically affect control (since they are essential parts of the control system). Less control surface stability with mechanical or hydraulic failures. Those engines mounted on the surfaces hanging off a hinge are very heavy, and in some failure cases they would hang low and create immense drag. Yaw (rotational) control is highly dependent on working engines on both sides. The glide ratio of the aircraft would be very poor with all the drag, even assuming the surfaces were still controllable (not hanging). I didn't see, but I assume a parachute is part of the plan for this. I doubt it could pass certifications (at least to carry passengers) without it.
- engineer_22 4y ago
  You repeatedly mention engines, but I'd point out there are no engines on this craft. This craft has electric motors. I don't know if electric motors are more reliable than ICE, but I speculate that they are. ------ Edit, my opinion below: VTOL is a HUGE WIN. It's the holy grail of flight. Fixed wing aircraft are inconvenient because they need a mile of flat blacktop for takeoff and landing. Affordable eVTOL craft could change general aviation forever. The problem with helicopters is insane maintenance overhead and low fuel efficiency. The problem with fixed wing is you can't land it in your back yard. EVTOL is interesting in that it could bridge the gap between these two to provide a personal aircraft that has the best of both. Napkin math shows it's possible, and we're seeing some really cool products now.
  - a_shovel 4y ago
    For most people, "motor" and "engine" are synonyms. Is there a technical difference between the two terms?
w10-1 4y ago
kybernetikos said it well: "spending a lot of novelty points" I would add: in a highly-regulated domain that segregates risk. FAA wants designs that won't kill people (including bystanders) when systems fail. Battery: using lithium with silicon anodes: unproven at scale? For landing, the Illium offers only a 60-second reserve after a expected 20-second hover. But can take time to land, particularly in wind: 20-80 seconds is too short. And since it is landing on rooftop helipads, without more reserve you could kill people just by blocking the helipad. Perhaps they could take-off via hover and land conventionally, but that would require stronger gear placed differently. Design: This relies completely on fans for directional stability? FAA even for experimentals, helicopters, etc. requires controllability on power failure, and e.g., 30 minutes of reserve power, more at night. It's doubling risk to integrate power and control, and engines into the wing. If some fans fail, you're adding controllability to power loss; it's unclear other fans could depower dynamically as required. And what if a fan goes catastrophic -- breaking the wing or nearby fans or control lines? Commercial airplanes can fly even when their engines blow up because the engines are largely segregated from flying and control surfaces (unlike military jets). I could imagine a more conventional hybrid stepping-stone to this ultimate concept. If you put fixed horizontal ducted fans at the front and rear of the fuselage, you get the benefit of lower disc loading for the bulk of vertical hover thrust. With colocated batteries, this would reduce power transit. On failure of both, fall back to conventional landing. On failure of one, balance out with tandem-wing alternate. As an aside: for homebuilt tandem-wing airplane, search for Rutan Quickie or Q200
- carstenhag 4y ago
  About the helipad blocking thing: supposedly these rooftop things have similar security gates like on airports. The helipad itself would be a restricted area. Would be relatively safe imo. But of course, that's not enough for regulators in the US/EU.
exabrial 4y ago
Do electric ‘jet’ engines need ‘bypass’ air for increased efficiency or is just a combustion problem?
- mberning 4y ago
  It is all bypass air. None is consumed by the engine.
  - exabrial 4y ago
    Good point. I guess I mean is there a channel where air is sucked in like a Dyson ‘bladeless’ ‘fan’?
    - ReactiveJelly 4y ago
      Didn't see one in the technical blog. Imagine a huge two-engine jetliner. Replace the jet turbines with electric motors. Shrink the entire nacelle. Keep shrinking it, and then multiply it until you have 24 tiny motors in 24 tiny nacelles. Then integrate those nacelles into the flaps on the back of the wings. That, and 12 more tiny motor-nacelle-flaps on the front canards, is how their diagram looked.
- borlox 4y ago
  Look for „Disk Loading“ - in short, the more rotor surface you have for every kilogram of mass, the more efficient your vehicle will hover. Turbo fan engines work more efficient, because with their huge fan diameter, they have lower disk loading than turbo jet engines without bypass. Lilium has a very high disk loading, resulting in low efficiency, resulting in short possible hovering times.
entropicgravity 4y ago
Here's a youtube (June 2022) about Lillium by the company and it covers off a lot of the engineering questions. [1] [1]https://www.youtube.com/watch?v=qZ73PftBfFg https://www.youtube.com/watch?v=qZ73PftBfFg
NonNefarious 4y ago
STOP CALLING THIS A JET. It is NOT a jet. I'm fully supportive of these innovators, but lying about what the product is hurts EVERYBODY. Grow up.
rob74 4y ago
TIL: an "electric jet engine" is a turbofan with an electric motor instead of a turbine.
l7l 4y ago
Not this story again
loufe 4y ago
I took a small plane for a work flight a couple months ago, and I feel something that's misleading about their ostensibly 7-seat configuration is the lack of space for luggage. People don't travel 200km+ often without at least a backpack. Sure some flights will be ok but I think many operators would use a configuration for this size of 5 seats with the back row for luggage.
- yencabulator 4y ago
  This is a rich people toy, they'll have fresh clothes waiting at their destination...

