[Milsurplus] L.O. radiation

[Jerry K]

I believe John is correct. This underwater noise subject has been
interesting. Please see
http://www.fas.org/man/dod-101/sys/ship/ssn-21.htm where the new SEAWOLF
class of Navy submarines is described. USS Jimmy Carter (SSN-23), third and
last of the series was commissioned about three weeks ago. I quote:

"The Seawolf has the highest tactical speed of any US submarine. Much of the
design effort was focused on noise reduction, and it is expected that the
fully coated boat will restore the level of acoustic advantage which the US
Navy enjoyed for the last three decades. The Seawolf's propulsion system
makes it ten times more quiet over its full range of operating speeds than
the Improved-688 class and 70 times more quiet than the initial generation
of Los Angeles 688-class submarines. The Seawolf's quieter propulsion system
will also enable it to have twice the tactical speed as the I-688. Tactical
speed is the speed at which a submarine is still quiet enough to remain
undetected while tracking enemy submarines effectively. Overall, the
Seawolf's propulsion system represents a 75-percent improvement over the
I-688's -- the Seawolf can operate 75 percent faster before being detected.
It is said that SEAWOLF is quieter at its tactical speed of 25 knots than a
LOS ANGELES-class submarine at pierside."

That last sentence should scare the pants off Russian submarine skippers,
since the LOS ANGELES class was their most feared adversary for many years.
It's got to be an eerie feeling to realize your enemy can do 25++ knots (if
the press release says 25, then it's more) while stalking you underwater and
you might not even know he's there. Sort of like attending a gunfight with a
club in your hand. Maybe now the focus will swing back to the electronics,
but this illustrates that at least up to now propulsion and hull noise have
been the driving factors in detection and tracking.

73, Jerry W5KP LT, USN (Ret)


-----Original Message-----
From: milsurplus-bounces at mailman.qth.net
[mailto:milsurplus-bounces at mailman.qth.net]On Behalf Of J. Forster
Sent: Wednesday, March 23, 2005 11:58 PM
To: Unserviceable but Repairable
Cc: kargo_cult at msn.com; milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] L.O. radiation


It's an interesting idea, but I'm a bit skeptical.

First off, bias power is pretty low

Second, any acoustic noise would have to come from some sort of intended or
parasitic electro-mechanical transducer. This could be electro-striction in
a
capacitor or magneto-striction in some magnetic device, or a vibration such
as a
loose lamination.
I doubt it would be the hydrophones themselves because there would be
amplifiers
between the hydrophones and the tape recorders and amplifiers do not usually
feed stuff from output to input (it tends to cause oscillations)

Third, I'd expect pumps, turbines, motors, and other stuff would make a lot
more
noise.

Just an uneducated opinion though.

-John