A company called Aviation Partners developed and licensed winglets. They developed the spiroid winglet that is a loop at the end of the wing, claiming increased

A company called Aviation Partners developed and licensed winglets. They developed the spiroid winglet that is a loop at the end of the wing, claiming increased efficiency over plain winglets. No takers so far, first tested 30 years ago. https://www.aviationpartners.com/aircraft-winglets/types-blended-winglets/ https://www.aviationpartners.com/aircraft-winglets/types-ble...