RR#4
The article “What is a ‘Raked’ Wingtip?” by Trifly (2018) discusses the groundbreaking design of the Boeing 787's wings. Unlike traditional aircraft designs, the wing engineers did something different from the typical formula, opting for a unique wing structure. Typically, aeroplane wingtips are upswept, an effective design for many years. However, in the 787, these were replaced with a raked wingtip, which sweeps backwards (Onemonroe, 2023). The primary function of any wingtip is to reduce drag, which results from the pressure differences between the upper and lower wing surfaces. The most compelling reason for using a raked wingtip is its enhanced fuel efficiency. According to Kim (2015), Boeing and NASA collaborated on wind tunnel tests to validate the theory that improved wingtips could reduce drag and increase fuel efficiency. The results show that the raked wingtip reduced drag by 5.5% compared to other wingtips, which showed a reduction of only 3.5% to 4.5%. However, as Trifly (2018) suggests, this technology is a relatively new innovation and requires more space than conventional winglets, leaving it uncertain whether raked wingtips will fully replace the older designs. *[BB1]
Despite some drawbacks, the raked
wingtips of the Boeing 787 show how having an unconventional swept-back design
is beneficial in several ways, which are improving fuel efficiency and
enhancing passenger comfort. *[BB2]
The raked wingtips of the Boeing 787
are beneficial as the fuel efficiency of the aircraft is greatly improved.
Vortices that are generated by the wingtips from the airflow through the wings
are undesirable. This poses some issues when the aircraft is in flight, as it
reduces the aircraft's efficiency. In fact, almost 40% of the drag produced by
the aircraft stems from the wings, decreasing lift (Zaccara, 2022). There is a
clear linear relationship between wingtip vortices and induced drag: The
greater the vortices, the more drag the aircraft experiences. Raked wingtips
help to minimise this issue by reducing vortices. As the raked wingtips are
swept back, they effectively channel and diminish vortices away from the main
wing, minimizing drag. As a result, less fuel is burned, as the engines don’t
have to overcome the extra resistance caused by drag. This leads to a
significant improvement in fuel efficiency, with the Boeing 787 achieving a 20%
gain in this area, offering substantial cost savings for operators. According
to Greenworldwide (2023), the Boeing 787 ranks second among the five most
fuel-efficient aeroplanes globally. Furthermore, the raked wingtips provide an
additional advantage over winglets during takeoff. Not only do they reduce
drag, but they also increase lift. This is especially important and a huge
contributing factor to achieving fuel efficiency, as the takeoff and climb
stages are when the aircraft consumes the most fuel rate.
Raked wingtips also contribute to a
smoother and more comfortable flight experience for passengers. Airflow from
the main wing to the wingtips plays a significant role in generating drag (NASA
Glenn Research Centre, 2023). With raked wingtips, this drag is reduced through
the increased wingspan of the sweepback, allowing for less turbulence and a
more stable flight.
The raked wings on the Boeing 787 also have the
ability to bend more than conventional wings (Turbli,2022).[BB3]
While this flexibility might make shock passengers from how much the wing is
bending, it offers several advantages. For example, when the aircraft is going
through turbulence, the wings would bend and flex, carrying the load from
turbulence away the cabin. This feature enhances passenger comfort, especially
for those sensitive to motion sickness, as the effects of turbulence are
reduced. Given that long-haul flights often encounter turbulence, the reduction
in these effects makes the 787 an attractive option for operators focused on
passenger comfort. The Boeing 787’s raked wingtips provide an edge over other
aircraft that rely on more conventional designs. The smoother, less turbulent
flights result in a more comfortable experience for passengers, making the
Dreamliner a preferred choice for many airlines.
(6)Despite the many significant
advantages, there are some factors worth considering. The swept-back
configuration of the raked wingtip differs from the more compact, upswept
design seen in conventional aircraft. The longer design can create challenges in
terms of manoeuvrability on the ground[BB4] .
