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Perhaps VTOL is entirely impractical and has no sizeable niche, but it appears Lilium is the least wrong out of all the existing VTOL physical layouts. - No

Perhaps VTOL is entirely impractical and has no sizeable niche, but it appears Lilium is the least wrong out of all the existing VTOL physical layouts. - No additional draggy/heavy structures for the VTOL components, they reuse the existing wings - No large exposed props, which have noise and hazard concerns - Propulsors are synergistically combined with the wing upper surface, enhancing lift during cruise - VTOL mode actuators are synergistically combined with ailerons/elevators, reducing part count - They have wings for efficient long-distance flight (surprisingly some don't!) - Contingency ability for runway landing if the battery is too depleted - The aforementioned canard advantage If any of the VTOL schemes are workable (which is admittedly an open question!) it will be Lilium.

cjbgkagh 2y ago
It appears you’ve drunk the coolaid. I looked into it more and can now confidently say it’s a total scam. The stuff you’re talking about is window dressing.
- schiffern 2y ago
  Maybe that's true! If you can elaborate on your confident saying with facts, sources, or explanations, I would certainly give it my full consideration. It wouldn't be the first time I've been wrong! What makes you think it's a "total scam"?
  - cjbgkagh 2y ago
    My prior for eVTOL these days is scam, but I googled ‘Lilium Jet scam’ and hit this; https://news.ycombinator.com/item?id=29651504 https://news.ycombinator.com/item?id=29651504 What I was looking for is someone to say it can’t work because of the math XYZ and for a person to say back that math XYZ is wrong because of ABC and that second part never happens. The stuff they talk about is window dressing and doesn’t answer questions like, where are your 500wh/kg batteries? I remember when Ballon Boy happened and I took one look at that Ballon and it was instantly obvious it wasn’t carrying a kid, but apparently others were still expecting to see a kid when the balloon landed.
    - schiffern 2y ago
      >My prior for VTOL these days is scam That doesn't answer my question. It just hides your 'scam' claim within your prior. _Why_ is your a priori expectation for all VTOL to be a scam? And does that generalized reasoning in fact apply to the specific case of Lilium? >where are your 500wh/kg batteries That's probably the least speculative out of all their bets. Moore's Law for microchips may have ended, but a similar (slower) scaling law for batteries seems to be holding for decades now. My prior is that batteries will continue on the same curve.
      - cjbgkagh 2y ago
        You can also check out their stock price. Down from peak 92%, so at least to investors it’s looking less likely they’ll deliver instead of more likely. I gave a link in which others listed their rationale for why they don’t think it will work. Their availability estimates for battery capacity is double the long term rate of improvement - which seems unrealistic. But yah know with enough wh/kg just about anything will fly.
        schiffern 2y ago
        Imagine thinking stock price pegged to peak price indicates company value. :-/ > I gave a link From your link: > 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... The variable nozzle is still present[1], but Lilium long ago dropped variable pitch[2]. "Tilt-wing" is also inaccurate, since they only move the (already moving) aileron and elevator surfaces, not the wing and its associated structures. Hopefully this can help clear up these (hastily-Googled) concerns. >Their availability estimates for battery capacity is double the long term rate of improvement This is an interesting claim that I'll look into, thanks. Do you have a source? I found a few slide decks but I couldn't immediately find this part, so any help would be appreciated. I do expect in the nominal case that Lilium will take perhaps twice as long to come to market, so in the end the delays may roughly cancel out. Time will tell. Note that battery density will effect all eVTOL startups equally, so it's not really a competitive disadvantage for Lilium per se, but rather an overall industry challenge. And I agree, there are many challenges facing the industry! Good deep discussion, thank you. Cheers mate [1] https://lilium.com/newsroom-detail/technology-behind-the-lilium-jet https://lilium.com/newsroom-detail/technology-behind-the-lil... [2] https://lilium.com/newsroom-detail/youve-never-seen-anything-like-this-an-introduction-to-the-lilium-jet https://lilium.com/newsroom-detail/youve-never-seen-anything...
kens 2y ago
>If any of the VTOL schemes are workable... That reminds me of the "V/STOL Wheel of Misfortune", a diagram of 45 different V/STOL designs, of which four made it into service. https://www.cmlx.co.uk/hawkerassociation/hamain/wheelmisfortune.html https://www.cmlx.co.uk/hawkerassociation/hamain/wheelmisfort...
- notahacker 2y ago
  On a similar note, the Aviation week ranking for current Advanced Air Mobility projects is named a "reality index"! https://aamrealityindex.com/aam-reality-index https://aamrealityindex.com/aam-reality-index (Lilium is in the upper middle of this, FWIW)
- marcosdumay 2y ago
  On that case, past performance is absolutely not a guide for future results. The weight/power ratio of electrical motors is so different from combustion engines that it's a qualitative difference already. Just because nobody has ever been able to solve that problem, it doesn't mean that a lot of people won't easily solve it now.
calmbonsai 2y ago
Joby aviation seems the furthest along. Joby has completed many test flights that mimic its real-world route distances and energy-altitude flight regeimes. Its flight avionics package (essential for VTOL fly-by-wire) has received FAA certification. Related to Lilium and noise, Joby has a lower overall emitted dB energy and, specifically, a much lower dB signature in the human hearing range.
renegat0x0 2y ago
Huh. What about Volocopter? Appears to be entering market. https://www.volocopter.com https://www.volocopter.com

cjbgkagh 2y ago

It appears you’ve drunk the coolaid. I looked into it more and can now confidently say it’s a total scam. The stuff you’re talking about is window dressing.

