nuclear Submarines

Paper...can I ask what the exact equasion is for finding the power needed?

Originally posted by devilwasp
Paper...can I ask what the exact equasion is for finding the power needed?

Fluid dynamics is a very, very complex system. There are no "equations" that will explain how any object behave while passing through a fluid (to include air) that work for all speeds, the best that can be done are rough estimations based on observed data (wind tunnel, scale models, etc.).

As advanced as our science/math is, these systems are so complex that no one can predict how a new golf ball will fly, let alone a large submarine.

So, the short answer is no one knows....

Ah thank you star,
Well if its that complex...how did he get the rough idea of cubeing it?
I mean is that what you would roughly use to measure to something moveing through water or is it something else?

Originally posted by devilwasp
Ah thank you star,
Well if its that complex...how did he get the rough idea of cubeing it?
I mean is that what you would roughly use to measure to something moveing through water or is it something else?

The effect of increasing speed varies with both the speed you start at and the shape. You can guess for a particular shape at a particular speed, but that may not work at all as speed changes.

Originally posted by Starwars51
Fluid dynamics is a very, very complex system. There are no "equations" that will explain how any object behave while passing through a fluid (to include air) that work for all speeds, the best that can be done are rough estimations based on observed data (wind tunnel, scale models, etc.).

As advanced as our science/math is, these systems are so complex that no one can predict how a new golf ball will fly, let alone a large submarine.

So, the short answer is no one knows....

True to some degree, however with the advent of massive parallel computing, things thought impossible to model even 5 years ago are able to be modelled today.

you are not right to say there are no exact formulae for the motion of a object, they are the Navier-Stokes equations (good luck solving those btw). There has however been a massive amount of work done to provide mathematical models that allow naval architects to predict the effects with suprising accuracy. The fact that power is proportional to the cube of the speed is a well known (to naval architects at least) empirical formula based on the analysis of a large number of resistance curves for many types of vessels. The power prediction i did was extreamly simple based on just the surface frictional resistance. In reality the resistance is probaly higher due to form drag (energy used pushing the water out the way), wavemaking resistance (even at depth waves are created) and various appendage drags such as fin drag and rudders etc. For the most accurate results a hull form would have to be either tested at model scale or an expensive CFD package (if i get bored i will do this one day).

posted on another forum but still good questions;

Some submarine questions...
-What was the yield of the Subroc? I have read 5 KT, and 200KT thermonuclear. Which is it? And was it in service to the end of the Cold War? (when the first Bush de-nuked the tactical navy) I had read somewhere long ago that the digital fire control of the Los Angelas class was incompatable, and thus retired early, but never got any info after that. I was suprised to see from one source that it was retired as late as the late 1980's/early 1990's.
-Do the Russians have an equivelant to the Mk-48 ADCAP? How does it compare in speed and range?
-What is the opinion of the other Russian submarine weapons? Starfish? Other ASW? Not necessary to recap the old Shkval issue here, that has been beaten to death...
-Does the Mk-48 have an insertable nuclear option? (rumor) 60 knots max speed? (less than the 70 kt Spearfish), 20,000 yard range max?
-How does the best torp decoy do against the best torps?

All that answer, thanks.

I can tell you that the shielding mechanisms which folded down from the ceilings on the Los Angeles class submarines in the torpedo rooms is no longer there as I have installed them in construction phases. They are designed to shield the warhead section of these weapons when doing maintnence.You need to know that these weapons over time have a tendency to leak contamination just by simple sweating or condensation.This was true of our nations nuclear anti aircraft missle inventory also ...not good on decking where it tends to spread by people going about natural processes. The boats have very sentitive atmospheric samplers which pick this up and alarms go off..to be expected on a nuclear vessel. This shielding was in place on the older 637 class boats and the early Los Angeles class.
Remember too that modern American submarines carry Tomahawk cruise missles in verticle launch tubes..these missles can be set up to carry different warheads and hit on land as well as on water anywhere within their range. The key to any of these systems ..is its accurate navigation/delivery system..otherwise you have only a Fourth of July sky rocket. This accuracy has reduced the need for huge warheads of any type ..conventional or nuclear. Very telling. This is obvious in Iraq and Afganistan.
I suspect that it is no longer needed as technology has eclipsed the need for these nuclear weapons. As to yeild sizes I will leave that up to experts. I am sure that nuclear torpedos are in use by other nations..as thier technology is some arenas is not up to speed with some of ours.
As to speeds of these other weapons..and other factors I am sure that this information is classified...and will leave that up to others too. Same with the decoys.

