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Subject: Would it be better to build more Burkes rather than DDG 1000s?
Charles99    3/17/2008 6:53:39 PM
Or an incremental improvement of hte Burke? Given the economy and the already high expense of the DDG-1000's, we might end up with a very small number of high end platforms. The Burkes aren't going to be as capable, but on the other hand, we might be able to build more of them, and I'd lay odds that they'll still be the most powerful surface combatant on the oceans for a good long time. Would it make sense to go for more of the good as opposed to a little of hte best, or does the DDG-1000 give such a tremendous leap in capability that it would be better to buy them, even if only a few?
 
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Herald12345       3/20/2008 1:43:45 AM

The internal ballistics of a gun certainly are more efficient than that of a pure rocket, but AGS can't fire a pure ballistic round 84nm.  The unguided, non-assisted round for AGS only had a (planned) range of 20nm or so.  AGS needs the rocket-propelled LRLAP to go the rest of the way.

So in effect, the gun is just a booster.  The rocket appears to do most of the work. 

So now we have the worst of all worlds, IMHO. 

We have all the added complexity and weight of a big gun just to boost a rocket-propelled missile.  And we have a missile who's engineering and construction is made far more difficult and costly to survive those efficient internal ballistics. 

Why aren't we using POLAR again? 

Exactly backwards.

That gun is still more efficient as it provides 90% of the  acceleration in the first step..A comparable rocket would be #x the propellant used at least.Plus you still have the casing.

Herald.
 
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doggtag    debate going quite nicely...   3/20/2008 8:31:01 AM

The internal ballistics of a gun certainly are more efficient than that of a pure rocket, but AGS can't fire a pure ballistic round 84nm.  The unguided, non-assisted round for AGS only had a (planned) range of 20nm or so.  AGS needs the rocket-propelled LRLAP to go the rest of the way....

...Why aren't we using POLAR again? 

Several months ago (year or more even?),
didn't ArtyEngineer post up a topic about the PzH2000 with its 155mm L52 barrel firing South African-designed long range projectiles to 60-some km, with the anticipated goal of reaching 75?
 
If I remember my conversions correctly, there's 6076 feet in 1 nautical mile,
5280 feet in 1 statute mile,
and roughly 1.6km in 1 statute mile (more precisely, 1.609344, if using 25.4mm per inch),
and ~1.852km per NM.
So even a 155/52 barrel, firing base bleed semi-boosted (at least as compared to the LRLAP) aerodynamically streamlined shells (VLAPs?), can still outrange, with unguided projectiles, the 20 or so NM previously suggested for the AGS's range with unguided "dumb" shells.
 
(20NM = a little over 23 statute miles, or in the neighborhood of 37km.
So with South African style VLAP ammo, a less bulky 155mm L52 naval mounting can still, theoretically, routinely reach just over 46&1/2 statue miles (75km), or about 40&1/2 NM...)
So anyhow,
yeah, a "standard" naval mounting (not as massive as AGS, something more comfortable to lesser vessels than DDG1000)with a 155/52 still barely gets half the suggested range of an LRLAP,
but other than coastal antiship missile systems, it still puts you outside the range of any other tube artillery that itself isn't using these 75km-ranged "dumb" projectiles (CCF-equipped or not).
 
Now as to the whole "POLAR vs AGS" argument,
if I have a vessel with Mk41 class VLS arrays (numerous 8-cell modules),
then each of those 8-cell modules could conceivably carry 32 POLARs in total (if they'll quad-pack ESSMs, they'll quad-pack POLARs).
Ideally, the support frigate would mix-n-match ESSMs and POLARs.
So a vessel with a combined 64 cell arrangement could carry a load-out of 256 munitions (quad-packing each cell), in the combination of your choice.
A 200km-ranged POLAR is going almost 108NM.
Even if it still can only get to that distance with, say half of the 90kg warhead of a 70+km G-MLRS,
that's still more payload (45kg, but I'll even round it down to an even 40) than an LRLAP is carrying to less range (80NM, although I though at one point I read somewhere that the preferred/suggested range of an LRLAP was 180km, or about 97.2NM.
 
