Question for the naval engineering folks

[CV32]

Here's something those of you with naval service experience or engineering knowledge might be able to help out with:

 

How long could a warship sustain flank speed? By this I mean pedal to the metal, all out pushing the ship at its maximum capable speed.

 

Now I realize that this varies among propulsion types (steam, diesel, gas, nuclear, etc), ship types, even among individual ships, and of course, flank speed is limited by fuel (something akin to afterburner on a fighter jet), but I'm interested in your educated guesstimate.

 

But if you can be more specific, then by all means please go ahead.

 

If you're really naval engineering tech savvy, then how long do you think before the ship could once again go to flank speed? (i.e. recovery time)

[CV32]

No one with any ideas?

[mack]

Well, if it's a sailing ship you can maintain flank speed as long as the captain/sailing master can stop the sails and rigging from being split by the wind (this is in a major blow), if it's in a more normal wind then it's about keeping the ship trim and maintaining the balance between too few sails, overloading with them and keeping the correct ones aloft.

 

Of course, that's probably completely unhelpful for you.

[CV32]

You're right, completely unhelpful, but the effort was appreciated.

[broncepulido]

As example, the speed of November class SSN (project 627A) is rated at 28 knots at 80% power, and 30 knots at 100% power (confusingly, the head of the series (project 627) is rated in some sources as maximum speed 30 knots and the rest of the class (project 627A) as 28 knots, but this is the explanation. The maximum speed of the project 645, a November hull with a diferent type of nuclear reactor, liquid metal cooled, is rated as 30,2 kn.).

i.e. a November SSN can sail without time limits at 28 kn., and I supposse at 30 kn. at flank speed for a while (20 minutes?), after the 20', risk of overheating of the primary and secondary water circuits increases, and the risk of breakdown (rupture of the steam conducts) also increases.

As an informed guess, sn the November SSN the time limit of flank speed can be stated at 20', and after this time, the sub is forced at a maximum speed of 30 kn. for 6 hours (for verification and normal maintenance of the steam conducts).

I think this values can be transfered, without more complexities, to all ships with steam (turbine or alternative engine),

And for me, as this is a very complex topic (very different power plants, new and olds, different types of nuclear reactor (less fiable the soviet reactors), different types of steam propulsion (turbine and alternative engines), gas turbine, diesel, electric transmisions in very old and new ships with electric/podded engines,maintenance in different navies and countries, etc...), the best answer is to implement the maximum and flank speed in the Future Harpoon as customizable values, similar to the readiness time in the aircrafts in ANW.

http://submarine.id.ru/sub.php?627

 

Another very important topic, relationed with the implementation in the computer Harpoon of flank speed values, is the sea state effect in the maximum speed of surface ships, I remember various situations in WWI and WWII in North Sea and North Atlantic, when in surface engagements, the capital ships outspeed the DDs because the sea state, and this determinates the outcoming of the engagements. In some of my personal databases I introduce some disminutions in the maximum speed linked to the displacement, for sake of moderation, as another no real limitation in HCE is the unlimited range of the conventionally propulsed units.

Also, I increase lightly the maximum speed of nuclear powered surface units, as implementation of her unlimited range and greater acceleration rates.

[CV32]

i.e. a November SSN can sail without time limits at 28 kn., and I supposse at 30 kn. at flank speed for a while (20 minutes?), after the 20', risk of overheating of the primary and secondary water circuits increases, and the risk of breakdown (rupture of the steam conducts) also increases. As an informed guess, sn the November SSN the time limit of flank speed can be stated at 20', and after this time, the sub is forced at a maximum speed of 30 kn. for 6 hours (for verification and normal maintenance of the steam conducts).

 

This is the kind of information I am looking for. Did you derive this from the Russian language site you linked?

[broncepulido]

This is the kind of information I am looking for. Did you derive this from the Russian language site you linked?

More or less, and from other sources, as "Cold War Submarines", but I'm sorry is only a informed opinion about very elusive information, I supposse I can remember some battles in WWI with data about those limitations, as the performance of the BC Lion in Dogger Bank, 2 knots over her maximum speed (The phrase in question is "В ходе испытаний мощность ЭУ ограничилась 80% от номинальной. При этом впервые в отечественном подводном флоте была достигнута длительная скорость подводного хода 28 узлов./During tests power was limited 80 % from the nominal. Thus for the first time in national underwater fleet long duration speed of an of 28 knots was reached", but I've read in other place the same data, and the comments about similar limitations for not wear the steam ducts, boilers or transmision gears).

But the idea is, as aproximative values, and if we can only fix one value/proportion for our ships/subs: x time travelling at flank speed, implies after 18x time with speed limitated to "full". We can replace 18 with the value of our choice, of course.

[divefreak]

Here's something those of you with naval service experience or engineering knowledge might be able to help out with:

How long could a warship sustain flank speed? By this I mean pedal to the metal, all out pushing the ship at its maximum capable speed.

