chinese laser weapon development


siegecrossbow

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Based on what I know (I did a module on phased array radars, lasers and military technology during my studies), there are a few issues that militaries haven't really addressed in their statements about laser weapon developments as well as defending ship's against ballistic missiles.

1. Radar tracking of ballistic missiles. This is an issue for current ship-borne radars, which are designed and mounted in optimum positions for sea-skimming missiles. They are also optimised to track aircraft at high altitudes at a distance (for threats such as those posed by bombers carrying ASCMs).

Unfortunately, there is currently no radar that I'm aware of on a ship that looks directly upwards. And this is where a ballistic missile is likely to come from.

Whilst Phased Array Radars may be able to provide some tracking at such elevated angles, their tracking performance is likely to be sub-optimal since it is likely to be at or near the extremities of the electronic steering capabilities of the radar.

To illustrate this, let's look at the Aegic cruiser, which mounts 4 PARs to provide all-round horizontal coverage. Thus, it can be deduced that the optimal coverage of each PAR is ~90 deg (or +/- 45 either side of its facing). Factoring in an arbitrary overlap (since the actual overlap is classified and not in public domains) of +/- 15 deg provides a good coverage of +/- 60 deg coverage either side of its facing. Applying this to the vertical plane (assuming the performance horizontally and vertically is similar), than a ballistic missile coming in at 80deg on top of its target will make tracking difficult for an Aegis ship.

Personally, I believe this is 1 of the factors that drove PLAN thinking in development of the ASBM.

2. Conventional CIWS. These weapons are traditionally optimised for sea-skimming missiles. Typically, these systems have their own tracker, but needs to be cued to the target by surveillance radars so that their trackers can lock on to the target. Thus, pt 1 above needs to be solved for these guys to be useful.

In addition, there is a upper limit to their elevation. The latest Phalanx CIWS can be elevated up to 85 deg.

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Thus, a ballistic missile coming in at more than 85 deg renders this weapon useless since it is beyond its firing arc.

Even if the ballistic missile is coming in at high elevations such as 80 deg, and the CIWS is able to hit the ASBM, the resulting debris travelling at hypersonic speeds will still hit the target ship. Not a happy prospect.

3. Laser Weapons. 1 of the most interesting aspects I find about Pentagon reports on their laser weapon developments is that they omit important information that relates to the effectiveness of the laser weapon itself.

a. How long does it take the laser (such as the ABL) to do damage to its target? The recent ABL test failure alluded to this aspect whilst previous statements did not mention how long it takes for the laser to cause damage at all.

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Personally, I think the laser will take some time to shine at the same spot before it causes any damage (based on my experience doing experiments with lasers in my physics lab during my student days). The duration is likely to be more than a few seconds. And the greater the range, the longer the duration required (tyranny of inverse square root). If the duration required is in the order of 0.5 mins or more, than laser as a CIWS defence against a ASBM is practically useless.

b. What is the recharge time for lasers weapons before they can fire again? This was never mentioned anywhere at all in reports. While the mobile THEL was mentioned as:



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The report did not mention whether the multiple mortar rounds were shot down within a few minutes, or the shooting down took place over an hour (or longer duration).

c. What is the effective range of laser weapons? For the ABL, the test range was never revealed, although the recent failed test was mentioned to be at a range of more than 50 miles. Since it was also mentioned that this is double the range of the previous successful test, the logical deduction is that the ABL was successfully tested at less than 50 miles previously.

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Assuming that the ABL has an effective range of 100 miles (double what was revealed), let's look at what this means for laser weapons (taking into consideration pt 2 above).

i. At current tech levels, a laser the size of a 747 aircraft is effective out to 100 miles. Scaling it down means that vehicle mounted lasers will be effective at much shorter ranges. On the other hand, ship mounted lasers can conceivably be effective at more than 10 miles (if mounted on a large enough ship, such as a cruiser). This makes the laser more effective than a CIWS, if it can have a high rate of fire and is lethal in short time durations (seconds, not mins).

ii. The ABL takes advantage of the rarefied atmosphere at high altitudes, which translates into reduced atmospheric dispersion for the laser beam, thus increasing its effective range.