Thanks
Orangetom

Something for some of you to think about ..
Modern nuclear aircraft carriers do not usually run at what we call high speeds...it is not usually necessary. They need enough speed to launch and recover aircraft and sufficient for maneuverability in this process.

However ..I have been told by sailors around here posted on them...that at high speeds they throw up rooster tails.....almost up to the flight deck if that tells you anything. Similar to what the high speed hydrofoil churns up behind itself. In a drydockbelow the water line a carrier is a very clean hull design.

However ..like submarnies ...no one tells you the actual numbers.

Consider this..event in history.

Years ago..the USS Nimitz was doing night training operations off the coast of Florida.
A airplane crashed on the deck killing the crew and many sailors. This happened about 10pm at night. As quickly as they could they got the fires under control and stabilized the situation , turned her around and zoomed straight back here to her Norfolk Navy Base port. They were given direct clearance to enger the harbor and tie up...they tied up about 1pm the next afternoon. That is a fast trip..up from Florida. Think about that.. This happened sometime back in the 1980s.

Thanks Orangetom

as i said the calcs i did here are based on published information and seem to support the published results. The actual speeds are classified but would seem to be faster. I doubt you can get a nuclear powered aircraft carrier to form a rooster tail unless it starts to plane (dynamic lift). i would not be suprised if the had some way of going a lot faster than publicly stated though. most likely through more powerful turbines than they have admitted.

And sailors have never been known to tell tall tails before?????????

No doubt about sailors being known to tell stories. No Doubt.
The main problem I have with this one is that I have heard it from so many.

However..I agree with you and others that they are sandbagging on the performance information for obvious reasons.

I cannot tell you what I know about the engine rooms and shafting of these boats/ships..but perhapsed this story will be of some use.

Years ago the Ocean Liner the USS United States was built here in this yard. When you see the bottom of the hull and its shape..it is very similar to an aircraft carrier hull. Also of course she had four wheels on her. Not the way most ocean liners today are constructed. Remember now..that back then she was also registered as a ship of the line..a warship for carrying troops to warzones if necessary. To the ignorant public her primary reason for being was passenger traffic and this of course was played up in all the press reports. When they opened her up at sea..she left everything behind...everything...including the ships of the US Navy. Now mind you ..she was not nuclear powered..but she was powerful..the powerplant being to military secifications.
This equipment has only improved...no doubt.

Thanks,
Orangetom

Paperplane,
You know on the lighter side concerning ..sailors telling tales...

I was told this one by a guy who loved history and tend to believe it. It concerned the Carthegenian sailors and them going ashore to different ports of call.

It seems that the Carthegenians had lost several wars to the Romans and had to pay huge tribute to them annually. As Roman historians would write in confusion.." We exact huge tribute to them and they arrive to pay in ships with silver lined oars. It seems that the Carthegenian sailors when going ashore would tell numerous sea monster stories ..and tales of falling off the world if one went outside of the straights of Gibralter. In this manner they were successfully able to keep superstitious Roman sailors on the correct side of the straights. Thus keeping their trading empire intact and unknown up the Atlantic side and down along the African coast. If I recall the events of history correctly these superstitions remained in effect until the time of Columbus and the Portugese Navigators.
I found this very intresting and amusing...if true ..quite an effective way to protect trade routes.

