EFFECTS OF FLIGHT DECK CONFIGURATIONS AND CONDITIONS ON HELICOPTER SECURING REQUIREMENTS AT LANDING

摘要

Securing requirements of a helicopter onboard a naval vessel can only be evaluated by performing detailed helicopter/ship dynamic interface analysis. This involves quantifying the dynamic loads acting on the helicopter and calculating the corresponding interface reactions and helicopter responses. It was concluded in previous studies by Indal Technologies Inc. that the aerodynamic loads generated by the main rotor contribute significantly to the overall loads. Although the rotor collective is normally set at its minimum after landing, the resulting rotor thrust may exceed 25% of the helicopter weight, depending on the wind speed and the roll angle. To evaluate these induced rotor loads, a computer model of the rotor could be used. However, the accuracy of the induced loads is dependant on the assumptions used, specifically in relation to the conditions of the wind over the flight deck. ITI and DCE undertook the challenge of investigating the assumption through wind tunnel testing. The testing examined the effects of wind speed, roll angle, flight deck width and height above the water line on the rotor induced loads. In addition, mapping of the flow over the flight deck was conducted to support the analysis of the results and establish a method to augment the induced rotor loads predicted by analytical methods for use in helicopter/ship dynamic analysis. These tests were performed at the NRC wind tunnel facilities in January- March of 2003. The paper presents a review of test results and discusses effects of the flight deck configuration on the helicopter/ship dynamic interface. The impact of the test results on establishing limits for on-deck operation of the embarked helicopter is also addressed.