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

mickjoebill 14th May 2016 22:45

Lilium vertical take off "jet"
 
Lilium Aviation
Another people carrying drone.
This simpler than others as it isn't trying to be a car.

Verticle takeoff and land using 36 electric fans.
2018 rollout.
The Lilium Jet, cruise 500km (310mi) max 400kph (248mph), and reach an altitude of 3km (9,900ft). Recharges overnight from a standard household outlet. Max range at 180mph. Autonomous landing.
Sports liscence.
360kw battery, over 400hp.
200kg payload.


I wonder what the endurance is in the hover...
The wing appendage that look like a flap is the array of motors that swivels down to hover.
http://lilium-aviation.com/img/stadt-takeoff.jpg

Price of a Tesla maybe?

Mickjoebill

Ascend Charlie 15th May 2016 03:31

The cg is WAY in front of the wing, with no canard to supply lift at the front, so that cylinder at the front will be permanently pointing down to provide upward thrust to counter the cg moment. Instant death if the battery goes flat or the motor quits.

Another dream of some dude playing with a 3-d drawing program and no understanding of physics. Where is the fan motor with its huge intake? Where do the wheels go? Will they add a "Verticle" fin for some stability? And just a little bit of sunburn from that big canopy.

Freewheel 15th May 2016 03:40


Originally Posted by Ascend Charlie (Post 9376463)
The cg is WAY in front of the wing, with no canard to supply lift at the front, so that cylinder at the front will be permanently pointing down to provide upward thrust to counter the cg moment. Instant death if the battery goes flat or the motor quits.


Yeah, but you'll get a great view!

DeltaV 15th May 2016 05:38

That looks daft.

I prefer this one,
http://www.maxon.net/uploads/pics/Sinus_4500px.jpg
and the CGI is better too.

mickjoebill 16th May 2016 02:19

The 36 motors are distributed to create some redundancy.

Not sure about CG as the battery could be rearward and won't alter during flight:)


For reference
A boffin has torn down a Tesla battery. It is a good reference for the weight and specs of a state of the art battery
https://teslamotorsclub.com/tmc/thre...ry-pack.34934/
Tesla battery (LiCoO2):
Total 85kwh battery cell weight is 900lbs plus uber strong housing of 300lbs.
The pack contains modules. Each module weights 56 lbs and delivers 5.31kWh with a mass of 1001 in^2 -

Or 10.55 lbs per kWh
188.4 in^2 per kWh

Edit: The above are specs of a tesla car battery for reference. No specs released yet for the Lilium battery.

M

Ascend Charlie 16th May 2016 03:56


Total 85kwh battery cell weight is 900lbs plus uber strong housing of 300lbs.
That makes 1200 lb or about 500kg, the total takeoff wt is 600kg, which minus the 200kg payload leaves an airframe of 400kg, 100kg short of the battery weight by itself - doesn't add up.

Go to the website, look for the photo looking up at the machine and see that everything is forward of the wing - it will not fly.

See also the pop-out cylinders for hovering - when they pop back in, the occupants' feet are crushed.

Looks very pretty, but somebody is playing with himself.

PDR1 16th May 2016 07:03

No vertical surfaces? Is the directional stability synthetic as well?

Also canard is at the same height as the mainplane, so the inner 25% iof each semispan won't do anything useful.

From that picture it looks like the man propulsion uses ducted fans embedded in the flaps, which would have intakes above the mainplane in forward flight. This could provide some "blown" surface enhancement in the cruise (when you shouldn't need it) which will suddenly disappear as soon as the flap/thrusters are dropped for transition to the hover (when you WOULD need it).

The originator should be given some crayons and left to amuse himself while grown-ups are talking. Oh, he was...

PDR

mickjoebill 16th May 2016 15:24


That makes 1200 lb or about 500kg, the total takeoff wt is 600kg, which minus the 200kg payload leaves an airframe of 400kg, 100kg short of the battery weight by itself - doesn't add up.
It doesn't add up because the figures you quote include the weight of the massive battery frame needed to form the superstructure of the Teslar Model S car.
Base your power v weight calculations on the individual battery modules, these weight 5 kilos and deliver 1kWh.

No specs available on the batteries planned for the Lilium, so using the tesla battery modules as a guide.

In respect to what look like flaps, perhaps they are not required to reduce stall speed.

Wouldn't lifting the nose, let's say, 45 degrees and simultaneously gradually tilting the canard and wing fans downwards, produce a smooth transition from the wing providing lift to the fans taking over?

The Lilium is mentored by ESA, so hard to imagine that they are crackpots.

