Engine Hydrolocking, Airspace

[BrendaEM]

If the diesel engines were running and mist went into the air intake, mist could likely cause the engine to misfire and perhaps stall.

Anything more, might fill an engine cylinder, bending or breaking a connecting rod or wrist pin, damaging the main bearings, perhaps throwing the rod through the side of the engine. It is possible that a hydrlocked diesel might endure more than a gasoline fueled engine because diesel engines are built to have a higher compression ratio, which means that the parts that water would break--would be stronger in a diesel than a gas engine.

If the engine were off or idling, the water might only hydrolock the engine. Because water is almost uncompressible, it would need to be drained from the cylinder before the engine could even crank. I couldn't find the video, but one Vespa had lost a head-gasket, and was hydrolocked. When they pulled the plug, water sprayed from the cylinder on each stroke. Perhaps that was an additional reason why they put the cylinder valve on the u-boat diesels, to drain water from the engine.

It's conceivable that, if you lost a connecting rod, and it didn't go through the block, and you repaired it, the water would have to be drained from the remaining cylinders. I think that in Das Boot, I saw a main bearing, they were working on.

Also, if water got into the engine the oil would be foamy yellow sludge.

https://www.youtube.com/shorts/SqLpcffZHOU



https://www.youtube.com/watch?v=ElgLDRoMpmI



Not now, but at some point, it would be cool that if the sub is damaged, it will fill with water, sort of like this, until the sailors float, under the remaining airspace, to get the full late-war U-Boat submariner experience.



In game, I don't know what could be done to save a flooding sub. In the movies, there's always a valve that can be tightened. : )
I suppose that it's possible that bolts on flanges that had yielded to tension, could be replaced.

An interesting game dynamic: deciding to abandon the U-boat, which has happened.

[BrendaEM]

I was trying to find a chart of the percentage of diesel engine hydrolock survivability. I should think that some military somewhere has one.
Though, I did find an actual submarine diesel repair manual, showing the repair components well enough to model: https://maritime.org/doc/fleetsub/diesel/chap3.php
Oddly, it appears that some diesels had an extra inspection port that a main-bearing cap and connecting rod could be swapped.

As a thought experiment, it would seem that flooded engines offer some interesting game scenarios. None of this has to be modeled, but perhaps there could game-wise be...

Levels of water intrusion:

1. Mist (Near the water surface, mist enters the intake)
2. Sip (Single wave enters intake)
3. Gulp (Intake is submerged for more than an instant

Levels of engine RPM:

1. Idle
2. Running Slow
3. Running Fast

Yielding 5 levels of engine trouble:

1. Sputter in warning, giving visible smoke to alert enemy
2. Engine stall without damage, giving visible smoke. Water needs to be cleared (See below)
3. Engine has minor damage. It runs with rapping sound and decreased performance
4. Engine is damaged but can be repaired. Main bearing cap would be removed, if available, a new piston-connecting rod installed, taking an hour or so (each)
5. Engine is irreparably damaged. Connecting rod penetrates engine block. Remaining engine, or battery power only

If the engine is not running, the engine cylinders would fill with water, same as a minor stall.

Stall Repair:

1. Flame valves are opened
2. Engine is cranked spraying water out, which would be humorous, if not for the destroyers
3. Flame valves are closed
4. Engine starts

Minor Engine Damage Repair:

1. Engine runs with rapping sound and decreased performance.

Major Engine Damage Repair:

1. Main bearing cap is removed.
2. Piston, connecting-rod combo is taken from inventory or corner of the engine compartment
3. Old piston and connecting-rod is removed
4. New piston is installed, by wrenching at crankcase
5. Main bearing cap is reinstalled
6. (Same as above) Flame valves are opened
7. (Same as above) Engine is cranked spraying water out
8. (Same as above) Flame valves are closed
9. Engine starts

Unrepairable Engine Damage:

1. Engine cannot be repaired, connecting rod is shown penetrating the engine block
2. Remaining engine can be used, if available, giving half the speed and charging

The Resources, if shown:

1. Good piston-connecting rod model and texture. (I can make one if you need it.) This can just be an inventory thing that sits somewhere in the engine compartment
2. Bad piston-connecting rod model and texture, same but bent connecting rod, which would be easier than a two-piece thing. This resource would also be toggled for engine failure, showing it penetrating crankcase.
3. Main bearing cap with bolts still sticking out of it model and texture. (I can make it if you need it.)
4. Water-spray particle-effect animation for the engine port. Perhaps I can make it, maybe.
5. (Extra) a wrench or socket-wrench model, for a submariner repair animation. A submariner would sit at the engine wrenching at the bottom of the crankcase
6. (Extra) damaged engine rapping sound. I could mix this in.

