Technical Question - Engines

[Tachyon]

1) a)Why are diesel engines used by Submarines on the surface? Why not Electric?
b)Again, why electric underwater...why not diesel?

2) Can ships use Electric engines? (WW2 era)

[AVGWarhawk]

Diesels require air as well as people in the submarine therefore under water you have just so much air to breath and run diesels. Not until the schnokel was developed that diesels could be run underwater as they had an air source above the water. When this schnokel would submerge for a split second, the pressure from the diesels sucking air from inside the boat would make ears pop and hurt the lungs of the crew.

Electric engines were used on the surface. Usually leaving port. Other than that, the batteries were saved for submerged action or escape.

As far as ships using electric engines. Does not make much sense for electric on ships unless your trolling for trout.

This game does not allow you to run electrics on the surface.

[3Jane]

As the diesels would require air to function, they can only be used whilst submerged by fitting a Schnorkel. In real life U-boats ofen used electric (e-motors) motors whilst on the surface, such as when entering and leaving docking areas. But the choice of switching off the diesels and using the e-motors when running on the surface is something which as far as I know isn't moddled into the games software.

[VIICDriver]

Was it not true that if for whatever reasons the diesels running at standard had only the air inside the submarine to feed them that they would evacuate the entire subs air supply in like 3 seconds and turn the tube into a vacuum?

Think I read that in Iron Coffins, then the men working in an almost "outer space" type environment would have to clear whatever was keeping the schnorkel from supplying air. Or die.

Chuck

[AVGWarhawk]

Yes, what would happen if the schnokel submerged for a brief second, this was enough time for the diesels to suck the air up inside the boat. Ears popped, eyes bulged, lungs hurt and headaches occurred. For a guy like me who has had three collapsed lungs, I would not want to try this out for fun:nope:

[Lanzfeld]

I do believe that it took longer then 3 seconds however. Not sure of the exact time.

[bigboywooly]

You have to remember to that with snorkel raised the uboat could only do around 6 kts or it would snap off
And I think its safe to say that in rough weather it wouldnt be used

[AVGWarhawk]

I do believe that it took longer then 3 seconds however. Not sure of the exact time.
I bet it didn't. These diesels were very large and I suspect each piston in high rpm sucked quite a few cubic feet of air rather quickly. There is a way to find out. We need to know the litre of each piston, the cubic feet air within the boat. How many revolutions (intake stroke) each piston is making. I do not have access to this information.

We also have to consider that the air taken is not replaced as the boat is submerged. I bet it gets real ugly real fast.....

[Sailor Steve]

To the first question: electric motors can be used on the surface, but the electricity has to come from somewhere. It can be (and is) stored in batteries, but the electricity gets used up (which is why they are actually known as storage batteries) and they have to be recharged. This can only be done by applying an outside source, such as a generator which has to be run by something like a diesel engine.

[_Seth_]

Does anyone know the names of the engines used by german u-boats? IE: MAN or anything like that...Like the ViiC, for instance.. How many HP, how many pistons and so on... Technical data, all in all...:hmm:

[Uboatace]

The following only applies to the type VII subs as my knowledge on other types is limited.

There were two makes of diesel engine used they were the Germaniawerft & the MAN,

They were fundamentally the same in appearance & HP, both were six cylinder direct reversing engines.

The main difference was that That the GW was supercharged (shaft driven) & the MAN had a turboblower. (turbocharger)


The horsepower ranged from 2310 to 3200 depending on year & variant, at a maximum of 485 RPM.

The bore And stroke was 40 cm x 46cm.

When snorkels were fitted the reversing cams were removed & replaced with snorkeling cams to overcome the increased exhaust back pressure, so reversing had to be done using electric engines as the diesels could no no longer run in reverse.

When the snorkel dipped under water it took about sixty seconds for the engines to consume the air in the boat but the effects were felt much sooner due to the sudden pressure drop inside the boat.

I hope this is of interest & helps answer a few questions.

[Tachyon]

Thanks for the replies guys, that was a valuable insight into the world of Pistons and grease.

[Letum]

You could make a hell of a vacuum cleaner with a pair of those motors.

[peterloo]

1) a)Why are diesel engines used by Submarines on the surface? Why not Electric?
b)Again, why electric underwater...why not diesel?

