Reader's response Draft 1
The article “What is a ‘Raked’ Wingtip?”, written by Trifly (2018) discusses that the design of the 787 is groundbreaking. It is groundbreaking, as the wing engineers of the B787 did not follow the usual methods that designers had been using for the aeroplane’s wings. The wing engineers did something different from the typical formula. The “upswept wingtip, [that] had been working [very] effectively” was redesigned to a wing that sweeps to the back Onemonroe (2023). The main function of a wingtip is to reduce the drag caused by the physics, and nature of the pressure differences between the upper and lower portions of the wing. The greatest push factor for using a raked wingtip is its fuel efficiency. According to Kim (2015), the writer mentions that Boeing and NASA conducted wind tunnel tests together, to prove the theory that wing tips improved fuel efficiency. The results from the tests show that the raked wingtip had the greatest reduction, 5.5% in drag compared to the other wingtips, 3.5% to 4.5% for the winglet as tested. However Trifly (2018), suggests that this raked wingtip technology might not be all good. As this technology by Boeing is still new and takes up more space than conventional winglets, the writer suggests that only time can tell if raked wingtips are a good replacement for winglets.
Despite having some disadvantages, the raked wingtips of the Boeing 787 show how having an unconventional swept-back design might be beneficial, as it improves the performance of the aircraft and is ideal for operators. (argument/hypothetical and then examples why it is better)
The raked wingtips of the Boeing 787 are beneficial as the fuel efficiency of the aircraft is greatly improved through the use of raked wingtips.
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 and safety. It significantly impacts passengers, by increasing the noise in the cabin. contributing a huge part, almost half of the drag (40%) is generated from the wing decreasing lift (Zaccara 2022).
https://www.sciencedirect.com/science/article/pii/S0894177721001345. This shows that wingtip vortices and induced drag have a linear relationship, wingtip vortices greatly increase as induced drag increases. With the raked wingtips, wingtip vortices are greatly reduced. When vortices are formed, the 787 raked wingtips are very useful as they are swept back. They successfully diminish the effects of the vortices flowing from the main wing, by channelling it away from the wing, thereby reducing drag. Lesser drag within the wing area means less fuel is burnt as the engine does not have to overcome the increased resistance from the drag. Thus, achieving a 20% better fuel efficiency and greater cost savings for the operator.
According to greenworldwide (2023), 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.The Boeing 787 ranks second on the list of five of the most fuel-efficient airplanes in the world. The raked wingtips have an advantage over winglets during takeoff as they improve not only by reducing the drag on wings but increasing lift, both of which are important for takeoff.
https://nap.nationalacademies.org/read/11839/chapter/5#37 This is especially important and a huge contributing factor to achieving fuel efficiency. This is because the phases that the aircraft consumes the most fuel rate are taking off and the climbing stage to reach the cruising altitude (maybe can put how high).
Why is it being ideal (fuel, passenger comfort)
TURBULENCE
Another reason why operators benefit from the raked wingtip is its passenger comfort.
Air that is flowing from the main wing to the wingtips is a crucial factor for drag to be generated (NASA Glenn Research Centre, 2023). With the help of the raked wingtips, drag is being reduced, through the increased wing span by the waked tips, allowing for a smoother flight as it has lesser turbulence.
https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/winglets/
The raked wings are also designed to bend more than conventional aircrafts. While it may look frightening when its bending, it has its advantages. Such as increasing on lift when the plane is stalling, which is a term used to describe when a plane is losing lift when the front portion of the wing is pointed too high up.
This increases passenger comfort as people who are more susceptible to motion sickness would not feel as much of an impact compared to other aircrafts. Especially on a long-haul flight, chances of experiencing turbulence are high and with the raked wingtips it reduces the effect.
The above-mentioned functions are crucially important factors for operators to decide whenever they are purchasing the aircraft. The 787 Dreamliner has lesser turbulent flights, and therefore making it at an advantage over aircrafts that have a conventionally designed wingtip.
Passenger comfort as it is quieter https://assets.ctfassets.net/v228i5y5k0x4/6g11nNHs7msGQ0gUk0uAi2/63846f6b5001d80586630fd745e331ad/Chapter_14_Noise_Management.pdf
One counter view ( might take up space for its wings)
However, the raked wingtips have some factors that might be worth considering. The design of the raked wing tips is in a swept-back configuration compared to the conventional upswept wingtip. It is therefore longer and makes manoeuvrability while taxiing or moving around an issue (Gudmundsson 2022). Upgrading of the airport taxiways and air gates from existing standards will be needed in order to be able to handle the 787.
Conclusion
Although the raked wingtips are still quite a new technology, it has proven to be very beneficial in improving aerodynamic efficiency and passenger comfort even Emirates President Tim Clark said this week: “The Boeing 787-10 aircraft is the best choice for Emirates, it's a good eight-hour aircraft.” Which they will be using to replace their soon ageing fleets of Airbus A380s and Boeing 777s
References
Trifly. (2018, August 25). What is a “raked” wingtip? Essential Pilot. http://essentialpilot.co.za/2018/08/25/what-is-a-raked-wingtip/
Winglets vs raked wingtips: What’s the difference? Blog Monroe Aerospace. (2023, July). https://monroeaerospace.com/blog/winglets-vs-raked-wingtips-whats-the-difference/?srsltid=AfmBOorhHwjT5SD9-ztzPg32jJgiiQ5TIV4LQ1wWFWaSk6fHt191fuQx
Kim (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
Zaccara, M., Widnall, S. E. (2021, July 22). Flow control of wingtip vortices through Synthetic Jets.ScienceDirect
https://www.sciencedirect.com/science/article/pii/S0894177721001345.
Lyakhovetskaya, O. (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.
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
Hepher (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.
NASA Glenn Research Center. (2023, November 2). Winglets. NASA Glenn ResearchCenter
https://www1.grc.nasa.gov/beginners-guide-to-aeronautics/winglets/
Guo (2021). Chinese Journal of Aeronautics. Chinese Society of Aeronautics and Astronautics.
https://www.sciencedirect.com/science/article/pii/S1000936121000480
Gudmundsson (2022). General Aviation Aircraft Design: Applied Methods and Procedures (2nd ed.). Elsevier Science.
Fehrm. (2017, November 15). Why did Emirates choose Boeing’s 787-10? Leeham News and Analysis.
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