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Chromatix · 06-06-16, 06:52 PM

Of the four major roles players are expected to take on, the Engineer was the most surprising to me in its implementation in the current alpha. Given that the developers are clearly trying for authentic operation in other areas, the number of both basic and subtle problems I found in the engine room were such that I must make a detailed criticism of it.

First, and most obviously, both the helm and the diving controls have been placed aft, along with the engine and motor controls. In every real WW2 (and later) sub I'm aware of, the helm and primary diving controls were actually in the control room, along with telegraphs to relay engine orders aft. There would only be an emergency helm control aft, in case of failure of the remote control system; if remote control of buoyancy systems failed, there would be local hand controls for every vent and valve throughout the length of the boat.

Also fairly obviously, no diveplane controls are provided whatsoever, with depth control being entirely by flooding and draining buoyancy tanks. In reality, the diveplanes were the primary means of depth control (both directly and via angling the whole boat), with the buoyancy tanks being set up for neutral trim and then left well alone under normal circumstances. British and American subs did have a "Q" or "negative" tank to assist rapid diving, but that was for use in urgent situations rather than as the routine method.

The above is excusable as a simplification, given that the game is in an early state of development and no AI crew is available yet. It should also be noted that modern subs use a "one man control" with both helm and diveplane controls operated by one crewman, though the engine orders are still telegraphed.

It seems reasonable to me to provide a helm station in the control room with engine telegraphs, rudder, fore-plane and aft-plane wheels, and controls for the main ballast, Q, safety and trim tanks all in one place, even though it was normal for a total of four or five crewmen plus a Dive Officer to operate these controls. The engine room itself can then be optionally manned, as it is relatively easy for an AI to interpret engine telegraph orders.

But now we come to the propulsion machinery, and I feel obligated to invoke Video Game Developers Have No Sense Of Scale. I've previously led a (partly successful) crusade on this subject for railway-based games - well, *one* railway-based game - and the principles are sufficiently similar to require only slight modification for naval technology.

First, the maximum speeds of the sub (both surfaced and submerged) are ridiculously high for a conventional WW2 design. The well-known American "fleet boat" design was among the first capable of a sustained 20 knots on the surface, and that after several failed attempts at achieving precisely that throughout the 30s. To do it required a long waterline (by sub standards) and the full power of *four* diesel engines. Marulken's top speed of 30 knots with two normal-looking diesels is not credible, even for a "black project".

Meanwhile submerged speeds of even 10 knots were found only in smaller boats (with less surface area) until full streamlining came into vogue with the Type XXI and the post-war GUPPY conversions. Marulken's underwater performance however ranks with the best of the GUPPYs, even though it has the tower design obviously lifted from an early-war German U-boat.

Putting that aside, one would expect the batteries to last a great deal longer when creeping around at low speeds than when dashing around at full speed. This is because, as a rule of thumb, the power requirements scale with the *cube* of the ship's speed, while the distance covered scales only linearly. Yet I found my batteries to be almost drained after an hour or two of creeping around at 3 or 5 knots, forcing me to surface and recharge before I had sufficiently left the bay. That's bad by *First* World War standards of underwater endurance.

If we assume that each battery is nominally 300V, the quoted 4000 Ah capacity corresponds to 1.2 megawatt-hours per battery. So Marulken was somehow using about a megawatt to trundle peacefully about at 5 knots under my command. To put that into context, a megawatt is roughly the full rated output of a Class 33 locomotive's main genset, consisting of a large 8-cylinder diesel engine which wouldn't be *entirely* out of place on a fleet-type submarine - but it would certainly achieve more than 5 knots if so fitted!

Meanwhile the Marulken's miraculous diesels fully recharged both batteries in about a minute flat (so, producing about 60MW

or 80,000 horsepower

each) - which was fortunate as by then I had an enemy destroyer bearing down on me. So much for remaining undetected.

There's a lot to be said for modelling systems with physical laws and energy equations in mind. I'll expand on that in subsequent posts in this thread.

