America’s Cup – AC72 Platform Aerodynamics

Platform Platform aerodynamics was key to performance in the AC72’s. Early on we realised that we couldn’t just look at the wing and platform in isolation. Using the platform to end-plate the wing increased the efficiency of the wing 25% and as speed increased and we chased ever lower centre of effort the platform aero only became more important. But as with everything in yachts there was a trade off, larger fairings increased the efficiency of the total aero package and provided lift but also reduced the dynamic stability of the yacht and provided bow up trim moment. A difficult design problem especially when working around the pre-existing structure!

America’s Cup – AC72 Pie Warmers

E It was a case of anything goes for fairings on the AC72, anything inside the extents of the yacht and under 2.6m from waterline. But where to start? Well… everywhere of course! An algorithm searched the entire box looking for areas where a lifting surface would provide force in the right direction without it’s mirror undoing all the good work. Once areas of potential were found the RANS code optimisation of the design and we had… pie warmers – as they affectionately became known. With vertical fins to provide lift and drive and a top plate to improve span efficiency.

America’s Cup – AC72 Wingsail

Wing Wings were new in AC34 so we spent a lot of time understanding the wing; how it needed to work, when to chase max-lift and when to focus on drag, how it interacted with the sails and how the crew would interact with it, what loads it produced and how the structure responded and deformed under those loads. We designed a wing that would give the yacht strong performance and flexibility over a range of conditions but the real challenge was getting it into optimal trim over a range of conditions and keeping it working through manoeuvres. A real team effort!