Do electric ‘jet’ engines need ‘bypass’ air for increased efficiency or is just a combustion problem?
Turbo fan engines work more efficient, because with their huge fan diameter, they have lower disk loading than turbo jet engines without bypass.
Lilium has a very high disk loading, resulting in low efficiency, resulting in short possible hovering times.
I guess I mean is there a channel where air is sucked in like a Dyson ‘bladeless’ ‘fan’?
Imagine a huge two-engine jetliner.
Replace the jet turbines with electric motors. Shrink the entire nacelle. Keep shrinking it, and then multiply it until you have 24 tiny motors in 24 tiny nacelles.
Then integrate those nacelles into the flaps on the back of the wings.
That, and 12 more tiny motor-nacelle-flaps on the front canards, is how their diagram looked.