Helicopter Rotor

Posted on | June 16, 2009 | 1 Comment

Helicopter Rotor

what is the motion of a helicopter rotor?

A helicopter is know as a rotary wing air craft. The blades of the main rotor rotate in a plane about a drive shaft. The pitch of the blades is determine by connecting rods which track along the position of a swash plate. The pilot controls the height and angle of the swash plate using a cylic and collective flight controls.

The pilot using these flight controls is positioning the swash plate and the rotor blades adjust there pitch via the connecting rods to match the elevation changes of teh swash plate as the blades rotate.

To move the copter forward more down ward thrust must be generated by blades moving at the rear of the copter compared to less thrust by blade moving at the front of the copter.

The cyclic control is therfore pushed forward by the pilot. This causes the swash place to angle so that it is higher at the rear and lower at the front. Looking at a single blade , as it rotates around its connecting rod tracks along the swash plate and adjusts the angle of pitch on the blade, So when the blade is in the fron of the copter (12 Oclock) it has less pitch, as it moves around to the rear of the copter (6 O'clock) the connecting is pushed higher by the angled swash plate and increases the pitch of the blade and generated more downward force.

With more force at teh rear of the copter than at the front the copter will pitch forward (nose lowers and tail rises) and start to move forward.

To make the copter go higher or lower while maintaining direction the pilot uses the collective. THis control raises or lowers the swash plate without changing its angle. "Collectively" the pitch of all blades is adjusted by the same amount regardless of there position as they rotate.

The pilot controls direction of the thrust of the main rotor by using a cyclic control. This controls the pitch of the blades as they rotate.

Amazing Flying Helicopter - Defying The Laws Of Physics

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A helicopter with a tail rotor is safer or not?

A helicopter with twin main rotors on top such as KA50 were design with a system that will replace the traditional functions of a a tail rotor which could halt due to system malfunctions. Why many helicopter manufactures still went on with the tail rotor eventhough they knew the hazards very well?Any ideas boys and gals...

You've got some good answers there, and here are some of my comments:

1. Helicopters equipped with tail rotors are by far the most common, efficient, and proven design around today. In a hover in a calm wind, a conventional tail rotor uses about 18% of total engine power produced.

2. Helicopter designs without tail rotors include 2 rotor designs (such as Kamov, K-Max, Boeing BV234), NOTAR (MD design operates mainly by Kawanda effect and low pressure air nozzle, NOT by a second engine as suggested above), and tip jets (experimental only). A tail rotor-less design is more efficient becuase there is no pwer "robbed" from the main rotor, but the design is incredibly complex.

Certainly a helicopter without a tail rotor is safer in theory, but they have mechanical design challenges and performance limitations. As a helicopter pilot, my biggest worry is for somebody to walk into the tail rotor as they are pretty well invisible. The pilot has to operate the helicopter in accordance with its limitations and therefore I would say that neither design is safer than the other. And as already pointed out by another response, the tailrotor-less helicopters are also prone to mechanical failures - every helicopter needs an anti-torque device to counter Newton's third law - for every action there is an opposite and equal reaction. A helicopter literally has thousands of moving parts - tailrotor or not.

I think the MD NOTAR system used on the 520, 530, 600, and 900 helicopters is brilliant and probably the best of the systems, but they are twitchy at high speed. Also its too bad all those MD designs have such a cramped cockpit which limits their appeal to a lot of customers. They are quieter and in theory eliminate tail rotor strikes, but give me a real tail rotor in difficult cross wind conditions any day.

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