>>20453342I'm
>>20440809Honestly a lot of stuff is found out through empirical observations instead of theory. But the following rule about control and stability holds. The more stable an aircraft is, the less maneuverable it is and vice versa.
Think of a ball inside a cup. If you push the ball slightly, it'll roll up the side and come to rest in the center. Subtle changes to the ball in a stable system like this means that the ball will return to an equilibrium state.
Now think of a ball on a hill. Nudge it and it rolls down and won't come to rest until some external force acts upon it.
Fighter jets are inherently designed to be unstable, where slight changes to control surfaces like ailerons, rudders, and fins incur large changes in pitch, roll, and yaw respectively. You want it to be agile to outmaneuver other aircraft. The pilot cannot physically respond quickly enough to control the aircraft the way he wants by himself, that's why modern jets have fly by wire systems. Even maintaining trim (level flight) involves the computer helping out even if the pilot keeps his hand steady on the stick.
In passenger or transport aircraft you want it to be more stable. That's why on large planes you see what is called dihedral, when the wings are turned upward slightly like a flat v shape. When a gust of wind hits the aircraft from the side, additional lift is generated on that side and the plane rolls. The opposite wing then experiences more lift, and the result of dihedral is a restoring moment that acts to stabilize the aircraft back to level flight.
It's my basic understanding but I hope that answers the question.
