OH-58 Block II Control Law Upgrades

The Bell Helicopter OH-58 Block II Concept Demonstrator was developed under an internal research and development program. In 2011, the Block II aircraft demonstrated HOGE Performance at 6000 ft pressure altitude, 95 degrees Fahrenheit (6k95F), for test conditions that exceeded the maximum gross weight. As part of the overall development program, the OH-58D baseline control laws were updated to improve handling qualities. This paper describes the control law changes and the resulting improved handling qualities. VMS studies were initiated to assess the main rotor cyclic actuator arrangement. CIFER and COPTER linear aircraft models were developed to support the analysis in conjunction with the CONDUIT flight control design tool. Ultimately, Level 1 Handling Qualities were achieved in the demonstrator aircraft. Predicted optimal SCAS gains were tuned during flight tests. ADS-33 MTE maneuvers were evaluated by both Bell and Army flight test pilots. Pilots were very impressed by the improved handling qualities achieved through this process, making the OH-58 Block II Demonstrator a great candidate for a potential future light scout/attack helicopter.