yksirroottorisia

Yksirroottorisia is a Finnish term that translates to "single-rotor" in English. It most commonly refers to a type of helicopter that has a single main rotor for lift and propulsion. This design is the most prevalent configuration for helicopters, distinguishing them from multi-rotor aircraft like quadcopters or tandem rotor helicopters.

The single main rotor is typically driven by an engine, which rotates the rotor blades. This rotation generates both lift to overcome gravity and thrust to move the aircraft forward, backward, or sideways. The directional control is managed through a cyclic pitch system, which alters the angle of attack of the rotor blades individually as they revolve, and a collective pitch system, which changes the angle of attack of all blades simultaneously for ascent or descent. A tail rotor, or sometimes an alternative anti-torque system like a NOTAR (No Tail Rotor) system, is usually present to counteract the torque generated by the main rotor, preventing the fuselage from spinning in the opposite direction.

This design has been the standard for helicopter development since the early days of aviation, providing a balance of maneuverability, speed, and payload capacity for a wide range of applications, including military, civilian, and emergency services. The simplicity of the single-rotor concept, despite its complex control mechanisms, has made it a robust and versatile platform.