Not to be confused with helicopters.
Starting with sketchyphysics3, true planes (as in, not attatched to a hidden car) appeared. At first, the were powered by magnets attatched to a magnetic object. That created a sort of engine. Then, actual thrusters were inserted into sketchyphysics. While the features of a plane have changed over time, the fundamental concept has stayed the same since the release of sketchyphysics3 alpha.
General control system
During the heyday of the sketchyphysics plane, many users tried to avoid using gyros, perhaps because it is somewhat of a cheat. They tried to make the plane control as close to the real thing, relying on pitch and thrust to remain stable. This can be hard for a new user to grasp, so there are also tutorial planes that have a constant upwards thrust. Still, a few users will crash every plane given to them. They usually either rely on helicopters or highly simplified versions of the plane.