What are aircraft winglets, and how do they improve efficiency?
How do winglets save fuel? See how aircraft winglets reduce induced drag, affect wake turbulence and differ from sharklets and raked tips.
Aircraft winglets are vertical or angled wingtip devices that improve a finite wing’s efficiency. They reshape the pressure-driven airflow near the tip, reducing induced drag. With less drag, the aircraft needs less thrust and fuel for a given flight condition, while often gaining climb performance or range without a substantially wider wingspan.
For our Aviation & Real-World Flying readers, the key distinction is that wingtip device is the umbrella term. Every conventional winglet is a wingtip device, but raked tips and wingtip fences are not necessarily winglets in the narrow sense.
What do winglets do on a plane?
Winglets make the wing more efficient by changing its three-dimensional airflow and spanwise lift distribution. Their main purpose is not to create extra lift for free, but to reduce the drag associated with producing the lift the aircraft already needs.
How do winglets reduce induced drag?
Winglets reduce induced drag by weakening and redistributing the airflow responsible for the wing’s trailing vortex system.
- A pressure difference develops: A lifting wing has higher pressure below it and lower pressure above it. Near a finite wingtip, this drives spanwise and outward flow.
- The wake rotates: The pressure-driven flow contributes to a trailing vortex sheet that rolls up behind the aircraft, with concentrated wingtip vortices as its most recognisable feature.
- Downwash tilts the aerodynamic force: The local airflow is deflected downwards, so part of the wing’s aerodynamic force points rearwards. That rearward component is induced drag.
- The winglet changes the loading: A correctly designed winglet carries an aerodynamic load of its own, improves the overall lift distribution and can produce a small forward force component in the tip’s crossflow. The result is less net induced drag at the intended operating conditions.
A common explanation says that winglets simply stop high-pressure air spilling around the tip. That is an incomplete picture. They do not act as walls, and they do not make vortices disappear; they reshape circulation over the wing and through the wake.
The effect is often described as an increase in effective aerodynamic span or span efficiency. An upright winglet can obtain part of the benefit of a longer, higher-aspect-ratio wing without adding the same amount of gate-consuming horizontal span. Its own skin-friction drag, interference drag, mass and structural loads still have to be included in the calculation.
How do winglets save fuel?
Winglets save fuel because lower net drag means the engines need to provide less thrust at the same weight, speed, altitude and configuration. For a jet that normally means lower fuel flow; for a propeller aircraft it means less required shaft power.
| Flight condition | Expected winglet benefit | Reason |
|---|---|---|
| Take-off and initial climb | Potentially useful aerodynamic and climb benefit | The aircraft is heavy and operating at a relatively high lift coefficient, so induced drag is significant. Flap, undercarriage and engine effects still account for much of the total performance. |
| Climb and heavy cruise | Often the most valuable part of the mission | A heavy aircraft needs more lift, increasing induced drag. Reduced drag can improve climb or reduce required thrust. |
| Later cruise | Smaller but cumulative saving | The aircraft becomes lighter as fuel is used, although even a modest thrust reduction can accumulate over a long sector. |
| Descent and landing | Limited fuel-saving value | The aerodynamic effect remains, but descent commonly uses low thrust and the landing phase is short. |
There is no honest universal fuel-saving percentage for airplane winglets. The net result depends on the wing and device design, aircraft weight, speed, altitude, route length, winds, engine installation and how much structural reinforcement was required. A percentage published for one certified installation should not be applied to another aircraft or even automatically to another variant in the same family.
Longer sectors often make the investment more attractive because small savings accumulate over more time. On very short routes, additional mass, maintenance and acquisition costs can outweigh the fuel saved. Airlines therefore assess total trip or block fuel and operating cost, not just the winglet’s best aerodynamic point.
Do winglets increase lift?
Winglets can change total lift and lift distribution at a given angle of attack, but their practical benefit is usually lower drag for the lift required. In steady level flight, the aircraft still has to produce lift equal to its weight and will trim to the necessary angle of attack.
Claims that a winglet automatically lowers stall speed or increases maximum take-off weight should be treated cautiously. Those outcomes depend on the complete certified installation and must come from the aircraft’s approved performance data, not from the device’s appearance.
Do winglets reduce wake turbulence?
Winglets can alter the strength, position and roll-up of the wake, but they do not eliminate wake turbulence or make normal separation unnecessary. Any finite wing producing lift leaves trailing vorticity behind it.
