[HOE] Helicopters and rotor noise

[John.Hostetter@hsc.com]

The distinctive noise of a Helicopter is mostly dependent upon the speed
with which the tip of the rotor is moving.  Faster=louder is a good rule of
thumb.  This noise can be controlled through a number of things:
- sound damping coatings on the blades
 - "twisting" the rotor the farther out it goes
- complex and VERY time consuming design of the airfoil cross section

All of these things will, however reduce the performance of the helicopter
in some way.

Also, the Russian made  Hind is louder than an apache, it also is faster in
the straight away, and does not hover well at all.  It has a pair of weapon
pod wings that it actually derives lift from.  Its engine is also less
isolated from the environment than the apache.

John








Sam & Max <samnmax@swbell.net>@gamerz.net on 01/22/2001 10:40:06 PM

Please respond to hoe@gamerz.net

Sent by:  owner-hoe@gamerz.net


To:    hoe@gamerz.net
cc:

Subject:  Re: [HOE] Re: hoe-digest.20010121




Patrick Phalen wrote:
>
> > Hmm. . . anybody know what the real world affect of
> > multiple rotors are?
>
> The simple answer is it depends...
> On a bigger copter it is most likely for added stability...
> For something like an Apache (or Hind) it is more sound
> dampening.  IIRC, there is some very complicated
> Bournouli-type equation going on describing the turbulent
> flow of the air around the rotors (and the speed at which
> they move)
>
> If you've ever NOT heard an Apache (or Hind) creeping up on
> you, you'd understand the result...
>
> Patrick "Not that I've *actually* seen a Hind, mind you,
> nor know that an Apache is quieter" Phalen

Sorry Pat, but on this one I have to mention that the Hind is without a
doubt
the god-ugliest loud helicopter I have ever heard. The thing is just loud.
And
if you ever get a chance they do have a fully flight worthy member of this
beastie at Fort Hood Texas. The Hind-D variant. Trust me, you will hear it
loong
before you see it.  :)
--
David Heth


To unsubscribe, send a message to esquire@gamerz.net with
     unsubscribe hoe
as the BODY of the message.  The SUBJECT is ignored.