Crasherboy, they use maneuvering jets. The wings don't work in a vacuum.

Esc, there's two things that give the wing section a different path length on the top compared to the bottom. Camber is one of them and angle of attack is the other. A symetrical wing is no longer symetrical when it has a positive angle of attack to the oncoming air.

Also the bedtime story about the lift coming about as a result of the different path lengths is just that. That old theory also relied on the idea that when the air split apart that the top had to race to the rear to meet up with the same air that it was split away from. However that's been shown often that it's not the case. It's far more complex than that. Yes there is a difference in pressure from the bottom to the top in a wing that is developing lift and there is also a redirecting of the direction of airflow from the leading edge to the trailing edge. The pressure differential and this deflection of the airflow being tied together. If you look at the pressure differential it adds up to the amount of lift created. If you also look at the difference in momentum created by accelerating the air into a downward flow it also adds up to the lift that is created. But they are different faces of the same thng.

To play and wonder google up Foilsim and go play with it. It's truly an informative and easy to use tool for studying airfoil basics and flow around different shapes. You can even generate an "upside down flat bottom" section by altering the camber value to a negative amount and then see how your upside down wing still generates lift after all.