VLS Underway Replenishment: When will the Navy get serious?

[buglerbilly]

by Craig Hooper
Defense Tech Naval Warfare Analyst

In a high-threat environment, the Navy’s AEGIS vessels have a problem. They cannot be re-armed. AEGIS cruisers have 122 vertical launch system (VLS) cells, while the destroyers have 96. Each magazine is “multi-use,” composed of specialized land attack and self-defense weapons, so a desired missile may not be available in sufficient numbers. Complicating matters, AEGIS vessels sometimes sail with a partially-filled magazines, and missile reliability rates aren’t often anywhere near 100%.

CSBA expert Jan Van Tol, in his recent AirSea Battle monograph (.pdf), is the latest to highlight this vulnerability, and pointedly suggests that, given the way high-end warfare is likely to be waged, “the Navy should continue its efforts to develop and field the capability to rearm surface ship VLS cells at sea.”

But…what efforts? VLS underway replenishment (UNREP) has been a long-standing—and long-ignored– vulnerability. Take this editorial snippet from a Fall 1988 issue of the long-unheralded UNREP Journal:

“In wartime the enemy decides when and where we expend defensive ammo, so an ammo UNREP may be needed any time, even when the seas are rough or the decks are icy. While we may be able to rearm our aircraft carriers under these conditions, our ability to handle missiles in dollies or in VLS canisters on cruisers, destroyers, and frigates is extremely poor.

The magnitude of the missile handling problem has been minimized over the past 25 years because of a lack of a missile war and the infrequent missile UNREPs to cruisers, destroyers and frigates. We do transfer stores in peacetime that have to be deck handled, but our peacetime UNREP policy is “safety first”, so we can wait for seas to abate and the ice to melt. As a result, a serious ammo UNREP problem has not had much visibility.

The U.S. Navy had an answer in the 1960’s to transferring and striking down missiles in heavy weather or even with icy decks. It was called FAST for Fast Automatic Shuttle Transfer. FAST demonstrated a transfer/strikedown rate of 24 TARTAR missiles per hour at night in sea state six conditions (compared to four VLS missiles per hour now in daytime and calm seas). While we can still transfer missiles between ships at a high rate, deck handling, and strikedown are the limiting factors. Deck handling was solved by FAST because missiles were automatically moved from the UNREP station to the magazine strikedown without sailors having to push-pull dollies or hand trucks. However, the complexities of the automated FAST handling equipment created an unacceptable maintenance burden on both the UNREP and combatant ships because FAST required the services of shipboard technicians that were either not available or were needed to maintain the ship’s missile launchers. As a result, FAST wouldn’t work when needed nor perform as planned. FAST had to be simplified in the 1970’s to our current STREAM system.

What should be done today about rearming missiles? The right missile handling system must be superior to what we have today, but not nearly so complicated as FAST. The right system must be highly reliable so as to withstand long periods of disuse and still work when needed. The right system must be simple in design so that no extensive specialized training is required for the crew. The right system must be able to safely handle missiles in heavy weather and on icy decks.…

…There are some who say that UNREP of missiles is too hard and, therefore, the requirement should be eliminated; however, the recent missile firing experience by U.S. ships in the Persian Gulf should alert us to the future.…When the going gets tough a great amount of ammo will be expended in a short time. The next urgent requirement is to quickly reload those empty magazines and be ready for whatever follows. Underway replenishment is the only answer for the fleet commander and we need to do it better.”

This passage was written almost a year BEFORE the USS Arleigh Burke (DDG 51) was even launched. So, it’s safe to say that AEGIS vessels have not been designed with missile UNREP in mind—and, yet, they’ve done just fine.

But today, given the anticipated growth in demand for VLS cells, is it time to start considering the need for rapid VLS UNREP? Is there a way to design VLS cells (and VLS-dependent ships) to facilitate fast underway replenishment of depleted missile batteries?

With the restart of the DDG-51 program, this is something the Navy community must discuss. Now that America has gone a couple generations without incorporating ease of missile UNREP in warship design, has the Navy simply overlooked the possibility of designing missile ships so they can quickly be replenished?

