helicopter noise reduction

[verticalairborne]

Does anyone know more about the silent hughes during the early 1970s?
A Darpa sponsored program to make the hughes 500 quieter.
How quiet was the helicopter?
5 bladed main rotor and 4 bladed tail rotor.

Was it quieter than the modern Notar or Eurocopter helicopter?

Does anybody have more information?

Where can I get a view of this machine?

thanks a lot

[Graviman]

Vert,

I recommend searching for "silent hughes" on PPRuNe Rotorheads. It is quite a resource:
http://www.pprune.org/forums/search.php?searchid=1956521

It might lead you to this thread (RIP Lu):
http://www.pprune.org/forums/showthread.php?t=131824&highlight=hughes+silent

Out of interest, is this for a project?