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August 16, 2006

Answering the mail.

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Nicholas, from Smell of Freedom, asked this question in a comment on one of yesterday's posts:

Sorry for being off topic, but I'd like to ask an artillery expert a question as google has drawn a blank.

I noticed some terrorist sympathizers making statements like "Israeli artillery is so inaccurate, it's only useful for attacking whole towns, thus they are effectively terrorists".

Now, I don't think anyone would bother using artillery if it were that inaccurate. Can 155mm artillery reasonably be used for counter-battery fire against targets like rocket launchers or infantry hiding in buildings and expect to hit where it counts? How discriminate is it?

I don't expect they're firing at maximum range. But probably nowhere near minimum either. I understand they've upgraded the American artillery they are using. What kind of accuracy figures would you expect?

Thanks, I'm looking forward to hearing from someone who actually knows what they're talking about.

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Well, lessee. That sounds like someone talking out of the well of deep ignorance, parroting what they've heard elsewhere. (Happens 'round here, too.) After all, that *is* true of Hezbollah artillery, so it must be true of Israeli, right?

The M109-series guns the Israelis are using are designed to be able to hit within 0-20 meters of their aimpoint under standard conditions, using standard (i.e., High Explosive) projectiles.

That requires that you have accurate surveyed (i.e., 8 digit UTM grid) location of both your gun and your target, including the altitude difference, and that you are following the basic steps of good gunnery, which the Israelis I'm sure are. For example, in the picture below of an Israeli M109 howitzer, you notice the smallish box at the base of the cannon? That's a radar chronograph - the fire control system monitors the muzzle velocity of every round fired, and automatically adjusts the firing solution to account for bore wear. If it detects large variations in muzzle velocity from previous rounds, the system will then alert the crew to check to ensure they have current data for things like propellant temperature and projectile weight, and that their ram is functioning properly to seat the round.

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They might be going so far as to be tracking their rounds with radar, but I suspect most, if not all, the counter-fire radars are being used to find Hezbollah's stuff.

The greatest component of error for the Israelis would be the target location. However, if they're using military GPS and laser rangefinders - or have accurate maps of the right scale, they can get sufficiently accurate target location. Another consideration in urban combat are tall adjacent buildings. Depending on the gun-target orientation and intervening buildings, getting to any specific target might be a challenge - low-lying buildings, not so much. You can shift to high-angle fire to try to get around that, but high-angle fires are not as accurate, especially if winds aloft are not supernaturally consistent. It's usually better to just shift to a gun that has a better angle to the target, that avoids the intervening buildings, if possible.

If they are using terminally guided or GPS-guided munitions, they can hit point targets. I've done it, and under combat conditions, it's not hard to do unless the bad guys are shooting uncomfortably close, and even then the round is going to be close.

Mortars, absent precision ammunition (which exists and the Israelis have) are a bit more problematic, but we're talking artillery.

Rockets, it depends. The Katyusha-style unguided rockets are area weapons. You orient the launch rails so they are pointing in the direction you want the rockets to go, you set the quadrant elevation to achieve the *general* range you want, and you let fly - and hope that you get your target by saturation. Hamas and Hezbollah have the capacity to build their own rockets - but their motors are not consistent from rocket to rocket - much less so than the more professionally-produced versions the Iranians supply - but these rockets are pure area-fire weapons.

If you are shooting single rockets, you're just hoping that you get lucky. That's what Hezbollah has been firing. They do sometimes volley fire them, but they don't fire too many at once or the launcher gets detected, which is usually the end of the launcher and if we're lucky, the crew, too. For the most part, however, the crews launch remotely, so that they don't get killed if the launcher gets hit. Not that training a Katyusha crew is a hugely time-consuming task. One reason the Russians invented them and people like Hezbollah like them.

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