Thanks! I’m so glad you enjoyed it! Is there anything specific you want me to cover about the Lilium Jet? Best, John

@@zhihenglou I watched it once and was about to comment but now says private. Incredible amount of work has gone into it. I did see this regarding battery tech "CATL's Condensed Battery will feature high safety and high energy density, with single cells having an energy density of up to 500 Wh/kg, the company's chief scientist Wu Kai said today at the Shanghai auto show."

Thanks, it's coming out soon! Stay tuned!

@@zhihenglou Fantastic. The simplest solution might simply be to not refer to the word Lilium. Perhaps use another word like Lilly VTOL jet or something like that. Also perhaps state via disclaimer that it's an opinion piece and not necessarily a statement of fact and encourage people to do their own research, in order to establish their own facts.

@@zhihenglou This was an example provided by Chat-GPT that I tricked into writing me a legal disclaimer. "Disclaimer: The opinions expressed in this engineering opinion piece are solely those of the author and do not necessarily reflect the views of any company, organization, or institution the author may be affiliated with. The information contained in this article is provided for educational and informational purposes only and should not be construed as professional engineering advice. The author assumes no responsibility for any errors or omissions in the content of this article or for any damages arising from the use of the information contained herein. Readers should consult with a qualified engineer for advice specific to their particular circumstances."

@@zhihenglou Although perhaps get advice, as you are already an engineer, however I think you could express an opinion, as long as you make it clear that it's only an opinion and not necessarily a statement of fact about the aircraft.

Thank you for your feedback! May I ask what the problem with the audio was? (I checked again and I could not detect anything wrong). Cheers!

Audio cuts in and out, similar to automatic gain control or a post equalizer set to flat. Your live (recorded) intro video from 2 months ago is better, although the recording settings are quite different on the two videos.

@@stevieathome4942 oh no! I indeed had problems with my microphone recording, which I then tried to fix retrospectively in the video editor. Thanks for the technical tips, I will ask some of my friends who know more about this. Apologies for the bad audio, I’ll try hard to get it right for next time. Thanks for your time!

Hi Michail, I’m glad to hear that you found the video helpful. The Lilium video is coming soon (around March)!

@@zhihenglou thank you for the reminding. But this video can't be opened! It looks like it's private!

@@zhihenglou actually I saw your video yesterday. Yes it’s a good idea to unlisted because I think it was a bit aggressive for a Nasdaq listed company. Anyway in my opinion since you can’t have the actual test flights exact data, your approach can not be 100% correct. Also there are a lot of things concerning an actual flight that can’t be explained solely with raw numbers. I fly commercial planes for long time and as I know from my experience there are things that an aerospace engineer can’t analyse correctly without actual test flights. In addition, the actual operation of a future eVLOT operator can choose initially to reduce the max range or the max operation altitude of the Lilium eVLOT plane. This could change everything…. Also there are other issues concerning the total battery consumption (for example: adverse weather operation, winds aloft, icing, air traffic, VFR or IFR flight rules, reducing the max take off payload for longer flights, en route landing alternates and too many other factors). As you know Archer have almost the 1/3 of Lilium’s projected max range, but already they are having a lot of plane pre-sales! In my opinion we need to support new ideas and aggressive plans, otherwise we can’t look the future with a positive attitude. In the past, there were so many different crazy aircraft types that under normal circumstances, we could bet all our money for an 100% failure but at the end the flights were unexpected successful. Since EASA is involved with the type ratings (and not FAA) I am trusting their safety standards. In my opinion Lilium management are professionals with a lot of experience. They can’t be so silly to spend billions€ for a project that is not having 2-3 back up alternative plans. As I said before, a reduced range and/or a lower max flight level operation can change the required performance dramatically. Even a retractable gear could change the numbers (lower drag) especially during the phase of climb/cruise/decent or a go around.

@@michailpachiadakis3651 I understand what you mean by those points and I respect your opinion deeply, especially considering you are a commercial pilot with such extensive experience. The reason for the video’s tone is based on the evidence and points I make in chapter 2 and 3 of the video. Considering the revelations I make in those video chapters, I think the tone could be considered appropriate. Where there any specific points I made in chapter 2 that you disagreed with? I appreciate that everyone has their own point of view, and I would appreciate it if you could share me your view of chapter 2 in more detail… Here’s the video in case you need a link: kzfaq.info/get/bejne/bbuXpaynu63MeXU.html Thank you in advance! Best, John

Hi Oluwaseun, Yes, I’m working on that video at the moment! Have a great day :)

are you sorry you asked?

