How Do Aircraft Propellers Function?
While propeller-driven aircraft were more popular in commercial aviation of the past, they are still favored by many pilots for implementation on light aircraft today. When compared to private jets, turboprop aircraft generally perform better at shorter distances. Moreover, the position of the propeller at the front of the vessel also enables turboprop planes to land on rougher terrain due to the fact that the propeller assembly is further away from the ground. As a popular choice for light aircraft, becoming familiar with the functionality of aircraft propellers can be very useful, especially in the case of an accident of fault. Here, we will discuss how propellers operate in detail, analyzing specific working principles and basic design features.
An aircraft propeller consists of two or more blades and a central hub where they can be attached. As propeller blades essentially act as a rotating wing, each blade has a similar shape which orients the air in such a way that pushes against the underside of all blades. More specifically, a cross-section of a typical blade would show that one surface is curved, while the other surface is flat. Because air flowing under a blade has less distance to cover than air flowing over a blade, a pressure differential is created that results in greater upward force against the underside of the blades than their opposite surfaces.
While the process of force generation is comparable to the way lift is created by wings, propellers must generate even greater force for forward thrust. As such, their shape is also designed to create thrust as a result of its rapid rotation. Rather than being angled perfectly perpendicular to the nose of the plane, propeller blades are tilted diagonally. This positioning has each section of the blade moving downward and forward. Consequently, the air deflection produced by this angle causes the dynamic pressure at the engine side of the propeller blade to be greater than atmospheric pressure, creating thrust. To help imagine this, one can think of a screw being driven into a wall. Though the solid wall is very different to the air, the forward motion of the screw as a result of its angled threading, and the manual force behind it is similar to how the angled blades of a propeller cut and push through the air. Helicopters use the same setup, but in a vertical fashion and with the added ability to angle the propeller in such a way to also navigate in every direction.
Using the principle described above, some propeller-driven aircraft will have their blades at a fixed angle, changing the speed of the propellers to affect their thrust. However, other aircraft use a constant-speed propeller wherein the blade angle must be adjusted to provide different levels of thrust. However, regardless of whether they are fixed-angle or constant-speed, all propellers have noticeably twisted blades. This is because the outer parts of the propeller blades travel faster than the portions near the hub. Therefore, propeller blades are twisted to change the blade angle in proportion to the differences in speed of rotation along the length of the propeller, keeping thrust more constant along this length.
Despite being disfavored for large aircraft due to their limited speed and power capabilities, propellers still find popularity in light aircraft for their fuel efficiency and proficient level of performance. If you are the owner or operator of a propeller-driven aircraft, Aviation Parts Online invites you to check out our wide range of parts for turboprop vessels. Moreover, we have a plethora of other aircraft components to suit any other fulfillment needs. Start the procurement process with us today to learn all that Aviation Parts Online is ready to accomplish as your strategic sourcing partner!
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