Army Laser Passes Drone-Killing Test

Nerval's Lobster writes "Commercial package-delivery drones such as those revealed by Amazon and DHL could face danger from more than shotgun-toting, UAV-hunting yahoos following the successful test of a drone-killing laser by the U.S. Army. Though it's more likely to take aim at enemy observation drones than Amazon's package-deliver 'copters, the U.S. Army's High Energy Laser Mobile Demonstrator (HEL-MD) did prove itself in tests last week by shooting down 90 incoming mortars and a series of Unmanned Aerial Vehicles (UAV). The original goal during the test at White Sands Missile Range in New Mexico was to burn out or blow up mortar rounds and blind the cameras or other sensors carried by drones. The laser proved capable enough to damage or slice off the tails of target drones, which brought them down, according to Terry Bauer, HEL MD program manager, as quoted in the Dec. 11 Army announcement of the test. The quarter-sized beam of super-focused light set off the explosives in the 60-millimeter mortars in mid-flight, leaving the rest to fall 'like a rock,' Bauer said. The laser could target only one mortar at a time, but could switch targets quickly enough to bring down several mortars fired in a single volley. The laser and its power source are contained in a single 500-horsepower, four-axle truck but was directed by a separate Enhanced Multi Mode Radar system. The next step is a move from New Mexico to a testing range in Florida early next year 'to test it in rain and fog and things like that,' according to Bauer."

Re:Advantages of DEWs

[C0R1D4N]

I don't think the laser beam has an arc and return trajectory.

Re:Advantages of DEWs

[barlevg]

Several things wrong with this.

-More like cooked--these beams aren't visible spectrum.
-Yes, I'd rather be blind than have a bullet to the head.
-Cities and buildings shouldn't be in the linear line of fire of these beams (which will mainly be shooting up). The issue that X0563511 brought up is based on that obscure sciencey concept that things that go up usually come back down.

Targeting and Speed of Light ...

[perpenso]

I was wondering why bother with directed energy weapons?

With speed of light weapons the target does not move very far between firing and impact. Point of aim is basically point of impact, unlike bullets. No guidance system required, unlike missiles.

Ammunition is unlimited as long as you have power.

And because sci fi fans have been waiting for this since 1898. The War of the Worlds, H. G. Wells.

Re:Reflective Armor

[Sique]

Yes and no. The 90% are only valid if the laser beam hits the object nearly at 90 degrees. Then indeed, the reflection will cause 90% of the energy to be reflected and 10% will be heating the surface. But still, this means we need to have a 10 times larger laser to have the same effect than on a non reflective (black) object.

But in general, the beam will hit the surface at lower angles, and then we have to multiply the energy with the sinus of the angle. So if it hits the surface at 45 degrees, only about 71% of the energy will be transferred, and we need to increase the laser beam another 40%. And at lower angles, there is total reflection, and 0% of the laser will be able to heat the surface, as 100% of the energy is reflected. In general: if we build a drone like a stealth bomber with a shell of plane, mirroring facettes, laser beams will be rendered totally ineffective except for the seldom case that they hit the drone's surface at 90 degrees with 10 times the necessary energy.

Re:Reflective Armor

[Tuidjy]

> If you paint them reflective, they don't get destroyed by the laser.

You wish.

Polished metal mirrors reflect about 90%. if you use some really expensive metals, you can push it to 95%. Milar, dielectric coatings, etc. can go up to 99.99%, but only in specific wavelength.

Sounds great? Well, no. That's the reflection you get in vacuum, when the mirror is pristine. Now fire it from a mortar, have it heated by the air rushing past, and then apply even 1% of the output of the laser we're talking about. Your nice upper layer is gone, and your reflection drops like a rock... followed by the rest of your round, once the payload overheats and blows up.

Very expensive reflective coating may buy you a fraction of a second, maybe even a whole one... but mortars are (1) cheap (2) slow to get to the target. So you just made each round a lot more expensive, and you still may not have bought enough time for it to get to the target.

Re:Reflective Armor

[CanHasDIY]

Maxim 37: There is no 'overkill.'

There is only 'open fire' and 'I need to reload.'