Read more: http://defensetech.org/2010/06/10/vls-underway-replenishment-when-will-the-navy-get-serious/#more-7603#ixzz0qbBdcFWb
Defense.org

[JimWH]

The reason that there hasn't been serious investment in an underway replenishment system for VLS is actually blindingly obvious, there really isn't a need. Back in the tail end of the Cold War I'll grant that there was the was the remote possibility that Aegis cruisers could run through their magazines in the event of having to face off against sustained and repeated regimental scale attacks by Soviet naval aviation.... but since then? Even the PRC, at their most threatening, wouldn't have enough ASM/SSM to saturate one DESRONs* let alone the 3-4 DESRONs which might be reasonably expected to be pulled in for any serious conflict involving the PRC. Hell, in the late 80s there weren't all that many VLS equipped escorts, on current plans the USN is going to have 90 by the end of this decade with over 9,000 VLS cells between them.
Basically, there isn't a realistic threat which really necessitates the need for the USN to have a VLS UNREP capability, a point which tends to be ignored by the 'analysts' who wail and gnash their teeth regarding the lack of such a system.
We, however, might actually be in greater need of the ability to UNREP missiles at sea given the planned introduction of TLAM onto the AWD, though realistically I'm again not convinced that the threat environment they'll operate in will really necessitate a VLS UNREP system (realistically we're not going to send an AWD into serious harms ways outside of a coalition scenario). I'd be far happier to simply go with an instillation of some additional self-defence VLS cells aft to make more strike-length cells available forward.

*e.g. the standard 3-4 Aegis equipped escorts of a carrier: 1-2 Tico, 2 Burke, a total of 314 to 436 VLS cells. Bear in mind that a significant fraction of those cells will be quad packed with ESSM

[Milne Bay]

The reason that there hasn't been serious investment in an underway replenishment system for VLS is actually blindingly obvious, there really isn't a need. Back in the tail end of the Cold War I'll grant that there was the was the remote possibility that Aegis cruisers could run through their magazines in the event of having to face off against sustained and repeated regimental scale attacks by Soviet naval aviation.... but since then? Even the PRC, at their most threatening, wouldn't have enough ASM/SSM to saturate one DESRONs* let alone the 3-4 DESRONs which might be reasonably expected to be pulled in for any serious conflict involving the PRC. Hell, in the late 80s there weren't all that many VLS equipped escorts, on current plans the USN is going to have 90 by the end of this decade with over 9,000 VLS cells between them.
Basically, there isn't a realistic threat which really necessitates the need for the USN to have a VLS UNREP capability, a point which tends to be ignored by the 'analysts' who wail and gnash their teeth regarding the lack of such a system.
We, however, might actually be in greater need of the ability to UNREP missiles at sea given the planned introduction of TLAM onto the AWD, though realistically I'm again not convinced that the threat environment they'll operate in will really necessitate a VLS UNREP system (realistically we're not going to send an AWD into serious harms ways outside of a coalition scenario). I'd be far happier to simply go with an instillation of some additional self-defence VLS cells aft to make more strike-length cells available forward.

*e.g. the standard 3-4 Aegis equipped escorts of a carrier: 1-2 Tico, 2 Burke, a total of 314 to 436 VLS cells. Bear in mind that a significant fraction of those cells will be quad packed with ESSM

You are right Jim in relation to a single attack.
How do the figures stack up to a couple of attacks per day for a week or more?

[JimWH]

You are right Jim in relation to a single attack.
How do the figures stack up to a couple of attacks per day for a week or more?

And just how many ASM do you suppose the PRC actually has in stock? That's a serious question by the way, I'm not being facetious, how many war-shots do you suppose the PRC (or any other likely adversary) actually has ready to go in a short space of time? I'm guessing enough for no more than half a dozen sorties by their front-line anti-shipping aircraft. The days of existential industrial warfare where over about 2 decades ago, which makes it highly unlikely (IMHO) that many adversaries actually have more than a strictly limited arsenal of front-line ASMs.
Which fits with the crux of my argument: even if USN escorts had to deal with the PLAAF and PLAN-AF without carrier based or land based fighter providing top-cover (spot what is unlikely about the scenario I've just outlined...) I very much doubt that the PRC would actually have enough ASM is stock to actually saturate USN escorts in theatre.