Going really far: In the long term, the crankcase oil needs to be changed, or engine degrades over time, for a campaign of something.
Perhaps it might be possible to damage an engine and it still run, with a rapping sound.

[Onkel Neal]

and that's why the air intake on a U-boat has an air gap between the intake manifold and the air induction.

Now, let's see a video of what happens when the exhaust line is flooded with 20meters pressure water!

.

[Onkel Neal]

Also, great analysis of the whole water/diesel thing.

[BrendaEM]

(Thank you @Onkel Neal)

I did a little looking, and I found a video showing an original U-Boat U-505 piston, with text stating that, yes they did carry spares, and they could be swapped at sea.

I haven't got a good look at a U-Boat engine, on it's own, but I've noticed that some diesels have a squarish access panel just above oil sump, which would be my guess as to how they got the piston and connecting rod out, as pulling a oil pan on any engine quite a feat.

You can stop the video here and there to read the text. I am not sure of the size, but if I knew the piston diameter, the rest would be easy. Well, it could be resized later, as long as it's in scale. In the video the some rings appear missing.

[BrendaEM]

Wow, that's big! And a mere 1,100 lbs!
"From top of the piston to the bottom of the connection rod that is one and one half [1 1/2] meters. "
It looks like the piston on the photo above is about 10" in diameter.

https://www.pinterest.com/pin/a-big-...9628502868161/

And there it is, though missing the (piston) rings:




Notice that the big-end bolts are on the top. That is how they could take it apart without dropping the pan.

[BrendaEM]

There's a piston @5:33, but it's different. I wrote the museum, the get the piston size.





LOL! Post from the thread: "...I also notice they are turning the engine over by hand; the Layman's term for that is "Barring" the Engine over, its done to make sure no Lube Oil, Fuel, or Coolant has gotten into the combustion chambers which would cause a "Hydrolock" condition, rendering the engine completely inoperable."

[BrendaEM]

Well, here is the translated bore and stroke for various engines. It didn't do well with Roman numerals.

https://www-u--historia-com.translat..._x_tr_pto=wapp

Interesting:

"...A pair of Motoren-Werke Mannheim (MWM) RS34S (six-cylinder) engines were to be used as generators in the type IXd2 Uboats. These engines developed a power of 575cv at 750rpm. and had a bore by stroke of 260x340mm.
An engine almost identical to the RS34S, the RS134S would be fitted to the Type XXIII Uboats that began entering service in 1944. This engine gave the same power as the previous one but at 860rpm.

In both engines the crankcase and cylinder block were made of one piece. Each cylinder had two intake and two exhaust valves, a starting air valve and a pre-combustion chamber. This pre-combustion chamber could be electrically preheated to aid in cold starting. The engine had a valve to purge seawater that could accidentally enter when the uboat was submerged. ...."

260mm is a pretty big piston, my 10" guess was pretty close, 10.236220 Inches : )

[BrendaEM]

(Updated)

For Haha's, I made a piston model (1st photo) in Rhino 3D. It's based on the U-Boat U-505 sub museum (3rd photo).
The German engine museum from the video above, wrote me back : ) They stated that the piston was a whopping 260mm in diameter, which makes the piston roughly a meter in length.

* Piston top is unclear in the drawings, done was added to top of piston.
* The flange/washer thing that holds the wrist-pin (gudgeon-pin) in is polygon-hungry, because the flatter of the areas is actually bend to match the piston radius. The original part appears stamped steel.
* Unlike a real-piston there is no gap on top/bottom of the rings in the model. This could save mesh complexity.

A U-Boat engine blueprint, with my piston drawing over it (rings would be compressed in cylinder):



A rendering 3D modeled piston. Boards are about 4" wide, like you would have on a deck. Piston is huge!:



The piston is pretty strange, in that the wrist-pin has a bolt and nuts holding it together--instead of C-Clips. I am unsure if they had distorted thread locknuts back then, such as Stover Nuts. It would be bad if the thing loosened up in the cylinder.
The piston is still huge. They must have had a special place for a spare.


