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From: cga66@ihlpy.att.com (Patrick V Kauffold)
Newsgroups: sci.military
Subject: Re: re: Electric warship propulsion
Message-ID: <1990Dec21.025725.10406@cbnews.att.com>
Date: 21 Dec 90 02:57:25 GMT
References: <1990Dec17.051438.29694@cbnews.att.com>
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From: cga66@ihlpy.att.com (Patrick V Kauffold)
> From: wilson@b11.ingr.com (Jon Wilson)
> 
> budden@trout.nosc.mil (Rex A. Buddenberg) writes:
> 
> I know of no other warships that used the combustion->steam->electricity
> powerplant. 
> 
Here are two I know of:

1. Icebreakers.  The Wind-class (Northwind, Eastwind, Southwind, Westwind,
Edisto, Staten Island, Burton Island), and the later Glacier, were
diesel-electric.  On the winds, there were six Fairbanks-Morse prime
movers directly connected (no gearing) to DC generators.  These could
be connected to two DC motors (@5,000 SHP max) with 2, 4, or 6 main
engines on the line at any one time.  Very flexible and efficient; very
high cruising radius at low speed (~6 kts), while providing lots of
power for operating in the ice.

The DC motors were controlled directly from the bridge - electro-
mechanically.  The controls varied the motor excitation to control
motor speed.  The controls (Westinghouse) were a bear to keep in
proper adjustment.

The OOD could go from full ahead to full astern in a matter of seconds.
Good control in the ice.  Plus there was no direct link to the engines,
which did not reverse direction.  If you hit some ice that stopped the
screw, the motor would overload and trip.  Very exciting when standing
watch in the motor room.

The Glacier had 10 diesel/DC generator sets for ~21,000 HP total.

The Polar class icebreakers use diesel-electric/gas turbine-electric
propulsion, 6,000 HP or 20,000 HP respectively.  These use variable
pitch screws, which have been the source of problems.

2. Owasco class 255' cutters.

Two foster-wheeler top-fired boilers, 630psi, feeding a single
two-stage turbine connected to a SYNCHRONOUS AC generator.  This
drove a single AC motor, 4,000 HP (in 1945).  Speed reduction was
attained by having a different number of windings in the motor.

Now synchronous motors are AC motors where the armature rotates
in step with the rotating magnetic field with no slip.  Speed
is controlled by speeding up/slowing down the generator.  Starting
from zero RPM was done by connecting the motor as an induction motor,
then switching to synchronous mode as the motor matched the generator
speed; called it "locking in".  These controls were electro-mechanical.
The design was used because it was relatively inexpensive (no reduction
gears, shafting), and was, for its day, efficient in the generation
of power.

Pilot-house engine control was designed, but I never saw it used,
as this was in 1968 - more than 22 years after construction.

This plant was quiet and smooth, very little vibration.