The Boeing 737-800 scimitar winglet represents a significant evolution in aerodynamic efficiency for one of the world’s most prolific commercial aircraft. This distinctively shaped retrofitted component, characterized by its upward-curving tip, has become a common sight on the fuselage of modern 737 fleets. Designed to optimize performance and reduce the operational costs associated with fuel consumption, the scimitar shape offers specific advantages over traditional blended winglets, particularly for the high-volume, short-to-medium haul routes that define the 737’s mission profile.
Understanding the Scimitar Design and Its Origins
The term "scimitar" is derived from the curved, single-edged sword of the same name, which provides an accurate visual description of the winglet’s geometry. On the 737-800, this component is part of the Aviation Partners Boeing (APB) winglet family, specifically designated as the 737-800 Winglet Performance Enhancement Program (PEP). Unlike the simpler, more angular blended winglets found on earlier 737 variants, the scimitar features a pronounced upward sweep in its upper section. This complex curvature is engineered to more effectively manage the induced drag created by the high-pressure air beneath the wing attempting to equalize with the lower-pressure air above.
Addressing the Drag Challenge
At the core of the winglet’s function is the mitigation of vortex drag. As air flows over the wing, it inevitably spills over the wingtip from the high-pressure zone below to the low-pressure zone above, creating a powerful rotating vortex. This phenomenon saps energy from the aircraft, forcing the engines to work harder to maintain speed and altitude. The scimitar’s unique shape is specifically calculated to interfere with this vortex, rolling it up and inwards. By doing so, the winglet converts some of the wasted energy into useful lift, smoothing the airflow and allowing the aircraft to cut through the air with reduced resistance.
Operational and Economic Benefits
The primary driver for the adoption of scimitar winglets is the substantial improvement in fuel efficiency they deliver. By reducing drag, the aircraft requires less thrust to maintain cruise speeds, translating directly to lower fuel burn. For airlines operating the 737-800 on dense point-to-point routes, this translates into significant cost savings over the lifespan of the aircraft. Furthermore, the reduction in fuel consumption leads to a corresponding decrease in carbon dioxide (CO2) and nitrogen oxide (NOx) emissions, aligning with global aviation sustainability goals and enhancing the airline's environmental credentials.
Fuel Efficiency: Operators typically report a 4% to 6% reduction in fuel burn on routes where the aircraft spends significant time at cruise altitude.
Range Extension: The improved efficiency can effectively increase the aircraft's range, allowing operators to open new routes without the need for additional fuel capacity.
Noise Reduction: The optimized airflow contributes to a slight reduction in perceived noise levels, a benefit for communities near airports.
Resale Value: Aircraft equipped with modern winglets often command higher resale prices due to their operational efficiency and modern appearance.
Integration and Certification Process
The installation of scimitar winglets is not a simple bolt-on modification; it requires rigorous engineering and recertification. Aviation Partners Boeing worked closely with Boeing and regulatory authorities to ensure the modifications maintained the aircraft's structural integrity and flight characteristics. The process involves creating new attachment points on the wing, which necessitates detailed structural analysis to ensure the wing can handle the additional loads. Following extensive wind tunnel testing and flight trials, the STC (Supplemental Type Certificate) was granted, guaranteeing that the modified aircraft met all safety standards established by the FAA and EASA.