06-06-16, 06:52 PM	#1
Chromatix Watch Join Date: May 2011 Posts: 26 Downloads: 11 Uploads: 0	In the Engine Room (build 144) Of the four major roles players are expected to take on, the Engineer was the most surprising to me in its implementation in the current alpha. Given that the developers are clearly trying for authentic operation in other areas, the number of both basic and subtle problems I found in the engine room were such that I must make a detailed criticism of it. First, and most obviously, both the helm and the diving controls have been placed aft, along with the engine and motor controls. In every real WW2 (and later) sub I'm aware of, the helm and primary diving controls were actually in the control room, along with telegraphs to relay engine orders aft. There would only be an emergency helm control aft, in case of failure of the remote control system; if remote control of buoyancy systems failed, there would be local hand controls for every vent and valve throughout the length of the boat. Also fairly obviously, no diveplane controls are provided whatsoever, with depth control being entirely by flooding and draining buoyancy tanks. In reality, the diveplanes were the primary means of depth control (both directly and via angling the whole boat), with the buoyancy tanks being set up for neutral trim and then left well alone under normal circumstances. British and American subs did have a "Q" or "negative" tank to assist rapid diving, but that was for use in urgent situations rather than as the routine method. The above is excusable as a simplification, given that the game is in an early state of development and no AI crew is available yet. It should also be noted that modern subs use a "one man control" with both helm and diveplane controls operated by one crewman, though the engine orders are still telegraphed. It seems reasonable to me to provide a helm station in the control room with engine telegraphs, rudder, fore-plane and aft-plane wheels, and controls for the main ballast, Q, safety and trim tanks all in one place, even though it was normal for a total of four or five crewmen plus a Dive Officer to operate these controls. The engine room itself can then be optionally manned, as it is relatively easy for an AI to interpret engine telegraph orders. But now we come to the propulsion machinery, and I feel obligated to invoke Video Game Developers Have No Sense Of Scale. I've previously led a (partly successful) crusade on this subject for railway-based games - well, one railway-based game - and the principles are sufficiently similar to require only slight modification for naval technology. First, the maximum speeds of the sub (both surfaced and submerged) are ridiculously high for a conventional WW2 design. The well-known American "fleet boat" design was among the first capable of a sustained 20 knots on the surface, and that after several failed attempts at achieving precisely that throughout the 30s. To do it required a long waterline (by sub standards) and the full power of four diesel engines. Marulken's top speed of 30 knots with two normal-looking diesels is not credible, even for a "black project". Meanwhile submerged speeds of even 10 knots were found only in smaller boats (with less surface area) until full streamlining came into vogue with the Type XXI and the post-war GUPPY conversions. Marulken's underwater performance however ranks with the best of the GUPPYs, even though it has the tower design obviously lifted from an early-war German U-boat. Putting that aside, one would expect the batteries to last a great deal longer when creeping around at low speeds than when dashing around at full speed. This is because, as a rule of thumb, the power requirements scale with the cube of the ship's speed, while the distance covered scales only linearly. Yet I found my batteries to be almost drained after an hour or two of creeping around at 3 or 5 knots, forcing me to surface and recharge before I had sufficiently left the bay. That's bad by First World War standards of underwater endurance. If we assume that each battery is nominally 300V, the quoted 4000 Ah capacity corresponds to 1.2 megawatt-hours per battery. So Marulken was somehow using about a megawatt to trundle peacefully about at 5 knots under my command. To put that into context, a megawatt is roughly the full rated output of a Class 33 locomotive's main genset, consisting of a large 8-cylinder diesel engine which wouldn't be entirely out of place on a fleet-type submarine - but it would certainly achieve more than 5 knots if so fitted! Meanwhile the Marulken's miraculous diesels fully recharged both batteries in about a minute flat (so, producing about 60MW or 80,000 horsepower each) - which was fortunate as by then I had an enemy destroyer bearing down on me. So much for remaining undetected. There's a lot to be said for modelling systems with physical laws and energy equations in mind. I'll expand on that in subsequent posts in this thread.