wilson@b11.ingr.com (Jon Wilson) (12/17/90)
From: wilson@b11.ingr.com (Jon Wilson) budden@trout.nosc.mil (Rex A. Buddenberg) writes: A couple years ago, Navy did some 'blue sky' work resulting in a Ship Operational Characteristics Study (which I'm in the process of cloning for USCG use, but different story). One of the conclusions of the SOCS was that electric power should be used as the prime mover on the next generations of ships. Interestingly, in the thirties the U.S. Navy was a proponent of electric propulsion. The large carriers _Lexington_ and _Saratoga_ were, I believe, the largest vessels ever fitted with it; I think that the _Tennessee_ and other battleships of that class were also fitted with turbine/electric propulsion. I recall the account of a crewman on the _Lexington_ who stated that several men in the engineering spaces were burned, zapped, etc. when incoming seawater from torpedo or bomb hits shorted the powerplants. I know of no other warships that used the combustion->steam->electricity powerplant. In a modern context, it might make sense to revert to an electric arrangement; quietness, plenty of power for laser, particle-beam weapons, massive radar arrays, etc. :-) Does anyone know if MHD generators would be suitable for shipboard power? ______________________________________ | | | Jonathan Wilson | | VMS Systems Support | | Intergraph Corporation | | | | email: uunet!ingr!b11!wilson | | phone: (205) 730-6397 | |______________________________________|
budden@trout.nosc.mil (Rex A. Buddenberg) (12/19/90)
From: budden@trout.nosc.mil (Rex A. Buddenberg) Electric propulsion has been around before. The reason the Navy is interested is because of some new ways to generate and convey electricity (superconducting) and batlle-group-wide systems engineering ones. Two classes of Coast Guard cutter were electric powered: Wind Class Icebreakers (7 hulls, plus Glacier) were all diesel-electric. Winds had 6 Fairbank-Morse diesels arranged with a pair in each engineroom. Two side-by-side motor rooms back aft with 5000 HP motors. 900 V DC system. Originally, these ships had a bow motor room with a third screw on the centerline. And the #1 engine room is a mirror image of B3, not a clone. This worked fine in the Finnish Baltic breakers which the Winds were modeled after, but they didn't work very well in multi-year polar pack ... kept finding bow motor parts back in B2:-) So the bow prop got taken off very early in the breaker's lives and the B1 generators were rewired to work in parallel with the rest of the generator plant and drive the stern props. In the mid-70s, Northwind and Westwind were re-engined with four Cats vice the six F-Ms; that lasted a decade. The Coast Guard's Polar class breakers -- 1970s vintage -- are both diesel/gas turbine geared drive with controllable pitch propellors; three screws aft. The new icebreaker in design now goes back to the conventional diesel electric plant. The other electric drive cutter was the Lakes class cutter (WHEC-255) that was the mainstay of the ocean station fleet. This plant was a steam turbine/AC electric drive system. Single screw. Beyond those basics, I can't say a whole lot -- the ships have been gone for 15 years and I escaped ocean station duty and drove icebreakers instead (much more fun to drive a ship where you are paid to run into things:-) Rex Buddenberg
ntaib@silver.ucs.indiana.edu (Nur Iskandar Taib) (12/20/90)
From: ntaib@silver.ucs.indiana.edu (Nur Iskandar Taib) >Electric propulsion has been around before. The reason the Navy >is interested is because of some new ways to generate and convey >electricity (superconducting) and batlle-group-wide systems engineering >ones. Has everyone forgotten that practically all diesel submarines run off electric motors and accumulators? And nuclear submarines might too, for all I know? -- ------------------------------------------------------------------------------- Iskandar Taib | The only thing worse than Peach ala Internet: NTAIB@AQUA.UCS.INDIANA.EDU | Frog is Frog ala Peach Bitnet: NTAIB@IUBACS ! -------------------------------------------------------------------------------
budden@trout.nosc.mil (Rex A. Buddenberg) (12/21/90)
From: budden@trout.nosc.mil (Rex A. Buddenberg) Iskandar mentioned submarines. Most conventional submarines (we'll ignore the British ones with steam plants and a few others...) had a diesel <or> electric plant. That is, you can run on the surface, with diesels that are directly geared to the shafts (and charging your batteries too). Or you can submerge and run on the electric motors; diesels secured. This is different from the diesel-electric drives I described earlier. Nuclear submarines are steam turbine plants (I know of no exceptions, but there might be). Even more than in surface ships, the power density is critical in submarines. This is the amount of go-juice you can get for a given weight and volume of propulsion machinery. Most likely primary reason. Rex Buddenberg
cga66@ihlpy.att.com (Patrick V Kauffold) (12/21/90)
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.
military@cbnews.att.com (William B. Thacker) (12/22/90)
From: sun!portal!cup.portal.com!Eric_S_Klien
The nuke subs have no electric batteries and we have no diesel subs.
