Dr . Bernard Ferrier , Dr . John Duncan UAV Deck Recovery Stability Analysis

A manned or unmanned helicopter-ship qualification program (Dynamic Interface Testing) evaluates, improves, and/or develops all aspects of shipboard helicopter compatibility. Issues addressed during a test may include the adequacy, effectiveness, and safety of shipboard aviation support facilities and helicopter recovery procedures. Manned and unmanned aircraft share a number of common issues as those related to deck handling, repositioning, tie down, refueling and maintenance tasks. Procedures are further affected by the ability of an aircraft to land and remain on deck, in a controlled or restrained condition from the moment of touch-down to aircraft deck handling and tie down anchor regardless of the environmental conditions. These conditions are largely the product of the turbulent deck environment coupled by the ship’s motion characteristics. The purpose of this Office of Naval Research sponsored Future Naval Capabilities and corresponding UK Ministry of Defence project is to demonstrate the feasibility to characterize the ship’s environment to, amongst other objectives, automatically signal the initiation of UAV descent or to safely launch and recover manned air vehicles regardless of the seaway. A significant portion of shipboard helicopter compatibility testing involves pilot evaluations. Dynamic Interface (DI) testing of unmanned vehicles is not straight forward. The methodology of replacing piloted evaluations with operator estimates and the corresponding test criteria is established prior to actual testing. Focus on one aspect of the interface model to forecast from deck motion the encountered forces acting on a UAV with and without restraints, and corresponding deck motion limits, is discussed. Deck limits are computed from the load factors applied by various securing configurations based on the motion characterization of a platform in terms of, and as a function of, oleo compression and deflection, torque monitor along with indications of precise weight on wheels. Defining a limit, since there is no piloted variation or technique, scales normally used do not apply. The settled approach is to assess system performance using multiple launch and recovery cycles but only one recovery is required to justify an envelope expansion. At-sea validation study results are discussed and compared with simulated scenarios. This computational method employs sufficient performance criteria and correlates well with forecasted quiescent windows of deck motion. Results are presented in relation to the deck energy problems normally confronted by a helicopter during recovery in progressively difficult conditions.