Mickjoebill

PDR1 16th May 2016 16:22

As far as I can see the concept is trying to use the fuselage as a canard, but even assuming this works I struggle to see how a canard surface with a sub-unity aspect ratio could ever be even vaguely efficient. It should be hideously draggy.

But it might be trying to do something clever with the heavily blown foreplane (more evident in this view):

http://lilium-aviation.com/img/oceanflight.jpg

Concepts like this have been done before. There was a Cessna 150(?) which was fitted with a tiny wing all within the propwash and on its sole flight appeared to fly very well - right up to the point where the engine stopped, revealing the essential weakness of the concept. When I get home I'll loook out the references for that one.

The thing is that other images on the site appear to imply that the "foreplane" and its thrusters would be retracted in the cruise:

http://lilium-aviation.com/img/mountainflights.jpg
http://lilium-aviation.com/img/londonflight.jpg

So it would then be dependant on the fuselage as a foreplane which (as I mentioned) should be hideously inefficient.

With that number of fans active (synthetic) yaw stabilisation should certainly be possible, but certifying it as an alternative to a fin could be a challenge. It's not at all clear how this machine would survive a complete power failure. for this and many other reasons.

PDR

Ian Corrigible 16th May 2016 17:04

The wing layout is reminiscent of the RQ-3A DarkStar, though the forward CG is far more extreme.

The propulsion approach is similar to the recently announced Aurora LightningStrike concept, which may have prompted the ESA 'business incubation' funding.

Given that the Lilium project was only "founded in February 2015 by four engineers and doctoral students," I'd say we have a better chance of seeing the sky blackened with Mollers, Hoverbikes or Terrafugias by 2018 than we do of seeing the Lilium reach the marketplace.

I/C

mickjoebill 16th May 2016 23:54

I don't disagree with comments about the aerodynamic puzzle.
Hard to see how it can be controlled with the forward canards retracted.
The things that looks like wings may not need to produce much lift if motors are tilted down?

They claim 325kw/435 horsepower and endurance at cruise of approx 1hr 25min. Empty weight of 400kg.
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.


Mickjoebill

riff_raff 17th May 2016 01:37

The vertical lift efficiency of all those small diameter/high speed rotors will be miserable. And it's VTOL operation that drives the size of the electric motors/power electronics. An electric propulsion system sized for VTOL operation that accounts for less than 5% of total flight time usually means the motors/PEs will be over-sized for the other 95% of flight time in conventional (wing-borne) operation. This weight penalty can be significant.

Compare this to a battery-electric 2 seat rotorcraft that was actually built and flown. It was a modified S-300C helicopter which already had a well developed rotor system and lightweight airframe. The electric motor was rated at 141 kW which was the same power produced by the original Lycoming piston engine. The lithium ion battery pack weighed 1100 pounds which was limited by the S-300C max GW capability . This allowed around 15 minutes of flight with a single pilot on board.

I'm sure the engineers that designed the Firefly were competent, and the motor/controls/battery were all based on current technology. So it would be fair to use the Firefly's demonstrated performance as a baseline to evaluate concepts like Lilium.

Rotorbee 17th May 2016 09:12

Apart from the things already pointed out - it doesn't even look as it should fly in an environment commonly know as air - , they should have studied the regs a bit more.
They want it to be a light sport aircaft.
A few points:
Max speed 180mp/h - Oh no. Max speed of an LSA can't be more than 138 mph.
No rotorcraft in the LSA category. Since it has lots of rotors, it disqualifies even multiple times.
One engine/motor only in a LSA.

... and a 600kg it would be just 1.2 kg too heavy for an LSA. But that's nitpicking.

Looks like somebody didn't even do the most basic research or they are just in the business to get crowd funding and then disappear to somewhere sunny ... to get in the mood for the project, I am sure.

Ascend Charlie 17th May 2016 21:45

No pix of it on the ground or with wheels showing - where in the nose could you put a retractable nosewheel that doesn't get in the way of the retractable cylinders? Where would the main gear go and still leave room for a battery?

And just imaging the NOISE from 36 screeching little fans doing 15,000rpm to push some air downwards. Pure pud-pulling.

Wageslave 18th May 2016 09:19

Come on, cut them a bit of slack, it's no more than silly verbiage applied to a series of pretty pictures drawn by someone with no knowledge whatsoever of aerodynamics.

It clearly isn't a serious proposal or anywhere close to one.

If anything it's a good troll judging by all the serious technical replies.

