"I always thought those koaxial helos were louder. "
Umm, yes, If you compare a 10 ton helo with 4,000shp of engine power with a huey of course it is going to sound louder. A better comparison would be to compare it with another helo with a 5 ton lifting capacity.
The tail rotor actually makes a lot of noise on a conventional helo and this noise is removed when it is removed.
"- Rotorhead construction is much more complex.
- You aso loose effeceny because of counter rotating rotors ad the resulting disturbances
- no mast mounted sights
- higher machine
The rotorhead is more complex. But the loss of the tail rotor system saves space and reduces vulnerability.
The Ka-52 has a Mast mounted radar.
Height is a factor.
It is quieter when compared with similarly powered aircraft.
The main limit is maximum speed.
The two sets of rotors reduces vibration.