Reader Response Draft 3

The article “What is a raked wingtip?” by Essential Pilot (2018) introduces the raked wingtip design, which Boeing employs in its 787 aircraft. Since entering service in 2011, the 787 has represented one of Boeing's most modern and efficient aircraft. This efficiency stems from the use of composite materials and advanced aerodynamic features like raked wingtips. One of the primary aerodynamic challenges faced by aircraft is drag, with vortex drag accounting for nearly 40% of total cruise drag (Kim, 2015). Wingtip vortices occur when high-pressure air under the wing meets the low-pressure air above, creating drag as downwash alters the angle of attack of the wing (Essential Pilot, 2018). To mitigate this, manufacturers use wingtip devices like winglets and raked wingtips, which improve the wing’s aspect ratio and reduce vortex drag (Tamayo, 2018). Boeing’s success with raked wingtips on the 787 has influenced the design of newer aircraft, including the B747 and B777-X.

The 787’s wingtips represent a breakthrough in fuel efficiency and aerodynamic performance, setting a new industry standard. However, it does face some setbacks in terms of airport compatibility and manufacturing practices.

The Boeing 787 has a cutting-edge wing that was designed from the ground up to maximize efficiency. This novel design allows it to be more aerodynamically efficient compared to previous-generation passenger aircraft. The increased sweep angle of the 787’s wingtips extend its wingspan to 60.12 meters. This extension improves the wing's aspect ratio, distributing lift more evenly and reducing turbulence and vortex drag at the wingtips. As a result, the 787 achieves greater fuel efficiency and produces less noise during flight. Additionally, this improved efficiency contributes to a range increase and lower emissions. For instance, the Boeing 787-9 variant has a maximum range of 7,565 nautical miles (Boeing, n.d.), which is a 25% increase over its predecessor, the B767-400ER (Flugzeuginfo.net, 2019). These improvements can be attributed to both weight savings from composite materials and aerodynamic advances like the raked wingtips. Moreover, the smoother airflow over the wing reduces vortex drag. This leads to fewer vibrations during flight, which helps decrease noise levels. A study by the Civil Aviation Authority (CAA) on aircraft noise at London Heathrow Airport found that the 787 was quieter by an average of 7 decibels during departure compared to the older 767. During arrivals, noise levels were 3 decibels lower on average (CAA, 2014). These reductions further emphasize the positive impact that raked wingtips have on both fuel efficiency and noise pollution in the 787.

Another benefit raked wingtips bring to the 787 is increased fuel efficiency. This is especially desirable for operators as it reduces operational costs and allows the aircraft to fly longer distances. The fuel efficiency of the 787 also translates into lower carbon emissions. A case study conducted by the International Bureau of Aviation (IBA) found that the Boeing 787-9 is the most fuel-efficient widebody aircraft in Qatar Airways’ fleet (IBA, 2021). When comparing Qatar Airways' Boeing 777-200LR and 787-9, the study showed that the 787 emitted 115 grams of CO₂ per seat, which is 34% less than the 777’s emissions. This study provides concrete evidence of the 787’s lower carbon footprint, underscoring its environmental benefits.

While raked wingtips represent a revolutionary advancement in aircraft wing design, they do present some minor challenges. This can be observed when drawing a comparison with their predecessor, the blended winglet. Boeing initially used blended winglets on its 737NG, 757, and 767 aircraft. Blended winglets reduce drag by smoothly transitioning between the wing and winglet, resulting in fuel savings of 4% to 6% (Teschner, 2012). While less efficient than raked wingtips, winglets offer certain advantages. Since winglets extend upward without significantly increasing wingspan, they are more compatible with airport gate sizes. Furthermore, the simpler design of winglets, which conforms to the existing aerofoil shape, makes them easier to manufacture compared to raked wingtips. This simplicity allows winglets to be retrofitted onto older aircraft, improving efficiency without requiring significant redesign or certification.

In conclusion, despite minor limitations—such as reduced airport compatibility and complex manufacturing—the aerodynamic efficiency of raked wingtips makes them a key innovation in aerospace. As such, they should be considered the industry standard for future aircraft designs.

References

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

Civil Aviation Authority. (2014). CAP 14924: Review of aircraft noise metrics and measurements. https://www.caa.co.uk/publication/download/14924

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

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

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

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