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Pearls of Weber

A collection of posts by David Weber containing background information for his stories, collected and generously made available Joe Buckley.

Point defense laser clusters

"Joe Buckley" wrote:

"martinenderle" wrote:

I've got the impression that reason for putting laser emitors into cluster is to increase their fire rate (if a recall correctly, there was mention about this issue in AAC) - while one emittor is firing, others charge it's capacitors. But if they fire multiple beams to each missile, than it explains a lot.

No, you have it right.

The cluster, as a whole, shares a common firing solution, but, as you say, one emitter fires while the others recharge and recycle.

Actually, Joe, they can be fired in either mode, which is one reason that the capital ships continue to build multi-emitter weapons rather than single-emitter installations.

Overall, you've done a very good job of explaining things, but there are a few points I haven't made explicit in the books so far. Where the laser clusters are concerned, the biggest point is that the laser clusters can fire in rapid sequence, using the emitter is as what you might think of as a photonic Gatling gun, or they can fire in multi-shot "bursts." At the consequence of somewhat less accuracy per shot, they can engage multiple targets with each cluster (the drop in accuracy results from the fact that the controlling software is optimized to provide the maximum accuracy against single targets and there are some trade-offs built into it), or each laser in a cluster can be directed at a slightly different protected intercept point.

Firing them all in a single "bursts" has the significant disadvantage of stretching out recharge time, which can be a significant problem (for fairly obvious reasons, I think) if there are multiple waves of missiles inbound. On the other hand, it means that a substantially larger number of targets can be engaged (albeit at that slightly lower [hit] probability I mentioned above) in a "we only get one shot as they cross the range" situation.

The sensor/fire control suites for each cluster are dedicated to that cluster, but one of the reasons that the Keyhole platforms are as big as they are is that the Royal Manticoran Navy has incorporated what you might think of as repeaters for those suites into the platforms. Basically, each of the platforms has highly sophisticated sensors designed to detect and track incoming missiles. The take from those sensors is then shared among the dedicated shipboard sensor/fire control suites or slots for each point defense station. The shipboard fire control allocation and AI assigns threats to each "slots" based on their immediacy, and the slot is then responsible for keeping track of its target based on the data being fed to it by the keyhole platforms. What this means is that even in a "crossing" shot, the RMN's point defense stations have been able to watch and follow their assigned targets even when their mother ship's own wedge would have made them invisible to direct observation.

Both the Manties and the Havenites are continuing to experiment with missile-defense, and both sides -- for what I think are readily apparent reasons -- are constantly upgrading their capabilities, although the difference in their tech [bases] mean that they go about it in different ways.

It should, perhaps, be pointed out that they are doing these things because of their firsthand experience with the new-generation missile threat.

People who have not yet experienced that new-generation missile threat probably (tum-te-tum-te-tum) aren't. I mention this because it seems to me that a lot of the discussion about the Manties' combat advantages in any war vis-à-vis the Solarian League seem to be focused pretty much exclusively on the offensive advantages the Manticorans might be expected to enjoy.