Take-off of the aircraft leads to significant loads on the on-board systems and the skin of the vessel. Therefore, it is important for maintenance personnel to monitor not only what is happening inside the air vehicle, but also outside. This is partly facilitated by the porthole of the aircraft, through which it is possible to fix the occurrence of an emergency situation, for example, engine fire or damage to the skin.
Can a porthole break when landing
As a rule, an airplane porthole is a structure formed of a three-layer double-glazed window. Such a system is able to withstand significant pressure drops.
Take-off of the aircraft and the last climb leads to the fact that the glass are loaded up to 4 tons. And if the porthole is able to withstand such pressure, it does not threaten anything when landing.
As for the inner glass, which passengers can touch, it is only decorative in nature. Its damage will not affect safety when in the aircraft cabin.
Why are curtains installed on the windows
Window blinds are required for several reasons:
- After landing, the eyes of passengers must adapt to the available lighting on board the aircraft. Only after this the curtains are opened, which allows you to see what is happening overboard.
- By pushing the curtains, the crew is able to concentrate on serving passengers. If necessary, these curtains can be pulled back if it is necessary to inform pilots about the occurrence of emergency situations overboard, for example, to confirm the presence of an accident.
- Curtains protect passengers from potential injuries that may occur, for example, during a hard landing, as a result of damage to the windows of the windows.
- Sliding shutters allow you to keep calm for passengers who are afraid of heights.
Why airplane portholes are streamlined
Such a design is not an artistic idea to give the interior an attractiveness. As practice shows, the rounded, streamlined porthole of the aircraft better tolerates increased pressure, due to its optimal distribution over the entire surface.
A confirmation of the foregoing is the testing of portholes of various shapes on devices with a jet engine. So, in the 50s of the last century, the aircraft manufacturer De Havilland released a passenger liner that contained square portholes. However, the innovative aircraft was expecting a sad fate. In 1954, during the flight, the square windows could not withstand the load, and depressurization occurred in the cabin. After the accident, the designers no longer resorted to installing inspection windows of a similar shape.
Why a hole in the porthole
Many passengers could notice the presence of a small hole in the window of the porthole. The named hole is required to stabilize the pressure between the individual glasses of the structure. If during takeoff the ambient temperature is on average 25 ° C, then when you set the optimal flight altitude of 10,000 meters, the indicator reaches -35 ° C and lower. As a result, the airplane window is subject to significant stresses due to expansion and contraction of the air.
Through the aforementioned hole, air exits when the temperature of the surrounding space rises and enters when the indicator drops. Without the implementation of such a design idea, the material for making portholes could crack and deform.
The hole in the porthole performs another function. Its presence prevents fogging of the glasses and, as a consequence, their icing.
It is worth noting that the Soviet-style AN-24 passenger liners did not contain the described holes. An alternative to them was tubular air vents, which were located in the skin of the fuselage of the aircraft. This decision helped to maintain a stable pressure level between the structural elements of the windows.
What functions do individual porthole panels perform?
During the climb by a passenger airliner, the pressure inside the cabin remains the same, and outside the aircraft, its pressure drops significantly. This leads to an increase in the load on the windows, which consist of several fiberglass panels.
The least durable is the inner glass with which the passenger can come into contact. It serves only to isolate from the noise made by the liner engines, as well as to retain heat in the cabin.
The outer panel of the porthole is much stronger. The specified element is made of the most durable material and is able to withstand significant atmospheric pressure.
As for the middle panel, it plays mainly the role of insurance. Such glass is used in case of damage to the outer element of the glass unit. However, the likelihood of such situations is extremely small.