A winglet is a wing-like surface attached to the tip of the wing that is used to improve fuel efficiency and climbing capability. It accomplishes this by acting like a small sail with a lift component that generates a traction force, draining energy from the tip vortices. Consequently, it reduces the vortex strength, lowering induced drag. "Induced drag represents 30-40 percent of the total drag of a transport air-plane at the cruise condition, so it has a big impact on fuel consumption," explains Bento Silva de Mattos, senior engineer at Embraer. "Because the induced drag coefficient is proportional to the square of the lift coefficient, a reduction in drag improves climbing capability as well, because the lift coefficient is high at this condition."

Despite the fact that winglets have been in use for many years, optimization of winglet design had been difficult because the complex airflow patterns around these wing-mounted airfoils could not be understood through wind tunnel testing. The Reynolds number has a big effect on the flow structure; f light tests always showed larger drag reductions than the ones from wind tunnel data. Using simulation results as a guide, the engineers fine-tuned the winglet geometry to further reduce induced drag, improving fuel consumption.