F. Arévalo, S. Claverías, H. Climent
DOI Number: N/A
Conference number: IFASD-2015-107
AIRBUS Defence & Space (DS) has designed, manufactured, and successfully sold the advanced refuelling tankerand receiver-role aircraft A330-MRTT. The A330-MRTT is based on the AIRBUS A330 platform that is modified for including the following refuelling devices: two under-wing pods, an Aerial Refuelling Boom System (ARBS), a slipway-type receptacle for receiving fuel and, as option, a Fuselage Refuelling Unit (FRU) installed at the aircraft belly. The Boom system is a deployable mast installed at the A330-MRTT rear fuselage with the aim of dispatching fuel at high rate. Once deployed, the Boom is free to rotate (lateral roll and vertical pitch degrees of freedom) relative to the tanker. Control over pitch and roll is obtained through aerodynamic vanes (Ruddervators) located at its rearward tip. In addition, an internal probe can be fore and aft extended to contact the receiver aircraft. The design of a Refuelling Boom System is a challenging process due to the inherent nonlinearities associated to the rigid body large displacements. For example, the downward pitchangle excursions lead to high angle of attack on the Ruddervators with non-clean unsteady aerodynamic loads that excite the structure (buffet). The characterization (flight tests), dynamic loads evaluation (computations), and design solutions to avoid long-term fatigue issues have been analyzed and are detailed into this paper. On the other hand, the high-performance design concept of the AIRBUS DS leads to highly dynamic scenarios that exhibit a strong coupling between the rigid body and the flexible normal modes. This paper analyses a typical evasive scenario as example of complex simulation that combines structural nonlinearities, rigid body modes, and dynamic loads including flexible effects. The analytical simulation is based on the classical frequencydomain methods coupled with feedback-type forces to introduce the non-linear terms. The integral convolution theory is used to couple the linear and non-linear part of the system. The paper shows that frequency-domain-based tools in combination with non-linear feedback loops are useful and robust tools to simulate complex non-linear dynamic load scenarios, showing fairly good results when comparing with flight test data.