I was recently speaking to a friend, who was a ship building architect, about US nuclear carrier and submarine, he was saying submarines and carriers could easily speed over 50-10 knots in open sea, and will lose destroyers and other battle group ships below if necessary. I am asking all the experts here if that is true and practical. Thanks.
Top submarine speed
- Thread starter Superbug
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There has been anecdotal evidence from some in the USN who talk about being passed by CVN's when they are doing flank speed.
It was a lively argument at one stage on Warships1 when a few ex USN sailors swore black and blue that they estimated that US CVN's on the way to the Gulf of Sidra were doing 45+ Knots. Some of the resident naval engineers said that under emergency power it was possible in theory. Others argued that sheer physics involving hull strength and design would make it unlikely.
I've seen it anecdotally "confirmed" by 4-5 ex task force sailors.
who knows
It was a lively argument at one stage on Warships1 when a few ex USN sailors swore black and blue that they estimated that US CVN's on the way to the Gulf of Sidra were doing 45+ Knots. Some of the resident naval engineers said that under emergency power it was possible in theory. Others argued that sheer physics involving hull strength and design would make it unlikely.
I've seen it anecdotally "confirmed" by 4-5 ex task force sailors.
who knows
Theoretical hull speed for displacement vessels is usually calculated at 1.25*(sqrt)LWL. So this would indicate ~40kts. for a carrier sized vessel. YMMV. Subs use a different calculation, but in both cases, I would say ~40 kts. would not be out of line. But 50-100 kts? Not likely, imo. A sub would have cavitation issues, and a surface vessel would just bury the stern (unless you could break the laminar flow of water at the transom). The more power you poured in, the deeper the hole you would dig, but you would not go any faster.
This issue caused a hell of a ruckus on Warships1. There were some ex skimmers responding who swore black and blue that they had timed CVN's at 45-48 knots.highsea said:
You'll never get an answer on US subs though as policy is to give no details - but USS Plunger timed an Alfa at 50 knots in the early years.
The topic seems to come up on a fairly regular basis, doesn't it? I think it's more difficult for the CVN than the sub though, since the drag at the transom where the water meets the air is the big problem. I would say it's possible for a CVN to go faster than the speed I mentioned. The formula is a rough estimate (constants usually vary from 1.15 to 1.35 depending on hull shape), and the key is to break the laminar flow at the stern to get rid of the drag. If you can do that, then you can go way past displacement hull speeds. The 105 footer I ran had a displacement hull speed of 12.5 kts, but it could easily go 24 kts. if I was willing to burn the fuel to get it over the hump.
Obviously subs don't have this problem, only cavitation issues. I guess if a tuna can go 50kts, a sub should be able to also.
If I was feeling ambitious, I could do some displacement/horsepower calculations, but I am too lazy today...
Obviously subs don't have this problem, only cavitation issues. I guess if a tuna can go 50kts, a sub should be able to also.
If I was feeling ambitious, I could do some displacement/horsepower calculations, but I am too lazy today...
knightrider4
Active Member
Hmmm top submarine speed is of no great consequence in my opinion. Nuclear powered subs of nearly every design create much noise at maximum speeds and therefore easy to detect. Speed may be of benefit in transiting great distances though but at the end of the day the noise generated by the cooling pumps for that big kettle will give the game away. Most submarines whilst on patrol will attain speeds of no more than 5 knots which gives them great levels of noise discretion.
The Virginia at 25 knots is quieter than a 688I moored. The 688I was the benchmark not that long ago for quiet nukes. The torpedo release on the Virginias has been quoted as quieter than a flushing toilet. Bear in mind that sounding explosions often are picked up from 1000k's away - and thats no mean feat.knightrider4 said:
Speed is also essential for escape and evasion of any incoming. Your reference to cooling pump noise is platform specific, a number of western designs don't suffer from this affliction to the same degree as their forbears.knightrider4 said:
"most" being the significant caveat here, ie the majority of conventionals and some nukes. It's an issue of tasking. Greater speeds allow an exponential increase in tactical flexibility - more than what has been implied in your response.knightrider4 said:
You can say that again. According to Andrew Cockburns book "The Threat", Soviet Nuclear submarines doing high speed runs in the Norweign Sea could be picked up by sonar at the Bermudas. This one in particular was an Oscar Class SSGN.knightrider4 said:
What about the system Russians use in VA-111 Shkval (Squall)? In case you are not familiar with it, it uses a system that ejects an envelope of supercavitating bubbles from its nose and skin (a technology already thought up in the 60s, I think), so it's surrounded by an envelope of "steam" that drastically reduces the water friction. VA-111 can reach speeds of up to 200Kt by conservative estimates. If that system could be fitted on to a bigger submarine (and in my opinion it could, albeit very expensively), you could achieve speeds of 100Kt+ easily. Of course, you would be heard all over the globe doing so, but hey... That should be the least of your problems with a fish on your tail!
