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Virtual Earth Exposes Nuclear Sub's Secret
NewsCloud alerts us to a story a few months old that has been getting a lot of play recently. A Seattle blogger, Dan Twohig, was browsing in Microsoft's Virtual Earth when he accidentally came across a photo of a nuclear sub in dry-dock. Its propeller is clearly visible — this was a major no-no on the part of someone at the Bangor Sub Base. The designs of such stealth propellers have been secret for decades. Twohig blogged about the find and linked to the Virtual Earth photo on July 2. The debate about security vs. Net-accessible aerial photography has been building ever since. The story was picked up on military.china.com on Aug. 17 — poetic justice for the Chinese sub photo that had embarrassed them a month before. On Aug. 20 the Navy Times published the article that most mainstream media have picked up in their more recent coverage. Twohig's blog is the best source to follow the ongoing debate. No one has asked Microsoft, Google, or anyone else to blur the photo in question. Kind of late now.
Hmm, do you believe that having subs means needing a big surface fleet to protect them? The US has a big navy because they have a need to be everywhere at once. Some places the US likes to get involved lack any friendly air bases so they need carrier groups. China has no need to try to match the US Navy, just as the US has no need to match the size of the Chinese Army. Additionally, any intelligence of value on current US sub programs is already in Moscow and Beijing: history has shown how simple it is to buy information in a debt driven economy.
Why three?
I am not a fluid dynamicist. But: To increase thrust at a certain RPM, it seems that you can either (1) increase the diameter of the propeller, or (2) increase the number of blades. The problem with increasing the diameter is that the velocity at the tips increases, which leads to effects like cavitation (which, besides being very noisy, damages propellers). So what you do is increase the number of blades.
Prop-driven airplanes produced near the end of WWII had many-blade propellers for this reason as well: They wanted a lot of thrust, but, if they made the blades any longer, then the tips would have been supersonic. (I think I got this factoid from the History Channel.)
My guess is that a quiet high-thrust propeller would spin slowly and have many, very wide and heavily-curved blades. Let's see if somebody who knows more agrees.
Your proliferation of this information, shameless and most likely premeditated, cannot but argue for an immediate and thorough dismantling of this abomination that is the Internet.
Clearly, the citizenry's desire to be on equal terms with its rightfully appointed overseers is misguided.
What could compare to the danger of such leaks? Only, perhaps, ability of the governed to guide the acts of the governors. (But, thank God and all that is holy, we need not contend with such a possibility.)
The proper solution to this satellite photo disaster is to establish government and international bodies, whose responsibility will be to oversee the propagation of information in its early stages. Press organizations, and other legitimately licensed speaking entities, could submit all reports and articles for government approval before publication, and thus dangerous knowledge would be stopped in its tracks. All information emanating from government bodies would be confidential by default, enforced by penalties befitting treason.
It is indeed a distant dream -- such a beautiful system of bureaucratic power and unquestionable hierarchy -- yet we must do what we can to stop out-of-control communication amongst the proletariat from further endangering the established, and righteous, distribution of power.
The secret bit of these propellors is what materials they are made of, how precisely they curve, and to what tolerance they are engineered. The big problem with propellors is that they tend to suffer from cavitation at high speed, where the sudden change in pressure causes bubbles to form and collapse. Apart from being rather noisy, referred to as "singing" (which is a bad thing for a stealthy submarine trying to make a fast getaway) it also causees damage to the blades (much like desert sand on engine turbine blades).
The purpose of having an odd number of blades is no secret - it is to reduce vibration. As the submarine travels through the water it leaves a wake behind it. Above the submarine there is less water pressure than below - so having two blades above and below at the same time is a bad thing. The more blades, the less vibration, but propellors are more efficient with fewer blades. You will see speedboat propellors with three or four blades, and fishing boats can have propellors with only two blades.
There is also the problem that having different metals in close proximity in a salt water environment, can lead to an electrolysis effect where the metals and water act as a kind of battery. Lots of technical papers on Propellor design
"The most frequent cure for a singing propeller is the popular "anti-singing edge". This is a chamfer applied to the trailing-edge to promote separation of the vortices."
Vintage computer adverts: http://www.vintageadbrowser.com/computers-and-software-ads
I have a friend who has a habit of repeating what was just said using slightly different language. Tell me, do you smoke way too much pot and work at Pizza Hut?
I suppose the Russians will now go for eight fucking blades and an aloe lubrastrip?
AT&ROFLMAO
"In a war against a major enemy, carriers will probably be useless..."
