Talk:Type 212 submarine

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The source from these changes is the Naval Institute Guide to Combat Fleets of the World 2005-2006; Their Ships, Aircraft, and Systems compiled by Eric Wertheim. I do believe the changes I made to be accurate, as according to the Type 212A entry for the German Navy in this book. --Laserbeamcrossfire 18:43, 12 July 2006 (UTC)

Seems not to be very accurate (or translation errors), see official specs here. 8 knots may be "Schleichfahrt" (silent cruise) or eco cruise. --Denniss 22:24, 12 July 2006 (UTC)
Quite possible. I'll see if I can't find some more information on the Type 212, or find an early copy of the Naval Institute Guide to compare entries. --Laserbeamcrossfire 08:20, 13 July 2006 (UTC)

[edit] General Characteristics section -- questions and comments

This is an interesting article and it raises some interesting questions:

"Speed: 20 knots (37 km/h) submerged, 12 knots surfaced"

Is the submerged speed attained when the boat is snorkeling or running on the battery? The diesel manufacturer's web site specifies that its output is 2150 kw. When surfaced, is the diesel directly coupled to the shaft or is it always coupled only to the generator?
The fuel cells only put out 306 kw -- on first glance, I don't see how you could get more than a few knots (perhaps 3) out of that sort of power, even assuming you turned off every other piece of equipment on board (lights, computers, etc). I'm not the expert, however, and it would be great if someone more knowledgeable could elaborate on the practical capabilities of this boat when operating on fuel cells only.

"In addition, the boat and internal fixtures are constructed mostly of nonmagnetic materials, reducing chances of it being detected by magnetometers or setting off magnetic naval mines. "

The MTU 396 16V engine is listed by the manufacturer as a general purpose diesel. I'm assuming it's made of ferrous materials -- is this true? I would think the boat still has a significant magnetic signature. The German Navy's Type 212 page refers to a non-magentic steel hull -- does anyone have any reliable information on this? Is this a stainless steel hull? (Some stainless steels contain no ferromagnetic materials). Iron is inherently ferromagnetic, but steel-hulled submarines can be degaussed -- is this what they're referring to? It would be great if someone could expand this or turn it into another article. I don't think there's ever been a stainless steel submarine before.

"According to a German tv-report, Type 212's radar signature is simillar to the one of a can of cola."

Is this the radar cross-section snorkeling or surfaced?

"The skewback propeller is designed to run without cavitation and therefore produces almost no noise."

How is this different from other submarine propellers? I thought this was true of all of the modern designs

"The fuel cell system doesn't require continuous running of coolant pumps that a nuclear reactor would."

Modern nuclear submarines often don't require pumps until they have to operate at high speeds; see natural circulation.

"Although hydrogen-oxygen propulsion had been considered for submarines as early as World War I, the concept was not very successful until recently due to fire and explosion concerns. In the Type 212 this has been solved by storing the fuel and oxidiser in tanks outside the crew space, between the pressure hull and outer light hull. The gases are piped through the pressure hull to the fuel cells as needed to generate electricity, but at any give time there is a very small amount of gas present in the crew space."

I'd say the risk of fire has been minimized, not eliminated. An analogous situation is the use of external oxygen tanks; that reduced but did not totally eliminate the risk of fire -- see USS Sargo (SSN-583)

"Even torpedo launching is stealthy with the 212A: It uses a water ram expulsion system, instead of noisy compressed air."

Isn't this what many other submarine classes use? My understanding was that U.S. subs have used this for decades and that it still makes noise. How do they move the water used for ramming?

--A. B. 13:55, 3 October 2006 (UTC)

