Peter wrote:
Another problem for air taxi stuff is that – unlike with a car which sits still most of the time, and people accept that – a taxi needs to have a high utilisation. So you get into the “how fast charge” or “swappable battery packs” which we did to death in the other “electric” threads.
Very true. This kind of aircraft will need every bit of battery capacity. So any kind of fast 80% charge will not work. Then you operate at helipads which charge you a 3 digit parking fee every 15 minutes. So to have at least the slightest chance commercially it has to be able to fly an outbound and inbound let on one charge and then recharge at base.
Also the landing gear will not work as shown. It is an aircraft with similar weight as a TBM so it will need a proper landing gear with dampers etc.
As with most battery driven aircraft the final reserve is the real challenge.
You could say that about cars too. It has not been solved for cars (except for a specific mission profile, and specific user housing/parking situation) and solving it for planes (where you don’t have the benefit of spending most of the time at 10-20% of max rated power) is going to be far harder.
Another problem for air taxi stuff is that – unlike with a car which sits still most of the time, and people accept that – a taxi needs to have a high utilisation. So you get into the “how fast charge” or “swappable battery packs” which we did to death in the other “electric” threads.
But nothing stops these “VC entertainers” entertaining VCs 
I know a guy who AFAIK has never delivered a viable product in 30 years, but who raised millions from VCs and lived off it all pretty well.
As with most battery driven aircraft the final reserve is the real challenge. And as that reserve has to stay constant every reduction in battery capacity (temperature, wear and tear etc.) further kills the usable range.
Also the power required to hover with such tiny engines is massive. Compared to a helicopter it uses 3 to 4 times as much power to hover.
What could help would be a different flight profile with minimal hover. Take off like a RATO aircraft accelearting immediately to aircraft speeds, no air taxi or similar. On landing do the same and only use the engines to support the weight for a second a bit like a Falcon rocket booster uses its engines. But obviously such agressive flight profile would increase the overall risk of the operation and might not be well received by passengers ;-)
Well, that went from cool to ugly fast.
Good on everyone who called it early!
They did post a very interesting video:
At least they seem to put some of the numbers on the table. The aspect which is new to me is that they want to achieve a final reserve by assuming the alternate landing site is an airpor,t so the aircraft can perform a rolling landing. This probably saves a lot of energy compared to a hover landing and a drained out battery can support it with the little peak power remaining as it gets discharged while it could not handle a hover any more.
Lilium once again confirmed the point that certification is 3 years down the road – at any given point in time …
Obviously this delay is good news as it only proves the point that they never get stuck with what they have but constantly improve everything.
Sebastian_G wrote:
Besides all the technical issues I do not understand how this should work out as an operation. Now they want to operate from “vertiports”…
I’d say probility is > 50% that in 2 years from now they will announce the next “wise pivot” of their business model to switch the idea from SR-VTOL to LR-VTOL and they have the thrilling news that they just signed an agreement with the market leading LR-VTOL manufacturer which is so much convinced of the great business model that they will share the technology (or to translate it for the less visionary readers: They will buy 50 H135 from Airbus).
This shift will unfortunately increase the fares slightly but that will be more than compensated by the increased safety and convenience of using an even more proven technology. For the investors that obviously only has advantages as increased fares lead to even more revenues.
This is the time when the German Landesbanken will invest big time in the business and Sparkassen will sell Lilliums subordinated notes to elderly people as “are rare and limited opportunity to participate in the hottest investment story of the last 20 years”.
gallois wrote:
Investing in these sort of projects is a bit like investing in a movie or theatre production.
It really is like investing in a musical production, but one without music – and without performers – on an empty stage – in complete darkness – that only “plays” on Tuesday morning between 9:15 and 11:15 – and the spectators hav to sit completely silent for the entire 3 hrs.
The producers, however, have a shiny programme (with great computer renderings of the stage – empty and dark…) already produced and swear that is the future of theatre if not entertainment and therefore the idea alone is worth a billion – not forgetting to quote a McKinsey report that in 5 years from now there will be a 100GPB premium paid per ticket if the production is completely carbon free and therefore musicals without music, performers and light will be a trillion dollar market!
Investing in these sort of projects is a bit like investing in a movie or theatre production.
Firstly there is the fulfillment factor, then you have to work out how much you can lose, taking into account tax and currency advantages etc.
Then you spread your investment between the very risk projects and the less risky investments. As someone wrote earlier 90+% of the very risky projects will fail somewhere along the line, but if even 1 project succeeds the returns can be huge. I met someone who was an original investor in “Jesus Christ Superstar” stage version. He was actually embarrassed by the amount of money he made on that deal.
I really like that sentence “CRI-A01 certification basis was received from EASA in 2020” to the investors that sounds like they have it certified but in fact it seems to mean they received a todo list ;-)
Besides all the technical issues I do not understand how this should work out as an operation. Now they want to operate from “vertiports” but if you need a few such facilites why not simply fly fixed wing from airportd? The whole point of VTOL is if you can operate directly from the backyard.
Then they want to “pool” flights. But especially on shot distances the entire time gain is gone if you have to wait for a flight to depart. The whole point of the helicopters for politicians etc. is if you arrive the flight leaves immediately.
Did any of the investors ever do a VFR flight at low level? In Florida during the day? I assume half the passengers will not feel very good after such a flight and never do it again.
Did any of the investors ever hear about VFR/IFR and icing? How should such a design where the 36 engines will ingest any leading edge ice ever work in IMC? Maybe you could deice it electrically but that would require large amounts of power which is not available. And a VFR only plane would be rather useless in many parts of the world. Or you fly very low like did the helicopter from Kobe Bryant.
Still no talk about a parachute? But in such a design if the eletronics fail or go crazy life is over, no autorotation, no gliding, just done. So at least I would want a parachute system as plan B.
