Morphing concepts in the field of rotorcraft

Drawing inspiration from avian creatures, aeronautical engineers strive to create an ideal wing design that can seamlessly perform in various flight conditions. Avian creatures, as well as bats and other flying organisms, exhibit a striking aptitude to adjust the lift produced by their wings, displaying the capacity to repeatedly tailor their wing configurations to match specific environmental conditions. An example of this is when their wings are tightly tucked during dives for hunting, or fully extended during gliding to conserve energy. Moreover, these organisms can manipulate the curvature and twist of their wings to maintain precise control over their aerial maneuvers. In contrast, engineers in the aircraft industry continue to rely on the standard, robust and structured “one-point design” approach, which remains the most practical and feasible method to apply. Nonetheless, advancements in technology have emerged to address long-standing challenges in wing manufacturing that were previously deemed insurmountable. This convergence of different technologies has given significant momentum and recognition to the field of “morphing discipline”. When considering an aircraft, shape changes primarily relate to the wing of a fixed-wing aircraft or the blade of a rotorcraft. The concept of achieving a "smooth" shape change stems from the crucial need for drag reduction and improved flow quality, resulting in improved overall performance. The state-of-the-art morphing concepts applied to rotorcrafts comprise a wide range of investigations aimed at improving performance. Looking ahead, the primary challenge for morphing technology will be to persuade the industry of its tangible benefits. This encompasses enhanced aerodynamic efficiency, minimized installation footprint when contrasted with conventional control surface mechanisms, reduced overall weight, and an equivalent standard of safety. This research provides an overview of the current development of different control devices and explores the impact of previous and continuous research endeavors in this field. Numerous ideas for managing airflow have been explored with the aim of enhancing the performance abilities of rotary-wing aircraft. These include active morphing in rotorcraft such as leading edge slats, trailing edge flaps, and passive morphing in rotorcraft such as variable rpm rotorcraft. The aim of these blade modifications is to achieve various desired effects such as increasing the maximum lift coefficient, reducing drag, and minimizing vibratory loads. Convincing the industry of these advantages will play a crucial role in shaping the future of morphing technology.