124 points by trollied 4y ago

I had this pop up as a recommendation on youtube. Video of a test flight, VTOL: https://www.youtube.com/watch?v=ywJWka1evH8 https://www.youtube.com/watch?v=ywJWka1evH8

_Microft 4y ago
The interesting part seems to be happening around 1:20-1:30 minutes into the video. The main wings and canadards (that's the smaller wings at the front) are oriented fully parallel to the direction of flight. The threads indicating the flow of air over the surfaces are no longer moving around and therefore air is moving smoothly over the wings. The aircraft seems to be relying fully on lift provided by the wings instead of the engines. As far as I know they hadn’t achieved that before. The thrust required for level flight with lift provided by wings is said to be ~ 10% of what is required for vertical take-off and landing. https://youtu.be/ywJWka1evH8?t=82 https://youtu.be/ywJWka1evH8?t=82

kybernetikos 4y ago

This is very cool. But it's also spending a lot of novelty points. I thought energy density was still a huge problem, so it seems weird to try to solve the problem of electric planes with acceptable range at the same time as tackling the enormously energy intensive problem of VTOL.

lordofgibbons 4y ago
It makes sense why they'd do this. Given current energy density of batteries, electric planes are only useful on very short flights. If you can only operate out of airports (without vtol), the useful range of the airplane will be significantly reduced
- kybernetikos 4y ago
  Great point. Reading a little more https://lilium.com/newsroom-detail/technology-behind-the-lilium-jet https://lilium.com/newsroom-detail/technology-behind-the-lil... you're exactly right, and the same thinking drives the requirement of low noise and the ability to utilise helipads.
  - nradov 4y ago
    There aren't many helipads either. Outside of regular airports, only a few urban areas have any helipads available for commercial use. More can potentially be built but that requires large open areas free of obstructions. Adding helipads to existing building roofs is generally impractical due to weight and safety issues.
    - RC_ITR 4y ago
      >large open areas free of obstructions. https://www.beaconhealthsystem.org/beacon-medical-transport/landing-zone-preparation-and-safety/ https://www.beaconhealthsystem.org/beacon-medical-transport/... You need roughly a football field of clear flat land for human-piloted helicopters. In the US at least, that's nothing. It's comparable to one quarter of a clover-leaf offramp.
      - nradov 4y ago
        It's not nothing. In the affluent areas where passengers would potentially be willing to pay for air taxi service there aren't many large vacant lots left. So not impossible, but it's hard to see how the economics would work. Medical transport helicopters have somewhat greater freedom to land in random places like roads and fields when necessary to pick up emergency patients. But that only works because police are on the ground to secure the area. And local residents don't complain about the noise from a single emergency flight. Those situations don't apply to air taxis.
        RC_ITR 4y ago
tlb 4y ago
Those are related. Part of what makes engine-powered VTOL difficult is the engines. The V-22 Osprey has two propellors and two engines, but in order to handle an engine failure, there's a complicated driveshaft and gear arrangement across the middle of the aircraft to send power from the working engine to the other propellor. I don't know that anyone has seriously tried more than 2 engines for a VTOL system. Electric power allows you to have lots of small fans, a few of which can fail without disaster. Also, throttling turbines up and down fast enough to stabilize an aircraft doesn't seem to work well.
