Concrete bomb: did I get the rules right?

[WaterAndWindSpirit]

So let's suppose there is some urban warfare, and one side wants to destroy a target with minimal collateral damage.

So they decide to drop a concrete bomb on it. (Note: concrete bomb = laser guided block of concrete dropped from an aircraft.)

So:

Someone on the ground makes a Forward Observer roll to designate the target.

The pilot can make a run by flying around as long as s/he is not spotted, which counts as aiming.

Then s/he makes an Artillery (bomb) roll, and then I roll for damage from a falling object on the target (or whatever s/he hits on a miss).

Which leads to the question: what are the range penalties on artillery, and what would the Accuracy of a laser guided bomb (concrete or not) be? Are they in a specific book?

[Fred Brackin]

Originally Posted by WaterAndWindSpirit

So they decide to drop a concrete bomb on it. (Note: concrete bomb = laser guided block of concrete dropped from an aircraft.)

Which leads to the question: what are the range penalties on artillery, and what would the Accuracy of a laser guided bomb (concrete or not) be? Are they in a specific book?

See p. 412 of Campaigns.

[WaterAndWindSpirit]

Originally Posted by Fred Brackin

See p. 412 of Campaigns.

Okay, thanks.

Since once fired, a concrete bomb cannot be re-aimed at something else, I take it it's only usable at stationary targets, but the rules stay the same, right?

[Kale]

A laser guided bomb usually has small steering fins. Depending on how high up the bomb was released, and the speed of the releasing aircraft, the bomb could travel a fair distance. Its even possible to have a two-stage bomb which uses GPS to maneuver to a specific waypoint, then turns on a seeker head to look for a designating laser spot. For this to work over any distance though the airplane should release the bomb from very high up.
Assuming the bomb has a fair bit of falling time left, it is conceivable that you could switch targets in mid drop. It would have to be the GM's call as to whether the bomb could turn enough to hit the new target though.
Off the cuff, I'd say maybe switching to the building next door (moving the designating laser spot) would be allowable for all but the last few seconds of 'flight'. If you want a big change though you'd better move that spot within a few seconds of the bomb release, and even then you would be limited to a cone in front of the bomb since it can't turn very much.

[Fred Brackin]

Originally Posted by WaterAndWindSpirit

Okay, thanks.

Since once fired, a concrete bomb cannot be re-aimed at something else, I take it it's only usable at stationary targets, but the rules stay the same, right?

Nope, move the laser spot and the laser-guided munition will try and follow it. Many anti-vehicle guided missiles use laser target designation.

[Anaraxes]

Originally Posted by Kale

For this to work over any distance though the airplane should release the bomb from very high up.

Also toss bombing.

[WaterAndWindSpirit]

Originally Posted by Fred Brackin

Nope, move the laser spot and the laser-guided munition will try and follow it. Many anti-vehicle guided missiles use laser target designation.

So it's possible to change the target of a laser-guided block of concrete mid-drop? Color me impressed at modern military technology! :P Though I've read it's often used on stationary targets to avoid collateral damage.

[Anthony]

Originally Posted by WaterAndWindSpirit

So it's possible to change the target of a laser-guided block of concrete mid-drop?

That's kind of the point of 'guided', though artillery and bombs with terminal guidance probably don't have a lot of course correction available.

[RyanW]

Originally Posted by WaterAndWindSpirit

So it's possible to change the target of a laser-guided block of concrete mid-drop?

There is effectively two gradually shrinking circles (more likely an ellipse aligned with the direction of travel) that define what the weapon can steer to and track. The size and shape of the first circle depends on the bomb's physical configuration (such as ratio of fin area to mass), and the second on the sensor being used. As long as the aim is changed while the new target point is still inside those ellipses, it can change trajectory just fine.

A smart weapon designer (in this case, both a smart designer of weapons and a designer of smart weapons) might limit the ability to suddenly change the aim by a large margin, since that very likely indicates user error (if the forward controller dropped the designator, you don't want a bomb suddenly targeting the bottom of his fighting position), and makes collateral damage more likely.

[Anaraxes]

Originally Posted by WaterAndWindSpirit

So it's possible to change the target of a laser-guided block of concrete mid-drop?

In fact, this is sometimes a deliberate tactic known as "offset designation". If you're concerned about laser alarms on the target, or enemy countermeasures, you might designate a spot nearby your actual target, and only later shift it to the actual target. Not really recommended for accuracy during the terminal phase; it's especially useful for helping the aircrew find the actual target before the drop so they can get the bomb going the right way without alerting the target.

Turning on the designator too early can also cause the bomb to turn downward too soon. It may be a "smart bomb" but it's not really that smart; it just angles toward the properly coded laser energy it can see, which is great during the terminal phase but not good earlier in its flight path. The designator (FO) and aircrew / artillery FDC are in communication, and the launchers tell the FO when to start designating the target near the end of the flight time (15-20 seconds before impact). In that sense, you're routinely changing the course "mid-drop".

If you're interested in details about how these weapons are used, the US military's Joint Laser Designation Procedures manual is worth reading.