[Milne Bay]

And just how many ASM do you suppose the PRC actually has in stock? That's a serious question by the way, I'm not being facetious, how many war-shots do you suppose the PRC (or any other likely adversary) actually has ready to go in a short space of time? I'm guessing enough for no more than half a dozen sorties by their front-line anti-shipping aircraft. The days of existential industrial warfare where over about 2 decades ago, which makes it highly unlikely (IMHO) that many adversaries actually have more than a strictly limited arsenal of front-line ASMs.
Which fits with the crux of my argument: even if USN escorts had to deal with the PLAAF and PLAN-AF without carrier based or land based fighter providing top-cover (spot what is unlikely about the scenario I've just outlined...) I very much doubt that the PRC would actually have enough ASM is stock to actually saturate USN escorts in theatre.

Good point.
Remember attacks don't have to be with front-line ASM's.
Any old thing will do.
Mount any kind of aerial attack and it will be met with whatever is in the VLS.
Knowing that there are a finite number means that all any adversary has to do is count.
Proceed with an attack on virtually undefended ships when the magazines are empty.
Just thinking out loud here.
MB

[JimWH]

And like I said, in the case of the USN, in order to first even get anywhere near the escorts, you first have to get through the air cover, which includes both bloody good fighters and bloody good AEW. Then the launching aircraft needs to avoid being taken out by long-range SM-6 shots (cued by the AEW or by the ship itself), and then it can launch its ASM. But if those ASM are determined to be severely old-school (which is done by ESM automatically in the first couple of seconds) then the ship can go to Plan B: ECM and decoys and CIWS, which should be more than adequate to deal with said old-school ASM if there is a need to conserve SAMs.
But will there really be a need to conserve SAMs? On any Aegis ship if you chuck over 16 VLS cells to ESSM (leaving ~70-100 cells left over per ship for SM-2/3/6, TLAM, and VL-ASROC) then each ship goes in with 64 odd SAMs perfectly able to engage incoming ASM before they start their terminal maneuvers. ESSM should have a pK in the territory of 0.9+, which means that if you decide to engage each incoming ASM with a single ESSM (leaving the SM-2/6 solely for long range intercepts) then you should be able to get around 57 or so ASM leaving the remainder to Plan B (ECM, decoys, and CIWS). And bearing in mind that each DESRON has 3-4 AEGIS ships, you're talking about engaging and destroying 150-200 incoming ASM using at most 15% of the available VLS cells.
If this is a numbers game, then I'd back the USN even with the PRC throwing everything it has at the problem. Pity help any nation smaller than the PRC.

[Milne Bay]

Still thinking out loud here.
OK if I was a potential enemy and presumably knew all these facts as you have presented them, then I would ask myself this question:
How can I make old school look like front-line ASM's to the ESM.
If this can be done then the anticipated response that I am looking for can be triggered.
Potential enemies don't have to be dumb, they may be inventive.

[JimWH]

Might I suggest that you're basically doodling in the margins Milne Bay? Initiating upgrades of old ASMs to make them look modern to USN ESM is a big undertaking and whilst potentially possible*, it still doesn't really answer the question of how many old ASM are lying around and how likely it is that an attacking aircraft is going to get within firing range. Like I said: AEW (carrier or land based, or both), CAP (carrier or land based, or both), and SM-6 (cued by AEW or ship based sensors [remember CEC]). Getting through that in order to be in a position to fire ASM in the first place is a big ask, and doing so in large enough numbers that you're able to cause meaningful attrition of the available SAMs (let alone saturation) strikes me as nigh on impossible.


*Though recall that there is nothing stopping the USN from working on their own discriminating ESM algorithms, or meshing CEC acquired radar data with the ESM picture in order to make a decision about whether the target 'feels' right. Initiating an upgrade program is the type of thing that'd get the US's attention, and if we're presuming that hostile nations aren't stupid we should probably apply the same logic to the US.