- scarier 4y ago
  There are a number of VTOL aircraft that have used multiple engines. The Yak-38 used two lift engines and one lift-cruise engine, the VJ101 used four lift-cruise engines and two lift engines, and the Do 31 used two lift-cruise engines and eight(!) lift engines. Out of these, only the Yak-38 was remotely successful, and not nearly as much as the single-engined Hawker Siddeley Harrier (and its derivatives). There are plenty of ways to stabilize an aircraft without relying on pure engine thrust, and turbofan aircraft have some advantages here. The distributed electric propulsion systems do have awesome redundancy, but they have significant losses in efficiency compared to fewer, larger props, which really isn't what you want in an aircraft with severe energy density limitations. I'm curious to see what the production Lillium's payload, range, and power margin end up being.
- nradov 4y ago
  There have been a few flying VTOL prototype designs with more than two turbine engines. The extra engines were used for powered lift during takeoff and landing. But that approach turned out to be impractical due to safety, cost, and weight. https://vtol.org/vstol/wheel.htm https://vtol.org/vstol/wheel.htm
- dingaling 4y ago
  XC-142 tiltwing, four turboprops https://vought.org/products/assets/images/1758_005_o.jpg https://vought.org/products/assets/images/1758_005_o.jpg
vidarh 4y ago
"Acceptable" range is short - they're not really trying to compete with planes, but with other modes of transport.

consumer451 4y ago

Wisk[0], backed by Kittyhawk and Boeing seems like they may have a more practical vehicle, and in some ways it is much further along. Flight Chops has a great video[1] showing a bunch of details, including the addition of "Digital Flight Rules" to VFR and IFR. Though I do love Lilium's aircraft, it is definitely more of a sports car. [0] https://wisk.aero https://wisk.aero [1] https://www.youtube.com/watch?v=yrEeCp5xJj8 https://www.youtube.com/watch?v=yrEeCp5xJj8

googlryas 4y ago
Why is kittyhawk investing in airplane startups, when they themselves are an airplane startup? Is that just a sign of too much cash to burn with too few ideas? Not that it matters much anymore...
- addaon 4y ago
  Wisk was spun off from Kitty Hawk when Boeing invested.
rootusrootus 4y ago
Sounds like Kittyhawk is shutting down [0]. Is the future of Wisk in question? [0] https://aviationweek.com/business-aviation/kittyhawk-shut-down-wisk-aero-continue https://aviationweek.com/business-aviation/kittyhawk-shut-do...
- rgmerk 4y ago
  Wisk claims not: https://twitter.com/wiskaero/status/1572677287455358976?s=46&t=qTX7rXKti4XeLNNt4eH5Ig https://twitter.com/wiskaero/status/1572677287455358976?s=46...

6stringmerc 4y ago

This seems viable especially as next generation power storage comes into the fold. Finally using the wings for sustained flight - something that doesn’t take nearly as much energy as getting whatever payload off the ground in the first place.

narrator 4y ago

The hydrogen conversion of the Cessna Caravan seems a little more practical. Hydrogen is bulky, but light. Fuel cells aren't cheap though. However, hydrogen is quick to refuel unlike battery charging. I think the weight to power is better with hydrogen than li-ion and weight is the most important thing for aviation. https://www.militaryaerospace.com/commercial-aerospace/article/14283551/textron-aviation-taps-zeroavia-to-develop-hydrogenelectric-powertrain-for-its-cessna-grand-caravan https://www.militaryaerospace.com/commercial-aerospace/artic...

