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-   -   Lilium vertical take off "jet" (https://www.pprune.org/rotorheads/578979-lilium-vertical-take-off-jet.html)

Winemaker 30th Nov 2021 01:32


It will be fueled by hydrogen, the most sustainable technology in development today.
Oh come on. Run some basic numbers re fuel energy density of hydrogen vs liquid hydrocarbons like petrol then do some basic calculations re volumes and storage (liquid hydrogen and/or compressed gas) and then look at the weight of the tankage..... etc. etc. Lets not even get into the weight, efficiency, and output of fuel cells; a battery system would be necessary for surge energy demands like take off, adding weight....

I have run these numbers many times and there is no way an aircraft is going to fly for any reasonable period of time using hydrogen as a fuel, especially a vertical machine; factor in endurance then just laugh. It just doesn't work, both from a weight and a volumetric perspective; let's not even talk about how hydrogen is produced, sources (probably a steam process on natural gas), energy requirements for chilling and liquefying the gas (pressure tanks would be WAY too heavy for aircraft), and the infrastructure to supply the fuel...... More grabbing headlines and money here, IMHO; buy stock early and then bail when the time is right..... The only hydrogen craft I see flying passengers are balloons, blimps, or dirigibles.

muermel 30th Nov 2021 15:13


Originally Posted by Less Hair (Post 11148543)
Will the noise and the blast when hovering make it acceptable for inner city and metro area flight operations?

Neighbours and local residents of hospitals in Germany are going to court against EMS helipads beccause of noise already nowadays. What makes people think that helipads for THESE things will be allowed in cities? There's a reason there's no helipads in larger cities except hospital pads. Not going to happen :=

Ascend Charlie 3rd Dec 2021 23:57

And here's the latest wet dream from the "gimme some development money" crowd:

https://cimg3.ibsrv.net/gimg/pprune....bf433dce0c.png

Not a lot of lifting surface for forward flight, and the wing has big holes in it with drag-inducing fan stuff.

The noise from those 2 piddly propellors (nose, tail) must be a real scream.

Less Hair 4th Dec 2021 03:20

I am impressed by all the money they collected but does this new design mean their own original tilt-impeller concept finally did not convince them?
Now it looks more like a toy. Love those tiny front and tail propellers.

Winemaker 4th Dec 2021 03:43


Originally Posted by Less Hair (Post 11151094)
I am impressed by all the money they collected but does this new design mean their own original tilt-impeller concept finally did not convince them?
Now it looks more like a toy. Love those tiny front and tail propellers.

Pretty funny. But you have to understand they are turning a 50,000 rpm Ī so the craft is supersonic....... I wish I could come up with one of these schemes for instant wealth.

Less Hair 4th Dec 2021 07:41

All the laurels for Bezos and Musk who fund their own visions. But should the more general financial community get a better technical education to prevent them from all this fantasy financing? How bad will risk capital investments be in other less visible areas, say bio, AI and quantum computing, if even this vapourware gets funded with hundreds of millions of dollars?
We might need stricter rules to prevent money getting extracted from funds on -hopefully not- intentional fake promises.

netstruggler 6th Dec 2021 11:03


Originally Posted by Less Hair (Post 11151094)
I am impressed by all the money they collected but does this new design mean their own original tilt-impeller concept finally did not convince them?
Now it looks more like a toy. Love those tiny front and tail propellers.

The photo posted by Charlie is not anything to do with Lilium.

Let me provide the missing source:

Ascendance revises the design for its long-range hybrid eVTOL (newatlas.com)

Less Hair 6th Dec 2021 12:02

Thanks for the clarification, a bit confusing to distinguish all those phantasies.

Ascend Charlie 6th Dec 2021 20:52

Oh geez, another one:


Sydney Seaplanes orders fleet of electric air taxis to provide escape from Sydney traffic


They have ordered the Embraer EVE toy.

Sydney Seaplanes has the advantage of Grandfather Rights on the Rose Bay flying boat base, and they do trips to Palm Beach and other places in Pittwater.

