launching something from 100miles away that makes the devils own noise and can't turn/can't turn well at a moving target, well...
Posted on 08/24/2014 6:00:06 AM PDT by sukhoi-30mki
Chinese eye 'supercavitation' technology as future of underwater travel
China has moved a step closer to creating a supersonic submarine that could travel from Shanghai to San Francisco in less than two hours.
New technology developed by a team of scientists at Harbin Institute of Technology's Complex Flow and Heat Transfer Lab has made it easier for a submarine, or torpedo, to travel at extremely high speeds underwater.
Li Fengchen, professor of fluid machinery and engineering, said the team's innovative approach meant they could now create the complicated air "bubble" required for rapid underwater travel. "We are very excited by its potential," he said.
Water produces more friction, or drag, on an object than air, which means conventional submarines cannot travel as fast as an aircraft.
However, during the cold war, the Soviet military developed a technology called supercavitation, which involves enveloping a submerged vessel inside an air bubble to avoid problems caused by water drag.
A Soviet supercavitation torpedo called Shakval was able to reach a speed of 370km/h or more - much faster than any other conventional torpedoes.
In theory, a supercavitating vessel could reach the speed of sound underwater, or about 5,800km/h, which would reduce the journey time for a transatlantic underwater cruise to less than an hour, and for a transpacific journey to about 100 minutes, according to a report by California Institute of Technology in 2001.
However, supercavitation technology has faced two major problems. First, the submerged vessel has needed to be launched at high speeds, approaching 100km/h, to generate and maintain the air bubble.
Second, it is extremely difficult - if not impossible - to steer the vessel using conventional mechanisms, such as a rudder, which are inside the bubble without any direct contact with water.
As a result, its application has been limited to unmanned vessels, such as torpedoes, but nearly all of these torpedoes were fired in a straight line because they had limited ability to turn.
Li said the team of Chinese scientists had found an innovative means of addressing both problems.
Once in the water, the team's supercavitation vessel would constantly "shower" a special liquid membrane on its own surface. Although this membrane would be worn off by water, in the meantime it could significantly reduce the water drag on the vessel at low speed.
After its speed had reached 75km/h or more the vessel would enter the supercavitation state. The man-made liquid membrane on the vessel surface could help with steering because, with precise control, different levels of friction could be created on different parts of the vessel.
"Our method is different from any other approach, such as vector propulsion," or thrust created by an engine, Li said. "By combining liquid-membrane technology with supercavitation, we can significantly reduce the launch challenges and make cruising control easier."
However, Li said many problems still needed to be solved before supersonic submarine travel became feasible. Besides the control issue, a powerful underwater rocket engine still had to be developed to give the vessel a longer range. The effective range of the Russian supercavitation torpedoes, for example, was only between 11 km and 15 km.
Li said the supercavitation technology was not limited only to military use. In future, it could benefit civilian underwater transport, or water sports such as swimming.
"If a swimsuit can create and hold many tiny bubbles in water, it can significantly reduce the water drag; swimming in water could be as effortless as flying in the sky," he said.
Besides Russia, countries such as Germany, Iran and the United States have been developing vessels or weapons using supercavitation technology.
Professor Wang Guoyu, the head of the Fluid Mechanics Laboratory at Beijing Institute of Technology who is leading another state-funded research project on supercavitation, said the global research community had been troubled for decades by the lack of innovative ideas to address the huge scientific and engineering challenges.
"The size of the bubble is difficult to control, and the vessel is almost impossible to steer," he said. While cruising at high speed during supercavitation, a fin could be snapped off if it touched the water because of the liquid's far greater density.
Despite many scientists worldwide working on similar projects, the latest progress remains unclear because they are regarded as military secrets.
Wang, a member of the water armament committee of the China Society of Naval Architects and Marine Engineers, said even he had been kept in the dark about recent supercavitation developments in China.
"The primary drive still comes from the military, so most research projects are shrouded in secrecy," he said.
Yes, super cavitation is indeed not new.
Perfecting it for either sub surface transportation, or as supercavitating torpedoes with any significant range remains a critical engineering challenge
The successful accomplishment of doing just that was a big part, as you know, of my:
Dragon’s Fury: World War against America and the West
http://www.amazon.com/Dragons-Fury-World-against-America/dp/0971577900
novel
the generic picture I supplied is the exact model I had....er HAVE.
my son now owns it. it is from late 50s early 60s. had to replace the rubber band propulsion system a few times.
Will this mean the end of “a slow boat to China” phrase?
Hmm, interesting since that contradicts the article’s claims that it is a new development that you can now guide things which are using super-cavitation.
Yes, that would certainly seem to be a pretty obvious arrow. Though at 100 miles out, you do have some time to run (certainly more time to run when launching at 10 miles and unless I understand poorly, that usually gives you away as well).
From the article it says you have to start with a large velocity, so the option of a quiet launch and then run before it gets up to ludicrous speed isn’t there.
It would have to travel at almost 4000 mph. Quite a feat underwater.
They claim the speed of sound in water in the article.
Looking that up, it’s 4748 fps at 50F and that’s pretty damned fast. Speed of sound in air for comparison is 1100 fps.
The article is misleading. The Russian torpedoes use rocket nozzles for guidance, as I recall. What the Chinese are doing is a different technique.
Interesting. Sorta like wrapping the ship in a subparticle displacement field, keeping the ship in bubble of unaltered space, in order to exceed the speed of light and to jump to warp speed.
But what about the whales and dolphins?
They’ll have follow up Boats to collect the Noms
I admit I do get the sense that the article could very well have been a feeder from the ChiCom government. I understand that the paper in question has a recent history of being in their pocket.
Someone with GIS capability should see if there is a straight line plot between PRC and CONUS. BTW, what about great circle plots, since there really isn’t a straight line on a globe.
Seems like atolls, biologics, internal waves, etc. are considerations. Lots of krappola to get in the way.
I believe it was the instability of the Shval torpedo that lead to the explosion on the Kursk...
Figure it from the perspective of the energy requirements to open a corridor in water for passage. The energy requirements go up a cubic curve relative to velocity. Maximum energy available is a limiting propulsion factor. At sufficient velocity the energy dissipated obviates the need for a warhead.
The dynamic pressure to the leading structure inflates the bubble and high pressure gas forms a barrier between water and the vessel hull. At some point the speed of sound within the gas will be exceeded by the vessel, and the barrier will fail. Cavitation damage results from fluid flow induced by the collapse of a gas bubble.
The nosecone of the Shakval was wetted and contained the seeker head. It also provided dynamic lift in combination with propulsion, to aid suspending the torpedo above the bottom of the gas cavity. Small attitude changes of the wetted contact area create large side thrust at speed. A minimal contact patch ahead of the main vessel bulk must be present for sensing, unless run blind with inertial guidance.
Simple answer, nuke the whales.
launching something from 100miles away that makes the devils own noise and can't turn/can't turn well at a moving target, well...
I resonate with what you are saying.
Speaking as a non-military person, I believe these have (far) more potential use as a military weapon, than a civilian submarine.
A civilian submarine would mean mass use, and would (inevitably) cause collisions between it, and living tissue in large sea animals.
However as a weapon that would not matter. It would be rare, and simply result in a miss for that shot. Just my take. I have no military background so this is just an opinion.
yeah..and all the other large fishies! Yikes!
They’ll be Spandex Jackets, one for everyone.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.