January 12, 2016

Thoughts About That Unexpectedly Underwhelming Blast

As we mentioned earlier, the North Korean government announced that they had successfully detonated a fusion warhead. Given the apparent small yield of the warhead, (6-10 kilotons) there has been considerable skepticism expressed. This skepticism is not unfounded especially given that getting such small yields are hard to get from what we normally think of as an H-bomb. There has been further speculation that the weapon is what is called a "boosted fission weapon". This does not get the majority of its explosive force from fusion, but it does set off a fusion reaction which causes the fission reaction to burn much more completely. This can as much as triple yields on fission warheads, or reduce the amount of fissionable material necessary for any given yield. This alone would be a big breakthrough as it would allow North Korea to make more bombs for the same amount of fissile material. An increase of 2 or 3 times the number of bombs in the arsenal is a very substantial benefit. 


Of course there is the problem of the very low yield. which has led many to conclude that this was a fizzle. That's possible, but the last three North Korean bombs have had very similar yields, in the 6-9 kiloton range. Small nuclear explosions are actually HARD. This was a problem the US had with the W-54 program, where some of the intended the applications (a bazooka!and short range AAM) called for a sub kiloton yield but the tests kept overshooting it. 

The North Korean's first test was very small and may well have been a fizzle, but the subsequent three have been very comparable in yields. Given the difficulties of getting a reliable nuclear yield below 10 kilotons this indicates extraordinarily consistent incompetence....or that it's by design.

It is possible that the North Koreans have had a string of fizzles, but this would mean that they thrice duplicated a design flaw that did not befall the Americans, Russians, Brits, Frenchmen, Chinese, Indians, Pakistanis South Africans* and (presumably)Israelis.

Furthermore, given that a good deal of this program is aimed at chest thumping and deterrence, it seems logical that the North Korean's, if they were experiencing difficulties with an implosion system, would, have at least one very simple gun type weapon like Little Boy. Such weapons are so reliable as to not strictly need testing, so a respectable 10-20 kiloton blast could have been had for propaganda purposes easily.
They have not done this, and after their first detonations their tests have been fairly consistent in yield. 

Doctor Jerry Pournelle has a discussion of this on his site...
There’s some speculation that this is an attempted enhanced EMP weapon. There’s other speculation. Add to that that I have never worked in weapon design, and the last time I seriously needed to know about the minutia of nuclear weapons was more than thirty years ago, and you will understand that I am not going to speculate. We know that North Korea tested something, and they call it a sophisticated fission weapon; what they tested was low yield, and the last time I looked, low yield was harder to do than higher yields: particularly lower than 10 kt....[/quote] 
Pournelle, caries on a discussion with Stephanie Osbourne (a retired rocket scientist who also worked on nuclear planning in the cold war) and they both reference, but do not link to speculation that this is fission boosted weapon designed to utilize the Compton Effect in conjunction with the Earth's magnetic field to produce a powerful electromagnetic pulse.

The Compton Effect

The yield of the tests is actually in the ballpark of the yields that are expected from a first generation EMP optimized nuke. Jerry Emanuelson, who appears to be an electrical engineer, has a very extensive page on what is publicly known about EMP optimization in nuclear weapons. This is part of his larger site on EMP in general. His conclusions seem to be quite consistent with those of Nigel Cook, a former physics professor who has a very heavily researched blog on the effects of nuclear weapons. Mr. Cook posted an extensive (to the point of rambling) post on this possibility after the North Korean tests and included patent data as well as multiple links. He has an earlier more general overview of the problem here.

Note that both sources indicate that this kind of small fusion assisted warhead could allow a 10 kiloton warhead to produce comparable EMP effects to a more conventional warhead in the megaton range (with the tradeoff that it would have to be detonated lower and therefore cover a smaller area). 

This tradeoff would double the number of weapons needed to blackout most of the U.S.A. and southern Canada.




"Well, maybe the Norks just want us to appreciate the night sky like they do."

This of course solves their targeting problems as the target area for this weapon is measured in states rather than meters. Additionally, it would make a small device of the type they can already deliver anywhere on earth (they can launch small satellites) an actual strategic threat. 

A total power failure involving hundreds of transformers blowing up (that requires replacement from France, Finland or China)  would take years to recover from. Add to that occasional widespread fires from overloaded wires and the collapse of the internet as well as the ancillary effects of no power, refrigeration, or heat and this could become a very bad thing. 

If this is in fact what the DPRK is doing (and we have little way of knowing)  it would be quite logical as it would give them a credible counter-value strategic capability that a few nukes, even very big ones would not provide. 

