Lilium vertical take off "jet"
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Sure. But you’ll find there are a number of controlled real-world tests and studies to quantify those public based studies. And one of the last large-scale, controlled tests of UAM using helicopters validated the concept but proved noise was the principal deterrent to helicopter use. It was this noise result that led NASA to develop a new electric-based propulsion/control concept called Distributed Electric Propulsion (DEP). Which in turn became the foundation for the e-aviation industry to include eVTOLs. Without DEP none of this would be possible.
The hybrid market is being driven more by the turbo-generator advances than anything else. But on the eVTOL side, Joby and Archer are in the final certification phases and the initial flight programs in NYC, Chicago, and LA have the infrastructure in place. So you won’t have long to wait to see if your theory is correct.
Electra is using a different blown-wing concept for their eSTOL. They’re currently flying the development prototype and finalizing the pre-production model.
Turns out hybrid helicopter seems to be the next hype after evtols fully exhibits their short coming.
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Lilium kept pushing the idea that a ducted fan is 41% more efficient, (yes it is true, it is called Froude efficiency), but their disk loading is more than 10 times that of a tilt rotor concept! Consequently Lilium concept is 50% less efficent than other tilt rotor concepts. This was known all along by the scientific community, it just took longer for the investor comunity to wake up to the truth.
its explained in great specific detail in that video (mark 25:00)
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From: The Gulf Coast
Originally Posted by AIN
February 26, 2025
Lilium’s dream of bringing a six-passenger eVTOL aircraft to market seems to have ended in insolvency, while Eviation has had to lay off almost all staff as its main shareholder seeks new backing.
Plus, Airbus appears to be slowing down its efforts to electrify aviation in what could make a turning point for a major aerospace industry trend.
Lilium’s dream of bringing a six-passenger eVTOL aircraft to market seems to have ended in insolvency, while Eviation has had to lay off almost all staff as its main shareholder seeks new backing.
Plus, Airbus appears to be slowing down its efforts to electrify aviation in what could make a turning point for a major aerospace industry trend.
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eVTOL is a technology-led product still looking for the killer application.
As wrench1 has said:
Joby has already shown that, with fuel-cell technology, liquid hydrogen can extend that range (currently at about 30 minutes) to several hours without adding dramatically to the take-off mass.
But to return to UAM, it is not quite as simple as it first appears; yes, eVTOLs with their many thrust units with modern geometry props/rotors are much quieter, and therefore acceptable, than the current crop of helicopters. But, they suffer from issues of downwash/outwash (some of them extreme) and, because of their certification basis (EASA - 'enhanced', and FAA 'increased performance'), will be subject to rules similar to Performance Class 1 (although for the FAA that is not yet clear).
EASA's enhanced certification requires that the safety target of 1 x 10-9 be achieved; depending on the reliability of the power-unit train, this might mean the loss of one or even several thrust units (and asymmetric power control might not be that easy).
However, for UAM it is the limitation of the take-off climb 'obstacle limitation surface' (OLS) in an obstacle-rich environment that might be the real issue. ICAO addressed this several years ago by permitting the elevation of the (origin of the) OLS sometimes by hundreds of feet - thus allowing it to be positioned above all obstacles. Helicopter manufacturers met that challenge (or might even have facilitated it) with the development of 'vertical procedures' - allowing the attainment of the OLS elevation by adding an all-engines-operating (AEO) steep/vertical (ascent/descent surface) element to the Category A profiles.
Elevation of the OLS remains the solution for vertiports in an urban environment. but the achievement of the steep/vertical ascent/descent requires an application of maximum power for a period that might wreck the previously designed flight profiles with the demand on battery power.
Yes, eVTOL development is moving at an impressive pace but still has to satisfy the population's (both those travelling and those over which operations are being performed) aspirations of safe flight.
Jim
As wrench1 has said:
Joby has already shown that, with fuel-cell technology, liquid hydrogen can extend that range (currently at about 30 minutes) to several hours without adding dramatically to the take-off mass.
