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enter image description here
Image source datawiki.net

Is this to slow down airspeed. I know that the high pressure and low pressure above and below the wing both contribute to downwash, but how does this airfoil form downwash?

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    $\begingroup$ What do you mean by 'slow down airspeed'? $\endgroup$ – aeroalias Oct 9 '15 at 23:54
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    $\begingroup$ @Ethan If you can post a link to an image then you can post the image directly without needing to upload it. I know others have asked you about this before. What is stopping you? (This isn't an upload issue so please don't blame your laptop) $\endgroup$ – user11516 Oct 10 '15 at 4:42
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    $\begingroup$ Also good to indicate image sources. (I grabbed it from Ethan's original post.) $\endgroup$ – FreeMan Oct 12 '15 at 13:48
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Downwash is simply the deflection of air due to airfoil (or wing etc.)

Symmetric airfoils don't produce downwash (or lift) at zero angle of attack.

Airfoil Zero angle of attack

Source: oppositelock.kinja.com

However, as the angle of attack is increased, the (symmetric) airfoil produces both.

Airfoil positive angle of attakc

Source: Effect of angle of attack on flow field and body forces by Paul Nathan from youtube.com

Symmetrical airfoils are used in rotary wing applications, vertical tail (and rudder) etc.

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  • $\begingroup$ Does a conventional airfoil produce lift at a zero degree angle of attack? I mean airfoils that are curved downwards on the top and have no curve on the bottom. $\endgroup$ – Ethan Oct 10 '15 at 15:15
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    $\begingroup$ @Ethan Cambered airfoils produce lift at zero angle of attack. $\endgroup$ – aeroalias Oct 10 '15 at 15:32

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