Defense against UAV's

Keith W wrote:

Can be any of these or their combination.
Or just maybe its harder than you think.
Somehow I doubt when they were overflying the tanker in daylight, they
still thought they are attacking an aircraft carrier. :-)

A UAV with realtime video image recognition and IR sensors is unlikely
to be especially cheap
Realtime video image recognition needs a source of video (probably a
wide-angle search camera + narrow angle scope with some decent
magnification for examining the suspicios contacts),

Problem 1 ) You have to process them to decide if they are suspicious
There are not so many big things floating in the ocean, just examine
them all.
While the waves move and provide clutter, in half-decent weather a
100m+ ship tends to stick out as a sore thumb from quite afar. And it
is quite unlikely there will be third party merchants sticking around a
US carrier group in time of armed conflict....

a decent CPU to do
the number crunching and a software to do the analysis. The first two
items are not particularly expensive. The software might take real
pains to develop, but afterwards the copies are free.
Understatement of the year
Yes, if you want to be able to do it in all weather, from 50km+ afar,
your target hidden among the merchants, in few moments of ultrasonic
flight.

In fair weather, from less then 15km, with closing speed of 200km/h, I
am not so sure. Warships do look quite differently then merchants/oil
rigs, and they also tend to radiate differently.

With real time image recognition systens cheap will be quite a trick.
The cost might be high for initial development, but there is not reason
the cost should be high on per-unit base. Cameras/CPUs and copying
software is cheap. Cooled IR sensors and other fancy sensor stuff might
rise the cost - the question is how much of it is needed, especially
if you don't ask for all-weather capability.

All of it or it wont work
See above. Fair weather, no clutter. You want sensors from different
spectra to work together, but they can be the cheap stuff...

On
the other hand RAM is IR homing and the IR signature of a 100hp piston
engine is negligible compared to the IR signature of a rocket/jet
engine of the current antiship missiles.
But not small enough to be invisible
Nothing is invisible. But if its signature is there with seagulls and
sun reflections off waves, the locking/homing task is so much harder.

Seagulls dont have 100 hp engines. Even cheap IR sensors
have no problem with people let alone IC engines
With the engine tucked at the back (like Predator) and with good mixing
of the exhaust gas, you are mostly looking at cold front face.
Seagulls/people tend to present warm bodies.

Moreover, those cheap sensors are not mounted on supersonic missiles
screaming to intercept you (the heat of the supersonic air alone might
wash out your meager IR signature).

Phalanx (or other gun-based CIWS) should be effective, but has rather
short range (and not THAT much reloads, if you are dealing with a huge
swarm). I suspect it is also looking at targets with much higher radar
signature and very different characteristics.

Thats just software and rather easier to do than deciding if
that 1000 ft long ship is a carrier or VLCC
An attacking UAV can make its decision to attack close enough - when it
can actually see the island/aircrafts on deck of the carrier.

First it has to decide to get close enough, then it has to survive
the transit
First is not that tough - with enough endurance reserve. Second is the
matter of identification distance. And if the suspected target is
illuminating me with targetting radar, I don't really have problem to
identify it as a target, even if I am relatively far.

And has a
lots of frames to base its decision on. It might even send some info to
the controller and ask whether to attack or not (again, tradeoff
between how much you send and how reliable you want your communication
channel to be).
Comms are BAD things for an autonomous UAV , they can be jammed
Yes - but low bandwith intelligently designed comms are tough to jam.

Earth Calling Planet Esteban - a UAV with 200kg warhead and
8-12 sub missiles will be neither small nor cheap.
Such an UAV will not be small: it will be Predator size, powered by a
Rotax, Jabiru or more likely cheap copy of them.
None of which carry 8-12 sub missiles.
Useful load of Predator is about thousand pounds. A hellfire is more
useful for predator then 8-12 short range anti-radar missiles.

Note that controlling
Predator involves 3 operators in a 30ft trailer packed with electronics
Predator does a lot more, and the operators/electronics are there to
analyze/evaluate what it sees, in a much harder to analyze environment,
and with much higher expectations.

Ultralight aircraft kits are essentially hand-made and
sell for 10-20k.

Indeed but of course they fly a around 70 knots
with a max gross weight of around 300 kg, not
much room there for 200kg warheads
Ultralights with 100hp engines are limited to cca 500kg and 100knots by
law, not by physics. Predator uses the same 100hp Rotax and has 220km/h
max speed, around 1000kg takeoff weight of which cca 500kg is dry
weight (200payload, 300 fuel).
That 500kg of dry weight also includes lots of sensors you will do
without.

Replace the cabin with the warhead(s), give it faster
wing (no need for low stall speed, this is on one way mission) and the
sensors/brains/communication kit and mass produce it.

Real easy huh , when do you plan to start production ?
The tough part is really the sensors/data analysis, not the
airframe....


That's why you are better of launching submunitions from
out of range of the gun CIWS. Those subminitions need to be reasonably
smart (once qued by the sensors of the main craft, they need to be able
to lock on their target and hit it), but not necessarily pack a lot of
punch (hitting radars, aircraft on deck and so on).

Hint CIWS reach a long way , the sort of missile you'd need would
be stinger sized at a minimum and you need a control system
smart enough to know WHEN to fire, sensor fuzion is harder than
you seem to think
Stinger missile proper weights 10kg, plenty of room in my 200kg
allowance for 8 of them.

Somehow identifying the range to the target (when you are within line
of sight and less then 10km away) does not seem too hard to me.

Knowing that I am being illuminated by targeting radars also helps in
making my decision.

Once the radars
have been damaged, the second wave can then just press on with large
warhead bringing general destruction. (Or, to keep it simple, they all
go together. If the radars are switched off, the large warheads will
arrive and do the damage, if the radars are on (likely), the
submunitions will home on them.)
So you now rely on a new development of small fast radar
homing sub munitions as well, and all this a grad student
technology , yeah right !
No, being India/China/Iran, I already have those - maybe a bit larger,
but no significant new development needed.

Keith