Thanks ,
Orangetom

Originally posted by orangetom1999

Years ago the Ocean Liner the USS United States was built here in this yard. When you see the bottom of the hull and its shape..it is very similar to an aircraft carrier hull. Also of course she had four wheels on her. Not the way most ocean liners today are constructed. Remember now..that back then she was also registered as a ship of the line..a warship for carrying troops to warzones if necessary. To the ignorant public her primary reason for being was passenger traffic and this of course was played up in all the press reports. When they opened her up at sea..she left everything behind...everything...including the ships of the US Navy. Now mind you ..she was not nuclear powered..but she was powerful..the powerplant being to military secifications.
This equipment has only improved...no doubt.

Thanks,
Orangetom

yes that is true she was a fine vessel, many people at the time tried very hard to figure out how she could go so fast. I have a technical paper on it somewhere, from the time. In the end it was just good underwater design.

[edit on 29-4-2005 by paperplane_uk]

You know..I am not a big sports fan...but I love to watch a beautiful graceful sailboat and also the racing yachts when they have them on the tube.
One of the things I learned from a engineer when he came on the boat one day was the constant attempt to get more speed out of these yachts in these races. He constantly spoke about wet surface area...wet surface friction. So I was amazed to see a sort of hydrofoil under the keel of a racing yacht. I realized how far these guys would go to get the last percentage of a knot of speed in a race. Same with auto racers...any technology advantage to get the prize.
You are of course correct when you explain the costs..that they rise exponentially for ever so much of an advantage..until the costs become prohibitive. Nevertheless it is fascinating to see and learn about the concepts and inventions that come about in the human quest for excellence...in any field.

Thanks
Orangetom

Paperplane sounds correct....32-35 knots is about right for a Nuclear SSN. It sounds like that sonar needs some calibration.


Max

orangetom1999...speaking of the Carthegenians Im playing an incredible game called Rome:Total War and I just got into a war with Carthegenians and got my a** kicked in their harbor....lost my fleet and all the Legions I loaded up for the invasion...


Maximu§

I dont play many of those games...but I know people who do...and furthermore..I am told that it is a staple in many of the military academys around the world.
As I understand it...they crunch alot of data in these computers trying out different senerios in war. The one which caught me short ..was a simulation between Alexanders Macedonian Pikemen and Napoleans Dragoons. You would think that the guys with gunpowder would have the edge. The simulation turned out to be even up. Apparently the Pikemen are that good. I would have never believed it.
It is a intresting tool of thought and concept..definitely.

Thanks
Orangetom

reply to post by paperplane_uk

reply to post by paperplane_uk


In a Discovery Channel special about the history of the U.S. nuclear sub, the speed of the U.S.S. Triton, one of our first nuclear subs, was clearly stated as 55 m.p.h. I was surprised. We also know of old, acknowledged data on the Soviet Alpha Class doing 45 knots or 51 mph. Based on this, it is NOT so unbelievable that 60 knots is already attainable. Furthermore, in a 1988 book entitled The Navy: Its Role, Prospects for Development and Employment written by three naval officers with a foreword by Admiral Sergey G. Gorshkov, the long-time head of the Soviet Navy, predicted "in the near future" the Soviet Union would develop submarines with 50 to 60 knot speeds, and more than 100 knots in the long term.
That was back in 1988!!!!!!

There is no magical barrier of physics that makes 60 knots impossible. Your calculations for the LA Class sub are based on the official power rating of the nuclear reactor at approx. 35,000 shp. This figure cannot be trusted and would likely be vastly underestimated.

As you state, subs generate far less hydrodynamic drag than surface vessels. Subs do not have to contend with the surface tension of water.
I may have spoken to various naval servicemen who probably would
disagree with your prediction.

I spent four years aboard the USS Stonewall Jackson (SSBN634-blue), a Lafayette class fleet ballistic missle submarine in the 1980's. Speeds were rarely discussed, but I WILL say that the highest we ever travelled while I was a member of the Ships Control Party was 34 knots.