China's new submarine engine
popsci.com
popsci.com
Some pictures of existing units: [1] They're mostly used as steerable thrusters for boats that need to be highly maneuverable, such as ferries. They're becoming very popular for ROVs, because they're much lower maintenance than existing thrusters used at depth.
The impeller pushes against the housing with the same force that a conventional shaft develops against a shaft-mounted axial thrust bearing would for the same speed and vessel geometry.
Is it possible to have a water-bearing with injected high-pressure water in a small area, or will that use as much power as the propulsion?
Hydrodynamic bearings running in water seem to be popular. Those have a design which self-pumps water between the bearing surfaces. The load is carried by the fluid, not the surfaces.
The neat thing about this design is that most of the headaches of operating in water become advantages. Water provides lubrication and motor cooling. No oil, no shafts, and no seals, the usual headaches of things which operate in water. There's still corrosion and general marine crud to fight, of course.
[1] https://www.schottel.de/fileadmin/data/pdf/eng/SRT_Flyer_A4_... [2] http://www.elkraft.ntnu.no/eno/Papers%202004/ICEM04-Krovel-N...
And this thing seems like it would generate an enormous magnetic field.
There are other thoughts on the current administration and their ability to see their way out of a Thucydides trap with a rising nation who also happens to be our largest trading partner...and the ability of the Pentagon to maintain primacy with the destruction of American STEM advantages...
1. hidden CIC nodes the enemy doesn't know to attack;
2. unpredictably-roving nuclear ICBM launch platforms which no amount of reconnaissance can paint as targets for pre-emptive strikes;
3. "sleeper agents" that can just enter a projected battlespace (e.g. foreign coastal waters) carrying medium-range missiles for quick engagement, then sit around for months in case said battlespace goes active, ready to throw those missiles out at a moment's notice.
#1 can be achieved by short-submersion vessels. #2 can, theoretically, as well, but it's much more costly (more boats in shorter shifts) and less effective because change-outs are the weak link for discovery and predictability. But #3 just can't work for non-nuclear AIPs—and it's one of the major keys to strategic deterrence.
And the land attack role isn't really about deterrence - that's what the boomers are for.
Though I agree if you want to operate subs in far-flung seas you pretty much have to go with nuclear propulsion. Diesel subs (of which AIP are just the latest iteration) just don't have the legs. They're also not magical, as some people seem to think. You can detect them.
None of that is going to happen, of course. The US will ride the military superpower party to the end of the line, where it's financially forced to cut back. That won't take more than a decade or two to conclude at this point (given the soon-to-be routine $1+ trillion deficits due to inbound entitlement costs). The US will properly cede its European military position to European nations and it'll cede its Asia military position to Asian nations.
To maintain primacy (and we should discuss _why_ maintain primacy in a second) the U.S. need to have the best conventional capabilities as well. My money is or more autonomous, robotic vehicles: in the air (armed UAVs), on land (small robot tanks), and in the sea (small robotic AIP subs).
As to why maintain primacy: because as much as I'm certain you dislike the U.S., it is the best hope we have for peace in this world. The Chinese are still bent on dominance and interested in various conquests. The Russians apparently still feel a desire for revanche. And the muslim world is increasing nuclear proliferation and state terrorism. The Pax Americana of the Cold War era was remarkable -- you might disagree and point to all the ill-advised interventions by the U.S., but those are as nothing compared to the levels of violence we have seen historically. At least until China democratizes and adopts closer-to-Western values, we must remain the foremost military power on Earth.
What evidence do you have for that, as opposed to this alternative hypothesis:
1. The Chinese have a bit of a thing about uninvited guests. C.f. world history from the industrial revolution until 1975, or go back a bit further to that Ghengis ratbag.
2. If any ininvited guests turn up in China in the next 30 years, they are, objectively, very likely to be Americans. Because a) who else can? b) go ask the Koreans, Vietnamese, Afghans, Iraqis, Phillipinos, pause for breath, Nicaraguans, Yemenis, Iranians, Indonesians, Somalians, Cambodians, ..., whose army it usually is that turns up in someone else's country.
3. Pfaffing around in their local seas is relatively cheap for the Chinese, and it provokes Americans to burn lots of money in order to "maintain primacy". Meanwhile, the Chinese get to save their money and build submarines.
