Definition of sideslip in helicopters

If you put more sideslip on the helicopter you will increase the total drag, just like a fixed wing. So, you will descend. THe maneuver is typically not used like it is in a fixed wing aircraft as the helicopter has a much higher descent rate / angle when the power is reduced.
Operationally, sideslip is used in performing what is known as a sideflare quickstop, where the observation pilot does not want to expose the helicopter above a treeline, or is at such a low height above the ground that he can't raise the nose (because he'd hit the tail).
(I'm the chief helicopter instructor at National Test Pilot School, if you were wondering).
Shawn

lateral stich and peddle = more drag = no big deal we use this to see out below the door in a confined approch to an L/Z IE Sikorsky 58 with no lower windows (the engines are there)