I wonder if we can repurpose mm-wave 60GHz panel antennas and SDRs for cheap short-range radars. Then combine with a commercial infrared camera for multi-mode target acquisition. Put those on a mount with servos to control a PKM or M240 machinegun, and mount the whole setup on the roofs of buildings. Critical infrastructure anti-drone air defense guns at fairly low cost.
Then you just get stealth drones (fixed wing). Bondo, styrofoam, electric ducted fans, frequency hopping radio links, all easily doable. Only hard part really is range. For that, I could see hybrid electrics that power down the gas/nitro engine for stealth.
> Put those on a mount with servos to control a PKM or M240 machinegun
Leaving weapons unattended like that is a recipe for disaster. Even worse if they're network-connected (look at the tons of insecure IoT devices already out there).
CRAMs are both several tons in weight, require a lot of power and special mounting, and are found mounted on a warship or in a military base; you're not really going to worry about some random insurgent carrying it off. Besides, they eat 20x102mm ammunition, which isn't exactly common stuff.
That is a far cry from the consequences of leaving a M240 around, which is both man portable and consumes the incredibly common 7.62x51mm NATO cartridge.
