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There is already a long series of questions about the downwash and tip vortexes with nice images, but I'm going to add another one...

Large airliners (A380, B747-8) have horizontal stabilizers competing with small Boeing wings, and definitely larger than business jet wings.

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How does the tail wake look like when the horizontal stabilizers produce significant lift? Does it merge with the wake from the wing or is there a second wake above the first one?

Edit: I've found this image:

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Which shows the tail vortexes below the wing vortexes, and apparently larger than them.

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    $\begingroup$ Oops - what looks like a tail vortex to you looks like the contrails of the inner engines to me. $\endgroup$
    – Peter Kämpf
    Commented Jul 2, 2017 at 21:19

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Yes, when viewed from far enough away.

Close up, both will have their own developing wake. The boundary layer leaving wing and tail will leave a speed discontinuity, and the downward moving wing wake will be complemented by a tail wake, which will slow down this downward movement directly behind the tail, and increase it left and right of the central tail wake. Normally, the horizontal tails of transport aircraft produce a considerable downforce during landing to compensate for the backward shift of the center of pressure when the high lift devices are employed.

Aircraft model flying through illuminated smokescreen

Aircraft model flying through illuminated smokescreen (picture source)

This animated GIF shows the wake of the tail as a darker box inside the bigger wing wake. It forms two small vortices which rotate against the rotation direction of the wing wake and get spread out when being absorbed by the wing wake.

Friction will soon dissipate the much weaker tail wake, so at some distance all what is left is a single wake which looks slightly distorted around its center, when compared to the wake of the isolated wing.

Fun fact: The negative lift on the tail can even contribute thrust.

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  • $\begingroup$ Awesome GIF, I'm mesmerized; have watched it like 100 times. Can almost see the opposite rotating vortices off of the tail, but its almost instantly destroyed by the churning of the wing-tip vortices and downwash. $\endgroup$
    – Devil07
    Commented Jul 20, 2017 at 14:53
  • $\begingroup$ @Devil07: Hehe, you made the same experience as I did. The tail vortex is hard to see, but is real. $\endgroup$
    – Peter Kämpf
    Commented Jul 20, 2017 at 16:01
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    $\begingroup$ If a picture is worth 1000 words, this GIF is worth 10,000 words. ;) $\endgroup$
    – Devil07
    Commented Jul 20, 2017 at 16:11
  • $\begingroup$ @CamilleGoudeseune: Thank you for the edit! $\endgroup$
    – Peter Kämpf
    Commented Sep 11, 2020 at 5:35
  • $\begingroup$ Heh. Thank you for the pretty answer! $\endgroup$
    – Camille Goudeseune
    Commented Sep 11, 2020 at 15:24

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