Why does a helicopter have two propellers

Solution: If there would be only one propeller, the helicopter start rotating in the direction opposite to the movement of the propeller. The two propeller rotate in the opposite direction as to cancel the torque produced by one propeller. When an object is placed between pole and focus of a concave mirror, then the images formed are Ray Optics and Optical Instruments.

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Magnetic energy density in an inductor is given by Electromagnetic Induction. Why use Doubtnut? Instant Video Solutions. Request OTP. Updated On: Share This Video Whatsapp. Text Solution. Solution :. Watch fullscreen. Have you ever thought why some helicopters have two propellers? The main rotor creates lift by re-directing the flow of air downward. Due to the torque produced by the spinning main rotor, the helicopter's fuselage body would rotate the opposite way until it reaches a speed which equal and opposite to the torque.

The tail rotor counteracts the torque on the main rotor by creating a re-direction of air. Helicopters like the Chinook are a unique design because they have two main rotors. Each main rotor turns in the opposite direction to one another so the torque on the fuselage created by the front main rotor is canceled out by the torque produced by the rear main rotor.

Coaxial rotor helicopters also provide a better power to weight ratio than traditional helicopters, produce greater lift and are also much more efficient. They spin in opposite directions meaning that they counteract each other to keep facing forward.