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.

[swuboo]

Originally Posted by AVGWarhawk

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.

[3Jane]

1. 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

[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]

Originally Posted by Lanzfeld

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.....

[peterloo]

Originally Posted by 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)

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

[AVGWarhawk]

Originally Posted by 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

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]

Originally Posted by 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

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]

Originally Posted by AVGWarhawk

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.