Note that this means that our nuke subs run louder than diesel subs
that are running off their batteries.
Eric Klienrobinro@bomber.ism.isc.com (Robin Roberts) (12/28/90)
From: robinro@bomber.ism.isc.com (Robin Roberts) In article <1990Dec22.033410.22947@cbnews.att.com> writes: > >From: sun!portal!cup.portal.com!Eric_S_Klien >The nuke subs have no electric batteries and we have no diesel subs. >Note that this means that our nuke subs run louder than diesel subs >that are running off their batteries. > Eric Klien Unfortunately none of this is exactly true. Nuclear subs do have batteries they even have diesel engines in case of a breakdown in the nuc plant. The U.S. even has diesel subs, just a handful of the Barbel class. Nuclear submarines have a higher minimum noise than diesel submarines because the nuclear plant has to circulate some water even at the lowest power levels to moderate the temperature of the core. The circulating water increases the minimum noise level. Diesel submarines can operate at very low noise levels on battery powered electric motors or no motor at all. Some experiments have been made with what are termed "natural circulation" power plants that can operate without any pumps going at low power levels some of this technology has been incorporated into the later U.S. nuke boats. The disadvantage of a diesel is that when it is charging its batteries it is as noisy if not noisier than any surface ship. It is slower to deploy to an operating area and has limited range. Its range is even more limited if for tactical reasons it cannot operate its diesels to charge. -- Robin D. Roberts | <This space closed for remodeling. Watch for Interactive Systems Corp. | a new witty quotation scheduled to open in Calabasas, Calif. | the Spring of 1991! > Internet: robinro@ism.isc.com CompuServe: 72330,1244 GEnie: R.ROBERTS10
ron@hpfcso.fc.hp.com (Ron Miller) (01/07/91)
From: ron@hpfcso.fc.hp.com (Ron Miller) > > From: sun!portal!cup.portal.com!Eric_S_Klien > The nuke subs have no electric batteries and we have no diesel subs. ^^^^^^^^^^^^^^^^^^^^^^^^^^ > Eric Klien This is flat wrong if you are referring to US submarines. ("we" who?) Nuke boats DO have a very large lead-acid battery. Picture about 148 cells 1'x1'x6' in series. It is essentially the same as one half of a WWII diesel boats battery. (It is primarily an emergency/auxiliary power source to be used for reactor startup or to ride out delays while getting a diesel generator online.) It is correct to say, however, that MAIN propulsion is not via the battery. However, that does not exclude other auxiliary forms of propulsion. I am not certain if there are any diesel boats left in commission. Rumors in the early '80's were that there were a few used for SEAL training. If you still doubt the battery, I have some "battery well T shirts" left I can show you-- big acid holes :-)) In general though, electric drive still requires a turbine generator to produce electricity on a nuke boat. One could suppose that electric drive might be more "efficient" but it might not be as light or as reliable as reduction gears from the steam turbine. Indeed, if one is operating a nuclear power plant, it is hard to be as quiet as a diesel boat on the battery unless the reactor is totally shutdown, cooled down, depressurized and one is DIW (dead in the water) that is. Ron Miller ex-Lt USN USS CINCINNATTI SSN-693 (former electrical officer, DCA, EMO, QA officer, Reactor Controls officer etc)
pataky@tove.cs.umd.edu (Bill Pataky) (01/14/91)
From: pataky@tove.cs.umd.edu (Bill Pataky) >From: sun!apple!cup.portal.com!Eric_S_Klien > >"I am not certain if there are any diesel boats left in commission. Rumors >in the early '80's were that there were a few used for SEAL training." > >The last diesel was mothballed in 1989. I'm sure there were a couple >diesels in the early '80s and that SEAL training was probably done with >them. The last U.S. Diesel Sub, the USS Blueback, was decommissioned 1 October 1990. There is an article about the boat in the December 1990 issue of "All Hands". Bill Pataky ------------------------------------------------------------------------------ Domain: pataky@itd.nrl.navy.mil voice: (202) 404-8355 Path: ..!uunet!itd.nrl.navy.mil!pataky fax: (202) 404-7942 ==============================================================================