109-G10 wing slats

[Midnight]

leading edge Slats extend while the plane is verticle. AFAIK, the slats are simply mounted on rails and have no actuators other than gravity. They should only extend when the airspeed is low enough and the wing angle is low enough (i.e <30 degrees)

[Spork42]

These automatic leading edge slats are held in the "out" position by springs. Air pressure pushes them back into the wings into the "closed" position. When you take off, look left or right and watch how they change state depending on your speed. At low speed the spring force is greater than the air pressure force so they stay out. When your speed hits a certain point, the air pressure is greater than the spring force and the slats retract.

When you get to a high AOA or low airspeed situation the air pressure is less than the spring force so the slats pop out.

(Something like that, anyway. I'm no aeronautical engineer so I'm sure there will be defects in the explanation.)

Found this picture, maybe it will help:

The top is like the leading edge on the Me 163

Bottom diagram shows slats like on the 109

[GScholz]

Actually that is not correct. The slats on the 109 uses no spring, they are completely "free floating" on their hinges. The aerodynamic lift on the forward portion of the wing pulls the slats open when a certain angle of attack is exceeded. Speed has nothing to do with the operation of the slats (as long as there is some speed), only the angle of attack.