Fortunately, the North Koreans have modest goals (clinging to power by the throats of their citizenry, possibly conquering the south, and killing every Japanese male on earth) . While the regime is odious, it's not like they want to return the whole planet to the 6th century...like some people.

Amongst the ranks of THOSE PEOPLE naturally are included the Iranians, who are working very closely wth the DPRK in the advancement of SCIENCE as part of their general pattern of good behavior in the wake of the nuclear deal that solved everything. One probably ought to assume assume that much of the North Korean nuclear expertise is shared by Tehran now. 

  
Of course the notion that a nation using slave labor to put together a nuclear bomb might bollox it repeatedly should not be utterly dismissed, but the consistency of the yields and the potential payoffs, mean that this option ought to not be rejected out of hand.


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October 29, 2014

Not Really Effective, but Surprisingly Good

While looking for info on the Ukranian situation I blundered into this, 
 It's an interesting post on penetration tests that the Soviets did matching their 14.5mm anti-tank rifles against captured German tanks. 

 
First is a "heavy tank". I have no idea what it is, aside from that it's German. Here are the results with a 14.5 mm AT rifle:
  • Lower front plate (45 mm at 10 degrees): does not penetrate
  • Turret rear (28-30 mm at 10 degrees): penetrates at 200 meters, 100 meters at a 30 degree angle
  • Turret platform side (28-30 mm): penetrates at over 300 meters, 100 meters at a 30 degree angle
  • Lower hull side (28-30 mm): penetrates at over 400 meters, 100 meters at a 30 degree angle

This is a bit better than I would have thought. 

The performance against what are described as medium and light tanks is correspondingly better. I would not want to face these in a Panzer2 or even some modern APCs, and certainly not in a Humvee.

The"rifles" are beasts of course, with the lighter, single shot version weighing nearly 41 pounds and being 79 inches long. I suppose if one put a bayonet on one it would be a serviceable pike. These were obsolescent later in the war, but it is apparent that they were still quite effective weapons if used well.  I knew these guns were still in use around the world as antimaterial rifles, but the linked post gives a much greater appreciation of how fearsome they can be.






 "That just ain't right!".

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April 07, 2013

Asking the Important Questions




I did not realize they were so resilient.

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March 27, 2012

The Medicine Gun

I blundered into information on Meriwether Lewis's air rifle.

The gun is important to U.S. history because it served to deter attacks on the Lewis and Clarke expedition (they demonstrated it to the tribes they met...and implied that they had quite a few more than they did). It also reportedly took down a Grizzly bear at one point, though its unclear how many shots this took.

I had known vaguely about the Austrian use of repeating air guns, but I had not realized just how impressive their performance was.


It was equivalent to a .45ACP carbine, had 22 shots and carried enough air for ~30 shots in each flask! (There were generally three flasks per soldier) The flasks could be charged by hand with an ingenious pump the soldier carried with him (although it took 1500-1800 pumps to do so).

This is seriously impressive performance for 1790. Something like this would be a really cool survival gun today.

More here and info on the whole family of weapons can be found here here. The second link is particularly thorough and has this interesting tidbit as well.

Made in the 1940s during WW2, this gun doesn't look like a Girandoni, but examination shows that it clearly was built by someone familiar with the Girandoni repeating airgun system. Purchased in Europe, the story is that this gun was built somewhere in occupied Europe by a partisan bicycle maker during the Nazi occupation in WW2



Cool!

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February 17, 2011

TRANSFORMATIONAL!

This takes 'Optimal Manning' to a whole new level.


I'm sure nothing whatsoever can go wrong.


Nothing at all...

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August 08, 2009

At the Ship Shopping Bazzar

Over at The Marine Forum there is a very large collection of pictures from the 2008 Euronavale, a European defense contractor convention with a naval focus.

A few trends are visible, and others have commented upon some of them at length. The poster/photographer at MF was obviously drawn to the frontline ship offerings,  in the distance there seem to be a lot of OPVs and similar vessels.



This is understandable as such vessels are the most important vessels in most navies, doing the sort of gunboat tasks that often are ignored by many but are absolutely vital.

There are a lot of logistics and force projection vessels too, which ought to come as no surprise. There are many reasons for this, they are versatile vessels in everything short of a balls out war (The Boxing day Tsunami put the utility of such vessels in the spotlight)...and they can be useful auxiliaries in a major conflict as well.

Submarines seem to be particularly well represented, particularly interesting are small relatively cheap costal units like the Andrasta shown above. There seem to be a lot of Air Independant Propulsion designs as well



There are several export designs from US firms particularly LockMart which is not only offering yet another aegis equipped export version of their LCS (this time retaining the 57mm gun) but also an Aegis corvette that may be aimed at an Israeli requirement. Then there is this...