joe_the_user 4y ago
If you can switch battery packs, refueling could be very quick.
- mikepurvis 4y ago
  And even though they're heavy and bulky, it's much more tractable to install that infrastructure at a few dozen key airports, and also to manage the tracing/ownership of "fleets" of batteries. Battery swapping has repeatedly faceplanted when it comes to cars, but it's a pretty different scope of challenge, and it seems like every major issue is more favourable to aircraft. On the other hand, planes are often on the ground for 2+ hrs between flights anyway, so maybe it could be realistic with enough power delivery capability to just charge a big pack in situ. Certainly simpler to plug in a big umbilical at the gate than having to have another ground vehicle reaching into the belly of the thing.
  - _hypx 4y ago
    Absolutely not. Airplanes have to be aerodynamic, and it would be incredibly challenging to make the entire bottom portion of the plane something that can open up and fit a giant battery. Never mind the weight of the whole system plus battery. The whole idea is absurd and completely impractical.
  - nradov 4y ago
    Batteries power will only be feasible for short-haul flights, and those have much shorter turn around times. Southwest Airlines has it down to 35 minutes. Recharging within that time limit might eventually become feasible but it's going to take some further battery innovations.

cpursley 4y ago

Can we pass a federal law prohibiting scroll-jacking?

Sophistifunk 4y ago
Or kickstart a team of black-ops mofos.
bestest 4y ago
Absolutely. I closed the tab once I felt being molested by the scrolling mechanism hijack.

polar8 4y ago

Why do electric planes like this one have many smaller motor, as opposed to 1-4 engines like typical planes do?

pvorb 4y ago
Perhaps it has to do with being failure-safe?
- mikepurvis 4y ago
  With a conventional turbofan (or basically gas-anything) the bigger it is the more efficiency gains can be realised. So I'd expect that conventional jets would really ideally have just one engine, and they typically have 2 or 4 for reasons of fault tolerance and isolating noise from the fuselage. None of this applies with electric, particularly a cleansheet design.
- UncleOxidant 4y ago
  But then they would've been using many smaller ICE or jet engines already to get redundancy. I suspect the reason is that it's easier to get that kind of redundancy with electric motors - they're more compact, lighter weight, less overhead for each.
  - jasonwatkinspdx 4y ago
    We do. It wasn't until the 80s that twin engine airliners were certified for long flights. Before then it was 3 or 4 engine only. It took a lot of effort to get jet engines that reliable too. Single vs dual engine helicopter is a big safety distinction. There's heavy lift and military helicopters with 3 engines.
iijj 4y ago
It's called Distributed Propulsion, and it theoretically has advantages over normal aircraft propulsion. Presumably using dozens of piston or turbine engines has enough drawbacks to make it not worth it, which is why it hasn't been a thing until electric planes became possible. https://en.wikipedia.org/wiki/Distributed_propulsion https://en.wikipedia.org/wiki/Distributed_propulsion

nharada 4y ago

What kind of range does this specific vehicle get? They've said they're aiming for 300km but that will require density increases to get there, curious what it is now

psadri 4y ago

I always wondered if this could work, that is if it'd be more energy efficient that using fuel/batteries to reach cruising altitude: - use lighter than air balloon to life an aircraft to cruising altitude - transition to powered flight while collapsing the balloon (by compressing the gas into liquid form?). Or maybe detaching from it? - cruise - at destination, glide towards touch down?