Back in the 90s we proposed a floating heliport to use this pre-approved water runway, the pontoons would have been designed for the task, but the EPA and Sydney MSB pounced on it for noise considerations. No landing was allowed within 1000m of the shore, which meant that there was a lot of moving the pontoons between flights, or using water taxis, both impractical. And the rabid Labor voters of Balmain stopped anything west of the bridge.

Be interesting to see how they plan on landing at Barangaroo, on the west side of the bridge and almost requiring an approach/departure under the bridge.

cattletruck 16th Dec 2021 09:26

The comments section in this link makes for interesting reading.

Monte-Copter Model 15 Triphibian helicopter - development history, photos, technical data

Even though the design still looks quite futuristic 60 years on I doubt the early investors will ever see their money back.

mickjoebill 31st Jan 2022 22:38

Lilium employs Andy Strachan as test pilot
 
The money keeps flowing for development.
The move to Spain to allow higher speed testing. Former RAF and Leonardo helicopters pilot Andrew Strachan steps up as test pilot.

https://lilium.com/newsroom-detail/l...ndrew-Strachan

Mjb

Winemaker 1st Feb 2022 14:25


Originally Posted by mickjoebill (Post 11177966)
The money keeps flowing for development.
The move to Spain to allow higher speed testing. Former RAF and Leonardo helicopters pilot Andrew Strachan steps up as test pilot.

https://lilium.com/newsroom-detail/l...ndrew-Strachan

Mjb

Looks like they are only flying RC models; that company website is absolutely devoid of actual hard information.

widgeon 4th Mar 2022 16:49

https://www.ainonline.com/aviation-n...-lilium-evtols
Hmm I wonder if Net Jets actually put any money down , if so they are either longsighted visionaries are complete idiots ,
Please send your vote on a 20$ bill to . [email protected]@me.rus

Winemaker 5th Mar 2022 16:51

Ilium says they will be all set, certified, and flying in 2024..... From their website:

Lilium is aiming to certify its eVTOL and start commercial services in 2024.
From FAA.gov

......the certification of a new aircraft type can take between 5 and 9 years.

Pilot DAR 5th Mar 2022 18:24


......the certification of a new aircraft type can take between 5 and 9 years.
Which might not include the time to establish a changed certification basis and special conditions, which could be necessary if the conventional power off landing requirements cannot be demonstrated. This type of aircraft will succeed, but acceptance for commercial fare paying transport will be a little further off, while operating standards are adjusted to accommodate a changed certification basis.

sandringham1 16th Mar 2022 19:29

An analysis of Lilium by Iceberg, financial and accounting fraud investigators.
https://iceberg-research.com/2022/03...cenbsp-strong/

And a Youtube glowing review.

sandringham1 21st Apr 2022 13:19

Can someone explain what is meant by this statement by Lilium, I tried a search on Helicopter footprint and the only references are to a noise footprint. https://ir.lilium.com/techfaq
'In the Lilium Jet we are using electric ducted fans for propulsion. The advantage of the ducted fans is that they are much smaller than open propellers to lift the same weight of an aircraft. Or in technical terms - they can operate in high disc loads. The consequence of this is that VTOL aircraft using ducted fans need less ground footprint for a given weight and passenger (PAX) capacity of the aircraft. This in turn creates the potential to scale the aircraft to higher PAX and take-off weight for a given size of landing infrastructure'


Protolanguage 21st Apr 2022 18:24

Somebody please wake me when its over

212man 21st Apr 2022 18:45


Originally Posted by sandringham1 (Post 11218885)
Can someone explain what is meant by this statement by Lilium, I tried a search on Helicopter footprint and the only references are to a noise footprint. https://ir.lilium.com/techfaq
'In the Lilium Jet we are using electric ducted fans for propulsion. The advantage of the ducted fans is that they are much smaller than open propellers to lift the same weight of an aircraft. Or in technical terms - they can operate in high disc loads. The consequence of this is that VTOL aircraft using ducted fans need less ground footprint for a given weight and passenger (PAX) capacity of the aircraft. This in turn creates the potential to scale the aircraft to higher PAX and take-off weight for a given size of landing infrastructure'

footprint in this context just means the physical surface area required. They are saying for any given area, they will be able use an aircraft with a greater payload.

mickjoebill 22nd Apr 2022 12:55


Originally Posted by Winemaker (Post 11195225)
From FAA.gov
Quote:
......the certification of a new aircraft type can take between 5 and 9 years.