schiffern 2y ago
Maybe that's true! If you can elaborate on your confident saying with facts, sources, or explanations, I would certainly give it my full consideration. It wouldn't be the first time I've been wrong! What makes you think it's a "total scam"?
- cjbgkagh 2y ago
  My prior for eVTOL these days is scam, but I googled ‘Lilium Jet scam’ and hit this; https://news.ycombinator.com/item?id=29651504 https://news.ycombinator.com/item?id=29651504 What I was looking for is someone to say it can’t work because of the math XYZ and for a person to say back that math XYZ is wrong because of ABC and that second part never happens. The stuff they talk about is window dressing and doesn’t answer questions like, where are your 500wh/kg batteries? I remember when Ballon Boy happened and I took one look at that Ballon and it was instantly obvious it wasn’t carrying a kid, but apparently others were still expecting to see a kid when the balloon landed.
  - schiffern 2y ago
    >My prior for VTOL these days is scam That doesn't answer my question. It just hides your 'scam' claim within your prior. _Why_ is your a priori expectation for all VTOL to be a scam? And does that generalized reasoning in fact apply to the specific case of Lilium? >where are your 500wh/kg batteries That's probably the least speculative out of all their bets. Moore's Law for microchips may have ended, but a similar (slower) scaling law for batteries seems to be holding for decades now. My prior is that batteries will continue on the same curve.
    - cjbgkagh 2y ago
      You can also check out their stock price. Down from peak 92%, so at least to investors it’s looking less likely they’ll deliver instead of more likely. I gave a link in which others listed their rationale for why they don’t think it will work. Their availability estimates for battery capacity is double the long term rate of improvement - which seems unrealistic. But yah know with enough wh/kg just about anything will fly.
      - schiffern 2y ago
        Imagine thinking stock price pegged to peak price indicates company value. :-/ > I gave a link From your link: > 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... The variable nozzle is still present[1], but Lilium long ago dropped variable pitch[2]. "Tilt-wing" is also inaccurate, since they only move the (already moving) aileron and elevator surfaces, not the wing and its associated structures. Hopefully this can help clear up these (hastily-Googled) concerns. >Their availability estimates for battery capacity is double the long term rate of improvement This is an interesting claim that I'll look into, thanks. Do you have a source? I found a few slide decks but I couldn't immediately find this part, so any help would be appreciated. I do expect in the nominal case that Lilium will take perhaps twice as long to come to market, so in the end the delays may roughly cancel out. Time will tell. Note that battery density will effect all eVTOL startups equally, so it's not really a competitive disadvantage for Lilium per se, but rather an overall industry challenge. And I agree, there are many challenges facing the industry! Good deep discussion, thank you. Cheers mate [1] https://lilium.com/newsroom-detail/technology-behind-the-lilium-jet https://lilium.com/newsroom-detail/technology-behind-the-lil... [2] https://lilium.com/newsroom-detail/youve-never-seen-anything-like-this-an-introduction-to-the-lilium-jet https://lilium.com/newsroom-detail/youve-never-seen-anything...

kens 2y ago

>If any of the VTOL schemes are workable... That reminds me of the "V/STOL Wheel of Misfortune", a diagram of 45 different V/STOL designs, of which four made it into service. https://www.cmlx.co.uk/hawkerassociation/hamain/wheelmisfortune.html https://www.cmlx.co.uk/hawkerassociation/hamain/wheelmisfort...

notahacker 2y ago
On a similar note, the Aviation week ranking for current Advanced Air Mobility projects is named a "reality index"! https://aamrealityindex.com/aam-reality-index https://aamrealityindex.com/aam-reality-index (Lilium is in the upper middle of this, FWIW)
marcosdumay 2y ago
On that case, past performance is absolutely not a guide for future results. The weight/power ratio of electrical motors is so different from combustion engines that it's a qualitative difference already. Just because nobody has ever been able to solve that problem, it doesn't mean that a lot of people won't easily solve it now.

calmbonsai 2y ago

Joby aviation seems the furthest along. Joby has completed many test flights that mimic its real-world route distances and energy-altitude flight regeimes. Its flight avionics package (essential for VTOL fly-by-wire) has received FAA certification. Related to Lilium and noise, Joby has a lower overall emitted dB energy and, specifically, a much lower dB signature in the human hearing range.

renegat0x0 2y ago

Huh. What about Volocopter? Appears to be entering market. https://www.volocopter.com https://www.volocopter.com