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The topic of this video is Translating Tendency which is the tendency for Helicopters to drift laterally in the direction of tail rotor thrust. This is also referred to as "torque effect." In rotor systems that turn counter-clockwise, this is a right lateral drift. It is also the reason why you see Helicopters lean left skid/wheel low when at a stationary hover. So why does this occur?
Remember Newton's 3rd law that states that for every action, there is an equal and opposite reaction? This is occurring when a rotor system is turning. As the main rotor turns counter-clockwise, it pushes the aircraft fuselage in the opposite direction (clockwise). If this were left uncompensated, the fuselage would continue to rotate around and around clockwise leaving the aircraft uncontrollable. So we fix this by adding an anti-torque device, aka a tail rotor. The tail rotor counteracts the torque of the main rotor by pushing the fuselage counter-clockwise to counteract main rotor thrust. The tail rotor does this by pushing the tail to the right and nose to the left with the mast as the pivot point. Not only this but the tail rotor also gives us the ability to have heading control by manipulating how much pitch is applied. So this fixes the problem of heading control but now introduces Translating Tendency. Because the tail rotor pushes the tail to the right and the main rotor torque effect pushes the nose to the right, the helicopter now develops a lateral drift to the right. The compensation of main rotor thrust has the Tendency to Translate into a lateral drift.
So how do we compensate for Translating Tendency? There are 3 ways.
1) Rigging - either by cyclic rigging of the flight controls or
structural rigging by offsetting or leaning of the transmission/mast.
2) Flight Management System - a computer automatically makes corrective actions in the flight controls.
3) Pilot Input- if the first 2 aren't present, then the pilot must add a left cyclic input.
In all the cases, the result is a left leaning of the rotor disk. Because the fuselage always follows the rotor, the helicopter will lean to the left when at a stationary hover. And that's Translating Tendency.
Thanks for watching and be sure to hit like and leave a comment! Safe flying.
If you're just getting started and want more information, pictures, and more explanations, I'd recommend reading the Rotorcraft Flying Handbook - amzn.to/2ifPlnZ
If you've already got a basic understanding, and want to further your professional helicopter education with advanced helicopter concepts, I'd recommend reading Cyclic and Collective, by Shawn Coyle - amzn.to/2ifQGLx