[Music] [Music] hello it's Jacob again and welcome back to helicopter lessons in ten minutes or less today we're gonna be talking about translating tendency so what is translating tendency well let's take our helicopter system just like before we'll be using a counterclockwise rotating helicopter system now translating tendency is the tendency for the helicopter to drift in the direction of tail rotor thrust so when a counterclockwise rotating system this is a tendency the helicopter to drift to the right it's also why you see a helicopter tend to hang left wheel or left skid low when it's at a stationary hover so why is it that it does that well let's blow it up to a slightly bigger drawing here's our mast will draw the fuselage around it our rotor system turning counterclockwise alright so due to Newton's third law of motion every action has an equal and opposite reaction so this rotor system is turning counterclockwise the pivot point for this is going to be right around the mast so as this helicopter is a rotor system is turning around to clown or clockwise it's pushing against the fuselage so it's turning the fuselage went uncompensated for to the right it's turning it in the opposite direction that the main rotor wants to travel because of that equal and opposite reaction so this is causing rotation around the mast of the fuselage because of the main rotor thrust on the on the helicopter so if this were completely uncompensated for the fuselage would just continue to spin around and around to the right being completely uncontrollable so what do we do we mount a tail rotor tail rotor is an anti torque device it's meant to stabilize the heading of the helicopter and give us the ability to even fly this thing without spinning around in constant circles so this helicopter with its tail rotor now it's taking the airflow pulling it through the rotor system or pushing the tail to compensate for that right turning of the fuselage so it's turning it's pushing all this air this way to the left to prevent the tail rotor from turning to the right so it's pushing it to the right the tail rotor thrust is pushing the helicopter or the tail of a helicopter to the right now this is compensating for this rotation of the main rotor thrust so now with this tail rotor pushing against the torque effect of this main rotor now we have some kind of heading control and now we have authority with our pedals to be able to turn where the helicopter is when we're flying but because of that now we have two things working against us we have the main rotor our correction the nose of the fuselage wanting to turn to the right the tail rotor being pushed to the right and that manifest is the entire helicopter drifting to the right and that is translating Tennessee it's also known as torque effect it's the drifting of the right of the helicopter due to main rotor thrust and tail rotor compensation of main rotor thrust so if this was just left unchecked every time you picked up to a hover it would naturally just stripped it left so we have to compensate for it so how do we compensate well one way is rigging and what do I mean by rigging you can either rig the flight controls and this means that you rig the flight controls so that you already have just an a slightly increase in pitch to fight this right drift so you have an increase in pitch of the tail due to charge our scopic precession this is going to manifest 90 degrees later as an increase in pitch on the right side causing a counter action of that right drift from the translating tendency another way you can have something like your transmission being mounted slightly offset so say instead of right in the center of the helicopter you shift it slightly to the left and this is going to cause a shift in your center of gravity which would normally cause a helicopter to drift to the left but because of translating tendency now that they counteract each other and it's at a stationary hover it just shifts the center of gravity another technique for this for compensation would be a flight management computer or some kind of flight management system that automatically makes these inputs for you whenever you pick it up to hover it knows that you're taking the helicopter up and it makes the necessary flight control input to maintain a stationary hover lastly and this is this this is mainly for your archaic Tyco that type of helicopters that don't have any of this you have your good old pilot input so you pick it up to a hover helicopter wants to drift to the right so what do you do you give a little bit of left cyclic and that counteracts just like in your flight controls or your FMC that counteracts that right drift by it's increasing the pitch over the tail which manifests 90 degrees later and stops that drift to the right but in all three of these cases what's going to happen the rotor disk tilts left to fight that right drift and because of that the the fuselage always always always follows the rotor system just like a pendulum hanging underneath it at all times with that disc tilted to the left it's gonna result in a left skid / left wheel low at a hover when you're compensating for that transparency so it's as simple as that it's the helicopters tendency to drift in the direction of tail rotor thrust it's all caused because of Newton's third law of motion action or reaction where the main rotor is fighting against the fuselage we compensated for it with a tail rotor and because of that both forces are pushing the helicopter to the right and the helicopter will drift to the right so to compensate for that we have rigging a flight management consists 'im or pilot input to compensate all right that wraps it up for translating tendency hope you guys enjoyed the video if you have any questions or comments just leave them in the comments section below hit like if you enjoyed the video thanks for watching once again stay fly [Music]