Nige321 18th May 2016 09:36


drawn by someone with no knowledge whatsoever of aerodynamics
Really...??
Well either the armchair designers here are wrong, or this lot are...:8


We are a team of visionary aerospace engineers and product designers from the Technical University of Munich, Germany.
Our academic and professional backgrounds span from aeronautics and aerodynamics to robotics and ultra-lightweight structures. Initially funded by the European Union and supported by the European Space Agency and its Business Incubation Centre Bavaria we are developing the most advanced personal aircraft the world has ever seen.

oggers 18th May 2016 09:53


This is the Lilium Jet, the world's first electric vertical take-off and landing jet
...just one problem with that: HELLO, it's only a pretend photo!

mickjoebill 19th May 2016 05:20


And just imaging the NOISE from 36 screeching little fans doing 15,000rpm to push some air downwards. Pure pud-pulling.]
But its German visionaries say it will be much quieter than a helicopter!??

Some reasonable criticism of most of its specs on Pprune, are we losing something in the translation or are they onto something new?

Mickjoebill

riff_raff 19th May 2016 07:22

"We are a team of visionary aerospace engineers and product designers from the Technical University of Munich, Germany. Our academic and professional backgrounds span from aeronautics and aerodynamics to robotics and ultra-lightweight structures. Initially funded by the European Union and supported by the European Space Agency and its Business Incubation Centre Bavaria we are developing the most advanced personal aircraft the world has ever seen."

Based on what this team is proposing, I would question their claims of expertise as "visionary aerospace engineers" or the ability to develop "the most advanced personal aircraft the world has ever seen". Unfortunately, this group of young inexperienced engineers will learn the cold, hard lesson of the difference between conceptual and real world designs. Those 36 tiny electric rotors will produce far less lift than they predict, the complete system will be far heavier than they predict, and it will be much more difficult to control this system than they predict.

Ascend Charlie 19th May 2016 09:48

Then these "Experts" should know that it is far more efficient to accelerate a large amount of air to a low speed, then a small amount of air to a high speed, as well as the noise. Compare the noise and downwash disturbance from a 5-ton helicopter (S-76) in the hover to a Harrier jet.

And their claim to hold degrees from a particular university is far outweighed by my degrees and doctorates from Snotgobbler University, Noo Joisey, they cost me $50 each.

Wageslave 19th May 2016 13:13


Initially funded by the European Union and supported by the European Space Agency and its Business Incubation Centre Bavaria
ie a glitzy prestige project funded by a irresponsible and financially corrupt body notorious for handing vast sums of cash as "subsidies" to anyone with a slick line of talk and maybe a bit of inside influence.
The "visionary" (quaaludes???) designers (aka ambitious permanent students) will live high on the hog for a few years just drawing silly pictures and issuing press statements before it all goes tits-up and they start again with another half decade of taxpayer-funded smoke, mirrors and champagne.
Not a bad lifestyle, all in all, even if it is ultimately one sponged off the taxpayer (ie us) with nowt to show for it.

konradb 19th May 2016 18:08

this looks like

LightningStrike X-Plane ? Aurora

it is going to use the AE1107 turboshaft as used in the v-22 to drive 3 x 1 megawatt generators
will weigh 12000lb, 3000lb of fuel and 1500lb of payload

mickjoebill 18th Jun 2016 04:42

NASA just disclosed design of their X57 experimental electric plane.
They too are exploring many small props rather than a couple of large fans.
The small props on leading edge are used for takeoff and landing, larger motors on wing tips used in cruise.
NASA's X-57 Hybrid Electric Research Plane | NASA

http://www.nasa.gov/press-release/na...umber-new-name
This one doesn't seem to have VTOL capability.
Yes, image is an artists impression.
http://www.nasa.gov/sites/default/fi...a_half_res.jpg
Mickjoebill

Ascend Charlie 18th Jun 2016 05:43

One heck of a yaw moment when one engine stops......asymmetric flight would improve your leg muscles somewhat.

PDR1 18th Jun 2016 07:21

Or you could just fire up a number of the T/O motors on that wing to bring it back into balance...

PDR

PDR1 18th Jun 2016 07:28


Originally Posted by PDR1 (Post 9377874)
Concepts like this have been done before. There was a Cessna 150(?) which was fitted with a tiny wing all within the propwash and on its sole flight appeared to fly very well - right up to the point where the engine stopped, revealing the essential weakness of the concept. When I get home I'll loook out the references for that one.

I'd forgotten about this - apols!. I've just looked it up and my memory was faulty. The aeroplane I was thinking of was the 1953 Larsen Speed Bird, which was based on a Taylorcraft BC-12:

http://www.aerofiles.com/larson.jpg

PDR

riff_raff 19th Jun 2016 02:40

Don't know if I believe the claims made by NASA for the benefits of this concept.