And where did that factoid come from? One would imagine that a ship with the capability to strike at extremely long distances is always useful, if you can hit your enemy before their weapons can reach you you have an advantage. As for carriers being vulnerable to subs that's only partially true. Certain types of submarines, especially advanced nuclear subs (and diesel ones, so long as they don't surface anywhere near the carrier group and have enough battery power to get in and out) could conceivably slip through the defenses around a carrier and then it's aircraft would be useless. Given that the last major (that I know of) engagement between large groups of submarines and carriers was WWII, and that was clearly decided in favor of the carrier groups (53 u-boats sunk to less than 10 of the CVE mini-carriers) I'd say a generalization like 'Subs counter carriers' is kinda...wrong. A carrier battle group at war would typically have at least 1 radar plane (Orion?) on CAP. If the sub surfaces nearby radar has a chance of picking it up. In addition the carrier's escorts have darn good sonar and wouldn't be too hesitant to use it.
So basically, 1 lone carrier vs sub is an easy win for the sub, unless the carrier sees it coming from a long way off and launches anti-sub efforts. 1 carrier battlegroup is at least a match for any similar number of warships, including subs, and very good at other tasks such as beach assault, long range support etc. A carrier battle group is currently the most versatile type of navy imaginable, as such it may not be the best way to counter all threats (a pair of destroyers working in tandem with some anti-sub helicopters would be cheaper and pretty effective against small numbers of subs). It's a Jack of All Trades, master of none type of thing, a Carrier group is good at anti-surface ship, anti-sub, and anti-land combat.
Sneaking up on a ship which is fully prepared for war is a lot harder than some things would lead you to believe. Just because you're underwater and pretty quiet doesn't mean your undetectable, and if you're too quiet you can be detected that way (one possibly problem with modern US subs is that they're actually quieter than the surrounding ocean and could *conceivably* be detected that way). No amount of noise-reduction is going to save you if even 1 enemy ship is using active-sonar, you're going to be detected unless it's a cloak-and-dagger fight which is something aircraft carriers rarely engage in, they're more 'Hey look, I'm right here, I don't need to hide because I'm that much better than you' style fighting, and in that arena (when radars are at full and sonars are active) subs lose all stealth benefits, and an unstealthed sub vs a carrier group is just asking for trouble.
So to sum it up, no, a carrier battle group is not useless. Subs are easily countered (unless you're trying to be stealthy as well) and missile blocking is what Aegis (common in CBG's) class destroyers were partially built for. Aircraft carriers are built for show, and are good against weaker enemies, but also against equals, it's against stronger enemies (few and far between at this moment) that they begin to look impossibly weak and fragile.
There are two kinds of fool One says 'This is old therefore good' Another says 'This is new therefore better'- Dean Ing
Still, the German Navy almost defeated them with their much more effective submarines.
The German U-boat fleet rarely engaged the Royal Navy. And with the occasional exception, when they did this, they were sunk. The U-boats were used as commerce raiders, and had great success. For a year or so. Now please look up the statistics on how many u-boats actually survived the war, and talk to me about "success". It was a disaster, like almost everything else Germany did after taking France.
Seven puppies were harmed during the making of this post.
(Obligatory disclaimer but without the obligatory tortured acronym: Yes, I am a former submariner (and have been to the Delta Pier many times), and am a student of naval history and related security issues.)
The props haven't been as jealously gaurded recently as in times past - in fact, I saw pictures openly published of them as early as the late 1990's. Though the less knowledgeable may drool over seeing them at all - the pictures on Virtual Earth are not particularly high res, nor particularly useful. The fact that the US uses scythe blade propellers has been openly acknowledged since the early 90's.
Or, to put it even more simply, these pictures show nothing not already publically known and acknowledged.
Ditto for the weapons magazines - there is nothing classified about the exteriors, existence, or location.
This article is however a interesting point on the problem of getting your news from blogs; sometimes the author knows what he's talking about. Usually, when it comes to specialized topics, he doesn't.
I wonder if Microsoft Visual Earth has been getting their data from Setec Astronomy??
Google says you're not the first, but what the hell...
That's almost precisely backwards. These submarines exist to ensure that never happens. They're part of the Mutually Assured Destruction balance. Neither side is going to launch a first strike unless it knows with absolute certainty that it's going to come out sufficiently ahead in the ensuing trade-off to survive as a viable state. Nuclear subs completely screw with any certainty you might think you've got in launching that attack, because it's damn near impossible to know that you'll be able to kill enough of the opposition's subs before they can launch. Stealthy propellers are a big part of that, helping to ensure that the enemy can't get and keep a lock on your position. These submarines aren't designed as first-strike weapons, but as an assured second-strike. To say that this technology cannot be used completely misses the point. In just existing, they are being used - as an insurance policy. If they were ever to launch, humanity would already be dead.
Reality is the ultimate Rorschach.