6 ms·
> that’s what you need to burn through a quarter inch steel plate?” Do you really need to burn through steel plate? Seems like something like this is for shoo
by gumby 2y ago
> that’s what you need to burn through a quarter inch steel plate?”
Do you really need to burn through steel plate? Seems like something like this is for shooting down cheap drones.
Though I've always wondered about laser weapons -- I'd think the obvious defense is cladding the device in a mirror surface.
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- chris_va 2y agoOr just something that gets smoky when it burns, then the energy is deposited entirely into the smoke boundary layer (and might even make a nice reflective plasma).
- ssl-3 2y agoIt would need to be a neutral-density-ish smoke, wouldn't it? If my dealings with (much, much) smaller lasers are an indication, "regular" smoke from laser-heated things is generally buoyant in air, and would tend to just float up and away from a presumably-horizontal beam. It seems like this would limit the smoke's abilities to diffuse and absorb the energy.
- chris_va 2y agoYes it would ablate at some rate, based on the drag, convective buoyancy, etc. If the smoke is optically thick at all, even if it pushed away almost immediately, the wall ablation rate would probably be a couple orders of magnitude lower than if the laser hit the wall directly... If you want a fun read, the Galileo probe wall ablation paper is fun, the re-entry power density (at the wall!) was ~10kW/cm^2.
- gpm 2y agoI'd be sort of surprised if the buoyancy mattered much in the face of the amount of air something needs to move to fly. On the time frames that buoyancy acts in I imagine (without data) it's no longer around the drone anyways.
- Retric 2y agoAs I understand it defenses depend greatly on pulse duration. Rotation dramatically increases effective armor thickness if energy is delivered over a long time frame etc. But drop to the nanosecond range and a cloud of plasma which used to be the armor is going to between the laser and what’s left of the armor. That said, you don’t need to drill through a target, a jet of ablated material means an equal and opposite force is going in the other direction. Really though the biggest limitation of a laser defense system is pure kinetic kill weapons. Big thing moving Mach 2+ is deadly even without pinpoint accuracy or being filled with high explosives.
- ortusdux 2y agoIntumescent paint would do the trick. Intumescent paints are considered the lightest form of passive fire protection. An intumescent is a coating that, when exposed to heat, is rapidly transformed through sublimation, and expands many times its original thickness (up to 100 times), to form a stable, carbonaceous char. The resultant char reduces the conduction of heat from the fire to the substrate, delaying the time it takes to reach structural failure. I'm considering getting some for my kitchen remodel. https://www.nullifire.com/en-gb/expert-insights/expert-advice/the-different-types-of-intumescent-coatings-their-benefits/ https://www.nullifire.com/en-gb/expert-insights/expert-advic...
- aerostable_slug 2y agoC-RAM: counter rocket, artillery & mortar. You have to be able to get into the incoming rounds, through the metal bodies of artillery shells, rocket warheads, etc.
- jareklupinski 2y ago> Do you really need to burn through steel plate? not if you're accurate enough to hit its sensors
- spartanatreyu 2y agoWhat if the sensors are on the inside? It's possible to have a pre-programmed map, objective destination and accelerometers to judge distance.
- jareklupinski 2y agoif the payload is just ballistic and its trajectory is known, the target can just move out of its way and let it hit dirt those things usually have some sort of heat/EM/something seeking sensor to make it accurate to the last meter, and those still can't "see" through metal (yet (that we know about))
- metal_am 2y agoJust because something is reflective in the visible light spectrum doesn’t mean it’s reflective for the laser’s wavelength.
- nuccy 2y agoMetal coating (Al, Ag, Au) is reflective in very wide range of wavelengths - from far IR to EUV [1]. 1. https://en.m.wikipedia.org/wiki/Reflectance https://en.m.wikipedia.org/wiki/Reflectance
- jandrewrogers 2y agoYes, this is for highly maneuverable soft targets. A mirror will not work. At the power levels involved, any mirrors must be precisely tuned to the exact wavelength of the laser (e.g. dielectric mirrors) and they must be immaculately clean. That level of cleanliness is impractical in a military environment. Furthermore, the US has developed "white" laser weapons, which will defeat any tuned dielectric mirror like it wasn't there since the lasers have a broad spectrum of wavelengths.
- ein0p 2y agoNah, it’ll totally work. For one thing, you won’t be able to precisely track the spot at which energy is focused. For another, most rocket shaped targets can be made to spin (and some already do spin and rely on rotation to scan for targets), thus defeating your “directed energy” entirely. It’s a boondoggle and a waste of taxpayer money, easily defeated from a couple of miles away with a 50bmg rifle or a salvo of cheap unguided mines.
- jjtheblunt 2y agoWhat if mounted on an airframe a la pave-low ?
- some_random 2y agoHow are you going to defeat a drone swarm with a 50bmg rifle or dumb mines?
- ein0p 2y agoNot “drone swarm”, this laser can be easily defeated with cheap as dirt weaponry that’s been in use on the battlefield since WW1. In general anything that’s high tech and expensive makes an excellent target. Doubly so if it emits any electromagnetic radiation, and doesn’t shoot very far.
- jandrewrogers 2y agoYour intuition about the properties and effects of high-power lasers is failing you. The original design targets for US military lasers several decades ago were specifically selected because there are no practical countermeasures. These design targets were ambitious; it took several decades to develop practical lasers that could start to meet them. There are fundamental limits to material physics. Spinning doesn't help because there are always fixed points by definition. There are both materials science and engineering limits to spin rates, so you can precisely design your laser power levels to be reliably effective at the upper bound spin rates. All of this was fully modeled out and calculated half a century ago. Other countermeasures, like dielectric mirrors, would be very expensive to use on cheap weapons, and the US already developed a counter-countermeasure anyway with the invention of lasers that emit "white" light. The scientists and engineers that did R&D on this over the last several decades weren't idiots. Everything "obvious" that armchair weapons experts might come up with were accounted for a long time ago.