There is no such luxury at sea level.

The salt content at sea level, and higher levels of moisture (dust in land environments) in the air will result in higher levels of atmospheric dispersion for the laser beam. Which translates into reduced effective range for the laser.

Conclusion.

While all the points above sound like serious constrains to laser weapons, it does not mean that they are not viable. However, it does mean that a lot of developmental effort will be required to overcome all these challenges to make laser weapons viable in an operational environment.

Furthermore, the advantages of a speed of light weapon is not to be dismissed lightly. If successful, laser weapons will probably revolutionise warfare the same way guided weapons did in the past.
Thank you for the indepth analysis! What is your opinion on pulse lasers, which deal damage through ablation and not through direct heating?
 

Spartan95

Junior Member
What is your opinion on pulse lasers, which deal damage through ablation and not through direct heating?
The principle of laser weapons is to deliver energy to a particular spot to cause damage. This comes down to how much energy can be delivered by the laser (either Continuous Wave or Pulsed is secondary).

Thus, how much energy a laser can deliver over a distance is the current technological bottleneck. And it seems the developmental laser weapons use CW rather than pulsed (this is my deduction).

I would say that CW is probably more feasible as it can deliver a lot more energy at a longer distance as compared to pulsed lasers (assuming both lasers have the same power output). However, pulsed lasers can probably achieve greater precision in the amount of energy to be delivered and how much material to be ablated (as can be seen in their applications in laser machining). But, this is at really short ranges.

For weapons use (i.e., destructive purposes), pulsed lasers are unlikely to be a favoured choice in the near future since their destructive potential is less than a CW laser.
 

siegecrossbow

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What is your opinion on the latest rumor that the latest Chinese DDG will employ point-defence lasers not unlike the ones that Popeye showed us?
 

Bltizo

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What is your opinion on the latest rumor that the latest Chinese DDG will employ point-defence lasers not unlike the ones that Popeye showed us?
Doubtful -- unless it's nuclear powered then I imagine there won't be enough power on even a conventional ~10k ton destroyer to power a pair of ciws lasers.

I'm sure they are under development, but it'll be a while until they're fielded. Did the rumor say give anything else about this "latest" DDG (displacement, date of launch, etc?)
 

siegecrossbow

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Doubtful -- unless it's nuclear powered then I imagine there won't be enough power on even a conventional ~10k ton destroyer to power a pair of ciws lasers.

I'm sure they are under development, but it'll be a while until they're fielded. Did the rumor say give anything else about this "latest" DDG (displacement, date of launch, etc?)
Between 2011 and 2015.
 

Bltizo

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Between 2011 and 2015.
I see -- do you consider the source reliable?

I'm less skeptical about such claims now than I was a month or two ago, with the well received unveiling of the J-20 the idea of laser based ciws on PLAN vessels doesn't sound too absurd now.
 

siegecrossbow

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I see -- do you consider the source reliable?

I'm less skeptical about such claims now than I was a month or two ago, with the well received unveiling of the J-20 the idea of laser based ciws on PLAN vessels doesn't sound too absurd now.
Well I don't know... the guy who leaked this news, Peishen, is the same guy who made the prediction about J-20's appearance in December.
 

ahho

Junior Member
I think tiered defence would be suitable. If somehow the laser cannot destroy the missile within a certain umbrella, then the ciws would be the secondary defence.
 

Quickie

Major
I think tiered defence would be suitable. If somehow the laser cannot destroy the missile within a certain umbrella, then the ciws would be the secondary defence.
It depends on how powerful is the laser. If it takes a split second to destroy a target, then it's probably effective for CIWS range too. With current laser technology, it'll probably take much longer that, making laser weapon more suitable for longer range, and maybe as a targeting device to heat up targets for heat seeking missiles.
 

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