A balance between aerodynamic pressure and surface tension—the classic engineering problem called aero elasticity—determines the optimal flying shape of a sail. Quantum’s sail designers address this challenge with computational fluid dynamic (CFD) calculations to assess the aerodynamic forces and finite element analysis (FEA) to evaluate elasticity. The first step is to determine the sail shape.
Using our own 3D design program, actual boat specifications and our extensive database of boat and sail types, the size and geometry of the sail are defined and a mold shape created. Sophisticated editing tools allow for the highest levels of accuracy and refinement.
Using a virtual prototype of the sail shape and computational fluid dynamic (CFD) calculations, designers compute and visualize aerodynamic forces, wind angles and velocities, and the distribution of air pressure on each side of the sail. The resulting images and data help predict performance.
Structural Analysis and Fiber Mapping
Using finite element analysis (FEA), Quantum designers visualize where the sail bends and twists and the distribution of stress and strain within the membrane. The virtual sail is attached to a rig model that takes into account the properties of the running and standing rigging and longitudinal and transverse stiffness. Data gained through in-house materials testing is added to the equation to evaluate the effects of different fiber types, amounts, and placement leading to the development of a custom fiber map.
The integration of 3D modeling, CFD and FEA allows designers to assess and refine varying elements of the sail design leading ultimately to the optimal size, shape, structure, fiber type, and fiber layout of the finished product. Quantum’s expertise in using these tools is particularly valuable when applied to large sailing yachts, which present unique challenges due to variable weight placement and heavy loads.
When collaborating with boat design teams, Quantum designers also use a velocity prediction program (VPP), to assess a sail’s impact on boat performance in different wind conditions by linking aerodynamic to hydrodynamic performance—in other words balancing hull and sail forces. The impact of rig position, rake, heel, rudder angle and other variables can be modeled and evaluated. Conversely, sail shapes can be optimized for the hull characteristics of specific designs.