Another hard-sci-fi military engineering idea: Shield against missile attacks built out of drone swarm.
Say you have little quadcopters that are about 10cm by 10cm square and contain about a bullet’s worth of explosive charge. You use them to make a flying “blanket” above your forces; they fly in formation with about one drone per every square meter. Then if you have 1,000 drones you can make a 1,000 sq meter blanket and position it above your vehicles to intercept incoming missiles. (You’d need good sensors to detect the missiles and direct the nearest drone to intercept) With drones this small they’d be cheaper than missiles (and therefore a worthy trade) and also you could carry around that many drones in a truck or something fairly easily.
Problem: Can they actually move quickly enough to scoot 1 meter in an arbitrary direction to intercept a missile? Not sure. To figure out I could look up typical missile velocities and compare to acceleration abilities of small drones to get a sense of how far out the missile would need to be spotted & tracked. You can always have the drones cluster more densely, but
Problem: Powering all those drones would drain a lot of energy. You’d need to have maybe 2x as many drones as actually fit in your shield, so you could be recharging half of them while the other half is in the air. To figure this out I could look up how much energy minidrones actually use and then compare that to what e.g. a portable gas generator can produce.
Problem: There are probably countermeasures, e.g. fuel-air bombs designed to explode in the air and take out a good portion of your drone swarm, followed by a normal missile to punch through the hole. Not too concerned about this because almost all military weapons and defenses have counters, it’s all a game of rock paper scissors anyway. (If there are good counters to it then that just means it’s only situationally useful, i.e. in situations where your adversary doesn’t happen to have those counters.) But worth thinking about more.
Problem: How is this better than just having CIWS point defense? Answer: Against a single missile it’s much worse. But point defenses can be overwhelmed by barrages of missiles; if 10 missiles are coming at you at once you simply don’t have time to shoot them all down with your single turret. Whereas a drone shield much more gracefully scales. Also, point defense turrets are heavy and need to be lugged around by the vehicles being defended, and also work less well in dense terrain with obscured views. Drone swarms are heavy too, but only when you aren’t using them; when they are deployed your troops and equipment can move freely and enter dense urban terrain and the drones can keep up with them and morph around the terrain.
It seems that if the quadcopters are hovering close enough to friendly troops it shouldn’t be too difficult to intercept a missile in theory. If you have a 10 sec lead time (~3 km at mach 1) and the drone can do 20 m/s that’s 200 meters. With more comprehensive radar coverage you might be able to do much better.
I wonder how large the drone needs to be to deflect a missile however. Would it need to carry a small explosive to send it off course? A missile is a large metal rod—in space with super high velocity even a tiny drone would whack a missile off course/ destroy it but in terrestial environments with a missile <=1 mach I wonder what happens.
If the drone has a gun with inflammatory bullets you might be able to blow-up the very flammable fuel of a missile. ( I don’t know how realistic this is but doesn’t seem crazy- I think there are existing missile defense systems with inflammatory bullets?).
Against a juking missile things change again. With airfins you can plausibly make a very swift & nimble juking missile.
Another hard-sci-fi military engineering idea: Shield against missile attacks built out of drone swarm.
Say you have little quadcopters that are about 10cm by 10cm square and contain about a bullet’s worth of explosive charge. You use them to make a flying “blanket” above your forces; they fly in formation with about one drone per every square meter. Then if you have 1,000 drones you can make a 1,000 sq meter blanket and position it above your vehicles to intercept incoming missiles. (You’d need good sensors to detect the missiles and direct the nearest drone to intercept) With drones this small they’d be cheaper than missiles (and therefore a worthy trade) and also you could carry around that many drones in a truck or something fairly easily.
Problem: Can they actually move quickly enough to scoot 1 meter in an arbitrary direction to intercept a missile? Not sure. To figure out I could look up typical missile velocities and compare to acceleration abilities of small drones to get a sense of how far out the missile would need to be spotted & tracked. You can always have the drones cluster more densely, but
Problem: Powering all those drones would drain a lot of energy. You’d need to have maybe 2x as many drones as actually fit in your shield, so you could be recharging half of them while the other half is in the air. To figure this out I could look up how much energy minidrones actually use and then compare that to what e.g. a portable gas generator can produce.
Problem: There are probably countermeasures, e.g. fuel-air bombs designed to explode in the air and take out a good portion of your drone swarm, followed by a normal missile to punch through the hole. Not too concerned about this because almost all military weapons and defenses have counters, it’s all a game of rock paper scissors anyway. (If there are good counters to it then that just means it’s only situationally useful, i.e. in situations where your adversary doesn’t happen to have those counters.) But worth thinking about more.
Problem: How is this better than just having CIWS point defense? Answer: Against a single missile it’s much worse. But point defenses can be overwhelmed by barrages of missiles; if 10 missiles are coming at you at once you simply don’t have time to shoot them all down with your single turret. Whereas a drone shield much more gracefully scales. Also, point defense turrets are heavy and need to be lugged around by the vehicles being defended, and also work less well in dense terrain with obscured views. Drone swarms are heavy too, but only when you aren’t using them; when they are deployed your troops and equipment can move freely and enter dense urban terrain and the drones can keep up with them and morph around the terrain.
It seems that if the quadcopters are hovering close enough to friendly troops it shouldn’t be too difficult to intercept a missile in theory. If you have a 10 sec lead time (~3 km at mach 1) and the drone can do 20 m/s that’s 200 meters. With more comprehensive radar coverage you might be able to do much better.
I wonder how large the drone needs to be to deflect a missile however. Would it need to carry a small explosive to send it off course? A missile is a large metal rod—in space with super high velocity even a tiny drone would whack a missile off course/ destroy it but in terrestial environments with a missile <=1 mach I wonder what happens.
If the drone has a gun with inflammatory bullets you might be able to blow-up the very flammable fuel of a missile. ( I don’t know how realistic this is but doesn’t seem crazy- I think there are existing missile defense systems with inflammatory bullets?).
Against a juking missile things change again. With airfins you can plausibly make a very swift & nimble juking missile.