For instance, the 787 requires more space while taxiing and parking, as its
wingtips extend further than traditional designs (Gudmundsson, 2022). As a
result, airports may need to upgrade their taxiways and gates to accommodate
and handle the 787.
Despite being a
relatively new technology, the raked wingtips of the Boeing 787 have
demonstrated great benefits for operators. The president of Emirates, the flag
carrier of the United Arab Emirates, had expressed a preference for the Boeing
787, indicating that it will likely replace the ageing fleets of Airbus A380s
and Boeing 777s in the future (Fehrm, 2017). The introduction of raked wingtips
in other aircraft models, such as the latest Boeing 747s and 777Xs, further
justifies the use of the raked wingtip technology. The raked wingtip has the potential to
save fuel, increase passenger comfort, and improve flying efficiency, making it
a crucial component for the development of aviation's future.[BB5]
Blog Monroe Aerospace. (2023, July). Winglets
vs raked wingtips: What’s the difference? https://monroeaerospace.com/blog/winglets-vs-raked-wingtips-whats-the-difference/?srsltid=AfmBOorhHwjT5SD9-ztzPg32jJgiiQ5TIV4LQ1wWFWaSk6fHt191fuQx
Fehrm, B. (2017, November 15). Why
did Emirates choose Boeing’s 787-10? Leeham News and Analysis.
Gudmundsson, S. (2022). The Anatomy of Lift Enhancement.
General Aviation Aircraft Design: Applied Methods and Procedures (2nd
ed.). Elsevier Science.
Guo, Q., He, X., Wang, Z., & Wang, J. (2021). Chinese
Journal of Aeronautics. Chinese Society of Aeronautics and Astronautics. 34(9)
https://www.sciencedirect.com/science/article/pii/S1000936121000480
Hepher, T., Plucinska, J., Singh, R.,
Lampert, A., Barrington, L., Jessop. S., & Janowski, T. (2024, May 22). Singapore
airlines: What is aircraft turbulence and how common is it? Reuters. https://www.reuters.com/business/aerospace-defense/what-is-aircraft-turbulence-how-common-is-it-2024-05-21/#:~:text=Long%20planes%20can%20feel%20most,handling%20turbulence%2C%20according%20to%20Turbli.
Kim, U. (2015). Numerical Analysis and
Optimization of Wing-tip Designs. San Jose State University.
https://pdp.sjsu.edu/ae/docs/project-thesis/Uram.Kim-S15.pdf
National Research Council. (2007). Assessment of
Wingtip Modifications to Increase the Fuel Efficiency of Air Force Aircraft.
The National Academies Press. https://nap.nationalacademies.org/read/11839/chapter/5#37
NASA Glenn Research Center.
(2023, November 2). Winglets.
https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/winglets/
Top 5 most fuel-efficient airplanes in
the world. (2024, March 12). Top 5 most fuel-efficient airplanes in the
world. Green Worldwide Shipping. https://www.greenworldwide.com/top-5-most-fuel-efficient-airplanes-in-the-world/#:~:text=The%20787%20Dreamliner%20is%20another,20%25%20better%20than%20comparable%20planes.
Trifly.
(2018, August 25). What is a “raked” wingtip? Essential Pilot. http://essentialpilot.co.za/2018/08/25/what-is-a-raked-wingtip/
Blog Monroe Aerospace. (2023, July). Winglets
vs raked wingtips: What’s the difference? https://monroeaerospace.com/blog/winglets-vs-raked-wingtips-whats-the-difference/?srsltid=AfmBOorhHwjT5SD9-ztzPg32jJgiiQ5TIV4LQ1wWFWaSk6fHt191fuQx
Zaccara, M., Paolillo, G., Greco C., Astarita, T., Cardone, G. (2021, July 22). Experimental Thermal and Fluid Science. Elsevier. 130
https://www.sciencedirect.com/science/article/pii/S0894177721001345.
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