Towards Closed-Loop Control Tests of the SHARCS Active Pitch Link in the Rotating Frame

This paper describes the first ever closed-loop control tests of an electrically driven Active Pitch Link (APL). Design and prototyping of a 3rd generation Active Pitch Link is described first, followed by the non-rotating and rotating tests of the Active Pitch Link. Non-rotating tests consisted of 3 stages: the test of functionality, the identification of the stiffness curve and the closed-loop control tests. The closed-loop control tests showed remarkable similarity to earlier CFD results, exhibiting close to 60% reduction in vibratory loads. The new state-of-the-art Carleton Whirl Tower facility is described too. It is this facility, in which the rotating-frame tests of the Active Pitch Link were conducted. It was found that the baseline vibratory levels of this facility - arising from the aerodynamic interference between the blade and the test stand - are sufficient to provide input to the APL. Preliminary functionality tests in the rotating frame are also explained at the end of the paper.