2) Can ships use Electric engines? (WW2 era)

Q1a: Because diesel engines (in WWII era) is capable to generate a large power for a huge U-boat

Q1b: Diesel engines burns diesels to generate power. Oxygen is used as a result

If it operates underwater, it draws oxygen from the boat and give out carbon dioxide (and even poisonous carbon monoxide due to insufficient air supply)
As a result, the crews will ... die

Q2: Yes, but practically impossible since no electric engine has been made to let a heavy merchant ship to cross Atlantic (due to lack in power and endurance)

[CCIP]

Also, I believe the US boats in WWII technically ran off electrics all the time, that is, the electric motors would always drive the screw shafts, and the diesels would be used simply to generate power for them.

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

[squirrel777]

Only 6 cylinders? OK, but when I remember Das Boot (I have not yet visited the boat at Laboe), it seems to me the engine is very long. The engine room seems to be something like 5m long with a lot of cylinders.
But I certainly have to watch it again :D

[HunterICX]

Only 6 cylinders? OK, but when I remember Das Boot (I have not yet visited the boat at Laboe), it seems to me the engine is very long. The engine room seems to be something like 5m long with a lot of cylinders.
But I certainly have to watch it again :D

you mean this ?

http://www.uboatwar.net/das%20boot%20engines.jpg


Source: Uboatwar.net
Das Boot

[E.B. Fluckey]

I toured the Clamagore (SS-343) at Patriot's Point, South Carolina. This sub was commissioned in 1945 - too late to see action in WWII. Anyhow...I was talking to one of the vets on the sub (not sure if he was a submarine vet) and he claimed the sub is always powered by electric motors. I'm a bit skeptical so perhaps someone can clear these questions up.

1. When surfaced does the submarine use electric motors?
2. If so, when surfaced is the current to run the electric motors drawn from the batteries?
3. Or is the current drawn directly from the generators when surfaced?

[squirrel777]

1,2,3,4,5,6! OK, six! But that's six BIG cylinders :p

I'm a bit skeptical so perhaps someone can clear these questions up.

1. When surfaced does the submarine use electric motors?
2. If so, when surfaced is the current to run the electric motors drawn from the batteries?
3. Or is the current drawn directly from the generators when surfaced?
Yes, US submarine were diesel-electric. Only the electric engines were connected to the shafts (2 engines per shaft = 4 engines).
When surfaced, the current goes directly from the (diesel powered) generators to the electric engines. (it's exactly like a modern diesel locomotive works).
When submerged, the same engines are powered by the batteries.
When recharging, the diesels power the generators, then part of the current goes to the engines and part to the batteries.

Read more here: http://www.maritime.org/fleetsub/index.htm
This is the complete manual for late war US submarines! Very interesting indeed.

[Corrupt_File]

That's correct, but why does SH3 shut off the starboard engine (or at least disconnect the drive shaft to stop the screw) if both engine are driving generators?

[AVGWarhawk]

Also, I believe the US boats in WWII technically ran off electrics all the time, that is, the electric motors would always drive the screw shafts, and the diesels would be used simply to generate power for them.

http://www.fleetsubmarine.com/propulsion.html
I don't know. Currently reading a book on Wahoo and the four engines were always used on the surface to charge and of course getting 20 kts. I think the electric motors were best saved for submerged running. But reading your link, that looks to be the case. The newer boats powered the electric traction motor off electricity generated off the diesels. This is the same for diesel engines that run the freight cars on the rails.

[mayandlex]

When reading on these matters the diesel power units are called "engines" while electric units are called "motors". The US submarines were certainly diesel/electric and did not have a direct connection between the engines and the motors unlike the U boats which had clutches to disconnect the engines to allow electric propulsion, I think when charging the batteries the motors served as generators (dynamos) and were disconnected from the propellor shaft to put all energy into the batteries. It was thus not possible to run them as diesel/electric as the motors cannot be a generator and motor at the same time.
Confused?
MayandLex

[AVGWarhawk]

When reading on these matters the diesel power units are called "engines" while electric units are called "motors". The US submarines were certainly diesel/electric and did not have a direct connection between the engines and the motors unlike the U boats which had clutches to disconnect the engines to allow electric propulsion, I think when charging the batteries the motors served as generators (dynamos) and were disconnected from the propellor shaft to put all energy into the batteries. It was thus not possible to run them as diesel/electric as the motors cannot be a generator and motor at the same time.
Confused?
MayandLex

That is correct. Therefore, one engine to generate electricity for the storage batteries and the other engine turning the electric motor turning the single screw. Ok, now we are both confused. :rotfl:The diagram above from the link explains it very well. It is explained the same for diesel/electric locomotives. ...just on dry land!