But to return to UAM, it is not quite as simple as it first appears; yes, eVTOLs with their many thrust units with modern geometry props/rotors are much quieter, and therefore acceptable, than the current crop of helicopters. But, they suffer from issues of downwash/outwash (some of them extreme) and, because of their certification basis (EASA - 'enhanced', and FAA 'increased performance'), will be subject to rules similar to Performance Class 1 (although for the FAA that is not yet clear).
EASA's enhanced certification requires that the safety target of 1 x 10-9 be achieved; depending on the reliability of the power-unit train, this might mean the loss of one or even several thrust units (and asymmetric power control might not be that easy).
However, for UAM it is the limitation of the take-off climb 'obstacle limitation surface' (OLS) in an obstacle-rich environment that might be the real issue. ICAO addressed this several years ago by permitting the elevation of the (origin of the) OLS sometimes by hundreds of feet - thus allowing it to be positioned above all obstacles. Helicopter manufacturers met that challenge (or might even have facilitated it) with the development of 'vertical procedures' - allowing the attainment of the OLS elevation by adding an all-engines-operating (AEO) steep/vertical (ascent/descent surface) element to the Category A profiles.
Elevation of the OLS remains the solution for vertiports in an urban environment. but the achievement of the steep/vertical ascent/descent requires an application of maximum power for a period that might wreck the previously designed flight profiles with the demand on battery power.
Yes, eVTOL development is moving at an impressive pace but still has to satisfy the population's (both those travelling and those over which operations are being performed) aspirations of safe flight.
Jim
Obviously that’s a very specific aircraft but backed by Uber and so one imagines maybe quite numerous if the concept gains traction. Not sure how that could ever be flown in an urban environment without accepting more risk that seems acceptable today.
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Background on failed bailout(s)
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That feels like their blame game going on. They had blamed a lack of tax funding they suddenly had requested for not being able to continue already.
Why don't they just demonstrate how far they had come and what their vehicle can do that others can't if this is so promising? Something doesn't add up.
Why don't they just demonstrate how far they had come and what their vehicle can do that others can't if this is so promising? Something doesn't add up.
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From: UK
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From: South East Asia
first come the government grants and sponsorships
then come the angel investors (and the kind, crowdfunding +++), they will group up to 20 millions, for a project without proven potential, mostly on gut feeling.
finally comes the venture fund: in the 200million per round investment category, they have experts on staff, and will not invest without their blessing.
when a project like that (with a fundamental technical handicap) comes to the last stage of financing, that is usually where they fail: because the smart money is not moving to them.
I am not saying the lower stage investing is stupid money, they just work with a different value system and a different reward system.
I have been brainstorming that in the context of the HX50 project, (not saying it has technical handicap as in this case) but if they would need 200+ million, could they get it...
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Where the Lilium and similar efforts have fell short has more to do with investment source and design. But while I’m sure there were a few “scams” out of the 100+ eVTOL start-ups a majority of the projects are/were an honest attempt to participate in the industry's next growth area: e-aviation. Like it or not its here to stay and if it follows the growth cycle of the civilian UAS market, it will be here sooner than later.
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Doubtful in a conventional sense as the HX is a very different investment type and overall project.
Where the Lilium and similar efforts have fell short has more to do with investment source and design. But while I’m sure there were a few “scams” out of the 100+ eVTOL start-ups a majority of the projects are/were an honest attempt to participate in the industry's next growth area: e-aviation. Like it or not it’s here to stay and if it follows the growth cycle of the civilian UAS market, it will be here sooner than later.
Where the Lilium and similar efforts have fell short has more to do with investment source and design. But while I’m sure there were a few “scams” out of the 100+ eVTOL start-ups a majority of the projects are/were an honest attempt to participate in the industry's next growth area: e-aviation. Like it or not it’s here to stay and if it follows the growth cycle of the civilian UAS market, it will be here sooner than later.
Joined: Oct 2006
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From: USA