I don't have all the details on this one right now, but can tell how it is generally done on similar subs.
First, the submerged speed is always measured as the full burstspeed without snorkeling. It includes all batteries, plus fuel cells, plus, if needed, reduced power on all noncritical systems except the engine. Snorkeling speed is separate, and usually lower than both submerged and surfaced speeds due to high drag on snorkel and snorkel strength limitations.
The required power for propulsion falls almost with 3rd power of speed and so required power for 20 knots, given the average drag hull with 1800t is about 4-5 MW. Fuel cells contribute only a little to that and are used for very slow moving or simply for life support. 20 knots are reached only with full batteries power, which is pretty high.
Non-magnetic steel is used for about 40 years by now, specifically most Soviet subs have their light hulls built of non-magnetic steel. Such steels aren't very strong, but have moderate price and are easy to work with, being basically a kind of low alloy steels. Of course, the engine is built of normal materials, it's just the reduced magnetic signature, probably up to a few times. I'll check the details of construction soon, as probably not even the entire hull is of non-magnetic steel.
Words about the RCS are just another piece of baseless advertising, usual for TV reports. A submarine neither really needs nor can achieve small RCS, and with sensible reduction measures the best possible is like a MBT.
Water ram expulsion system is used for over 40-50 years by at least US, Russia, UK and France. Exactly the same with skewed propellers. It is just presenting a typical solution as unique feature.
Generally, this article needs serious cleanup and sourcing. Probably most of unique features and cola-can RCS would be gone, while other characteristics would become more realistic. CP/M comm |Wikipedia Neutrality Project| 18:08, 3 October 2006 (UTC)
Thanks for all the useful information delivered so quickly!
Based on your formula for power, if all fuel cell power went to propulsion (impossible -- people have to breathe, eat, etc.), then the top speed would be about 1 knot. Given the "hotel loads" (non-propulsion power loads) on larger subs, my guess is that all the fuel cell output is for hotel loads which would imply that to get the 3 week underwater time, this boat would need to mostly either hover or sit on the bottom. Since the screw is behind the X-planes, 1 knot would probably insufficient to get much control from those planes.
The "non-magnetic steel" remains an interesting point. The Soviets used non-magnetic titanium for some hulls. That's expensive and I'm not sure anyone besides the Russians have ever sufficiently mastered titanium technology to do this. Ferromagnetism is a fundamental quantum-level trait of iron and nickel, so I see no way to eliminate it. A magnetic signature, however, requires a non-random average alignment of all the individual atomic magnetic fields and that nonrandomness can be reduced, for instance by degaussing.
--A. B. 18:49, 3 October 2006 (UTC)
Probably not as low as 1 knot; 20-fold decrease would give result (high estimate) of about 3-4 knots, or 1.5-3 knots plus life support. Slow moving requires very little power (however, I'm not sure about 20 knots at 3 MW - it is quite good for 3 MW, and the hull is short with constant diameter). Actually about 200-300 kW engines are considered sufficient backup propulsion for nuclear submarines in case of reactor failure. The low power and capacity of fuel cells and other AIP systems makes them unable to substitute diesel-electric system, only to complement it with ability to stay submerged.
Non-magnetic steel isn't a substitute for titanium neither by magnetic properties nor by strength, but is much easier to work with. Titanium requires massive industry to produce in large quantities, is difficult to weld, and there are only two facilities in the world capable of constructing titanium subs of considerable size. According to evaluations, the cost of reproducing Alfa outside the specific industry and economy would be in range of five to seven billions; no country is planning to build titanium subs in foreseeable future. NMS is merely steel where most qualities are sacrificed to enable effective degaussing so that impact on the magnetic signature is minimized. Most probably the light hull is built of such steel. However, it would be hardly effective to build a sub completely with it; even on surface combat ships NMS is to date used only as the thin outmost layer. For strong hull it is inefficient, and Type 212 can have it built of normal HY steel. I'll check the details soon, but there is little doubt. I'll also clean out some particularly outstanding statements now. CP/M comm |Wikipedia Neutrality Project| 20:07, 3 October 2006 (UTC)
OK, I've got the data. The low-magnetic steel is actually used for most of the hull. Speed can reach up to 20 knots at full burst, as they have efficient propulsion system (not pumpjet, good transmission). Noise levels normal for d-e subs. Radar signature when surfaced is reduced. Cells give 3 knots. Crush depth not known, operation depth around 300, design somewhat more, no details. CP/M comm |Wikipedia Neutrality Project| 10:52, 21 October 2006 (UTC)

There are mistakes in the datas and equotation above. The Permasym e - motor has an maximum Power Output of 1,7 MW. This leads to following conclusion. The Sub has a speed of 20 knots at a Poweroutput of 1,7 MW. The Fuel Cells are delivering 0,3 MW. When all the Power is transfered to the screw, the sub is able to reach 8 knots. To estimate the speed, this equtation has to be solved: P_drive=c(drag)*v(Speed)^2. The constant(drag+fluid_constansts+ etc.) c(drag) of the Type 212 A in water is 4.25. When the half of the Fuel Cell Power is deliverd to the screw the sub has an crusing speed of 6 knots. At a fourth of the Fuel Cell Output the speed will be 4.3 knots. The operation deep is around 300m. To estimate the crush deep, you have to know that german engineers are using the saftey factor of 2 in the design of submerged vessels. Other countries are using 1.5. The eqotation (opperation_deep*saftey_factor=crush_deep) leads to a crush deep of approximatly 600m (or 1800 feet). Another Topic is the loudness of the vessel. The groundbrake is the permasyn engine designed by siemens. Compared to direct current engines this ac - motor is a torque monster. Now it is possible to use a bigger slow rotating screw with less cavitation, without losses in the transmission gear. The engine is in the condition to rotate really slow with a lot of torque. The Andvantages are: Less sound emisson of cavitation and of the transmission. 138.246.7.10 08:28, 21 December 2006 (UTC)

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