How did they supply air to diesel engines on submarines?
rich asked:
I know that they could re-surface to re-establish a normal supply of air but what about when they were under attack and couldnt surface for long periods of time,wouldnt those engines use up a lot of the oxygen inside the sub?
Caffeinated Content for WordPress
I know that they could re-surface to re-establish a normal supply of air but what about when they were under attack and couldnt surface for long periods of time,wouldnt those engines use up a lot of the oxygen inside the sub?
Caffeinated Content for WordPress
Either the submarine remained close to the surface with a pipe (snorkel) supplying air, or they stopped the diesel engine and relied on batteries.
Some experiments were made where the submarine would bring oxidizer (oxygen or sometime oxygen peroxide) in tanks. But of course the supply was limited.
Subs don’t move much (if at all) when they are underwater for precisely this reason.
Water is H2O they use and used a process where they take the water and filter out the hydrogen leaving them with oxygen and they just pump out the hydrogen into the ocean
Diesel submarines that were used during WWII actually have two different types of engines. The main Diesel engine, and an electric one. When a boat submerges they use the electric engines only, these usually only have an hour or so worth of power. Once they resurface they fire up the diesel. They are stuck on the surface until the electric engines are re-charged by the diesel. Prior to the advent of the nuclear submarine (which can remain submerged almost indefinitely), the submarine spent most of its time on the surface like any other ship.
As others have stated the diesel engines could be used under water only with a snorkle system which wasn’t very practical to do if you were indeed under attack.
The have ports at the engine room to take in combustion air (oxygen) and to exhaust the combustion gases. The generator/motor was built inline with the drive shaft to the main propeller. As the diesel engine powered the prop it used the generator/motor to charge a bank of batteries. When the sub went under the diesel engines were shut off and the sub was powered by the battery bank.
There is a huge switch station just to the rear of the engine room for this purpose.
First, the diesel engines could not be used submerged without raising the snorkel mast, for those that had snorkel capabilities, or coming to the surface for those without snorkel capabilities. You are correct that they would use a lot of oxygen.
Second, if you were under attack you would want to be as deep as possible and the diesel engines would have to exhaust their combustion gases somewhere outside of the boat and at that depth the diesels did not provide enough combustion pressure to overcome sea pressure.
Third, and most importantly, THE DIESEL ENGINES MAKE A HELL OF A LOT OF NOISE!!!!!! The best defense a submarine has is its ability to be quiet, especially when operating on its batteries. A running diesel engine would be a signal for the enemy to “drop depth charges here”. If one were under attack and had to start the diesel engines due to the battery running low, odds are the oxygen level would barely be enough to sustain life, much less provide for a diesel engine. There are many tales of submarines surfacing due to this and fighting with torpedos and their deck guns while skeedatling out of the area on the surface.
The boats that were capable of direct diesel drive didn’t use those engines for both propulsion and battery charging at the same time. It wasn’t possible to control a charging rate when you have to control ship’s speed by throttling the diesel. There were other diesel engines that charged the batteries. There were few of this type of submarine in the US fleet.
Most diesel submarines were diesel electric. There were generally 4 diesel engines connected to DC generators. There were electric motors that drove the two shafts. Submerged the batteries would supply the propulsion (and the batteries would last for a lot longer than the one hour stated by one answerer). When the boat came to snorkel depth to charge the batteries two of the engines would generally provide power for battery charging and two for propulsion, or whatever lineup they needed.
To take in air a snorkel mast is raised just above the surface of the water. On the top of the mast is a head valve that closes quickly if water is detected being sucked in and will quickly reopen. Exhaust is discharged just below the water line so as not to tell everyone from one horizon to another that there is a diesel powered vessel in the area that wasn’t there five minutes ago.
Now there are non-nuclear air-independant propulsion (AIP) systems, but I’m sure not many of those have been pinned down in an attack
And who is the fool that stated submarines don’t move while underwater? What an idiot!