The Anonymous Widower

Flying Taxi Start-Up Raises $240m From Existing Investors Led By Tencent

The title of this post, is the same as that as this article on the Financial Times.

This is the introductory paragraph.

Lilium, a German flying taxi start-up, has raised $240m from existing investors led by Chinese technology group Tencent to fund the next stage of its growth.

The article has a picture of the Lilium Jet, which looks to be an interesting design.

  • It is an electric VTOL aircraft.
  • Power comes from no less than thirty-six electric motors driving ducted fans.
  • The fans will tilt for take-off and landing.
  • Maximum speed will be 190 mph, with a cruise of 170 mph.
  • Range will be 300 kilometres or 186 miles
  • Total installed power is 320 kW.
  • Less than 150 kW will be needed for cruise.
  • A MW (?) battery will be fitted according to Wikipedia. Do they mean MWh?
  • It can carry two passengers with five from 2025.
  • Empty weight is 440 Kg.
  • Maximum take-off is 640 Kg.
  • Initially, it will have a pilot, but the aim is for a completely autonomous aircraft.

Lilium aims to run a city-to-city taxi service starting in 2025.

I have a few thoughts.

Aerodynamics

There have been a lot of developments in aerodynamics in the last few years and the Lilium Jet and other electric aircraft like the Eviation Alice take full advantage of the developments.

So don’t expect electric aircraft to look convectional, unless perhaps they are an electric-engined conversion of an existing conventional aircraft!

Structure

The structure of aircraft is getting lighter and Airbus and Boeing with the 787 Dreamliner are showing what is possible.

Will an empty weight of 440 Kg be possible? Especially, if that includes the battery.

The Wikipedia figures allow a payload of 200 Kg. That must be only two passengers.

Power

Wikipedia talks about a one MW battery, but I suspect they mean one MWh, as this is the unit of battery capacity.

In Sparking A Revolution, I quoted Hitachi’s predictions and suggested that they could have a five-tonne battery, that held 15 MWh by 2035.

This would mean that a one MWh battery would weigh 333 Kg.

This must be near to the target weight of the battery needed to power a Lilium Jet.

But a one MWh battery that weighs just 333 Kg. would be a tough ask given the limitations of today’s battery chemistry.

Fire

Wikipedia says this about a fire.

The first prototype was destroyed by fire during maintenance on 27 February 2020.

As the Eviation Alice also suffered a fire, are these aircraft pushing batteries too hard.

Conclusion

I am sceptical about some of the figures quoted for the Lilium Jet in Wikipedia.

When I see the following.

  • A Lilium Jet in the air, taking-off and landing.
  • Two passengers flying in the aircraft.
  • A Lilium Jet on a set of scales.

I’ll revise my opinion.

There is this video.

Obviously, I’m doing something wrong in my calculations.

March 23, 2020 - Posted by | Transport | , ,

2 Comments »

  1. I like your presentation of info and honesty. It feels like a participation. That’s fun. I used to work for JoeBen B., founder of Joby Aviation. Have you seen their version? http://www.jobyaviation.com They started out with high altitude wind energy, this is a spin-off company after we developed the “toy” back in 2010, that Google since acquired for drone delivery.

    Comment by e | May 26, 2020 | Reply

  2. Thanks, innovation should be fun. I’ll take a look at Joby!

    Comment by AnonW | May 26, 2020 | Reply


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