The Farres line refers to a term used in aviation, specifically in aerodynamics. It is named after its creator, a Spanish engineer named Juan de la Cierva y Codorníu, 1st Count of De La Cierva, who is widely recognized for his contributions to the development of the autogiro, an early precursor to the modern helicopter.
The Farres line, also known as the Cierva–Farres line, is a curved line depicted on a graph that represents the maximum speed attainable by a rotorcraft, such as an autogiro or helicopter, at a given altitude. It serves as a boundary between the regions where the aircraft can be operated safely and those where it may experience instabilities or even a loss of control.
The line takes into account various factors such as the aircraft's rotor speed, altitude, and air density to determine the limitations of the machine's performance. Crossing the Farres line implies a risk of the rotorcraft entering an aerodynamic regime where forces may become uncontrollable or unstable, jeopardizing the safety of the aircraft and its occupants.
The Farres line is an essential tool for helicopter pilots and engineers to assess the flight envelope of a rotorcraft, helping them to understand and avoid dangerous operating conditions. It allows for optimal flight planning, ensuring the safe and efficient operation of these aircraft, particularly at higher altitudes, where atmospheric conditions can significantly impact the performance and stability of the rotor system.