...The Chuck Norris of FACs...Yes...it appears to be a fast attack craft about 200-220 feet long that has a 5"62 caliber gun on its bow. This is an extreme example of what seems to be a mini trend, larger guns on surface vessels from corvettes on up. Even the French, are offering frigates with the US weapon.....

...and the Russians appear to be offering  100 and even 130mm guns on what appear to be some fairly small corvettes and frigates.


 ( the 3 furthest from the camera in the picture above). Such weapons are good for costal bombardment, but it may be that they are intended for close range antiship use as well. A few 100-130mm shells might well provde a mission kill on a corvette or smaller ship and lots more shells than missles can be carried.

The natural predator of the small costal surface warship is an aircraft but SAMs might make this untenable in some circumstances. So the guns may be a hedge as well as being potentially usefull against small boat swarms,

One other thing needs to be mentioned, though it is not a trend...behold the solar powered Offshore Patrol Vessel (with force projection capability!)


Anyway...discuss.

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July 14, 2009

A Fashionably Late Debutante

Although there have been cost overruns and delays, the second of the competing designs for the Litorral Combat Ship has started sea trials.

Over at Information Dissemination, Galrhan provides the world with the first pics of the sea trials of LCS-2, which will be named USS Independence.



It appears that Austal and General Dynamics have successfully weaponized 'bad ass'

Good grief that thing is maneuverable!

One of the reasons this ship has hit so many time and budget snags may be that it was designed by Aussies, who are the world leaders in the trimaran hull form it uses and aluminum-smithing. I have heard that there was a very steep learning curve for the US Yard in these areas. This is a riskier design and it pushes US shipbuilding to the limit, but I strongly suspect this design will be more stable at all speeds and most sea-states than the Locheed Martin designed LCS1. It ought to have more room for growth and be more fuel efficient too, all other things being equal (which they may well not be).

As always there is a highly informed and interesting discussion in the comments of this post over at Information Dissemination. If this sort of thing interests you, then you should be stopping by there every day.

UPDATE: Gahlran  has a bunch of gorgeous high res pictures of the trials.

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July 13, 2009

The Natural Preadator of the Submarine

January 29 2009 was a dark day for the US Navy.

On that date the last active squadron of S-3 Vikings, once one of the USN's  primary antisubmarine aircraft was retired. It does not currently have a replacement, which is a cause for some concern. This happens as the main surface ASW platform, the Oliver Hazard Perry class frigates are nearing the end of their useful lives. As the last of those go, the helicopters that operated off their decks go away. The Destroyers with helicopter assets are not very numerous and in any event as they are effectively combination battleships and anti air pickets..... and ABM platforms....are likely to be stretched thin with their other duties. This unhappy state of affairs coincides with an explosion of the number and effectiveness of diesel boats in the  worlds submarine forces.


Worse still, is the fact that the USN is saddled with a broken procurement system. Ships and even planes can now take years if not DECADES to reach operational capacity. This will take years to fix. Thus any replacement aircraft that are to be acquired quickly and cheaply must be more or less off the shelf, preferably Commercial off the shelf...unfortunately there just is no carrier capable aircraft sitting on a shelf right now.

Topping off this perfect storm of grief is the current financial crisis which is only going to get worse in the near term and the horrific debt the US has incured in the last few months that threatens to bankrupt us...thus any replacement MUST be relatively cheap.


It would be unwise to postpone such a program.
The Second World War experiences of the US and Britain in the Atlantic and Japan in the Pacific demonstrated the price a nation can face when antisubmarine warfare is put on the back burner. Japan did not survive. Its ASW was an afterthought and the island nation was cut off from supplies of both food and industrial materials. Its navy instead put a huge ammount of their maritime industrial bandwidth into building comparitively small numbers of huge, expensive ships that were designed to be qualitatively superior to their foes....and which now litter the Pacific seafloor.


The US and the UK did beat the submarine menace in no small part because at the UK's urging the United States built over 100 escort carriers thanks to its massive industrial capacity...a capacity that has deteriorated. Now to a large extent such capacity exists only in....China.

That is, therefore, a lesson that is non-applicable in the short term.

There was one other interesting and generally unsung weapon that was unique to the USN in WW2. It may fit the requirements of cheap, off the shelf and effective airborne antisubmarine assets.

Dirigibles like the K class airship were astonishingly effective.

