Wing types?

@poly track and I flat bottom aircraft should only be utilized at small speeds since it produces a lot of drag, which is excessive at greater speeds. However, it does provide lift even at low speeds and zero angle of attack.

flat bottom is best wing
-Lots of lift
-high AOA before stall
-very smooth, predictable stall characteristics

Flat bottom generates lift even at low speed and zero angle of attack, so it should be used at slow aircrafts, because it produces also a lot of drag, too much for higher speeds.

Symmetrical Airfoil generates lift only with a positive or negative Angle of Attack, and produces less lift than other airfoil shapes. But to generate lift you need AoA and enough speed, much more than the flat bottom airfoil, so it's most effective at supersonic airplanes.

Semi-symmetric is "somewhere in the middle", it generates an smaller amount of lift (and drag) at low speed and zero AoA, so it's the best choice for airspeed between mach 0,7 and 0,95.

That's the short version of an text I've found on Simpleplanes, you can find it
[here]
(https://www.simpleplanes.com/Forums/View/1172990/Flat-Bottomed-vs-Semi-Symmetrical-vs-Symmetrical-Airfoils-In-SP-and-RL)

It has to do with lift with an AoA of 0 degrees. Symmetric provides no lift, semi delivers some, and flat bottom supplies great lift.