pqdbr 4y ago
Those are crazy ideas. I love them. Anywhere they have been experimented with before?
- psadri 4y ago
  Looks like quite a few companies worked on the idea for orbital launches -- lift a rocket with a balloon and then launch from a high altitude.
  - 6stringmerc 4y ago
    There is a lot of talk about horizontal launch for spacecraft - I’m pretty sure steam catapults and aircraft designed to use them could change things as well.
  - Ekaros 4y ago
    Rocketry really isn't about height but speed. And balloons don't actually help so much with that. At least if you want to stay up there once the lift is gone.
    - psadri 4y ago
      Most of a rocket's weight is fuel. Ironically, most of that fuel is needed to lift the rest of the fuel from ground level to some altitude A, then the remaining fuel is used to get to A', and so on. If you could first lift the rocket to a high altitude, you could get away with far less fuel. The smaller mass would mean faster acceleration (think a rocket fired from a jet fighter). note: I'm not a rocket scientist or physicist :-)

zac23or 4y ago

All electric airplane designs today appear to be frauds (like all crypto currency projects), because no one airplane project answers the most important problem: battery power density.

6stringmerc 4y ago
Nope there’s already one flying in England testing for commercial service and its twin is about to get FAA clearance to start testing here as well. It’s an electric aircraft with a hydrogen fuel cell system.
- zac23or 4y ago
  > hydrogen fuel cell system. It's not a battery.
  - 6stringmerc 4y ago
    Would you consider graphene based next generation power storage a battery or something different? I'm pretty keen on the RC hobby realm and the up and downstream innovations for batteries is still on the uptick I believe. I believe there are some Experimental (by FAA standards) battery based planes flying today, which again, simply is proof of concept to counter the doom and gloom potential outcome. For what it's worth, I felt the same way for years - batteries will never work - but now I'm not so sure.
J5892 4y ago
My crypto project is powered by D batteries. I don't know how dense they are, but they're pretty heavy.
- LightG 4y ago
  Your batteries are my ... my density ... I mean, I mean, my destiny ... (someone will get this).
  - 4y ago

jimbru 4y ago

Does anyone know why you would choose a ducted engine design here? Why not a more traditional propellor?

chroma 4y ago
Ducted engines make less noise, which is handy for helipads in cities. They also increase thrust efficiency. If done right, the duct can contain any shrapnel if the fan blades come apart. The disadvantage of a duct is extra weight.
Sophistifunk 4y ago
They're chasing the rich-guy helicopter market (think trips to/from/airports) due to the energy density issues of current battery tech, which is going to be much easier without the noise of supersonic blade tips.

z9znz 4y ago

I'm glad people take on crazy projects and push them to some level of completion. That's how we learn and progress overall. Unfortunately for the people who do follow through with unconventional ideas, actually getting a thing to work doesn't necessarily mean (financial) success. In this case, there's really one big benefit at the cost of a lot of negatives. It can VTOL/VSTOL. Most fixed wing airplanes cannot do that. So it can theoretically take off in a parking lot or a helipad or a small field. That's really the only plus as I can tell. The negatives are many compared to a traditional plane. In no particular order: Less efficient cruising due to much more drag from all the ducts and engines. Much less likely to fly with engine failures as they can dramatically affect control (since they are essential parts of the control system). Less control surface stability with mechanical or hydraulic failures. Those engines mounted on the surfaces hanging off a hinge are very heavy, and in some failure cases they would hang low and create immense drag. Yaw (rotational) control is highly dependent on working engines on both sides. The glide ratio of the aircraft would be very poor with all the drag, even assuming the surfaces were still controllable (not hanging). I didn't see, but I assume a parachute is part of the plan for this. I doubt it could pass certifications (at least to carry passengers) without it.

engineer_22 4y ago
You repeatedly mention engines, but I'd point out there are no engines on this craft. This craft has electric motors. I don't know if electric motors are more reliable than ICE, but I speculate that they are. ------ Edit, my opinion below: VTOL is a HUGE WIN. It's the holy grail of flight. Fixed wing aircraft are inconvenient because they need a mile of flat blacktop for takeoff and landing. Affordable eVTOL craft could change general aviation forever. The problem with helicopters is insane maintenance overhead and low fuel efficiency. The problem with fixed wing is you can't land it in your back yard. EVTOL is interesting in that it could bridge the gap between these two to provide a personal aircraft that has the best of both. Napkin math shows it's possible, and we're seeing some really cool products now.
- a_shovel 4y ago
  For most people, "motor" and "engine" are synonyms. Is there a technical difference between the two terms?

