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