Why Are Helicopters So Loud? + more videos | #aumsum #kids #science #education #whatif

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Why Are Helicopters So Loud?
The primary reason is blade-vortex interaction. Let me explain.
When the main rotor of a helicopter starts rotating, the blades start spinning.
Due to this spinning, air pressure above the blades starts dropping while air pressure below the blades starts increasing.
As a result, there exists a huge air pressure difference. Now, air from high pressure area starts moving to low pressure area.
This produces a lift which causes the helicopter to rise. But, it also leads to the creation of various airflows. One of them is a vortex.
This vortex is generated by the tip of a rotor blade. When this vortex hits the next advancing blade, the blade vibrates.
This is called blade-vortex interaction. The vibrations of the blade generate a loud sound. Hence, helicopters are so Noisy.

References:
https://aerocorner.com/blog/why-are-helicopters-so-loud/
https://verticalmag.com/features/the-science-behind-helicopter-noise-how-the-industry-is-working-to-reduce-it/
https://scholarworks.sjsu.edu/cgi/viewcontent.cgi?article=1041&context=mcnair

Timecodes
0:00 - Why Are Helicopters So Loud?
1:33 - How do Drones Fly?
2:41 - How do Electromagnets Work?