The 35th America’s Cup is currently underway in Bermuda, with national sailing teams competing for one of the most coveted trophies on the competitive sailing calendar. One of the challengers to compete against defending champion Oracle Team USA in the final match is the Land Rover BAR team, led by Sir Ben Ainslie. As you might expect, teams invest a huge amount of time, effort and money into their pursuit of success and this includes the design, development and production of the race boat.
Ahead of the 35th America’s Cup this year, the Land Rover BAR team invested heavily in technology and talent. One element of this was setting up a Technical Innovation Group with the aim of bringing together the best of British engineering to support the Land Rover BAR challenge. Renishaw, a global engineering organization with its headquarters in the UK, is a member of the Technical Innovation Group and collaborated with the Land Rover BAR team on a number of projects, including the production of complex, customized manifolds using Renishaw metal additive manufacturing (AM) technology.
Land Rover BAR’s America’s Cup Class (ACC) race boat is called Rita, but reportedly goes by the code name R1. At time of writing, Rita is performing well and has just won a qualifying race to progress to the next stage of the competition. Pleasing results for the 85,000 hours of design, build, on-the-water testing and rigorous construction performed prior to race days.
Rita is a 15 meters racing catamaran and features 130 meters of hydraulic pipes and more than 1,200 meters of electronic and electric cabling connecting 190 sensors. The wing has a sail area of 103 square meters and is 23.5 meters high. For comparison, this is a similar span to the main wings of an A320 aircraft. Each hull on the R1 features a manually deployed dagger board that bends beyond 90 degrees to create a hydrofoil. Anyone following the America’s Cup race coverage will have seen the boats lifting out of the water to achieve seemingly impossible speeds (for boats without engines) across the water.
The design of the boat is critical in this regard, meaning that once the boat speed reaches around 16 knots (18 mph) the force of the water over the foils creates sufficient lift to raise the boat clear of the water so that it literally flies above the water. This state of ‘flying’ reduces drag and improves efficiency to increase the speed. On the R1, the control surfaces are all driven by hydraulic actuators. Hydraulic pressure is provided by the sweat and toil of the crew’s ‘grinders’, who turn specialized hand-cranks. There are no batteries (except to provide electrical power for computers and sensors), the four grinders act as a human engine to generate all the hydraulic energy required.
Land Rover BAR understood the potential of AM to save weight and improve the efficiency of its hydraulic system. Put simply, this allowed the boat’s designers to create a perfect balance between the performance of the hydraulic system and the energy required to run it. This in turn helps the grinders conserve energy whilst still allowing the boat to perform at the optimal level. Renishaw’s AM team, including product marketing engineer David Ewing, were heavily involved in the development.
According to Ewing, Renishaw’s technology and expertise has been used extensively for numerous applications such as the prerequisite rapid prototyping of parts as well as to produce fully functioning end-use manifold parts for the boat, including hydraulic manifolds. Indeed, this exemplifies the extent to which metal AM can be applied today and highlights where AM is a good fit for the production of complex parts more economically than traditional manufacturing methods.
Ewing explained the contrast between traditional manufacturing and the benefits of AM. Traditionally, such a hydraulic system would have been made using a subtractive manufacturing method, whereby an aluminum alloy or stainless steel billet would have been cut and machined to size and subsequently drilled at 90 degree angles to create the flow pathways. Specialized tooling would often be needed due to the complex drilling that is required and passages would require blanking plugs to properly direct flow through the system. Just one of the limitations of this traditional manufacturing process was abrupt angled junctions between flow paths, which can cause flow separation and/or stagnation—a major contributor to efficiency loss.
However, using AM it was relatively easy to design in and build smooth rounded corners into the manifold to promote the flow of fluid and improve efficiency. Another benefit was the ability to save weight compared with a traditional block manifold. This is achieved at the design stage by adjusting the wall thickness of the manifold so that it is fit for function rather than over-specification due to the limitations of a subtractive process. The manifolds used on the boat are all customized and built in titanium to be both lightweight and strong.
Ewing highlighted another benefit of AM, specifically the ability to produce many iterations rapidly, which is ‘essential in the race to innovate,’ as he put it. ‘You could liken the way we have been working with Land Rover BAR to that of producing parts for high-performance racing cars, with design changes right to the wire,’ he said.
The specifications of the actual parts produced for the R1 understandably remain highly confidential, but Ewing was able to outline the principals involved:
‘A hydraulic manifold is used to take fluid from one part of the boat and deliver it to another part of the boat and it is very important that the component is efficient in delivering the fluid into the correct place. What is interesting is when you look inside the manifold you have multiple fluid passageways. Because using AM we can make these in any shape we want, we are not constrained by manufacturing techniques or tooling. We can construct these in a way which is most efficient for the function of the component. By manufacturing it additively we can give the flow path a nice conformal sweeping bend, increasing its flow efficiency.
‘Once the manifold design is agreed, it is drawn up and finalized in 3D CAD software. Land Rover BAR sends the CAD file electronically to Renishaw and we convert it to a .stl file. This is a file format that can be exported into metal additive manufacturing build preparation software. Renishaw’s own build preparation software, QuantAM, is specifically for use with Renishaw high-performance metal AM systems. Using this software, the Renishaw AM team can take the virtual Land Rover BAR manifold, configure and orientate the part correctly on the build plate and apply the necessary supports. Build supports are required to bridge any gaps, support overhangs and to hold the part stable and in place as it builds up layer by layer. The Renishaw AM team uses its know-how to ensure that the minimum number of supports are applied to avoid waste and to reduce the time needed to remove them.
‘Once the build is complete, any excess powder is brushed away whilst still sealed within the system. The build plate carrying the part may then be removed from the system ready for finishing using post-processing techniques. Most metal parts are removed from the build plate using wire EDM. They may then require some surface finishing and heat treatment. Machining is used to add in threads and in areas where high tolerances are required.’
Summing up the project, Ewing said: ‘The R1 is an incredibly advanced racing catamaran that pushes the boundaries of what technology can provide and it has truly been a race to turn around the optimum parts in time for the America’s Cup. The challenge has been immense and we have been operating in a similar manner to what you might expect if working on a high-performance racing car—many design changes, demanding timescales and rapid production of parts running up to a fixed race day. I’m proud of how we have met those challenges by working as a team and that the breakthroughs that we have made to improve the boat’s performance will help train and educate future generations of engineers through the work of the Land Rover BAR team.’