Lockheed Martin completes new battle laser for U.S. military

Presumably the amount of energy dumped into the target is a function of how long the laser dot is on it. You'd probably need the laser on a particular area of the target a little while to disable it.

If your target is ducking behind waves and goes from beyond the horizon to onto of you fast enough, that would be pretty good against a laser probably?

If you can launch 20, I can add another laser. Just in terms of economics, you aren't going to win that fight.

A rail gun: If I shoot a laser at a missile, I can detonate the warhead, or the propellant, or destroy the guidance system. If I fire it at a railgun projectile, I can vaporize the whole thing, or I can vaporize part of it and hope that it changes the course due to either ablation forces or changing the aerodynamics. That's harder. On the other hand, a railgun isn't really a precision weapon, either.

Yeah... that's a lot of momentum to deal with, in a rail gun. Deflecting it would be hard, and disrupting it would tend to turn the slug into a co-moving cloud of superheated particles/plasma. I'm not sure that's hugely desirable either!

Yeah, on a landing craft, expect some form of ablative armor. (How friggin' Star Trek is that?!)

A pawn for a rook? That's like a pawn for 1000 queens.

Mechas will always remain SF. There's just so much that's impractical about them, where do you even begin. Balance is one issue: if you can make it fall over, you've killed it. Speed is another; anything that big will be extremely slow. Another issue is the ground pressure (weight divided by surface area of feet); they would destroy most surfaces (including all roads), and they would easily get stuck this way. Another issue is the huge amounts of fuel and frequent refueligs it would need. Another is the huge cost, which coupled with sluggishness and corresponding permanent proximity to the battlefront makes them a prime target for infiltration and sabotage.

Even something as comparatively small and practical as the Boston Dynamics robots have failed to gain traction; years after even being in actual service for testing with the military, LS3 has been literally shelved because it's just not useful.

One of the funniest battle mecha scenes is from Pacific Rim (which is chock-full of stupidity) where the one mecha is just a crappy missile delivery system. Once it's waded half way out to sea and spent its missiles in about two seconds, it's bloody useless. Why didn't they rather spend the cash on other, more sensible launch platforms that could deliver orders of magnitude more firepower using the same kind of missiles? Or why not just attack the alien things much further away from shore with torpedoes launched from fighter jets? Or why not just launch nuclear-tipped torpedoes down the portal hole? (Well, it would be a boring movie, that's why.)

Yeah there's nothing quite like horrendous human suffering to satisfy your hunger for sci-fi. /s

The protocol only prohibits the use of weapons whose intended purpose is to blind people. If a laser is meant to be lethal and happens to blind you, that wouldn't violate the protocol.

What happens when a photon interacts with something that has mass?

You'd be right. It would need to dwell for considerable time on the same part of the tank's armor to have any meaningful effect, and even that would rely on slow, inefficient heating as a mechanism. (Assuming a rather improbable 100% kinetic energy transfer from a 60kW beam, that equates to about three .50 BMG rounds per second from contact range. That's a big round, but not big enough to have a significant effect on tank armor.)

To address another commenter's point, it would not set off explosive reactive armor (ERA). While I don't have detailed information on the ERA compositions in common use, the constraints at hand effectively necessitate the use of relatively insensitive plastic explosives, broadly similar in characteristics to the well-understood C4. Such explosives require a shock wave, provided by a special device or (in the case of ERA) by the impact of a shaped charge, to detonate; heat and fire will not set them off. (Vietnam-era American soldiers burned pieces of C4 from Claymore mine charges as cooking fuel. The smoke was toxic, but that was the only danger.)

You need a composition like this for ERA because it is not an actively controlled system. It's not as though there is a computer in the tank which detects an impact and detonates the corresponding ERA segments; the physical processes of such impacts play out far too quickly for such active control to work. ERA therefore has to work on a purely physical basis if it's going to work at all, and that means you need to use an explosive susceptible to detonation on impact. But you don't want an explosive that's very sensitive to impact, or to heat or fire, because you don't want to waste ERA or unnecessarily endanger infantry operating near the tank. (ERA's dangerous enough already that way without giving it a hair trigger!)

So it's already not all that plausible that a beam like this might transfer enough energy, even on direct impact with a mass of such explosive, to set it off. But the impact won't be direct, because ERA isn't constructed of bare explosive blocks; there's always going to be a layer of metal, not armor but still relatively thick, between the explosive and the outside environment. This structure would intervene between the explosive and the beam, and would dissipate the transfer energy as heat. That might eventually set the underlying explosive on fire, but, for the reasons we've already covered, it would not cause a detonation.

Could it make the reactive armour explode?

Interestingly flying through volcanic ash, even in small amounts, is exceptionally hard on aircraft. So hard in fact that in one of the DARPA call for wild ideas rounds I suggested a "puffer ball" defense system consisting of a steam or air pressured dispenser on ship that could fire a 'plume' of volcanic ash to a height of up to 1000 meters. If any aircraft 'buzz' your ship with that plume up they are going to lose their engines. It could also make for a shore based cruise missile defense where you puff it infront of the missile and hope that the missile's radar can't see enough of it to jog left or right. It is remarkable stuff[1]

[1] http://www3.alpa.org/portals/alpa/volcanicash/03_NASADC8AshD...

Some of that, for sure. I'm not saying that Raytheon et al are angels or anything, but in their defense, most of the "overhead" is likely due to the hoops they have to jump through to do things the way that their customer wants them to be done.

I haven't worked with Government or their suppliers, but I have worked for a large company that did a lot of manufacturing of semi-exotic stuff, and their procurements demands were completely irrational. They didn't want to maintain an inventory of parts that were complex to manufacture, but required that they be available to purchase on short notice without any kind of contract or schedule, and were willing to pay any price to get that. So suppliers sprang up to hold these parts in inventory for them and supply them on-demand at vastly marked up prices, to cover their costs of maintaining the inventory. I'm not sure if any explicit corruption was involved in setting that up, but that's the kind of thing that tends to happen at large organizations.

Then again, even if there wasn't any explicit corruption when setting these things up, it tends to happen later on as suppliers get established and try to bend the customer into having even more bizzare procurement rules, so that no other company could possibly comply with them and take their business.

Partly, but mass production in time of war simply isn't a thing in this day and age — hot wars between roughly-comparable adversaries (as opposed to the asymmetric conflicts such as counter-insurgency campaigns) are generally over in double-to-triple-digit hours, a couple of weeks at most.

So the policy of most developed nations' militaries is "come with whatever you've got" and don't plan on building more kit until it's over.

Huh, thanks for the link to the talk. That wasn't in the original article so I could hardly believe they got that correct.

Still, I don't see how that's justifiable even if they can drop grenades. They won't be able to do it very effectively, and in fact if it's close enough to drop a grenade on troops you probably don't want to be detonating a Patriot missile in the same area.

Water is also pretty good at muffling explosions. If you can take out torpedoes at 30 meters (80% of energy wasted, needs 5x more power), it might still be worth it as a point defence.