Stopping the cabin spinning
Why Does the Little Tail Rotor Matter?
Turning the main rotor twists the body the other way, and the tail rotor cancels that twist.
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Step 1 of 5
The blades are just spinning wings.
Each blade has the same curved cross-section as an aeroplane wing. Instead of the whole aircraft moving forward, the blades travel in circles.
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Step 2 of 5
Turning the blades twists the body back.
The engine has to push against something to turn the rotor, and that something is the fuselage, which gets twisted the opposite way.
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Step 3 of 5
Unchecked, the cabin would simply spin.
With nothing to stop it the fuselage would rotate steadily beneath the blades, leaving the aircraft impossible to point or control.
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Step 4 of 5
The tail rotor is a sideways propeller.
A small propeller mounted at the very back blows air sideways, and being far from the centre gives its modest thrust plenty of leverage.
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Step 5 of 5
The same pedals also steer.
Deliberately using a little more or less tail thrust than needed lets the pilot swing the nose left or right while hovering.
A tail rotor can absorb around 10% of the engine's power purely to stop the fuselage from spinning.
The short version
A helicopter needs a tail rotor because turning the main blades twists the body the opposite way, and the tail pushes sideways to cancel it.
Try it yourself
Sit on a swivel chair and spin a heavy bag held flat in front of you. You rotate the other way — the twist a tail rotor fights.
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