[Milne Bay]

Might I suggest that you're basically doodling in the margins Milne Bay? Initiating upgrades of old ASMs to make them look modern to USN ESM is a big undertaking and whilst potentially possible*, it still doesn't really answer the question of how many old ASM are lying around and how likely it is that an attacking aircraft is going to get within firing range. Like I said: AEW (carrier or land based, or both), CAP (carrier or land based, or both), and SM-6 (cued by AEW or ship based sensors [remember CEC]). Getting through that in order to be in a position to fire ASM in the first place is a big ask, and doing so in large enough numbers that you're able to cause meaningful attrition of the available SAMs (let alone saturation) strikes me as nigh on impossible.


*Though recall that there is nothing stopping the USN from working on their own discriminating ESM algorithms, or meshing CEC acquired radar data with the ESM picture in order to make a decision about whether the target 'feels' right. Initiating an upgrade program is the type of thing that'd get the US's attention, and if we're presuming that hostile nations aren't stupid we should probably apply the same logic to the US.

Well of course.
Doodling in the margins is what we all do on this forum.
Still, coming up with a scenario that would enable penetration of a CBG's air defences must have been seriously considered by others.
I'm sure that my doodling has raised nothing original.
It still seems to me that ignoring the possibility of VLS re-supply at sea, is a recipe for future regret.
I have always thought that our own RAN frigates face similar problems with their limited loadout of missiles and lack of CIWS.

[JimWH]

I don't think it's necessarily a case of ignoring the possibility, so much as not putting resources into the problem at a time when the capability isn't needed. Given the magnitude of the problem facing potential adversaries (and the lead-time that'd be required to rectify such problems) I'd hazard that the USN has made the right decision.

WRT to the RAN, you'll note that I did make this point above, but against this one must question what messes we're actually like to get into that we'll run through the ESSM magazine aboard the Anzacs let alone aboard the AWD. I also live in hope that the VLS nest aboard the Anzac replacements will be quite a bit larger.
However, the question of replenishing VLSs in theatre is a not unreasonable one for Australia to consider. One thought I toyed with a while ago was the idea of a rapidly transportable (i.e. C-17 sized) crane for the purpose. As is (AFAIK) the major rate limiting step is that the missile canister is free swinging, and has to be made to match the ship motion by handling parties on deck, and to me it seems that this is the part which could most benefit from a technological fix. If you used highly accurate sensors (LIDAR would be my choice) to determine the position and acceleration of the ship deck relative to the crane, and similarly accurate servos to control the motion of the missile canister, you'd be able to speed up the loading of the missile canisters by aligning them to the VLS prior to (essentially) dropping them into place. Of course there'd be limitations on the relative motion (which is the reason I can only imagine it being used from a dock rather than whilst underway), but I could imagine it really speeding up an in-theatre pit-stop.

[Chunder]

From a design point of view, you'd probably rather transfer through a dynamic load transfer system & actually leave the reloading to a mechanism on board the ship itself. At least underway.... Ive never seen a reloading system operate outside of relative static equilibrium... But no doubt there is one somewhere...

Even if that reloading mechanism of that ship is transferred by crane onto the ship... for the purpose.Otherwise looks like your on your way to some pretty expensive (& high tech) ballarina gizmodo there Jim.

[Chunder]

Was thinking about the above a bit more overnight about the above & the application of tech from other fields.

Before GPS (and I think they still have them) passenger aircraft had a navigational system which measured external & internal inputs to the aircraft (I think including beacon inputs). So a flight from Heathrow to JFK would result in about a 5-7nm offset overall. Which is pretty damned good. But it's advantage is that it only has to compute forces & resultant effects on one body instead of two (of different mass), whilst accounting for effects of these on a third body. Has a certain wow factor behind it if someone had the brains to pull it off/already has. The more I think about it the more the original line of thinking about stock replenishment seems to make sence.

[JimWH]

That's inertial navigation you're describing Chunder, though I can't really see the point in this instance.
My thought was using realtime measurements of the position and acceleration of the deck to tell you where the deck will be in a fraction of a second time. If you feed that measurement back to the crane, you can then use servo actuators to align the missile canister the the position and orientation of the VLS cell it needs to fit into, which will then allow you to get the missile canister to just above the deck and then rapidly lower it in. This is as compared to doing it by hand, which requires a team of blokes to manhandle the missile canister so that it aligns into the VLS cell, and then slowly lower it in (whilst maintaining the correct orientation.