[Razman23]

That's correct, but why does SH3 shut off the starboard engine (or at least disconnect the drive shaft to stop the screw) if both engine are driving generators?

You are confusing U-boats with American boats.

U-boats used only one engine to recharge the battery packs while the other drove the boat. When the battery pack is charged, they switched the engine back over to drive to help with populsion. As a matter of fact, some U-boats used only one engine to save on fuel when transiting long sea passages.

[Razman23]

The newer boats powered the electric traction motor off electricity generated off the diesels. This is the same for diesel engines that run the freight cars on the rails.

American railroad locomotives have one diesel engine/generator (typically a 'Catepiller' brand engine) with a traction motor for each wheelset. So if the locomotive has six wheel sets (typical for modern locos), there will be six traction motors.

However when the train is going down hill and the normal brakes (pads against the wheels) are not enough for braking, the engineer will actually switch the traction motors to generator motors which slow down the train. The only offset to this is that the generators create allot of heat and must be vented out the top of the locomotive.

http://members.kos.net/sdgagnon/st1.jpg

[CCIP]

What SHIII doesn't take into account, though, is the fact that U-boats had a system where one engine could drive both propellers. I wonder how accurate the 'dead screw' thing is :hmm:

[Patboot]

Only 6 cylinders? OK, but when I remember Das Boot (I have not yet visited the boat at Laboe), it seems to me the engine is very long. The engine room seems to be something like 5m long with a lot of cylinders.
But I certainly have to watch it again :D

Keep in mind, it's a 1600hp engine ;)

Not your daddies Oldsmobile.

Biggest diesel built to date is what, 4 stories tall? Container ship main engine?

[AVGWarhawk]

Only 6 cylinders? OK, but when I remember Das Boot (I have not yet visited the boat at Laboe), it seems to me the engine is very long. The engine room seems to be something like 5m long with a lot of cylinders.
But I certainly have to watch it again :D

Keep in mind, it's a 1600hp engine ;)

Not your daddies Oldsmobile.

Biggest diesel built to date is what, 4 stories tall? Container ship main engine?

Yeah man, those engines are enormous and that is an understatement:up:

[johnno74]

Yeah man, those engines are enormous and that is an understatement:up:

you mean like this :)
http://people.bath.ac.uk/ccsshb/12cyl/


It would be quite some submarine that used this diesil :)

[K-61]

The newer boats powered the electric traction motor off electricity generated off the diesels. This is the same for diesel engines that run the freight cars on the rails.

American railroad locomotives have one diesel engine/generator (typically a 'Catepiller' brand engine) with a traction motor for each wheelset. So if the locomotive has six wheel sets (typical for modern locos), there will be six traction motors.

However when the train is going down hill and the normal brakes (pads against the wheels) are not enough for braking, the engineer will actually switch the traction motors to generator motors which slow down the train. The only offset to this is that the generators create allot of heat and must be vented out the top of the locomotive.

http://members.kos.net/sdgagnon/st1.jpg

From the way I understand it, they use dynamic braking before or in preference to the wheel brakes. The generators are switched to reverse mode, with the electicity generated being put through a rheostatic grid in the roof of the engine, dissipating heat that way. Dynamic braking can't do all of the braking, especially at lower speeds, but it is a good way of slowing down a fast moving train to lower speeds, so that the conventional brake pads last longer.

[mayandlex]

Hi CCIP how did the u boats drive 2 propellors with one engine? I understand they were two separate single shafts, one per engine, and that they did not have the ability to connect the shafts, although I think british submarines did have this facility. Did they have a sepatate dynamo and motor per shaft? In any event this would probably be an emergency system as one diesel driving two shafts and props would be less efficient than driving a single shaft surely?

[Krupp]

from the "Hitler's U-Boat war, The hunters, 1939-1942" - by Clay Blair:

"Stern compartment was known as the electrical room. It contained two 375-horsepower electric motors, or more precisely, motor-generators. The main driveshafts of the diesel engines ran through the core of the motor-generators. When the diesels were operating, either or both motor-generators could be clutched onto the turning driveshafts to serve as generators to charge the batteries. Or, as a fuel-saving (and range-extending) measure, the power produced by one motor-generator, operated by one diesel engine, could be routed to the other motor-generator to turn the other shaft (so rigged, the maximum cruising speed was a leisury 6 knots). Upon diving, when both diesels were shut down, the motor-generators were clutched to the driveshafts, drawing power from the batteries."

