Shape Adaptive Blades for Rotorcraft Efficiency - Active Tendon

SABRE undertook ambitious and comprehensive research into ground-breaking shape adaptive blade technologies to enable rotorcraft emissions reductions that are significantly beyond the state-of-the-art. SABRE was ambitious across the board, from its development and experimental validation of novel morphing structural concepts, to the introduction of entirely new ways of addressing the challenges of actuation in the rotating frame, to the employment of sophisticated, multi-fidelity emissions focused rotor analyses to optimise achievable emissions reductions.

Task 2.1.6 Active tendon concept development: The use of controllable blade tendons for dynamics tuning whilst in-flight can constitute a revolutionary concept. Its highly compact design and favourable layout will not interfere with existing blade architecture and it will provide fail-safe dynamics changes. The concept does not require substantial modification of the blade design principles as it acts in parallel with existing loads bearing structures. Classical blades operate under very specific set of conditions and constraints. Future shape adaptive blades will operate under changing conditions (such as mass distribution) and will therefore benefit from ability to adapt their in-flight dynamics. Identical or similar concepts are not known to be applied in the helicopter rotor context. The mechanical control power transfer through the blades is known to be used for primary control purposes in K-MAX and SH-2G helicopters. This approach indicates that the proposed blade alterations can be flight certified.

The key findings are summarized in the disseminated publications (linked below). The key achievement in this task was a successful demonstration of the active tendon concept in collaboration with German Aerospace Center (DLR) in Braunschweig using their state of the art whirl tower (https://doi.org/10.1016/j.ymssp.2022.109286).