This thread is approaching it's 6th birthday, how many candles will be on the cake celebrating the maiden commercial flight?

Mjb

mickjoebill 12th May 2022 20:30

New test flight video
 
Two videos.

45kts test flight

Interview with engineer
Mjb

mickjoebill 7th Jun 2022 02:18

Houston, we have transition
 
Lillium state this is the first transition from hover to wing-borne flight for a full scale, all electric aircraft.

130Kmh, 1200fpm climb.
Transition occurs at 1:30 in the clip.

Mjb

Lonewolf_50 8th Jun 2022 12:13

mjb, as I watched the video, I wasn't sure if there was a person in the aircraft. Was that whole flight accomplished remotely?

CTR 8th Jun 2022 13:01


Originally Posted by Lonewolf_50 (Post 11242711)
mjb, as I watched the video, I wasn't sure if there was a person in the aircraft. Was that whole flight accomplished remotely?

All Lillium flights to date have been remote. This is due to both pilot safety and pilot mass. They have barely enough battery energy to fly, a pilotís mass on board would make it almost impossible to leave the ground.

mickjoebill 9th Jun 2022 23:07

Specs announced
 

Originally Posted by CTR (Post 11242742)
All Lillium flights to date have been remote. This is due to both pilot safety and pilot mass. They have barely enough battery energy to fly, a pilotís mass on board would make it almost impossible to leave the ground.

Latest video today from CTO Alastair McIntosh, states the range and power density. They apparently have confidence these specs can be achieved, a range of 250km empty operational and 175km max take off weight. They state with a run-on landing the range will increase ( as the hover landing phase uses more juice)

This is the most revealing video thus far, they outlined the finalised design of the production model.
As CTR states, the battery density of existing commercially available technology is a hurdle. In this video they claim new battery tech will deliver the stated range and a full payload, presumably full payload is a person in each seat?
In other videos they mention the production model will have 7 seats and 30 engines (The prototype is full scale 5 seater with 36 engines)
The engine guru states there will be a mechanical connection to adjust flow to optimise energy use between landing and cruise. (10x more energy required for the hover) This is a repeating theme with electric aircraft, hover phase is a means to an end, gas powered helicopters will rule slow orbit tasks until battery density is improved.


WillyPete 13th Jun 2022 08:55


Originally Posted by mickjoebill (Post 11243660)
Latest video today from CTO Alastair McIntosh, states the range and power density. They apparently have confidence these specs can be achieved, a range of 250km empty operational and 175km max take off weight. They state with a run-on landing the range will increase ( as the hover landing phase uses more juice)

To put it in perspective, this is almost the same range as our VW ID4 Life model. (Shorter range battery, less tax)


Originally Posted by mickjoebill (Post 11243660)
They state with a run-on landing the range will increase ( as the hover landing phase uses more juice)

What about take off?
I don't foresee these ever taking hold as rooftop delivery for pax, but on shorter controlled fields in well regulated air corridors.

A short takeoff could be assisted with a cable tow, similar to gliders, but may not be what passengers might appreciate.

Petit-Lion 13th Jun 2022 17:31

My take-away is: 9 times more power to hover than to cruise. A conventional helicopter is close to 1:1. It starts to worsen with tiltrotors. Then there are those oversized multicopter drones. Did Lilium chose the worst way to hover?

widgeon 13th Jun 2022 20:41


Originally Posted by Petit-Lion (Post 11245537)
My take-away is: 9 times more power to hover than to cruise. A conventional helicopter is close to 1:1. It starts to worsen with tiltrotors. Then there are those oversized multicopter drones. Did Lilium chose the worst way to hover?

https://aviation.stackexchange.com/q...-when-hovering
i don't think there is a helicopter that burns same fuel in hover as fwd flight ,I am sure ratio is much better than 9 to 1 though
.



Non-PC Plod 14th Jun 2022 19:53


Originally Posted by Petit-Lion (Post 11245537)
My take-away is: 9 times more power to hover than to cruise. A conventional helicopter is close to 1:1. It starts to worsen with tiltrotors. Then there are those oversized multicopter drones. Did Lilium chose the worst way to hover?

