What do they do? How do they work?
Winglets give aircraft a performance improvement of anything between five and seven percent. They do that by reducing the powerful vortexes that curl out behind the wingtip as the aircraft slices through the air. These occur when low-pressure air flowing over the wing and the high pressure flowing under the wing meet at the tip. The vortexes create drag, slowing the aircraft down and need to be countered with increased thrust and therefore more fuel burn. With clever aeronautical design –– and it is really complicated –– winglets can change and drastically reduce the vortex, so the aircraft needs less thrust to maintain the same speed.
The evolution of the winglet
Apart from some small wing tip plates seen on military aircraft during the wars, the first time the winglet appeared was on an enthusiasts aircraft called the Rutan VariEze in 1975. This was designed by our friend and Virgin Galactic founder Burt Rutan. A legendary aircraft designer, Burt is known for designing extremely efficient and sometimes unusual looking aircraft. The next stage in the winglet story came in the executive jet sector when they appeared on the Learjet 28 in 1977. Originally a test aircraft, the vertical winglets had first been conceived by NASA aerodynamics genius Richard T. Whitcomb at the Langley Research Center.
He went on to fit winglets to large tanker aircraft and realised impressive efficiency gains of up to 5%. Winglets really hit the mainstream after aviation was hit hard by a huge hike in oil prices in the mid-70s. This precipitated the jump to commercial airliners. Airbus put tiny fences on an early version of their A310, but the real beginning of winglet mania came with the new variation of the mighty Boeing 747 – the 400 series. The first 747-400 was delivered to Northwest Airlines in 1989, the first commercial aircraft with proper winglets.