I did a test in CAD. If the piston could have been removed from the bottom, then perhaps the notches on the piston crown would help the piston clear the lower part of the cylinder liner. The access panels on the side of the motor are pretty big. I had read that they could do a piston replacement at sea, but I have not yet read whether or not the head would have to have been removed or not. If they head had to be removed, that would be a major undertaking. But if the piston could be unbolted with a spanner, and sneaked out through the access port, then it wouldn't be so bad. Most pistons have their bolts on the bottom of the connecting rod, and perhaps the spanner nut would have allowed the connecting rod to be removed from the panel. The blueprint does not give a good indication of the stroke, which would let the position of the crank big-end be known. So it looks like the piston could be removed--if the connecting-rod would clear the crank.

[BrendaEM]

This is how I think the spanner-nuts went on. (Edit, added the square-drive broached in the top, to aid loosening/tightening them)

In real life the part under the nut that holds the wrist-pin center, would be thinner, as it looks very much like a stamped part. In real life the connecting rod is drilled from big-end to little end. That center rib on the connecting rod, leaves material for drilling.

I might write the engine-museum, to see, if the piston can be taken out of the access-plug on the motor. I have read that the piston could be changed at sea; I don't know how else they could pull that off, as taking the heavy head off, with only hands to lift it would not be easy. There's a lot of parts that would have to come off otherwise.

I still suspect that the piston notches on top allow the piston to be turned in the crankcase, so it can be taken out of the access-opening. The whole thing would depend on the crank being made in such a way that it could be swung opposite the access opening.

[BrendaEM]

I wrote the engine museum, again, to ask if the piston could be removed from--without removing the head. And/or how they changed a piston at sea.

They were nice enough to help me before.

Google translate:

Firstly, thank you for explaining how large the piston is. : )
I am not an official part of "Wolfpack" game, but because I was curious, I modeled/shaped in 3D, a U-Boat piston.
https://www.subsim.com/radioroom/sho...09#post2854409

It has been stated that the piston and or connecting rod could be changed at sea.
Could the piston be removed from the access openings or did the cylinder head have to be removed?

Any information would be welcome,
BrendaEM

~

Google Übersetzung:

Zunächst einmal vielen Dank für die Erklärung, wie groß der Kolben ist.

Ich bin kein offizieller Teil des "Wolfpack"-Spiels/simulation, aber weil ich neugierig war, habe ich in 3D einen U-Boot-Kolben modelliert/geformt.

https://www.subsim.com/radioroom/sho...09#post2854409

Es wurde festgestellt, dass der Kolben und/oder die Pleuelstange auf See gewechselt werden könnten. Konnte der Kolben aus den Zugangsöffnungen entfernt werden oder musste der Zylinderkopf entfernt werden?

Jede Information wäre willkommen,

Vielen Dank,
BrendaEM

[BrendaEM]

I received a reply:
"Wenn bei einem Motor ein Kolben gezogen werden muss dann geht das nur nach oben heraus. Dazu muss der Zylinderkopf abgebaut werden. Die Montageklappen an der Seite der Kurbelwanne sind dazu da die Pleulstangen von der Kurbelwelle zu lösen ohne die Ölwanne abzubauen."

Google Translate:
"If a piston has to be pulled in an engine, it can only be pulled out upwards. To do this, the cylinder head must be removed. The assembly flaps on the side of the crankcase are used to detach the connecting rods from the crankshaft without removing the oil pan."

So, it's not as easy as I hoped, but still the whole crankshaft and oil sump/pan doesn't have to be removed, which in other engines, would usually require removing the entire engine.

That was nice of them to reply.

[Kralizec]

Don't see how there would be mist in the engine room. Any water would end up in the bilge before getting anywhere near the intake: the vent was on the opposite side of the diesel engine room. Vent on the forward, engine intake by the supercharger at the aft part.

The exhaust is a different matter. When the engine was stopped the exhaust could leak seawater which could flood the manifold up to the exhaust valves. You would need to deal with that by manually cranking the engine with the indicator cocks open.

[BrendaEM]

I am looking at blueprints. I see air induction, but am unsure where it leads, from the plans I see.

If a pressure-hull exhaust outlet valve open while diving, there more than likely would be at least one engine valve open in the engine open at any given time, to let water in the cylinder.

What's worse: at depth, because the ocean pressure is on the outside of the valve, water entering the exhaust might have enough pressure to open engine valves.
https://bluerobotics.com/learn/press...th-calculator/

That stated, salt water entering an engine is bad.