w10-1 4y ago

kybernetikos said it well: "spending a lot of novelty points" I would add: in a highly-regulated domain that segregates risk. FAA wants designs that won't kill people (including bystanders) when systems fail. Battery: using lithium with silicon anodes: unproven at scale? For landing, the Illium offers only a 60-second reserve after a expected 20-second hover. But can take time to land, particularly in wind: 20-80 seconds is too short. And since it is landing on rooftop helipads, without more reserve you could kill people just by blocking the helipad. Perhaps they could take-off via hover and land conventionally, but that would require stronger gear placed differently. Design: This relies completely on fans for directional stability? FAA even for experimentals, helicopters, etc. requires controllability on power failure, and e.g., 30 minutes of reserve power, more at night. It's doubling risk to integrate power and control, and engines into the wing. If some fans fail, you're adding controllability to power loss; it's unclear other fans could depower dynamically as required. And what if a fan goes catastrophic -- breaking the wing or nearby fans or control lines? Commercial airplanes can fly even when their engines blow up because the engines are largely segregated from flying and control surfaces (unlike military jets). I could imagine a more conventional hybrid stepping-stone to this ultimate concept. If you put fixed horizontal ducted fans at the front and rear of the fuselage, you get the benefit of lower disc loading for the bulk of vertical hover thrust. With colocated batteries, this would reduce power transit. On failure of both, fall back to conventional landing. On failure of one, balance out with tandem-wing alternate. As an aside: for homebuilt tandem-wing airplane, search for Rutan Quickie or Q200

carstenhag 4y ago
About the helipad blocking thing: supposedly these rooftop things have similar security gates like on airports. The helipad itself would be a restricted area. Would be relatively safe imo. But of course, that's not enough for regulators in the US/EU.

exabrial 4y ago

Do electric ‘jet’ engines need ‘bypass’ air for increased efficiency or is just a combustion problem?

mberning 4y ago
It is all bypass air. None is consumed by the engine.
- exabrial 4y ago
  Good point. I guess I mean is there a channel where air is sucked in like a Dyson ‘bladeless’ ‘fan’?
  - ReactiveJelly 4y ago
    Didn't see one in the technical blog. Imagine a huge two-engine jetliner. Replace the jet turbines with electric motors. Shrink the entire nacelle. Keep shrinking it, and then multiply it until you have 24 tiny motors in 24 tiny nacelles. Then integrate those nacelles into the flaps on the back of the wings. That, and 12 more tiny motor-nacelle-flaps on the front canards, is how their diagram looked.
borlox 4y ago
Look for „Disk Loading“ - in short, the more rotor surface you have for every kilogram of mass, the more efficient your vehicle will hover. Turbo fan engines work more efficient, because with their huge fan diameter, they have lower disk loading than turbo jet engines without bypass. Lilium has a very high disk loading, resulting in low efficiency, resulting in short possible hovering times.

entropicgravity 4y ago

Here's a youtube (June 2022) about Lillium by the company and it covers off a lot of the engineering questions. [1] [1]https://www.youtube.com/watch?v=qZ73PftBfFg https://www.youtube.com/watch?v=qZ73PftBfFg

NonNefarious 4y ago

STOP CALLING THIS A JET. It is NOT a jet. I'm fully supportive of these innovators, but lying about what the product is hurts EVERYBODY. Grow up.

rob74 4y ago

TIL: an "electric jet engine" is a turbofan with an electric motor instead of a turbine.

l7l 4y ago

Not this story again

loufe 4y ago

I took a small plane for a work flight a couple months ago, and I feel something that's misleading about their ostensibly 7-seat configuration is the lack of space for luggage. People don't travel 200km+ often without at least a backpack. Sure some flights will be ok but I think many operators would use a configuration for this size of 5 seats with the back row for luggage.

yencabulator 4y ago
This is a rich people toy, they'll have fresh clothes waiting at their destination...