From: JAY DUGGER (duggerj1@charter.net)
Date: Mon Jun 23 2003 - 19:29:08 MDT
On Mon, 23 Jun 2003 20:15:18 +0000 (UTC)
naddy@mips.inka.de (Christian Weisgerber) wrote:
On Mon, 23 Jun 2003 20:15:18 +0000 (UTC)
naddy@mips.inka.de (Christian Weisgerber) wrote:
>Mike Lorrey <mlorrey@yahoo.com> wrote:
>
>I'm out of my depth here, but I wonder whether thinking
>about maximum
>range doesn't miss the issue.
I served in the US Navy, where I operated and maintained
gun fire control systems (everything that told the guns
where to point and when to go bang). This just means I
have direct experience with the subject, and that I have a
little bias in favor of my former work. In short, maximum
accurate range makes a big difference. Indeed, accuracy
makes up for explosive load. That's why battleship's
needed sixteen-inch guns. The large shells went far with a
big load. That big load compensated for their poor
accuracy by modern standards.
>
>A while back I read a bit about WWII-era battleship
>fights. One
>aspect that stuck in my mind was the difficulty of
>hitting your
>opponent at all.
That was technology, at best, of the 1930s. Ships in the
American Navy aren't much more than twenty years old
today, if that.
>I'm not sure how stable a gun platform
>a steaming
>ship in heavy sea is.
It's not a very stable platform. I remember rolls of
fifteen degrees. Ships make very stable _gun_ platforms,
because the directors (turrets, missle racks, etc.) take
correction from the ship's gyroscope. Directors that don't
take that correction (e.g., RAM launchers, VLS cells, and
Harpoon tubes) don't need it. Generally they fire weapons
that home, or have guidance independent of the ship's
position.
> The target keeps moving around,
>too. And
That's why you have radar. The radar antennas also have
gyroscopic stabilization where its needed. Surface-to-air
radars need much less stabilization. Remember the ships of
a fleet can compare radar fixes on a targets from multiple
sources too. Accurately knowing the target's location
isn't nearly as hard as you might think. The limit on
accuracy I remember came from the limitations of the radar
set's angular resolution. Over the ranges of the ship's
guns, this wasn't a real problem. Modern radar sets have
even less trouble.
>while the ballistics of your guns are known (from
>empirical testing,
>I suspect, rather than first principles)
Mostly the latter, actually.
>environmental conditions
>are variable with wind, rain, etc. When you are shooting
Wind is well known at launch--it's continuously measured.
>at a
>distance of several km's, these things add up. I
>understand ship
>artillery started shooting with a guesstimate, observed
>how far
>they were off, and tried to compensate.
>
They still do, when shooting at a surface target on the
ocean. We tracked fall-of-shot by the radar return of the
splash when a shell missed. Then we corrected as needed.
Not too hard to do, even with user interfaces that dated
from the 1970s. Ships don't have short turning radiuses,
nor do warships go all that fast, and they accelerate and
decelerate poorly by the standards of land vehicles. You
can predict a ship's course with good confidence, and that
confidence varies directly with the size of the ship.
Remember my eariler post's comment about "digging holes"?
I wasn't kidding. That's just with GPS improving the
knowledge of ship's own position. Of course, shooting at a
geographic position reduces uncertainty a whole lot. You
don't perfectly know where you are, but you know the
target's position very well indeed.
>With this in mind, shooting dumb rounds beyond the
>horizon looks
>entirely pointless to me.
Good reasoning, but not true.
>Certainly for anti-ship use.
> You are
>not going to hit anything.
Wanna bet? In live fire exercises, we used to shoot at
sleds towed behind speedboats. We were forbidden to fire
unless we had an offset set into the firing solution. You
don't want to hit the sled, just demonstrate accuracy
enough that you would've hit the sled save for that
offset--
generally not a problem. A target's speed mattered more
than environmental conditions, and then only because the
radar tended to lock onto the rooster-tail of the craft
rather than the boat itself.
>For engaging targets at long
>range you
Long range to Naval Gun Fire means more than 30,000 yards,
or out of gun range.
>really want something with homing ability, either
>missiles or, if
>fired from a gun, at least smart projectiles that have
>terminal
>guidance.
>
Oh no argument there. Harpoon anti-ship missiles hit
_much_ harder than gun shells. They carry more explosive,
penetrate farther into a ship, and also have a secondary
explosion after the warhead detonates. All that fuel
usually explodes too, y'know. They can also be programmed
for things like hitting from above (flying down the
target's exhaust stack) or hitting right at the waterline.
Shells don't do that. On the other hand, a ship carries
hundreds of shells loaded with HE, a few dozen
illumination rounds, and a small number of shells loaded
with white phosphorous. Shells cost little. Harpoons cost
plenty.
>speed at your opponents, you are going to hit them
>instead of just
>harassing the fish.
>
Sonar harasses fish. Naval gun fire feeds them.
Jay Dugger : Til Eulenspiegel
http://www.owlmirror.net/~duggerj
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