B4RT wrote:

BTW: The tail rotor makes the most amount of noise. People say fennestrons
are quieter, I think their sound is more obnoxious , but kinda kewl in
small doses.

The London Air Ambulance has a MD 902 Explorer
of which
http://www.answers.com/topic/london-air-ambulance
says:

"...does not use a tail-rotor. This was felt to be a useful feature,
as the helicopter has to routinely land in confined inner city
areas..."

It is noticably quieter, so much so that when I
first saw it pass overhead I recognised that it was
unusually quiet and looked it up to see if I could find
any reason for that. There appears to be.

I would like the use of any other design of
helicopter to be prohibited over my house.
(Nomex suit at the ready:-)