Yes, the statement about Lilium’s horizontal and vertical power is true! I am currently working on graphs to present this characteristic in a more thoughtful and structured way. Do you have any other thoughts about the Lilium Jet (that you want me to look into)?

@@zhihenglou yes there’s some test about a new engine with propeller outside the turbine intake I’ll post the link here

kzfaq.info/get/bejne/pdCGgbKbkteXg4U.html CFM RISE engines might be the answer why outside propellers is the best choice for evtOLs (idk) … Another concern is battery energy density and fire safety over 350Wh/Kg. Lilium might need some beefier batteries than the other EVTOLs. Maybe they all are short on energy for a 150 mile trip plus 50mile reserve? I believe the minimum density required is around 320wh/Kg I believe the best batteries are only 230-250wh/Kg (Tesla and Panasonic)

Hi, I've watched the video you linked, and I think I've seen this project before. I believe it is part of a larger umbrella programme called European Clean Sky 2. The closest resembling idea for eVTOLs is an electric pusher propeller. For example, the Kittyhawk Heaviside has several pusher propellers.

The energy density values you have quoted are definitely well-researched! The Lilium Jet likely requires significantly more advanced and higher performance batteries. I remember some optimistic forecasts in 2016 that assumed an annual improvement in the battery's energy density of 5-10%. Now, in 2023, I do not think these forecasts have come to fruition. The most sensible assumption is to use the values you have quoted 230-250Wh/kg. From my knowledge, this is the state-of-the-art.

Hi Brad, I see where you are coming from though I think there are some legitimate use cases for eVTOL aircraft. If you calculate the transportation efficiency (e.g. energy consumption per passenger kilometre), I agree that eVTOL aircraft are less efficient than ground transportation methods and, hence, investing in this technology could be considered wasteful. However, ground transportation heavily depends on infrastructure, like roads, bridges and rails. A case in point is the coastal cities where rivers and water are natural barriers for ground transportation (e.g. San Francisco, London, Shanghai). Bridges help people cross these waters, but they are usually congested during rush hours. In these situations, the car's transportation efficiency can be lower than an eVTOL's. If you have ever been unfortunate enough to commute on such bridges during rush hours, you would see why supplementary solutions are necessary. The potential benefit of making these aircraft electric is to lower the acquisition cost (in theory, electric propulsion is mechanically less complex than conventional propulsion methods). The best case scenario is when economies of scale can then be used for eVTOL manufacturing, making the volume of production and manufacturing processes more like cars than traditional aircraft. I think the bottom line is that electric aircraft make as much (or as little) sense as electric cars. Batteries are only energy carriers; we still need renewable energy sources. Just my two cents :). Have a nice day, John

Thanks for your thoughts! Indeed, the V22 Osprey and AW609 all have two tiltrotors. However, I am not sure if it possible to trim a V22 Osprey with OEI. Does anyone reading this comment know? For eVTOLs, I think we can consider having more than 4 rotors for redundancy. Electric motors are cheap, and electrical power can be transferred easily to the motors via a power cable. I would assume that eVTOLs have a higher safety requirement, too. The cost of jet engines and the difficulty of transferring power mechanically may have limited the V22 Osprey to 2 rotors. Personally, I like 6 or 8 rotors. Have a nice day!

@@zhihenglou i think the only way to get one to lift a decent amount for a decent amount of time is use one main rotor with conventional fuel for the primary lift and smaller electric motors sticking out the side for steering and spinning and slight height adjustment. if the main rotor could achieve the equivalent of neutral buoyancy then the electric motors could have an easier time and last longer than 2 minutes

@@frankyflowers I imagine this will be like a compound helicopter, with a hybrid propulsion? Sounds like a cool idea! I definitely agree that the battery is limiting the aircraft range (like electric cars)… hopefully the energy density will improve 👍🏻

@@zhihenglou not so much for propulsion just to keep it stable and tilt the craft so the main rotor can give the thrust