> At least until China democratizes
Because, of course, external threats from the world hegemon are just the kind of setting where people have always been willing to give more open and democratic ways of life a try.
Maybe address the premise before going off on tangents about Nicaraguan or Filipino invasions of the Chinese mainland.
> What evidence do you have for that, as opposed to this alternative hypothesis:
Your hypothesis is a bunch of non-sequiturs.
The evidence is bare for all to see. Their behavior on the South China Sea mainly, but not only. ASEAN exists in great part to combat Chinese aggression.
The US hegemony was largely a result of a world devastated by WW2, it was never and should never have been seen as a permanent position.
Mind you, the other ASEAN countries need to do their part.
A military whose first line of defence is nuclear weapons is not a functioning military. I don't think you want what you say you want. We all wish the military were cheaper, but that doesn't mean it should be at any cost.
What's the relevance of this statement towards OP? Reducing nuke does not harm US' strategic supremacy at all. The current arsenal is plainly too much...
It's dead simple to reduce cost and still maintain the same strategic position.
But you know what, USA won't do it...
For example, what if China decided to invade Diego Garcia or Guam or some other strategic asset? Or even the Aleutian Islands? Would you really launch a retaliatory nuclear attack? Would you send John Kerry to the UN to wag his finger at the Chinese representative? Would you call the Chinese ambassador to the White House and tell him that you're very cross with his leaders?
Which is one thing the anti-nuke, give-peace-a-chance crowd has always been absolutely stupid about.
The entire idea of nuclear deterrence is predicated on continuously issuing as rabid statements as possible about your willingness to use nuclear weapons in retaliation for any strike (while simultaneously issuing statements that you never intend to use nukes as a first strike).
Whether you would or would not actually use them, in the emphasis of Strangelove, it is essential that your potential adversaries have no suspicions that you might not use them.
So any statements that don't sound like a madman with his or her finger on the button, just waiting for a chance to nuke the foreigners are actually incredibly dangerous and destabilizing (regardless of actual beliefs).
It also states that their device is symmetrical and so is equally efficient in either direction. My understanding is that, for optimal efficiency, a ducted propulsor should be narrower at the exit, but I guess there is no particular difficulty in making a rim-driven thruster of this form if its primary use is one-directional.
> "They called it a tunnel drive. You know how out West they have lots of hydroelectric power plants? Mostly dams. The water spills onto wheels that turn generators. Now there's a few new ones that kind of turn that around. They tap into underground rivers, and the water turns impellers, and they turn the generators instead of a modified mill wheel. An impeller is like a propeller, except the water drives it instead of the other way around. There's some minor technical differences, too, but nothing major. Okay so far? "With this design, you turn that around. You suck water in the bow and your impellers eject it out the stern, and that moves the ship." Tyler paused, frowning. "As I recall you have to have more than one per tunnel. They looked at this back in the early sixties and got to the model stage before dropping it. One of the things they discovered is that one impeller doesn't work as well as several. Some sort of back pressure thing. It was a new principle, something unexpected that cropped up. They ended up using four, I think, and it was supposed to look something like the compressor sets in a jet engine."
That said, this could be a similarly effective improvement to the submarine's acoustic signature and stealthiness.
Note also, misleading title. Supercavitation technology has been around for a long time, the Chinese have solved some of the technical issues regarding scaling up to full size Submarine and steering. Still no solution to range and many of the related issues. Also unlikely to be put into service any time soon.
https://qz.com/915110/china-wants-foreign-submarines-to-stop...
Active Sonar can detect the water void/material difference with reasonable accuracy.
U.S. sub streamlining and cavitation avoidance makes them nearly undetectable under running, much less full stop, and that's with a large prop rotating.
Also, magnetic fields don't self propagate, really. That means they fall off extremely quickly with distance unlike electromagnetic waves.
[0] https://en.m.wikipedia.org/wiki/Magnetic_anomaly_detector
Free space impedance is 377 Ohms/meter; the ratio of E/H fields. Seawater is much, much lower, but the ratio is still there. If there's a propagating H field, there is a corresponding E field; that's the law according to Maxwell.
The VLF antennas on the subs are trailing wires; electrically short dipoles. Those are mostly sensitive to E fields.
Nowhere to be found
This should allow you to access it from anywhere: