Original Article Proc IMechE Part M: J Engineering for the Maritime Environment 1–10 Ó IMechE 2017 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1475090216689172 journals.sagepub.com/home/pim Aerodynamic effect of the aircraft carrier island on flight deck flow with cross wind Rafael Bardera-Mora 1 , Marina Leo ´ n Calero 1 and Adelaida Garcı ´a-Magarin ˜o 2 Abstract Regarding the importance of helicopter operations over aircraft carriers and the increment of the workload of the pilot during take-off and landing manoeuvres, it has been performed a study of the flow downstream the island of an aircraft carrier in cross-wind conditions. The main objective of this work is to characterize the aerodynamic flow in that critical area providing insight for future investigations directed to reduce the workload and improve safe operational conditions. Then, a wind tunnel test campaign was carried out using particle image velocimetry and laser Doppler anemometry tech- niques. Finally, wind tunnel results have been compared with on-board measurements showing a good agreement between full-scale and model-scale wind tunnel tests. Keywords Aircraft carrier, aerodynamic cross wind, wind tunnel, particle image velocimetry, laser Doppler anemometry, on-board measurements Date received: 8 March 2016; accepted: 18 December 2016 Introduction As long as helicopters appeared, it has been desirable to land them on ships at sea to perform different roles such as anti-submarine and surface warfare, surveil- lance, troop transfer or to supply replenishment at sea. 1 Since First World War, the most powerful countries understood the strategic importance of aviation shipped to deal with conflicts far from their country. Nowadays, aircraft carriers are essential for modern naval operations and one of the most powerful weap- ons of an army. Despite routine operations and experi- ence of the pilots, the ship–helicopter dynamic interference is one of the most challenging environ- ments in which pilot will operate. 2 Over the years, numerous accidents have occurred during flight opera- tions; 3 therefore, the study of this problem has become more important in the last years in order to optimize helicopter capabilities. The ship superstructure is essentially a combination of bluff bodies 4 since it has been designed with practical rather than aerodynamic consideration. 5 Therefore, sharp edges because of corners and the presence of the island, antennas, stacks and radomes cause a highly complex and turbulent flow around the ship that interacts with helicopter performances. 6 At certain flow conditions and close to the regions affected by the ship’s superstructure, an area of massive flow detach- ment appears as in tall buildings and airports. Flow appears around corners generating a series of vortices which results in a horseshoe vortex structure. 7 Hence, depending on the distance from the lateral edges of the island to the operational point, the flow would have three-dimensional (3D) effects. At these conditions, high-frequency disturbances are damped by the rotor system and low-frequency unsteady loads produce a large amplitude helicopter displacement that can be counteracted through low- frequency corrective control activities. As a result, pilot workload is not significantly affected at the highest and lowest frequencies (i.e. outside the 0.2–2Hz range). 8 However, unsteady loads in the frequency range 1 Instituto Nacional de Te ´cnica Aeroespacial (INTA), Madrid, Spain 2 Ingenierı ´a de Sistemas para la Defensa de Espan ˜a (ISDEFE), Madrid, Spain Corresponding author: Rafael Bardera-Mora, Instituto Nacional de Te ´cnica Aeroespacial (INTA), Ctra Ajalvir pk 4, Torrejon de Ardoz, Madrid 28850, Spain. Email: barderar@inta.es