Lilium vertical take off "jet"

[Ascend Charlie]

By Brian Garrett-Glaser

Doubts persist over Lilium’s aircraft design

Lilium is a polarizing company in the eVTOL space, with many outspoken in their dislike of the company’s aircraft design, which employs 36 small electric ducted fans embedded in the wing and forward canard. Mark Moore, for many years the chief evangelist of electric air taxis at Uber Elevate — recently handed off to Joby Aviation — concluded in 2019 that the aircraft’s disc-loading, a measure of power consumption in hover, is far too high.

In January 2020, an article published by German aerospace magazine Aerokurier titled “Hoffnungsträger Oder Hochstapler?” — “Hope Bearer or Imposter?” — an anonymous aerospace engineer concluded it was impossible for the Lilium jet to reach its desired flight time and range. The author calculated that, using current battery technology of 240 watt-hours per kilogram, the jet would only be able to sustain a hover for 67.7 seconds. Allowing only 60 seconds of hover time without reserve — parameters that regulators will almost certainly not approve — the engineer found the jet would be able to fly for less than four minutes, or 11 miles (18 km).

“Either Lilium has found solutions for technical problems no one else knows, or Lilium’s promises can’t be kept,”

In February, Lilium’s first full-scale technology demonstrator was substantially damaged in a fire during ground maintenance activities — an unfortunate but somewhat common occurrence for electric aircraft developers.

“Our second demonstrator was not damaged in the fire and we will continue our flight test campaign with this aircraft once we have fully understood the cause of this incident,” a Lilium spokesperson said at the time. Lilium has made no announcements concerning its root cause analysis of the fire, which may still be ongoing. The company has not flown a demonstrator aircraft since then,

and on and on the veneer goes.