"NASA’s aeronautical innovators hope to validate the idea that distributing electric power across a number of motors integrated with an aircraft in this way will result in a five-time reduction in the energy required for a private plane to cruise at 175 mph."

They claim the thinner wing will reduce drag in cruise flight. But it does not seem to come close to offsetting the added drag/weight of the 12 electric propellers that are not used in cruise flight.

mickjoebill 6th Dec 2016 06:29

The Venture Capitalist company "Atomico" are backing Lilium Aviation to the tune of €10M

Atomico - Great companies can come from anywhere



New pictures of the prototype/mockup
Big announcement

https://gallery.mailchimp.com/6880a4...98243bb315.jpg

https://gallery.mailchimp.com/6880a4...4dc1c5b4af.jpg

Mickjoebill

mickjoebill 20th Apr 2017 20:34

Lilium test flight
 
It flys.(unmanned)

https://youtu.be/ohig71bwRUE

For a measure of the potential significance of this test flight, read the previous posts from the many whom doubted it was possible.



Mickjoebill

CTR 20th Apr 2017 21:41

Nice video editing
 
[QUOTE=mickjoebill;9747213]It flys.(unmanned)

https://youtu.be/ohig71bwRUE

Mickjoebill,

Please rewatch the video and pay close attention to the editing cut from the full scale non flying mockup to a much smaller flying model.

Also notice that the landing gear is different and no one is photographed next to the flying mode to give a reference to scale.

PDR1 20th Apr 2017 21:42

Erm...that looked like an RC model at about 1/4-1/3 scale (compare its size to the taxiway it landed on, and look at the wobble when it first lifted off).

If so I'm not sure what it proved.

PDR

fatmanmedia 21st Apr 2017 02:19

I was laughing so loud I nearly peed myself watching it, it was clearly a RC scale model, the video was a nicely edited bt of junk.

I'll take more interest when they fly with a person in the cockpit.

mickjoebill 21st Apr 2017 15:49

Hey CTR, PDR1 and Fatmanmedia, in response to your claims about the video, Lilium Aviation posted the following;

As a founder, I can guarantee on behalf of our amazing investors and all you people out there, we did NOT use CGI or a size scaled model. This is the original size of our previous two-seated concept.

Their published timeline is for the first manned flight in 2019.

Mickjoebill

Nige321 21st Apr 2017 16:03

I've just watched it on a very big screen. I'd say it's full size, there's just too much detail for it not to be... Some armchair experts need to go to Specsavers...
:8

CTR 21st Apr 2017 16:13

Please provide weight data
 
I am willing to be convinced with two pieces of data.

Flying model size compared to non flying prototype shown earlier in the video.

Most importantly, the flying models actual weight.

mickjoebill 21st Apr 2017 16:34


Originally Posted by CTR (Post 9748077)
I am willing to be convinced with two pieces of data.

Flying model size compared to non flying prototype shown earlier in the video.

Most importantly, the flying models actual weight.


A multicamera recording, along with a personal guarantee from Paddy, a co-founder, that it is their full size two seater in the video has already answered your first data request..but you still don't believe them, because...?


Mickjoebill

CTR 21st Apr 2017 17:27

Because I have done the math...
 
Mic,

I don't believe because I am an engineer and have done the math. Battery and motor technology is not viable yet. And will likely not be for 10 to 20 years at best.

Regarding scale, the founder stated "This is the original size of our previous two-seated concept". He did not state it it was the same generous size as the mockup shown earlier in the video. I believe it is about 3/4 scale at best.

Regarding weight, I have seen mockups of full scale cars flying. Using one or two pies of composite cloth you could make a good scale size Lilium model that weighed under a 60 lbs fly. But this is far less difficult than what is required to make a real two passenger weight aircraft fly.

So give me real dimensions and weight of what is flying in the video. Then I can check my math.

PDR1 21st Apr 2017 17:38

So all this happened at an airfield in Germany?

If it is a full-size, remotely piloted version where are the certification papers and NOTAMs required for legally flying an untethered SUAV of that size? Germany has rules about that sort of thing.

Personally I'm still sceptical and will remain so until the videos stop using the typical tricks used to obfuscate the size - showing it with nothing at all in the frame to scale it being one of the main ones.

I also don't believe that fans which are lifting what must be over 1,000kg of airframe could be anything like that quiet.

PDR

mickjoebill 22nd Apr 2017 03:42


"This is the original size of our previous two-seated concept".
The point he is making is the production model will be a four seater.
Do you agree that what was flown was a full size two seater craft, ie of a size that could fit two adults?

Mickjoebill

Vertical Freedom 22nd Apr 2017 05:23

Auto....Auto......wanna see an AUTO :D :mad: :D


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