What causes blade slap?

Blade slap appears to be caused by a blade passing through the tip vortex shed by another blade in its proximity. This has been simulated on a rotor whirl stand under controlled conditions and the effect of various parameters investigated.

What sound do helicopter blades make?

The vortices created off the back of each main rotor blade produce an aerodynamic condition called BVI – Blade Vortex Interaction. As the vortices leave the trailing edge of the main rotor blade they get hit by the next rotor blade coming round. When the next blade hits each vortex it creates a snap or slap sound.

Why does the Huey make that sound?

The classic example of the “helicopter sound” is that produced by the Bell UH-1 Iroquois (‘Huey”) helicopters used in the Vietnam War. Helicopters generate their lift through the spinning of rotor blades. The spinning blades generate aerodynamic pressures and forces that create acoustic waves.

What is mast bumping in a helicopter?

Mast bumping is contact between an inner part of a main rotor blade or a rotor hub and the main rotor drive shaft (or ‘mast’). Serious mast bumping in flight usually results in the helicopter breaking up in flight, which is fatal for those on board.

What is a low G pushover?

LOW-G PUSHOVERS – EXTREMELY DANGEROUS. Pushing the cyclic forward following a pull-up or rapid climb, or even from level flight, produces a low-G (weightless) flight condition.

What is the sound of a helicopter called?

In helicopters in forward level flight, apart from the already mentioned noise generated by the rotation of the main rotor, another distinctive type of noise can be recorded, which is called “blade slap” or “impulsive noise” [1].

Why are some helicopters so loud?

TLDR – Helicopters are so loud due to blade-vortex interaction. The air pressure decreases above and increases below the blades as the main rotor spins, providing upward thrust. A vortex is created to even out the air pressure, which produces sound vibrations when it hits the next blade.