A particular design may reduce peak vortex strength under some conditions, yet wake behaviour also depends on aircraft weight, speed, configuration, atmospheric stability and time since passage. Pilots and controllers must use the published wake category and separation for the aircraft rather than assuming that visible winglets make following more closely safe.
Are sharklets, raked tips and winglets the same?
No. They are all wingtip devices intended to improve aerodynamic efficiency, but their geometry, loads and optimum operating conditions differ.
| Wingtip device | Typical form | Main distinction |
|---|---|---|
| Conventional or blended winglet | Upturned surface, often with a smoothly curved junction | The blended transition reduces interference drag between the main wing and winglet. |
| Wingtip fence | Surfaces extending above and below the wingtip | Influences tip flow on both sides of the wing while adding relatively little span. |
| Sharklet | Tall, swept and blended device | Sharklet is an Airbus name used for certain installations. Our explanation of how A320 sharklets change wingtip aerodynamics covers a common real-world example. |
| Split or scimitar-style device | Upper and lower elements, or a reshaped upper winglet with a lower ventral element | Spreads aerodynamic loading across more than one surface; the exact arrangement depends on the certified installation. |
| Raked wingtip | Swept, mostly horizontal extension of the main wing | Increases physical span and aspect ratio rather than using a conventional upright surface. The comparison between 747-400 winglets and the 747-8’s raked tips shows the distinction clearly. |
A raked tip is not automatically better than a blended winglet, or vice versa. The answer depends on span limits, cruise Mach number, wing structure, aeroelastic behaviour and the aircraft’s intended mission.
Why do some aircraft not have winglets?
Some aircraft obtain a better overall result from a longer wing, a raked tip or no added device at all.
- Airport span limits: A clean-sheet aircraft may use a longer horizontal wing when gate dimensions permit it. An upright winglet becomes attractive when extra span would move the aircraft into a less convenient airport category.
- Structural penalties: Wingtip loading increases wing-root bending moments. Retrofitting may require reinforcement that adds enough mass to reduce the fuel benefit.
- Mission profile: An aircraft flying short sectors may not spend enough time in efficient climb and cruise conditions to recover the installation’s weight and cost.
- Existing wing optimisation: A modern high-aspect-ratio wing may already use its available span efficiently, leaving little net gain from an additional upright device.
- Aeroelastic and handling effects: Designers must account for flutter margins, gust loads, stall progression, lateral stability and control characteristics.
In broad terms, an upright winglet is useful when horizontal span is constrained; a longer or raked tip is attractive when more span is available; and no retrofit is sensible when structural and operating penalties exceed the drag saving. Folding tips provide another way to combine a long airborne span with a smaller parking footprint.
Can winglets be added to any aircraft?
No. A real winglet retrofit must be engineered, flight-tested and approved for the exact aircraft type and configuration. Bolting on a cosmetic shape can alter loads, flutter behaviour, stall characteristics and stability, even if it appears aerodynamically plausible.
The installation may also change empty weight, centre of gravity limits, inspection requirements and performance documentation. A winglet approved for one model cannot be assumed suitable for a related model without separate engineering and approval.
Do winglets make an aircraft fly differently in a simulator?
Only if the simulator or add-on’s aerodynamic and performance model represents their effects; a visible winglet does not by itself guarantee lower drag or fuel burn. Most simulators do not derive a complete, accurate aircraft performance model solely from the rendered exterior mesh.
Physics engines vary in how they use geometry, coefficients and configuration data. Our explanation of how simulators turn aircraft data into aerodynamic behaviour covers why a convincing visual model may still miss the real performance change. A winglet-equipped Boeing 737-700 model for FSX is useful for recognising the external geometry, but appearance and a WL label are not fuel-efficiency validation.
When comparing winglet and non-winglet simulator variants, avoid the failure modes we see most often:
- Match the airframes: Use equivalent engines, weights, payloads and configurations. Otherwise an engine or mass difference can overwhelm the winglet effect.
- Standardise the flight: Hold weather, altitude, commanded IAS or Mach, centre of gravity and automation settings constant. Remove wind unless the same weather can be reproduced exactly.
- Measure the right result: Compare trip fuel or fuel used per distance, not instantaneous fuel flow alone. A faster aircraft can show higher fuel flow while still covering distance more efficiently.
- Check what is modelled: Read the add-on documentation and inspect its stated performance basis. Do not reduce a drag value merely because winglets are visible; the benefit may already be included, and an extra edit would count it twice.