Of course, having said all that, all a rapid shore-side reloading mechanism will really do is lower the time it takes to reload a ship from 1-2 days to a few hours, which is actually unlikely to really alter the amount of time the ship spends in port. At best it'd free up people to work on other tasks during a rapid pit-stop.

[Weasel]

That's inertial navigation you're describing Chunder, though I can't really see the point in this instance.
My thought was using realtime measurements of the position and acceleration of the deck to tell you where the deck will be in a fraction of a second time. If you feed that measurement back to the crane, you can then use servo actuators to align the missile canister the the position and orientation of the VLS cell it needs to fit into, which will then allow you to get the missile canister to just above the deck and then rapidly lower it in. This is as compared to doing it by hand, which requires a team of blokes to manhandle the missile canister so that it aligns into the VLS cell, and then slowly lower it in (whilst maintaining the correct orientation.

Of course, having said all that, all a rapid shore-side reloading mechanism will really do is lower the time it takes to reload a ship from 1-2 days to a few hours, which is actually unlikely to really alter the amount of time the ship spends in port. At best it'd free up people to work on other tasks during a rapid pit-stop.
(Polite clearing of throat) If you were going to recharge VLS canisters at sea, I think it would be a wise course to deep six the crane concept. It is dangerous.

I would put forward that CH-47s have been used successfully to offload containerized cargo from a LOLO vessel. It is a different game to load a vessel though.

So given the above a derrigible might be the ticket. It could land on the VLS and use its buoyancy to both stabilize the canister so it could be slotted in (like a a crane) and that same buoyancy will keep the deck loading within acceptable margins.

cheers

w

[JimWH]

Wasn't thinking of reloading at sea Weasel. On reply #10 I speculated about using a robotic crane (for lack of a better word) rapidly deployed to the nearest port facility to provide the ability to rapidly reload VLS whilst the escort stays in-theatre. Trying to calculate the relative position of two mobile structures gets too complicated in terms of predicting future position, and quite besides, the stability of a ruddy great huge crane hanging over the side of a ship in motion (i.e. at sea) fills me with more than a little fear. I'd agree that a robotic crane deployed at sea would be dangerous.
Though the idea of a lighter than air vessel, (and the last month spent in orthopaedics) does give me an idea. What if you used removable jig? I'm going to have difficulty explaining it, but here goes:
It's easier to accurately position on deck a canister moved across from the UNREP vessel (by VERTREP of derrick) if the canister is horizontal rather than vertical. If you lowered the missile canister onto a jig with a tray which could then be swing up through 90-degrees then the process of slotting the missile canister into the VLS cell becomes relatively straight forward and comparatively easy (since the canister's motion is fixed with relation to the ship). The real trick would be doing it with a jig that was light enough to be carried over to the escort by VERTREP and adjustable so that it could fit more than one ship/VLS position. The available deck space may also be a problem (i.e. you need to find enough space to lay down a canister which is ~7m long).

[Zen9]

If I was designing a ship to replenish VLS at sea, I'd probably look at a system for moving the silos inside the ship out of the array and then moving a fresh silo into its place. This would require a very different design of vessel and arrays of silos. In some ways a distributed set of silos might be easier than a single large block as you'd need to be able to access all the silos not just those on the edge of the array.

Would require a slightly larger ship I suspect, but it is mainly space being added.

However each silo would still have be moved from the replenishment ship to the warship and then empty silo's returned in a similar manner.

[ADMk2]

If I was designing a ship to replenish VLS at sea, I'd probably look at a system for moving the silos inside the ship out of the array and then moving a fresh silo into its place. This would require a very different design of vessel and arrays of silos. In some ways a distributed set of silos might be easier than a single large block as you'd need to be able to access all the silos not just those on the edge of the array.

Would require a slightly larger ship I suspect, but it is mainly space being added.

However each silo would still have be moved from the replenishment ship to the warship and then empty silo's returned in a similar manner.

Breech-loading missile cells, eh?

