High Performance Yacht Design- Team NZ’s foiling breakthrough

by Keith Taylor on 11 Mar 2015 A foiling breakthrough was one of the early and critical elements that helped drive Emirates Team New Zealand to near-success at the America’s Cup in San Francisco in 2013.

The Kiwi boat was the first contender for the 34th Cup to achieve stable 100 per cent foiling performance but the defending Oracle Team USA ultimately retained the Auld Mug in a winner-take-all 19th race.

This week at the fifth High Performance Yacht Design conference in Auckland during the Volvo Ocean Race stopover, Burns Fallow, part of the four-man ETNZ aerodynamics team responsible for the impressive wing sail, shared the research and design methodology that along with foil design and other work contributed to the race boat’s performance.

Nick Hutchins, Design Director at ETNZ, Steve Collie, Harold Youngren and Fallow comprised the aero team. Fallow presented their paper 'Aerodynamic Design Development of AC72 Wings.

The replacement of the traditional mainsail with a wing was expected to be a major aerodynamic design challenge requiring a wide range of new expertise, Fallow said.

'As it turned out the design process involved some new tools and tricks but was largely a refinement of computational approach and methods used in the 32nd America’s Cup.'

Fallow described the range of computational tools and techniques used to develop and validate design decisions for the wing. The main difference, he said, was the increased fidelity and sheer volume of simulations afforded by advanced computational resources.

The aero design team had its first meeting in November 2010 and by April the next year was 70% on its way to the final aerodynamic design. Two identical wings were built for ETNZ’s 33-foot SL33 catamarans in late November and early December.

That project was focused around gaining experience in building wings and for validation of the control system design but also provided opportunities to verify and test many aerodynamic assumptions and choices.

Decisions made in the first two weeks of the program, including a straight leading edge and two wing elements, stayed the whole way though.

Along with the aero work there was a parallel process where the structural team were developing their structural models. Addressing their concerns led to an iterative process as the project went forward. It was 'pretty intense,' given that the team was also launching its Camper VO 70 for the Volvo Race, commissioning an AC45 and building its SL33 catamarans for foil and wing sail testing.

Although largely secret until now, the only other team to directly benefit from the ETNZ work was Italy’s Luna Rossa which bought the first Kiwi boat together with blueprints and, in effect, the whole package.

Fallows said that the reason the design process was being shared now was because the wings of the new AC62s will essentially be one-design although there will be variations on individual control systems.

Graeme Finch, chairman of HPYD5 noted that delegates were surprised to discover they were receiving the same presentation that was made to Italy’s Luna Rossa, when ETNZ transferred the boat and technology to the Italian Syndicate. 'This is unprecedented at a technical conference, and certainly one of the highlights this week,' he said.

New Zealand Trade and Enterprise is the principle conference sponsor. Gold sponsors include North Sails, Southern Spars, Callaghan Innovation, the Volvo Ocean Race and Auckland Tourism, Events and Economic Development.