Salty,
The whine is caused by the "fan in fin", the Aerospatiale way to make a tail rotor do something other than provide counter torque. Above a certain speed that is what the assembly of horizontal and vertical tail planes do, keep the helo going straight. Provided of course you have a button pusher in the cockpit that can accomplish that mean aerodynamic feat as well.
When brought into USCG use in the mid 1980's, the HH65A Dolphin was the most advanced helicopter in the US inventory, no kidding! (How the Coast Guard managed that I will never know).
BTW, the cowling on the Trumpeter model is not accurate for the HH65A. The engines were Avco-Lycoming, not the Turbo-Mecca included int he SA365N model. The HH65C will have the newer model of the Turbo-Mecca, and thus the smoother looking cowling.
Don
I know it's only rock and roll, but I like it.