Now I realize that this varies among propulsion types (steam, diesel, gas, nuclear, etc), ship types, even among individual ships, and of course, flank speed is limited by fuel (something akin to afterburner on a fighter jet), but I'm interested in your educated guesstimate.

But if you can be more specific, then by all means please go ahead.

If you're really naval engineering tech savvy, then how long do you think before the ship could once again go to flank speed? (i.e. recovery time)

 

as written in the other post it depends on the load and the type of propulsion.

 

an example from smaller Diesel Engines.

 

Rated for pleasure Duty a 7liter Volvo might have around 400HP and may use 100% Power for 1h out of 20 running hours.

 

Rated for heavy Duty the same engine will have only 250-300HP and may rund at 100% continous.

 

I can see what datasheets are avaible in english and post it here...

 

I read/unterstand Flank as more than 100% Power of the rating for continiuos running. So it will be limited to 5 to 10% of the running time. Maybee less (overheating for nuke propulsion for example). In War time you can and will go closer or over the limit, but break downs will be come more and more likely.

 

IRC correctly i once saw a report about a Burke DDG on discovery and they talked about running at Flank for 1-2 h during the trial runs performed during the delivery tests by the shipyard.

[VictorInThePacific]

You're right, completely unhelpful, but the effort was appreciated.

 

Completely unhelpful?

 

Not so fast, my friends!

 

http://www.lowtechmagazine.com/2007/09/sailing-ship-re.html

[Akula]

You're right, completely unhelpful, but the effort was appreciated.

 

If you were to add in a 'Flying Dutchman' that information could be very usefull...

[CV32]

... but I'm sorry is only a informed opinion about very elusive information ...

 

No worries. I know the hard information is elusive, so that leaves us only with informed opinion.

 

... I've read in other place the same data, and the comments about similar limitations for not wear the steam ducts, boilers or transmision gears).

 

Yes, that's what I would expect. Flank speed being limited only by conditions (e.g. sea states), fuel expenditure, or the physical limits of the machinery (overheating, etc). So a broad guideline, or a collection of specific examples, is perhaps the best I can hope for.

[JMS]

Here's something those of you with naval service experience or engineering knowledge might be able to help out with:

How long could a warship sustain flank speed? By this I mean pedal to the metal, all out pushing the ship at its maximum capable speed.

Now I realize that this varies among propulsion types (steam, diesel, gas, nuclear, etc), ship types, even among individual ships, and of course, flank speed is limited by fuel (something akin to afterburner on a fighter jet), but I'm interested in your educated guesstimate.

But if you can be more specific, then by all means please go ahead.

If you're really naval engineering tech savvy, then how long do you think before the ship could once again go to flank speed? (i.e. recovery time)

 

Please see here: http://www.navweaps.com/index_tech/tech-095.htm

 

"However, Bainbridge was really not a fast ship. Many ships were much faster, particularly conventional destroyers. It is very important to note that the only races she won were cross-Pacific races and those requiring great acceleration. Bainbridge could accelerate at a greater rate than any ship in the fleet in the 1960s, because she didn't have boiler limitations and was not a heavy ship for the size of her power plant. Her only limits were shaft torque, which we measured in turbine chest pressure, and steam generator levels. Many ships simply pulled away from her in short high speed races (that Captain Sheridan avoided, of course). Many ships could run at greater sustained speeds. So how did she win so many races across the Pacific? Simple: She could cruise at a constant 25-30 knots indefinitely. As she was nuclear powered, she didn't have boiler limitations and she didn't need refueling. "

 

"You see, you just can't wing the throttles open in a tin can like you can in a "nuke." Heat input is too low. Steam pressure falls off, you lose critical heat, the boilers depressurize and cool down, and the steam bubble collapses… nastily. You have to increase speed slowly on a conventional critical steam plant. You have to build up heat (actually heat flow), and maintain temperature and pressure as you slowly accelerate in a tin can. "

 

Diesels and gas turbines have no such incovenient, but the first are slower and the second eats a lot of fuel. And fuel is very important, according to my in-law (former Captain) tanks have to be at 60-70% capacity at its lowers to cater for emergencies and stability, in peacetime.

 

Obviously, in times of war, requirements relax, but relaxing them too much may leave the ship unstable or dead in the water.

[CV32]

Thanks, JMS. Appreciated.

 

At this rate, we'll eventually build up some idea of what the parameters are.

 

Or, at least, until someone comes along with an epiphany.

[TonyE]

Thanks, JMS. Appreciated.

 

At this rate, we'll eventually build up some idea of what the parameters are.

 

Or, at least, until someone comes along with an epiphany.

 

I think Brains had the epiphany (track fuel capacity and usage) but yes, I'll shut up for now.

[CV32]

I think Brains had the epiphany (track fuel capacity and usage) but yes, I'll shut up for now.

 

Hehe, no opposition to a logistics model here (far from it), but will it keep the AI from racing at flank speed until he runs out of fuel?