Republic of the Philippines PHILIPPINE STATE COLLEGE OF AERONAUTICS Institute of Engineering and Technology Module 1 Case Study 2 Shapes and Design of the Passenger Cabin Windows HONESTY CLAUSE As a student of Philippine State College of Aeronautics, I hereby pledge to act ethically and uphold the values of academic integrity, honor and excellence. I certify on my honor that I have neither given nor received assistance from anyone in completing this assessment. I understand that suspected misconduct on given assignments, activities and examinations will be reported to the appropriate office and if established will result in disciplinary action in accordance with the rules, policies and procedures by the College. Submitted by: Carcido, Ashley Dale Llamera, John Lhedzel F. Course Year-Section: BSAeE 2-6 1 Republic of the Philippines PHILIPPINE STATE COLLEGE OF AERONAUTICS Institute of Engineering and Technology Abstract The Cabin Passenger windows are rounded or elliptical because rounded windows are stronger and have high resistance in deformation and it can also withstand repeated pressure differences between the inside and outside of the aircraft. Square windows or windows with corners were used before but an accident occur during the de Havilland Comet aircraft where they had square windows and the square windows are unable to withstand the stress and causing the aircraft to crash and killing 56 people in total. Corners are the weak spots of stress because stress in corners were concentrated in a single spot causing it to break while curvy windows can distribute stresses reducing the percentage of breaking to happen. 2 Republic of the Philippines PHILIPPINE STATE COLLEGE OF AERONAUTICS Institute of Engineering and Technology Body According to the Aircraft Nerds (2016), windows are not always in round shape, in fact, in the 1950s, the de Havilland Comet aircraft of British Airways had square windows. The aircraft crashed while killing 56 people in total and the crash of the aircraft taught a very important lesson about the shape of the aircraft windows to aircraft engineers. In the case of square windows, this stress is greatest at the corners, where the edges of the square windows meet at 90°, causing fuselage damage. The force will also concentrate on the angles in any other shape with an angle. As stated by Aerotime Hub (2016), “Where there’s a corner, there’s a weak spot”. Windows with corners have potential weak spots making them likely to crash under stress due to air pressure. Curving the window distributes the stress that would eventually crack the window corner and reduces the likelihood of it breaking. Circular shapes are also stronger and resist deformation, allowing them to withstand the high-pressure differential between the inside and outside of the airplane. In an article by Marisa Garcia (2018), she stated that airplanes are not so different from submarines because both involve structures that have to withstand a difference in pressure and temperature inside and outside and a tiny flaw or weak 3 Republic of the Philippines PHILIPPINE STATE COLLEGE OF AERONAUTICS Institute of Engineering and Technology point can quickly spread and lead to tragedy. Although, airplanes face other challenges due to very high speeds in the environment and other debris may pose a threat. Windows have to withstand different kinds of stress and it must be tested like pressure, temperature control, bird strike test, and including chemical resistance. Square windows were dangerous for airplanes because the pressure inside and outside the cabin was so dissimilar that the sharp edge corners couldn't take it and gave in. Sharp corners naturally concentrate more stress, which is weakened even further by the high air pressure. Curved or circular windows distribute the stress of outside air pressure, making them stronger and less susceptible to deformation. (India Today Web Desk, 2018) 4 Republic of the Philippines PHILIPPINE STATE COLLEGE OF AERONAUTICS Institute of Engineering and Technology The graphic above is from Sharise Cunningham (2019), where it shows how the stress from the square windows on the de Havilland Comet caused the aircraft to break apart in the mid-air. Due to the lack of corners where stress can concentrate, rounded windows are able to evenly transmit pressure, reducing the chance of fractures or breakage. Circular shapes are also more durable and resistant to deformation, allowing them to withstand repeated pressure differences between the interior and outside of the plane. 5 Republic of the Philippines PHILIPPINE STATE COLLEGE OF AERONAUTICS Institute of Engineering and Technology References: Aircraft Nerds, 2016; Why are Aircraft windows round; Retrieved from May 7, 2022, from https://www.aircraftnerds.com/2016/06/mystery-of-aircraft- windows.html#:~:text=But%20oval%20shape%20windows%20are,won%27t%20 damage%20the%20fuselage. AeroTime Hub, 2016; Why Airplane Windows are Round? Aerotime Extra; Retrieved May 7, 2022, from https://www.aerotime.aero/articles/23023-whyairplane-windows-are-round Marisa Garcia, 2018; How Airplane Windows are designed to withstand enormous stresses, and How they can Fail. Forbes; Retrieved from May 7, 2022, from https://www.forbes.com/sites/marisagarcia/2018/05/19/airplane-windows-cancope-with-more-stress-than-you-think-expert-explains/?sh=1e5cd4ed149f India Today Web Desk, 2018; Why are airplane windows round; Retrieved from May 7, 2022, from https://www.indiatoday.in/lifestyle/travel/story/why-are-airplanewindows-round-1380496-2018-11-01 Sharise Cunningham, 2021; Why are airplane windows round? Howstuffworks; Retrieved from May 7, 2022, https://science.howstuffworks.com/transport/flight/modern/airplane-windowsround.htm 6 from
