I just had a look on some of the recent development in the personal VTOL electrical aircrafts. I am wondering if the Lilium VTOL wings produces lift during takeoff? I would expect a quit high wind speed moving over the wing generating negative pressure, hence, beside the thrust force generated by the fans additional lift is generated over the wings? Is this correct?
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$\begingroup$ The Lilium seems to have a bank of mini - thrusters encased in flaps. the flaps are angled straight down on takeoff - how would there be windspeed over the wings? The part of the intake air coming from the front? Why would that be 'high speed', seeing as the air can also reach the intake from every other direction? $\endgroup$– bukwyrmNov 13, 2018 at 8:27
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$\begingroup$ @bukwyrm you are expecting that there will be no high speed flow over the wings? $\endgroup$– MokusNov 13, 2018 at 8:31
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$\begingroup$ If the thrusters point straight down, the inlet can get airflow from every angle , why would the air above the airfoil be especially moved? $\endgroup$– bukwyrmNov 13, 2018 at 10:25
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2 Answers
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The take off is aided purely from the mini fans which is pointed vertically at the aft of the wing to generate pure vertical thrust. The wings will generate only drag and zero lift because the airflow(aerodynamic force) is attacking perpendicular to the chord line. Hence the wings are used only to aid the flight in cruise.
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$\begingroup$ +1, the "claim to fame" with Lilium is the seamless transition from "all lift from engines" to "all lift from wings" in a simple and robust manner. Or that is at least what their marketing material suggests. Whether it will actually work like that... $\endgroup$ May 8, 2019 at 9:52
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We don’t have enough information, but there are electric fans mounted on flaps which are sucking air over the wings - even when the flaps are vertically placed, it still should produce some suction (and airflow) over the wing area, too. This amount is probably small, and in my view, this high lift system be would ideal for STOL configuration – Lillium is a bit secretive, but on the recent photos there is a conventional landing gear – so, maybe, they will go for STOL, instead of pure VTOL operation.(https://lilium.com/technology/) But, this configuration – “fans in the flaps” is quite a novelty, most probably this is also the best and most elegant way to get full benefits of blown flaps concept – on blown flaps than “suction flaps” configuration!
