What is a "spar" in aircraft structures?

A spar is fundamentally a primary supporting member that plays a crucial role in the structure of an aircraft's wings. Its main function is to provide strength and stability, allowing the wing to withstand aerodynamic stresses during flight. The spar runs spanwise along the wing and is designed to carry loads that the wing experiences, including lift, during various phases of flight.

In the context of aircraft design, the spar is often constructed from materials that offer a high strength-to-weight ratio, enabling it to effectively support the structural integrity of the wing without adding excessive weight. This is vital for the overall performance and efficiency of the aircraft.

Understanding the spar's role helps to clarify why it is a critical component in aviation structures, as it directly influences the safety, functionality, and performance of the aircraft.