FWIW, LockMart's own LRLAP pdf suggests 74NM, or about 137km,
; ,about 304kb)
 
...and taking the Wiki entry with a grain of salt, their suggested bursting charge is a "mere" 11kg: http://en.wikipedia.org/wiki/LRLAP
,which is still even a few pounds less than the P44's 28 pound metal-augmented charge (although just how much of that is explosive remains an open-source mystery...
 
So a 200km POLAR with even a 30kg warhead is still offering more range and lethality than an LRLAP, and splitting a Burke's foreward Mk41 array only still could, theoretically, mean more POLARs available than those 120 proposed rounds for a Burke AGS, plus we aren't sacrificing ESSM carrying capabilty as well.
(Let the stern array handle all those bigger SM-sized missiles for those of you who feel every ship should be ABM capable.)
 
Again, not everybody will be able to fit even an AGS-sized turret,
but anyone with SeaSparrow or ESSM-compliant cells could carry POLARs.
Advantage goes to the POLAR over the LRLAP, because the LRLAP is primarily GPS and INS guided, whereas there's no reason a 9"diameter POLAR
(assuming it's still an MLRS rocket, although we could develop the ESSM's 10" diameter rocket motor into a new SSM class entirely)
can't be kitted out with the P44-type tri-mode seeker, allowing better attacks against
 
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B.Smitty       3/20/2008 9:11:19 AM


Exactly backwards.

That gun is still more efficient as it provides 90% of the  acceleration in the first step..A comparable rocket would be #x the propellant used at least.Plus you still have the casing.

Herald.
The gun may use propellant more efficiently, but is it more cost effective, when you tally up the additional complexity, weight and volume of the mount, and the significant engineering challenges of developing a guided, gun-launched missile?

It would be interesting to compare a pure missile plus VLS mount solution, designed to the same mission parameters as AGS/LRLAP, to the gun/missile combo in terms of total cost, effectiveness, and ability to integrate with the fleet.

POLAR wouldn't be directly comparable to AGS/LRLAP, as it is a much larger munition.  An extended-range P44 would be closer. 

 
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B.Smitty       3/20/2008 9:20:19 AM
doggtag,

The one, big problem I see with using POLAR/P44 is VLS reloading.  We currently don't do it.  Rapid UNREP is a big selling point for AGS.

Of course since DD(X) was a clean-sheet design, a VLS UNREP system could've been built.  My guess is this would have been far cheaper to engineer than AGS. 

 
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doggtag    VLS UNREP, yeah, I'll concur...   3/20/2008 10:37:58 AM
Thought about this.
Is it really going to be that much harder to restock VL-configured P44-sized munitions, which are inserting into vacant cells (I'm assuming either singly encased missiles, or more ideally, a complete loaded pod, depending on the VLS array being used),
as it is to transfer onboard a pallet (?) of VLRAPs, which not only have to be loaded onto the ship, but also hauled down inside somewhere and stowed in an ammo magazine?
Is the DDG1000 going to be configured with ease of replenishment for its two guns, by some rapid means to get the shells offdeck and quickly stowed below?
 
I vaguely remember in the early days of the USN's VLS installations aboard Ticos,
where the idea was to use a strikedown crane/gantry to assist in cell reloading.
The system was supposed to occupy the equivalent area of 3 or 4 cells, off to one corner,
but the idea was later adandoned.
I think it was realized (estimated? anticipated?) that it was doubtful that any given vessel would need to expend its entire missile compliment (100+ anti-air, anti-surface, land attack, ASW) before another vessel was called on station to relieve it,
fully loaded.
 
Especially for P44 and POLAR-class weapons, I don't believe it would be so overly complex to implement a capable UNREP system, if needed. Not in the sense when compared to replenishing bigger missiles like Standards and Tomahawks (although a full multiple round pod of P44s or POLARs could weigh just as much and be just as bulky, so yes, that is the catch.).
 
But for the capacity we would need the strikedown crane/gantry to be able to hoist, position & reach across the deck, and insert into a vacant cell,
it's certainly not beyond us.
Overall, would it really be any more dangerous and cumbersome than replenishing crates, pallets, or skids of any other ammunition or bulky supplies?
 
