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Why does it have anhedral wings and not "normal" wings? Many other similar aircraft with low-wing have dihedral wings.
enter image description here
Source: DassaultFalcon.com

Edit: This is about the Falcon 900, which apparently has a low-wing design and it's not used for cargo like the An-225

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    $\begingroup$ Possible duplicate of Why does An-225 have anhedral wings though it is a cargo aircraft? $\endgroup$
    – GHB
    Mar 12, 2016 at 18:29
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    $\begingroup$ Aside from the size difference, the same effects should apply on the Falcon 900. $\endgroup$
    – fooot
    Mar 12, 2016 at 18:48
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    $\begingroup$ @fooot but this has not high wings, so there is a fundamental difference. $\endgroup$
    – Federico
    Mar 12, 2016 at 19:14
  • $\begingroup$ @Federico right, that too, but it still has the wing sweep, and the fact that it's only very slight anhedral. $\endgroup$
    – fooot
    Mar 12, 2016 at 19:17
  • $\begingroup$ I'm not an aerodynamics expert, but the raised horizontal stabiliser is a clue - T-Tails seem to have pretty neutral dihedral as well. $\endgroup$
    – Ben
    Mar 12, 2016 at 20:42

3 Answers 3

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For the same reason why the Lockheed F-104 Starfighter had such a pronounced anhedral: It is the size and location of the vertical tail.

Lockheed F-104 Starfighter

Lockheed F-104 Starfighter (picture source).

In both cases, the vertical tail is large relative to the wing and fully above the roll axis. In a sideslip it produces a high rolling moment, so any more rolling moment from the wing would reduce the handling qualities of the aircraft.

Especially in case of the F-104, the raised position of the horizontal tail shifts the center of pressure on the vertical tail upwards, exacerbating the offset location of the vertical tail.

The rear-mounted engines on the Falcon 900 move the center of gravity backwards, so the wing is more backwards than usual for aircraft with wing-mounted engines. Therefore, the part of the fuselage ahead of the center of gravity is large, requiring a larger vertical tail to overcome the destabilizing yawing moment of the fuselage.

The same is true for the Tupolev 134 and 154, and - surprise! - they also have no dihedral, even though both are low-wing configurations.

Tupolev 154M of the Polish Air Force

Tupolev 154M of the Polish Air Force (picture source)

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    $\begingroup$ I wonder if the DC-9 and B727 would be good comparison points as well.... $\endgroup$
    – UnrecognizedFallingObject
    Mar 13, 2016 at 7:21
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enter image description herePicture source

It may seem so when on ground, but in flight the wings flex up. Judging from the photo, the wings seem to have the tiniest bit of dihedral. They also have wing sweep, which provides sideslip-to-roll stability as well.

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  • $\begingroup$ A swept wing can create a visual illusion re dihedral or anhedral from any angle other than straight-on from the front. I would be cautious about concluding that that photo shows dihedral. I would very surprised if the wing flexed enough to remove all the anhedral visible in the photo of the plane on the ground. $\endgroup$
    – quiet flyer
    Nov 17, 2019 at 4:34
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It's because anhedral wings remove one of the biggest disadvantages of dihedral wings - maneuverability. Although dihedral wings give roll stability by pushing up on the wing which is lowered while banking, it also means that whenever the pilot is rolling to one particular direction, the wings have a tendency to oppose that by rolling the aircraft to the opposite direction, giving the aircraft reduced maneuverability. But anhedral wings don't come with such a problem.

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