So the german U-Boats could drive two prop-shafts with one diesel engine when other diesel powered the generator to charge batteries.

[mayandlex]

Interesting subject, thanks for the info but surely if say the port deisel is running the motor as a generator while clutched through to the propshaft to drive this and the starboard diesel is driving the motor as a generator to charge batteries then how can it also act as a motor to drive the prop shaft? My reading in this is that each motor can only do one or the other tasks but certainly not both at once. I think this was a flaw in the basic design but the system was very robust, simple and efficient.
British boats shafted through a gearbox arrangement and could run both shafts off one engine using gears, and of course US boats had separate generators and motors on each shaft with no shaft connection between them.

[RoDent]

Simple question:
Does the speed matter when recharging batteries?
What i mean is that if you go
"ahead standard".... do they charge at normal rate compared to lets say... "ahead flank"= full/maximum recharge rate?
Or do they all charge at same rate irregardless of your speed settings?

[Mooncatt]

i would say the faster u run the engine the faster the recharge rate.

also just going back a little....whats the point of running diesel underwater even with a snorkel, wouldnt it give ya position away really easy even if you wasnt attacking anything

[johnno74]

No when you in recharging batteries only one engine (and one prop) are used for propultion - the other engine is disconnected from the prop and used to charge batteries, at constant RPM. You can verify this by looking at the port/stbd engine RPM dials in the control room when you are on the surface charging batteries - one engine is stopped, the other stays at 500rpm (or something)

[Brag]

I toured the Clamagore (SS-343) at Patriot's Point, South Carolina. This sub was commissioned in 1945 - too late to see action in WWII. Anyhow...I was talking to one of the vets on the sub (not sure if he was a submarine vet) and he claimed the sub is always powered by electric motors. I'm a bit skeptical so perhaps someone can clear these questions up.

1. When surfaced does the submarine use electric motors?
2. If so, when surfaced is the current to run the electric motors drawn from the batteries?
3. Or is the current drawn directly from the generators when surfaced?

WWII era American subs were powered with Diesel-electric engines like the ones in diesel-electric locomotives. On the surface the diesels drove the electric motors directly and were disconnected from the electrics when submerged. The electrics then drew power from the batteries.

[RoDent]

i would say the faster u run the engine the faster the recharge rate.
Nope....it charges all the same. However i never noticed this until i searched the forums and found a post about "other unreleased user controls" that you can use while in the game such as Shift + F2 =free movement while in the command room.

Now when i did the free movement and looked around it showed the starboard engine at a constant 550 RPM while charging irregardless of current speed settings. :up:
Thanks for the reply M8.
Eventhough i've been playing this game for approx 2yrs on a regular basis i still consider myself a swabbie when it comes to tech stuff and info.

[Sailor Steve]

also just going back a little....whats the point of running diesel underwater even with a snorkel, wouldnt it give ya position away really easy even if you wasnt attacking anything
When using the diesels underwater you're not draining the batteries, hence there is theoretically no reason to surface and recharge.

[swuboo]

This game does not allow you to run electrics on the surface.

A fact which I discovered one day when I ran out of diesel 50km outside of Wilhelmshaven.

I had to sail into harbor submerged.

[carlos26]

1) a)Why are diesel engines used by Submarines on the surface? Why not Electric?
b)Again, why electric underwater...why not diesel?

2) Can ships use Electric engines? (WW2 era)

Hi...
Well you got a lot of answers for the 1a 1b questions... About question 2 Yes... The sips in the WW2 era could have electric engines as the main motion source and they had... For example two american carriers Lexington and Saratoga had combined steam turbine and electric drive... The boilers were used to generate steam, the steam powered turbines, turbines' shafts were connected to electric generator, and they powered slow rotating electric motors... This solution is great for ships with fixed propelers so you dont have problems with stoping, starting, reversing engines with internal combustion... Well i don't want to be boring so i think i'll stop writing right now... And sorry for my english but it's not my native language :rock:

[AS]

Hi, interesting topic. I know about U-Boat engines/motors, but I didn´t know about the US-subs. What is the advantage (or disadvantage) of the US-subs diesel-electric system? And why is it that they had 8 engines altogether?:o Seems strange that they spent so much money (and manpower) on such a redundance...

Thanks for replies, AS