Print Email Facebook Twitter Investigation of the effects of autorotative flare index variation on helicopter flight dynamics in autorotation Title Investigation of the effects of autorotative flare index variation on helicopter flight dynamics in autorotation Author Scaramuzzino, Paolo Francesco (TU Delft Control & Simulation) Pavel, M.D. (TU Delft Control & Simulation) Pool, D.M. (TU Delft Control & Simulation) Stroosma, O. (TU Delft Control & Simulation) Quaranta, Giuseppe (Politecnico di Milano) Mulder, Max (TU Delft Control & Simulation) Date 2019 Abstract Autorotation is a flight condition whereby the engine of a helicopter is no longer supplying power to the main rotor system, which is driven solely by the upward flow of the air moving through the rotor. For helicopters, autorotation is a common emergency procedure performed by pilots to safely land the vehicle in the event of a power failure or tail-rotor failure. In the classic analysis of dynamic stability of helicopters in powered flight, it is common practice to neglect the effect of variation of rotor angular velocity, as the rotorspeed is constant. However, this assumption is no longer justified in case of autorotative flight. Therefore, the rotorspeed becomes an additional degree-of-freedom in autorotation, giving rise to a new stability mode that couples with classical rigid-body modes. The present paper aims at understanding the role of the rotorspeed degree-of-freedom in modifying the stability characteristics in autorotation of rotor systems with different autorotative flare indexes. Results show that the helicopter dynamics are considerably affected in autorotation as a consequence of the fact that the rotorspeed degree of freedom couples with the heave subsidence mode. Therefore, autorotation requires a different control strategy by the pilot and should not be mistakenly considered only as an energy management task. Furthermore, the autorotative flare index, used to characterize the autorotative performance during the preliminary design phase of a new helicopter, provides only energy information. Indeed, this paper demonstrates that high values of this index, representative of good autorotative performance in terms of available energy over required energy, may lead to degraded stability characteristics of the helicopter in autorotation. To reference this document use: http://resolver.tudelft.nl/uuid:8cbf901e-1319-4083-8a36-bb54821fc062 ISBN 9781713805922 Source 45th European Rotorcraft Forum 2019, ERF 2019 Event 45th European Rotorcraft Forum, 2019-09-17 → 2019-09-20, Warsaw, Poland Series 45th European Rotorcraft Forum 2019, ERF 2019, 2 Part of collection Institutional Repository Document type conference paper Rights © 2019 Paolo Francesco Scaramuzzino, M.D. Pavel, D.M. Pool, O. Stroosma, Giuseppe Quaranta, Max Mulder Files PDF ERF2019_089_final.pdf 839.71 KB Close viewer /islandora/object/uuid:8cbf901e-1319-4083-8a36-bb54821fc062/datastream/OBJ/view