Reader Response Draft 1

The article “What is a raked wingtip?” by Essential Pilot (2018) highlights the concept of the raked wingtip design used by Boeing in their B787 aircraft. Having entered service in 2011, the 787 is one of the newer aircraft in Boeing’s lineup. Its design was heavily conceptualised around efficiency which was achieved with its substantial use of composite materials and raked wingtip design. One of the primary aerodynamic challenges for aircraft is drag, with vortex drag amounting to nearly 40% of the total drag during cruise (Kim, 2015). Wingtip vortices are formed when high-pressure air meets lower-pressure air at the wingtip during lift generation. This induces drag as a downwash is generated which alters the angle of attack of the aerofoil (Essential Pilot, 2018).  To address this, aircraft manufacturers employ wingtip devices such as winglets and raked wingtips. Wingtip devices increase the aspect ratio of the wing, reducing the tip vortices and induced drag (Tamayo, 2018). Boeing’s success with raked wingtips in the 787 resulted in the newer generation of B747 and B777-X employing the use of these wingtips.

By having a greater sweep angle on the wingtips, Boeing was able to increase the wingspan on the 787 to 60.12 metres. This increases the aspect ratio of the aerofoil and distributes lift more evenly throughout the wing causing less turbulence at the wingtips and a decrease in vortex drag. The result of this is an increase in fuel efficiency and an overall reduction in noise during flight. The 787's wingtip is a revolutionary advancement in aerodynamic efficiency and fuel consumption and thus should be an industry standard moving forward. 

The improvement in fuel efficiency from using raked wingtips also resulted in several additional benefits, namely an increased range and lower emissions. The Boeing 787-9 variant has the longest range at 7565 nautical miles (Boeing, n.d.). This is a 25% increase over the B767-400ER, the aircraft it was set to replace (Flugzeuginfo.net, 2019). This increased range can be attributed to both the weight savings from the use of composites as well as the aerodynamic efficiency achieved by the raked wingtips.

The predecessor to raked wingtips was the blended winglet, which Boeing installed on its newer aircraft at the time. As its name suggests, this device was able to reduce drag experienced by the aircraft by blending the wing and winglet reducing fuel costs from 4 to 6 percent (Teschner, 2012).

 

 

 

References

Essential Pilot. (2018). What is a raked wingtip? Essential Pilot. http://essentialpilot.co.za/2018/08/25/what-is-a-raked-wingtip/

Kim, U. (2015). Numerical analysis and optimization of wing-tip designs [Master’s thesis, San Jose State University]. San Jose State University. https://www.sjsu.edu/ae/docs/project-thesis/Uram.Kim-S15.pdf

Tamayo Ibáñez, A. (2018). Numerical study of current wing-tip devices for commercial aircraft [Bachelor’s thesis, University of Barcelona]. UPC Universitat Politècnica de Catalunya. https://upcommons.upc.edu/handle/2117/174536

Teschner, T.-R. (2012). A comparative study between winglet and raked wingtip wing configurations [Bachelor’s thesis, Hamburg University of Applied Sciences]. HAW Hamburg Reposit. https://reposit.haw-hamburg.de/handle/20.500.12738/6042

IBA. (2021). Aviation carbon emissions case study: Qatar Airways. https://www.iba.aero/resources/articles/aviation-carbon-emissions-case-study-qatar-airways/

Boeing. (n.d.). Boeing: 787 family. https://www.boeing.com/commercial/787#family

Flugzeuginfo.net. (2019). Boeing 767-400ER technical data. https://www.flugzeuginfo.net/acdata_php/acdata_7674_en.php