[Deks]

I think ideally you'd want to automate the process as much as possible. I'm assuming that to replenish a cell, you'd first have to remove the empty box and then replace the empty space with a new container, presumably with some associated connecting/disconnecting of control cables.

Given this, ideally you'd want whatever you're using to be able to do both I'd suppose. You'd want it secured to the deck so that it's movement is in sync with the ship itself, though I suppose you'd also want to ensure it isn't going to put the ship off balance when in use. I propose a sort of floating dock, a catamaran with a high arch that the ship would basically sail into and then be latched on by. To make it easier, it would need to have some sort of storage for the containers themselves or you're back to doing replacement via helicopter.

It would have the ability to 'swing' the containers around from a horizontal storage position to a vertical for insertion into the ship. Weight would most likely be an issue, not sure what the solution is. Perhaps the 'dock' sails some tens of meters off the side of a supply ship, and the containers are supplied / returned via some kind of conveyor ?

In any case, just thinking aloud. Feel free to destroy the idea :)

[Weasel]

Wasn't thinking of reloading at sea Weasel. On reply #10 I speculated about using a robotic crane (for lack of a better word) rapidly deployed to the nearest port facility to provide the ability to rapidly reload VLS whilst the escort stays in-theatre. Trying to calculate the relative position of two mobile structures gets too complicated in terms of predicting future position, and quite besides, the stability of a ruddy great huge crane hanging over the side of a ship in motion (i.e. at sea) fills me with more than a little fear. I'd agree that a robotic crane deployed at sea would be dangerous.
Though the idea of a lighter than air vessel, (and the last month spent in orthopaedics) does give me an idea. What if you used removable jig? I'm going to have difficulty explaining it, but here goes:
It's easier to accurately position on deck a canister moved across from the UNREP vessel (by VERTREP of derrick) if the canister is horizontal rather than vertical. If you lowered the missile canister onto a jig with a tray which could then be swing up through 90-degrees then the process of slotting the missile canister into the VLS cell becomes relatively straight forward and comparatively easy (since the canister's motion is fixed with relation to the ship). The real trick would be doing it with a jig that was light enough to be carried over to the escort by VERTREP and adjustable so that it could fit more than one ship/VLS position. The available deck space may also be a problem (i.e. you need to find enough space to lay down a canister which is ~7m long).There is nothing "wrong" with this idea ( and deks above). Its called a "deck cell guide" and is (funnily enough) an australian invention from the 60's. The only limiting factor is the splayed flange for a wheel to run into and use as a guide. The rougher the sea state the larger or more flare this flange needs for the wheel that is connected to your box of whatever to mate with the guide rail. This increase in flaring increases the risk of the contaner jamming crossways, so the guide rail has to have some sort of pneumatic "give" not unlike active suspension on a formula one car. Then all you need is a mobile derrick to run a big zip line between the replenishing vessel and the receiving vessel.

cheers

w

[SteveJH]

I could have sworn I once read an Article stating that the USN was having enough trouble finding enough money to fill all its current VLS cells up let alone putting aside enough money for additional missiles as reloads. Not sure how much an SM2 or SM6 costs, but werent SM3 costing something crazy like 10 million per warshot?

Fairly sure Meteor is supposed to be roughly $2 million per warshot. Isnt ASRAAM over $400,000 per shot?

[Zen9]

I would imagine the cells could be stepped down onto a set of rails inside the ship space for the array, not so much breech loading as a set of guide rails along which the cell is moved, still in the vertical position to a transfer bay for movement to and from another vessel or to a lift upto the deck from where the same transfere process occures.
To make this work an 'normal' array would have be more widely spaced apart per cell to make room for the movement paths of a single cell. But clusters could remain very tightly spaced, though each cluster would have to be an oblong or else just four cells.

The point of this is its workable in foul weather at least as far as moving a cell out or into the array. The movement of weight should be relatively safe too.

But it all does depend on good design, for which there is no substitute.

[Deks]

Fairly sure Meteor is supposed to be roughly $2 million per warshot. Isnt ASRAAM over $400,000 per shot?

Given that the AIM-120A/B missiles were something like $170k over 10 years ago, it wouldn't surprise me in the least to see a C-6/C-7/D to hit $400 today.