You are looking at it the wrong way - It has fixed wings , which is makes it much more efficient in the cruise than a helicopter. So, its not that it is inefficient hovering, it is instead more efficient in forward flight.

Mee3 15th Jun 2022 03:50


Originally Posted by Non-PC Plod (Post 11246137)
You are looking at it the wrong way - It has fixed wings , which is makes it much more efficient in the cruise than a helicopter. So, its not that it is inefficient hovering, it is instead more efficient in forward flight.

Rotors are wing surfaces. You'd be surprise how much lift they produce in forward flight.

Ascend Charlie 15th Jun 2022 05:43


Rotors are wing surfaces. You'd be surprise how much lift they produce in forward flight.
They are quite inefficient. The retreating blade is the limiting factor, with only around 40% of it producing useful lift, and at a high AoA with resultant drag.

The advancing blade has to throw away all that beautiful lift it gets from the added forward airspeed, to match the poor old retreating blade.

If both blades were advancing, lotsa lift both sides, no need to worry about retreating sides, hence the ABC test aircraft and Hokums and intermeshing tandems.

mickjoebill 15th Jun 2022 08:06


Originally Posted by WillyPete (Post 11245317)
To put it in perspective, this is almost the same range as our VW ID4 Life model. (Shorter range battery, less tax)



What about take off?
I don't foresee these ever taking hold as rooftop delivery for pax, but on shorter controlled fields in well regulated air corridors.

A short takeoff could be assisted with a cable tow, similar to gliders, but may not be what passengers might appreciate.

They only quote the run on landing in the context of flight endurance for certification for commercial flights.


Mjb

Mee3 15th Jun 2022 08:38

Dissymmetry lift is not 0 lift at retreating side and plus with multi blades also gets the benefit of multi wings instead of a pair. And rotorcraft limits 150kt Vne not only preventing shock wave but also to make sure retreating blade still plane air faster than relative air flow.

Powered flight always been dealing with dilemma of disproportion power requirement between MTOW and cruise. Compound design like lilium is one of those went physically challenged approach to this. If they resort to running takeoff, might as well venture into extreme STOL dropping the expensive vector thrust part. I predict first 10 years into the market operation will be limited from airfield of some sort instead of helipad. And a super STOL might even be a winner.

Ascend Charlie 15th Jun 2022 19:19


Dissymmetry lift is not 0 lift at retreating side and plus with multi blades also gets the benefit of multi wings instead of a pair. And rotorcraft limits 150kt Vne not only preventing shock wave but also to make sure retreating blade still plane air faster than relative air flow.
Never said it was 0 on the retreating side, just that the limit to the aircraft's lift generation is the retreating blade.

Be nice to have an advancing blade on each side, and not have to worry much about the retreater.

Petit-Lion 19th Jun 2022 18:09


And a super STOL might even be a winner.
Or a conventional helicopter... With these much-awaited (still non-existent) great batteries, right-sized motors... ground effect, translational lift, well-understood flight regimes...
And what about the very high nozzle velocity of those tiny fan-jets? Ultraclean FOD-free Lillipads?

Winemaker 19th Jun 2022 23:06

Endurance seems, to me, to be the big problem. With the much bigger power demand with a vertical landing and take off, a go-around would see to be a real deal breaker for certification. As for the machine(s) as extreme STOL, that seems to totally destroy the entire concept of their potential use as some sort of city air taxi. How did the New York rooftop helicopter flights turn out? Probably a good reference. I suspect their business case with the huge number of passengers is a bit off the mark....

Ascend Charlie 20th Jun 2022 02:36

Does their claimed range include 30 mins reserve? If not, why would CA$A approve them to operate with less reserve than a real aircraft?

Silver Pegasus 20th Jun 2022 16:28


Originally Posted by mickjoebill (Post 9378315)
Is this achievable if applying the specs of Tesla batteries of 5kilos per 1kWh? The Tesla modules themselves in an 85 kWh Model S are about 900 lbs. The other ~300 lbs is everything else for the pack.

Previously, the battery pack was 157-watt hours per kilogram in the 85kWh Model S, and in the new 100kWh Plaid it is 181.5-watt hours per kilogram.


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