IRL "rudder" (anti torque) wont work at higher speed.

probably, because you stay at over speed for this model of chopper.

I hope you know how helicopters work

helicopters (and all aircraft for that matter) are made aerodynamically stable so they don't fail and crash to the ground. now a helicopter has two rotors. (A)the main rotor and (B)the anti torque rotor. "B" is the rotor that makes you rotate in mid air (it also keeps the helicopter from randomly rotating because of the spin of the main rotor hence the name anti-torque). once the helicopter gets to a certain speed the aerodynamic shape kicks in an prevents the anti-torque rotor from rotating the helicopter because the air is moving past the helicopter to fast, the anti-torque rotor is not strong enough to rotate that much force (Plus many other problems against physics).

hope i straightened things out

+1 Scorpion!

I did not want to explain so technically but very good Scorpion.

Thats the point.

Overspeed results in loss of aerodynamics of the aircraft, causing the loss of control, in some cases system failure or even destruction of the equipment.

Actually what scorpion said happens way before the overspeed state

Actually the tail rotor still has effect on helicopter attitude, even at higher speeds. Just not good for the aircraft, will put a lot of stress on the tailboom.

A CH47 "tail rotor" works slightly differently from a common design helo :)

I'm sure about what in my previous comments because i had the opportunity to fly in a private ultra-light helicopter with a friend

it works 47pilot, but like in arma it's HIGHLY ineffective, not only bad for the bird

I have about 100 hours on tailrotor helicopters, yaw IRL has more effect than it has in Arma3.

I realise the rudder would have less effect at speeds,but don't you guys think it should work at all speed for coordinated turn. It seems the only way to turn the helicopter righ now is to roll it and pull on the cyclic.

... as speed is rising = pedals effect are decresing rapidly because tail (fin)
is working as stabilizator..
At 100 kts almost no effect of pushing on pedals ( just a lot of extra stress on tail boom what can lead to tail rotor or boom damage )

All turns have to be made by banking aircraft...

700h on r44 in RL.

Hmmm... This is simply not true. I haven't ever flown such a tiny helicopter like a R44, maybe that R44 doesn't have the power to use the tailrotor at speeds, but bigger helicopters can most certainly give yaw inputs. You'll break stuff if you overdo it, but a heading change like 10-20 degress at higher speeds is not much of a problem, at all.

Going to ask about this matter to a friend of mine which is pilot on Nardi MD-500 (basically the italian licensed version of OH-6) which is most likely the kind of helicopter that we have in the game.
Will report as soon as i get an answer

You can also just ask me. I've flown TH67, UH1, Allouette-3 and CH47.

Tailrotor still has effect at higher speeds, you need it to fly coordinated. Pushing harder on the pedals at high speeds isn't something you'd normally do, but it most certainly can be neccesary and it is possible.

course adjustments of 10-20 degrees are indeed easily doable with the current in game tailrotor. It seems people are arguing over a none issue here.

Consider.... Wind can exert influence in aerodinamic and fly!

well 47pilot, since I also only flew on R44, you may be right

Non-issue, it is possible already.