Just in thinking about it, it'd probably be pretty hard to get funding for this sort of thing in today's operational environment. That being said, if such a thing were built (ie, for australia / spain etc) and available it's introduction could be used as a driver to reduce the number of expensive ships being used today, say from 4 to 3 per group. The cost savings in crewing and maintenance could potentially be quite large, and that might be an easier sell in today's climate.

[Gubler, A.]

by Craig Hooper
Defense Tech Naval Warfare Analyst

This is a classic example of what happens when people write articles with no idea!

Mk 41 VLS has an UNREP system and was fitted as part of the early "61 cell" VLS fitouts to Ticos and strike destroyers. It was never a very good UNREP system but that is an inherent limitation of VLS. The DDG 51 was the first USN VLS ship to not have the VLS strike down system. Because a DDG with 96 missile shots (and even more in later DDG 51 flights with quad packed ESSM) was replacing a DDG with 40 missile shots. Because these ships only fight by themselves in the minds of armchair admirals the massive increase in missile sots per naval task force significantly reduces the need for reloading at sea. Now the China Strong crowd will have as believe that every US and friendly ship has 200 missiles pointed at it but thats pretty crazy. A typical USN carrier strike group is going to have ~400 anti air missiles to defend it not to mention the strike fighters. If the Chinese ever deploy a moving target capable ballistic missile then quad pack PAC-3 MSE provides a way to guard each CSG with >200 BMD terminal phase shots.

[Chunder]

That's inertial navigation you're describing Chunder, though I can't really see the point in this instance.

That rings a bell somewhere. I appreciate that you can't really see the point, it's somewhat hard to describe, The point I was trying to make (in regard to post #10) was that to make a system static in relative motion (I presumed it would be an @ sea replenishment) you need more than just one variable, a whole heap (when transferred into mechanical motion) for a mechanism that "dangles". Inertial navigation/whatever, it's a measurement system which can be interpretated into a plot, if it can be plot it can que. Except that in such a dynamic environment of at sea replenishment by crane, (interpretated from post) you'd want 3 such measurement systems in place which must have some sort of wow factor trying to piece it together to make a 'servo resultant'.

At present I am trying to design a reloading mechanism for a relatively dynamic bit of agricultural kit. Situating the reloading arm on the machine itself so it is in relative static is the only way this particular one is going to be simple (relatively speaking)/unchanging in operational reqs) No computers on this thing... but it's still an Aust. First AFAIK.

[JimWH]

The reason that I can't understand the application Chunder is that inertial navigation systems will only tell you where you are, not where you'll be. Similarly, whilst you can easily add accelerometers to the individual components, and couple that to an INS, unless the components are communicating with one another it's relatively pointless. My work around (which I'm less keen on, the more I think about it) would be to use real-time measurement of position and acceleration from the perspective of the crane, which removes the need for communication but achieves the same result of an integrated situational awareness picture which can be fed to servos (if that makes sense).
But I'm more keen on my removable jig idea now. [Definitely spending too much time in orthopaedics...]

[Chunder]

The reason that I can't understand the application Chunder is that inertial navigation systems will only tell you where you are, not where you'll be. Similarly, whilst you can easily add accelerometers to the individual components, and couple that to an INS, unless the components are communicating with one another it's relatively pointless.


Thats what I thought was trying to impress, as in systems exist for accurate measurement, but it's making them work in unison for dynamic applications :confused: Anyhow, I was just trying to pick your brain on it, anything that gives me some new ideas is worthwhile, not many new ideas here in SA :). Always looking at mechanisms!

Your work sounds pretty interesting to say the least! The medical industry seems to benefit a lot more from knowledge of what is available for various applications internationally as well. Mine seems like re-inventing the wheel at great cost :(

Anyway...
Orthopaedics, yes, went to there yesterday for acupuncture... today I'm getting a cast made up for a sole. Im sick of the damn pain relief gel Im using although I have one pair of god send shoes, you never appreciate your damn feet until they are in constant pain (agony if you step on anything not flat!) She says that my feet can be corrected too without too much trouble which should remove a lifetime of embarrassment! So I think we both may be stuck on the Orthopaedic funny tree albeit at different ends!