USS K-2 gets ready to kick DasBooty



Equipped with sonabuoys, radar, magnetic anomaly detectors, depth charges, and bombs, these little ships became one of the U-Boat commanders worst nightmares. They were actually much smaller than was thought necessary but they still had an endurance of a day and a half at ~60 kts and could hover to boot. There utility can be measured by the fact that not a single merchant vessel escorted by a U-Boat was lost to enemy action during the war.
After the war airships of improved types served as antisubmarine craft, and, increasingly, in the airborne early warning role. In the early 1960's, as part of a larger overall policy of making bad descisions, Robert MacNamera oversaw the dismantling of the Navy airship program. A few years later, it was discovered that hovering and being able to dunk sonars were very useful ASW traits and helicopters were pressed into service as ASW platforms.

Now the lack of any naval blimps today might make one think that there is no way to get this off the shelf. That is not necessarily the case.

The Viking, the plane we want to replace has a payload of about 4,000 pounds of ordinance.


The Zeppelin NT, a rigid airship has a useful payload of about 4100 pounds, so we are in the ballpark. Note though that sensors, like a good radar and a magnetic anomaly detection boom will eat into this, not to mention crew quarters.

 The Sentinel 1000 was originally designed with the Navy in mind. It has a payload of 6,000 pounds which allows a bit more leeway in installing sensors.


Endurance of most off the shelf designs  would be low, between 12 hours and two days , but they would have far more loiter time than a helicopter or even the Viking they replace. They could replenish at sea vertically like a helicopter to extend their range.  Larger airships could be developed incrementally with lessons learned and applied in small construction batches. All of these are smaller than the frontline airships the Navy was operating in the 1950's, so in a few years we could incrementally build up at least to that capability.

Airships are not perfect. Because of their large sail area they have difficulty handling typhoons, or hurricanes  and they tend to react badly to nuclear ordinance...

Yes, we nuked a blimp...because...well, we just HAD to know.
Click here for supahsize

...but as a quick and dirty solution to ASW aircraft they do seem to have some promise.

This post would not be complete without a brief mention of Aereons, hybrid airships and other developments of the airship concept that promise far greater performance...and have been promising since the early sixties....but have gotten no results. Military Airships is a very comprehensive site dedicated to these craft and Darrell Campbell is quite an ardent and eloquent proponent of their capabilities. His arguments are valid up to a point, namely that the hybrid airship he advocates have vastly greater potential than regular blimps. Specifically these designs combine a lifting body airframe and modern materials to greatly increase performance. However, while the tech is not unsound, it only works on very large ships and, more importantly it is, not mature technology. It will require considerable integration efforts as well as trial and error. These take time and money that we don't have. Rather than letting the best be the enemy of the good, it seems prudent to me to go with what we have and develop the ideal capability through trial and error.

There are many promising technologies that might aid us in hunting submarines, USV swarms, or small craft with dipping sonars using sprint and drift tactics for instance. But the good old blimp is here now, has a proven track record and might be had rather economically. It certainly warrants a look.


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June 09, 2009

The Wreck of HMS Victoria

When commissioned in 1890, HMS Victoria was one of the most powerful ships in the world. A test bed for several new technologies she nevertheless represented in some ways a technological and tactical dead end being intended to fight end on with an eye towards ramming. To that end her main armament was concentrated forward and consisted of two huge experimental 16.25 inch guns in a massive armored Coles turret.  There was also a very heavy secondary armament of 6 inch and smaller weapons as well as some torpedo tubes. Finally there was a massive armored ram below the waterline. All that armor and armament forward on a 10,000 ton ship meant that freeboard was low at the bow and the ship was considered best suited to the Mediterranean squadron. She was very well equipped as a flagship however and as such bore Admiral George Tryon's flag on 22 June 1893 when, off the coast of Syria, the Mediterranean fleet was engaged in maneuvers.


  A miscommunication via signal flags resulted in the battleship HMS Camperdown ending up on a collision course with Victoria. The Helmsmen of both vessels waited to get permission to change course, by which time it was too late to avoid a collision and Camperdowns fearsome ram pierced Victorias bow. Damage control efforts were hampered in part by Watertight hatches that were unable to be fully dogged due to paint and rust as well as bulkheads being pierced for ventilation and wiring. HMS Victoria sank in 13 minutes with the loss of 358 men including Admiral Tryon.

The Wreck  has now been found 500 feet beneath the Mediterranean.



Its in surprisingly good shape.

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May 03, 2009

This is a Destroyer

A Japanese destroyer.
There is no such thing as a Japanese aircraft carrier...


Nope nosirree .

Nothing to see here move along.

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