I'm still looking at the overall picture:
what're the odds of ever needing a stand-alone DDG1000, with no other support vessels, to fire 600+ rounds at an adversary's coastal areas and a few dozen miles inland?
I'm gauging the same instance for the P44/POLAR-armed ship: will it be there all alone with no other support for the foreseeable future, with no back up to relieve it, and therefore actually needs the ability to fire off several hundred missiles in its offensive and defensive time on station?
(No SSGNs for land attack, no LCS, etc?)
 
And again, I'm also taking into account that not everybody will have access to DDG1000/AGS-sized artillery assets,
so the notion of equipping frigates, corvettes, and any other vessels with P44/POLAR-capable systems does have some merit (but only so long as said vessel has the means to target said missile, which could just as easily be called-for-fire just like any other naval artillery systems, cued up by UAV drones, satellite relay, or whatever means, no different from what is used now, or will be used eventually with the AGS).
 
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B.Smitty       3/20/2008 10:53:03 AM
I believe there is supposed to be some sort of ammunition conveyor to rapidly move AGS rounds from the deck down to the magazines.
 
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doggtag       3/20/2008 12:28:07 PM
I would hope so.
Can't imagine an ammo detail of a dozen people or more with carts and carrying straps trying to stow a few hundred 200+ pound projectiles into ammo magazines and feeders by hand after a long period of going without replenishment.
 
 
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Yimmy       3/20/2008 12:45:26 PM
Yeah that does make sense.
Yimmy, gun chamber pressure is much higher than you can obtain with a rocket, simply because of the amount of structure you have in a gun to contain it that you cannot have in a rocket.

More pressure with a propellant means a faster burn and more energy.


 
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Herald12345       3/20/2008 1:30:26 PM





Exactly backwards.

That gun is still more efficient as it provides 90% of the  acceleration in the first step..A comparable rocket would be #x the propellant used at least.Plus you still have the casing.

Herald.

The gun may use propellant more efficiently, but is it more cost effective, when you tally up the additional complexity, weight and volume of the mount, and the significant engineering challenges of developing a guided, gun-launched missile?

Yes. With a shell you have a small boost engine and either an aerodynamic or reaction control system steering jets and the GCU whereas with the rocket you have a large propulsion motor in addition to all of the above-yielding a much larger projectile diminishing the cargo/propellant ratio of the projectile [rocket boosted shell shell can be as 70/30% by mass whereas the  rocket  for the same range rarely is  80/20%]  This is in spite of the thicker walls that a shell requires to withstand the extremely large magnitude sudden acceleration forces that throw it in the first step [stage].  The cost of a $30,000 shell  is also cheaper than the $80,000 equivalent rocket matching the SAME performance.

It would be interesting to compare a pure missile plus VLS mount solution, designed to the same mission parameters as AGS/LRLAP, to the gun/missile combo in terms of total cost, effectiveness, and ability to integrate with the fleet.

CREF above.

POLAR wouldn't be directly comparable to AGS/LRLAP, as it is a much larger munition.  An extended-range P44 would be closer. 

Well...........CREF above......................specifically.
Herald

 
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dwightlooi       3/20/2008 1:30:40 PM
Rockets are superior for range. The reason is that the amount of chamber pressure you can manage and the amount of acceleration you can produce in a fraction of a second is VERY finite. In a gun, you only have the length of a barrel with which to accelerate the projectile. In a rocket you can take minutes to do so if you wish. The advantages of throw weight per unit assembled ammunition volume or weight is also often off set by the size, weight, complexity and dedicated nature of a gun mount. For instance, instead of a 155mm mount and magazine you can use the space and weight for 360 10" class VLS to deliver firepower at a higher rate to a longer range. There is no turrent, no hoist, none of that. The VLS can also be used for other AshM, SAM or whatever ordnance unlike space in a gun magazine. The disadvantage is that per shot COST is much higher even for rockets with no terminal seekers -- one guided only by post launch TVS and GPS steered fins to impact.
 
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