I know it's a trivial observation but Fig 1 really shows how huge these blades are: that relatively tiny winglet tip is nearly 3 metres long, much taller than a

I know it's a trivial observation but Fig 1 really shows how huge these blades are: that relatively tiny winglet tip is nearly 3 metres long, much taller than an adult. The rational side of me supposes it's not surprising that a single blade that can pull 3-plus megawatts out of thin air would be rather large! Also, if the power output can increase by anything near the claimed amount (8 and 4 percent for different sizes of winglet), why don't current turbines use them? They're heavily used in aviation, and turbine designers are huge on geometry tuning via numerical simulation, as well as wind tunnel testing and so on to squeeze every last joule out of the device. On a proportional basis, at 8 million per 10MW turbine, every 1% is worth $80k per unit. Surely one of them tried winglets by now? Is there a patent minefield or does it make the blade manufacture infeasible or expensive or damage the blade's reliability or maintainability?