Were US subs Diesel-electric powered?
 

I was reading about the USS Pampalino(sp?) on display in San Francisco, CA. Since I live about an hour away, I am planning on dragging my girlfriend with me (Hey, she dragged me to the Titanic exhibit, now we're even :|\\ )

While reading the specs of the boat, it mentioned that the propulsion was generated by having 4 Diesels powering generators, which then powered electric motors which in turn rotated the shafts to the screws. I found this interesting- it reminds me of the way a Diesel-electric train functions.

Did most class boats operate like this? and what are the advantages of using a combustion engine to generate electricity to power an electric motor? Sounds like an awful lot of steps just to make a submarine go.

All boats of the period operated on this principal.

In fact, modern boats do too. But instead of using a deisel motor to turn the generators to create electricity, they use an atomic reactor to do it.

JCC

I think the train engines gave the Navy the idea. It saves weight for the gearing and makes it easier to shift from diesel to electric.

Front line German subs and early US subs used a clutch system to engage and disengage the diesels from the screws when switching between surface and submerged propulsion modes.

US fleet boats used a form of the Alphine-MacPherson (I think that's what they called it... have to check my sources when I get home :-?) drive pioneered on the USS Jupiter (later USS Langley) in 1912: internal combustion engines turned a generator which powered electric motors which turned the prop shafts. Batteries are cut in, in place of the diesels, when submerged.

Unless I'm mistaken US WWII submarines were "Diesel / Electric" at the beginning of the war and later models became truely "Diesel - Electric." The distinction being that Diesel/Electric would alternate which powerplant turned the propellers and Diesel-Electric would always have the Diesels power the Electrics that turn the propellors.

The best reference for this is CDR John D. Alden's The Fleet Submarine in the U.S. Navy- A Design and Construction History, specifically Appendix I. This appendix lists the drive arrangement for every class of boats form the T class (preceding the Narwhal class) to the Tench class. It also has schematics as well as engine and motor and generator manufactures and model numbers listed for virtually every fleet boat that was built.

All fleet boats up to SS 171 had clutches and diesel engines directly driving the motor/generator and the props.
SS 181-193 had composite drives that allowed a reserve engine to directly drive the prop through a clutch. All others had various arrangements of diesels turning generators driving electric motors or charging batteries.

Respectfully Submitted;
CDR Resser

Except that US (and British, and I believe Russian) nuclear boats have steam turbines for propulsion. Steam turbine generaters do produce the boats electrical power, but steam directly drives the propulsion turbine. The French navy uses nuclear power to generate electricity only, which then in turn powers electrical propulsion motors.

Things may be different with the US Virginia class, but the older nuke's used direct steam propulsion in a closed loop pressurized reactor system.

Very close!
 

The switch to diesel trains was financed by the US Navy who was using trains as test beds for their submarine project.

As already said, all submarines of the period were diesal-electric. What the beautiful thing about US boats was, is they were an indirect drive.

From FleetSubmarine.com:http://www.fleetsubmarine.com/propulsion.html


RDP

I was under the impression that Uboats had direct drive. When submerged, the props were powered directly either from batteries or the diesal engines, with a clutch that engaged between the two, but the power was directly applied. Hence when charging their batteries, one engine was taken completly offline, while the other propelled the boat. (hence why in Sh3 you had one prop spinning, and the other not)

Simiarly i was under the impression that the props a fleet boat were always powered by the Emotors, ie a constant source of electricity as opposed to direct mechanical force, with the power to turn the Emotors coming from the batteries or the diesal engines which, in reality were nothing more then glorifed electrical generators. This is why ive always thought of fleet boats as having an indrect drive.

I was under the same impression, at least where the fleet boats are concerned. I thought that the S-boats were direct drive, and possibly the V-boats, but I can't find any credible information so far.

That's my understanding as well. There is no physical connection between the diesels in a fleet boat and the screws at all.

From the navy's manual:

You are thinking correctly here. It was the engineers that designed diesel electric configuration for trains that lent itself to the submarine. On the USS Torsk, the four diesels are not connected in anyway to the prop shafts. They only make the electric juice to turn the electric motors. These motors are a big as car. The manerveuring room was situated right on top of them. Two crew man manned the controls for each individual motor. People get confused when told this is the maneuvering room. They believe this is how the sub was steered. It was not, this was only to work the motors. So working in unison with the helm was essential.

I do belive the old S Boats were direct drive much like U-boats

Okay! Here's the rundown from Conway's All The World's Fighting Ships: 1906-1921 and 1922-1946:

'S' Class, Elco type (S-1, S-18 - S-41): BS diesels plus electric motors.

'S' Class, Lake type (S-2): BS diesels plus electric motors.

'S' Class, Navy Yard type (S-3 - S-17): NSLE, MAN or BS diesels plus electric motors.

'S' Class, 2nd group (S-42 - S-47): BS diesels plus electric motors.

Barracuda class: diesels plus electric motors.

Argonaut: diesels plus electric motors.

Narwhal class: diesels plus electric motors.

Dolphin: diesels plus electric motors.

Cachalot class: diesels plus electric motors.

Porpoise class: diesel-electric plus electric motors.

Shark class: diesel-electric plus electric motors.

Perch class: diesel-electric plus electric motors.

Salmon class: diesels (composite drive) plus electric motors.

Sargo class: diesels (composite drive) plus electric motors.

Seadragon class: diesel-electric plus electric motors.

Gato, Balao and Tench classes: diesel-electric plus electric motors.



So the Porpoise class were the first to have diesel-electric drives. The Salmon and Sargo classes reverted to direct-drive diesel because of rising fears of leaks disabling the electrical systems. The Seadragon group of the Sargo class went back to diesel-electric, and they stayed with that system afterwards.

Conway's isn't clear as to what is meant by (composite drive), so I can't explain that; I just copied it as they have it.

I also can't verify the information with another source, but the editor for the United States ships section was Norman Friedman, so it's almost certainly correct.

So there it is.

On Gatos the wheel shaft was connected to emotor via geared housing. On Balaos and Tench the shaft was directly off the emotor. This was done to further quiet underwater noise. In addition Balao and Tench used 5 blade low cavitation wheels. Gato 4 blade.