The speed of helicopter rotor blades through the air is limited by the speed of sound (approx. 760Mph) at which point the pressure wave disrupts the airflow at the blade tip (which is moving through the air faster than the blade root). So the larger the rotor diameter (the longer the blades), the lower the allowable RPM (the slower they 'spin')
Helicopter blades operate from a transmission or gearbox immediately under the blades. They have to spin fast to give the helicopter lift. Once they are in the air the blades twist slightly to give forward motion.
Some helicopter main rotor blades spin at roughly 185 rpm and extend out up to 20 ft so your question is subjective to the helicopter you are speaking of.
Helicopter blades spin due to the engine providing power to the rotor assembly, which causes the blades to create lift and generate thrust. The rotation of the blades also allows the helicopter to maneuver and change direction in flight.
What do you mean by tail spin? How the blades turn? How the back of the helicopter turns?
The rotating blades are angled in the same direction (at about 35 degrees) and spin fast enough for the air pressure beneath the helicopter to be higher than above so much so that the helicopter lifts off.
The rotor is like the engine to the propeller. A propeller is the fan like blades on the top that spin to make the helicopter fly.
The top part of a helicopter would most commonly be considered the rotor blades (which spin to provide lift).
A helicopter gets its lifting force from the rotation of its main rotor blades. As the rotor blades spin, they create a pressure difference between the top and bottom surfaces, generating lift that enables the helicopter to become airborne. The angle of the rotor blades can be adjusted to control the amount of lift produced.
The rotor blades continuously spin until at a certain speed causing thrust to happen and the air pressure under the blades lower as said in daniel bernoullies principal when air or water moves at a certain speed the air under the blades lower allowing lift hope this helps a little, im not positive its correct. The above is not correct as the bernoullie effect has little to do with causing the helicopter to fly. The blades(rotors) spin at a fast enough rpm and are tilted as they spin thereby forcing air downward very fast so that this downward airstream compresses and pushes against the ambient air beneth the chopper thereby causing it to rise into the air.
The rotor blades on a helicopter work the same way as wings on a fixed wing aircraft. The air passing faster over the top of the airfoil generates lift. Helicopter rotors spin so that the lift is generated without having to have forward airspeed like a fixed wing aircraft.
My understanding of how helicopters work is that they (suck) the air from above the blades and (blow) it down wards to create lift. the rear blades counter the spin of the top blades of it wasn't for them the helicopter would just spin round in circles (fun but not recommended) :-)
A helicopter achieves lift through its main rotor blades, which spin rapidly to create lift by generating airflow over the rotor blades. The shape of the rotor blades and the angle of attack can be adjusted to control the lift produced. This lift overcomes gravity, allowing the helicopter to become airborne.