How Winglets Save Fuel

Aerodynamics

At the tip of a wing, high-pressure air beneath the wing wraps around to the low-pressure area above, creating a wingtip vortex — a swirling mass of air that trails behind the aircraft. These vortices represent wasted energy: they increase induced drag, the drag penalty paid for generating lift.

A winglet is an upward extension at the wingtip that effectively increases the wing's aspect ratio (span-to-chord ratio) without extending the physical wingspan. Higher aspect ratio reduces induced drag because a longer wing generates the same lift with less spanwise pressure differential. The winglet redirects the wingtip vortex outward and slightly rearward, partially recovering energy from it.

The fundamental trade-off: winglets add weight and some parasite drag. The benefit must exceed these penalties — which it does on virtually all transport aircraft, with returns of 3–8% depending on design and mission profile. Long-range cruise conditions, where induced drag accounts for a larger share of total drag, favour larger winglets.

Types of Winglets

• Classic winglet (blended, upward-swept): Original design by Richard Whitcomb (NASA, 1970s); used on early 747-400 and 767-400; typically 15–20° cant angle; reduces induced drag by ~3–4%
• Sharklet (Airbus): Slender, upward-curving design with 35° cant angle; standard on A320neo family; reduces fuel burn by ~3.5% versus A320ceo winglets
• Split Scimitar (Aviation Partners Boeing): Standard retrofit for 737 NG family; adds a downward-angled lower blade, increasing efficiency to ~5.5% fuel saving
• Raked Wingtip: Used on Boeing 787 and 777-300ER; swept extended tip rather than an upturned winglet; achieves similar induced drag reduction with potentially lower weight
• Blended Winglet (Aviation Partners): Smooth curved junction; reduced fatigue stress at root; used on 737-800 and 757

Verified Fuel Savings

Retrofit Economics

Installing winglets on existing aircraft involves a fleet-wide modification programme. Per aircraft (737-800): $800,000–1,200,000 for hardware and installation; ~10–14 days downtime per aircraft. At $0.80/litre jet fuel and 2,500 flight hours per year, a $1M winglet kit saving 4% pays back in approximately 3–4 years. Southwest Airlines retrofitted its entire 737 fleet with APB winglets, crediting annual fuel savings of $150–200 million. Ryanair's fleet-wide blended winglet programme was calculated to save 8–10 million gallons of fuel per year.

CO2 Reduction

If every 737-800 in service (approximately 4,000 aircraft globally) installed split scimitar winglets achieving 5.5% fuel savings: average annual fuel burn ~6 million litres per aircraft, saving ~330,000 litres/year per aircraft = ~860 tonnes CO2/year. Fleet total: approximately 3.4 million tonnes CO2 per year avoided. This illustrates why winglet retrofits are consistently among the highest return-on-investment sustainability programmes available to airlines operating legacy fleets.