One distinctive feature of the P-38 Lightning is its counter-rotating propellers. In most single engine aircraft, several aerodynamic forces combine to pull the plane to the left, a set of effects pilots learn early as “turning tendencies.” With twin engines, designers can cancel out much of this behavior by having the propellers spin in opposite directions. On the P-38, the blades rotate outward at the top, which balances the forces from each engine and eliminates a critical engine. The result