Asmodeane said:
The Skval has been an unmitigated disaster. There are substantial issues with guidance, propellant and range. If you're interested then go to one of the Indian Forums and you'll eventually find a discussion I had with someone who is in the Russian navy named Vepr. We've discussed the problems with it quite extensively.
The USN trialled cavitating torpedos in the early 70's. They're basically a weapons system that has become an urban myth rather than a fully functioning reality.
From an underwater warfare perspective I can give you 4-6 reasons why they've failed to deliver.
That's why they're shaped more like a cucumber than a needle. Navies like the USN, Russian and the German do look at natural shapes as part of their research. The heaviest influence on bow design comes from fast aquatics like the dolphins/porpoises and killer whales.Northax said:
If you notice the shape of new generation submarine sails/cons they are heavily influenced by the dorsal fins of fast moving marine animals. eg Virginia/Seawolf, Collins, 212, Akula all have modified sail fairings emulating those fish that are "thrusters" That is a deliberate move to reduce wake flow aft of the sail when travelling on the surface/sub-surface. It also reduces cavitation effects when submerged.
If you look at the 1st generation Collins Class they hah an ordinary non-faired hull to sail design. During the modifications to that design the Americans allowed Aust access to some of their research and then provided assistance in modifying that structural area so as to reduce noise and cavitation.
Jason_kiwi
New Member
where do the Collins class stack up?
Yeah. I've seen this topic produce rants far and wide.
Here are some of the tidbits i've gathered and rest myself assured with...
1- CVs/CVNs are capable of above 45 knot speeds for limited periods of time. Almost always these come during flight ops to aid in the launching of the aircraft. I found it interesting that they were supposedly not 'allowed' or able to do the max speeds as an escape measure, yet can do them almost regularly for flight ops.
2- SSs/SSNs are also capable of 45+ knot speeds, supposedly for longer periods of time. It stands to reason this; while any general shape is going to be subject to the same forces that could limit speeds, the standard teardrop/cucumber is the most ideal for getting the most out of speed limits while providing all the crew amenities (quarters, sonar, weps, etc).
3- DDGs of the new Arleigh Burke class are also capable of these higher speeds, explicitly for these ships. While the USN did indeed want new vessels with some of the technologies the Burke exhibits, they also wanted to ensure they'd have more escort ships that have less trouble keeping up with the bulk of a CBG. Knox, Perry, & other smaller classes are the ones that have trouble keeping up during the brief high speed runs. But not all, just some. Ask sailors; they'll tell you of how the flattops have had to run circular routes during flight ops to launch aircraft then come back around and meet with the lagging group. Additional note: check how USN doctrine changed in the 90s about fleet replenishment ships and oilers no longer accompanying battle groups directly.
4- Now, this is kind of extrapolated. But certain engineers fully believe that almost every reactor and corresponding drive system in their respective vessels are designed from Navy requirement that they are NOT supposed to do their max potential to save them for their expected 40+ year service life. Meaning in essence if there was ever a need for a true max speed with total disregard for the ship, her drive system and maybe even the crew, these ships could forseeably push out some revolutions for speeds around 55+ knots.
Here are some of the tidbits i've gathered and rest myself assured with...
1- CVs/CVNs are capable of above 45 knot speeds for limited periods of time. Almost always these come during flight ops to aid in the launching of the aircraft. I found it interesting that they were supposedly not 'allowed' or able to do the max speeds as an escape measure, yet can do them almost regularly for flight ops.
2- SSs/SSNs are also capable of 45+ knot speeds, supposedly for longer periods of time. It stands to reason this; while any general shape is going to be subject to the same forces that could limit speeds, the standard teardrop/cucumber is the most ideal for getting the most out of speed limits while providing all the crew amenities (quarters, sonar, weps, etc).
3- DDGs of the new Arleigh Burke class are also capable of these higher speeds, explicitly for these ships. While the USN did indeed want new vessels with some of the technologies the Burke exhibits, they also wanted to ensure they'd have more escort ships that have less trouble keeping up with the bulk of a CBG. Knox, Perry, & other smaller classes are the ones that have trouble keeping up during the brief high speed runs. But not all, just some. Ask sailors; they'll tell you of how the flattops have had to run circular routes during flight ops to launch aircraft then come back around and meet with the lagging group. Additional note: check how USN doctrine changed in the 90s about fleet replenishment ships and oilers no longer accompanying battle groups directly.
4- Now, this is kind of extrapolated. But certain engineers fully believe that almost every reactor and corresponding drive system in their respective vessels are designed from Navy requirement that they are NOT supposed to do their max potential to save them for their expected 40+ year service life. Meaning in essence if there was ever a need for a true max speed with total disregard for the ship, her drive system and maybe even the crew, these ships could forseeably push out some revolutions for speeds around 55+ knots.
Jason_kiwi
New Member
I was watching a documentry last night about the US sub that crashed. That went 45knots under water and 10 knots on the surface