Defense against UAV's

Andrew Swallow wrote:

Many UAVs are flown under remote control. Radio direction finding may
permit the location of its headquarters to be found.

Good point, few countries have enough satellite bandwidth to manage
UAVs the way the US does, so unless Iran is buying bandwidth from
someone else, they'd have to be RC controlled UAVs.

That would make the controller VERY vulnerable to counter fire and
would severly limit range. It would also make the control of the UAV
somewhat easy to jam, or even commandeer.

wrote:
[snip]


A swarm of highly autonomous UAVs (perhaps better viewed as a swarm of
ultra cheap cruise missiles accompanied by some stealthy UAVs with good
sensor suites) launched on a 'kill everything that floats and
resembles a warship'' need not. The swarm flies silently (no

Try launch at night and attack anything that is between 2 and 150
degrees warmer than the sea. The Iranians would destroy the odd Iraqi
or Saudi car but that may not worry them. The upper limit stops the
second wave from attacking the same targets are the first wave.

Andrew Swallow

wrote:
With due respect I don't understand the argument fully in a naval
context. Surely a modern anti-ship missile is much more difficult
target, after all? In general they have small RCS towards target, they
fly very low and very fast. Furthermore their signature can be reduced
even further if design effort is put upon the problem. If we are
talking about small UAV used for anti-ship duties it's either a very
slow and small ASM or it can carry only a very limited payload.

The speed is the key. Most radars are programmed to filter out small
returns that aren't moving very fast, because its probably a bird.

If you get a small return, but its moving at Mach 2, that's a pretty
good indicator that you are not tracking a bird. Also, any inbound ASM
is going to have a visible heat signature as well, especailly the newer
supersonic ones.

Therein lies the problem with a UAV, the radar system ignores it
because its too slow.

Henry J Cobb wrote:
Jim Yanik wrote:
There's a lot of ASSUMPTION that this "UAV" was a small drone and not
a full-size RC military aircraft. Does anyone know for certain what it
was?

Well the USN hasn't said anything yet, so all we have to go on are what
the Iranians are known to have.

http://www.globalsecurity.org/milita...ran/ababil.htm
wing area 1.76m²
Max. launching weight 83 kg
Cruise speed 165 Knots
Endurance is 1.5 h

Minus 25 minutes on station leaves 30 minutes there and 30 minutes back
or a range of 80 nm.

-HJC

If it is cheap it does not have to make a return journey giving a range
of 160 nm.

Andrew Swallow

wrote:

An Iranian UAV was able to circle a U.S. aircraft carrier undetected
for 25 minutes.

How can we protect our forces against UAV's when other countries or
terrorist
organizations start using them against us?

Carrier launches it's own swarm of 1/6 scale Hellcats to cut the
intruders' crepe-paper streamers with their props...

Hezbollah also flew a UAV over Israel in 2004:

http://www.signonsandiego.com/news/w...on-israel.html

So this isn't a new problem.

Come to think of it, didn't an Israeli UAV photograph a U. S.
Helicopter carrier
off Lebanon while the Marines were in Beirut in the 1980's?

Keith W wrote:
If you are using video imaging (backed up by some other, e.g.
IR/passive EM sensors),
I suspect it is a graduate student's exercise in image recognition to
distinguish a warship (esp. aircraft carrier) from an oil
rig/tanker/finshing ship. Especially if you are flying slow.

As a software engineer I'd suggest you are wrong. If such recognition
is so easy how did an Argentine aircrew drop bombs on an
American tanker in 1982 believing it was a RN Carrier ?
Scared ****less of being shot down?
Wishful thinking?
Orgasmic about being able to release their weapons and claim kills?
Darkness/lousy weather/bad visibility?
Flying fast and having only few short seconds to make decision?
Releasing their weapons from way too far range for positive
identification (perhaps because being scared ****less)?

Can be any of these or their combination.

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), 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. Perhaps the
costliest part of the development would be sea trials (to see how is
the real-time identification working and debug it), but then who knows
what they use their small UAVs for now (see the first message of this
thread).

snip
200 km/hr UAV's are going to be rather vulnerable to all forms
of active defence including point defence missiles like RAM
and to CIWS.
Yes. That's why you want them to be really cheap and use swarming.

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.

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.

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. 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).

The CIWS mounts look rather distinctly and will obviously be among the
targeted areas of the ship. You don't need that much of a warhead to
put CIWS radar ot of commission - so perhaps an UAV with 200kg warhead
can actually carry 8-12 short range missiles designed for homing on
CIWS radar and launch them while being out of range of CIWS.


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. But it can be cheap,
especially if mass produced and intended for one-way cruise-missile
type missions. Ultralight aircraft kits are essentially hand-made and
sell for 10-20k. 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. Be smart
designing it (ease of mass production) and try to reduce the IR/radar
signature, but don't go overboard with that - keep the costs down. The
only potentially expensive parts on the aircraft are sensors and
warheads. The 200kg is the total useful load, some UAVs will have it
divided as sub missiles for massed attack on air defense radars, other
UAVs will simply have a big explosive load (hoping that the radars have
already been damaged, so they can get in close to do BAM).

....
simple systems are easier to debug/design correctly). However, a
country like China/India or even Iran should be able to mass produce
good enough UAVs for peanuts (i.e be able to field thousands of them).
The key term being 'good enough', not 'super duper, all weather, high
reliability and long service life'.

But with real time image recognition, organic SEAD and large warheads
Yeah, you need real time image recognition. That is the enabling
technology. I think we can agree to disagree whether that is possible
in the next 5-10 years, for operation in good visibility.

The quoted 200kg was just quoted as an example - about what an
ultralight aircraft can carry. You need your aircraft big enough to
have enough range to engage the carrier group operating off your
shores, so a 200kg payload will not significantly increase it anyway.
A modified ultralight can't fly that fast, leaving it rather
vulnerable. 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). 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.)


DUH !

Keith

Airyx wrote:
Therein lies the problem with a UAV, the radar system ignores it
because its too slow.

That lasts only as long as it takes to recognize the potential threat
that little, slow UAVs could pose. I can't imagine that developing a
new algorithm to pick out non-avian flight patterns would be that
tricky. I doubt that there are many birds that follow as linear and
consistent a flight pattern as your average UAV, and a cheap
lightweight UAV won't be able to spoof the behavior of a seabird.

Jeb wrote:
wrote:

The problem here is that it could be a kind of 'asymmetric warfare', in
that the costs and problems of the defence are potentially far more
costly than those of the attackers.

It would seem to me to be likely that a simple software code
modification would allow an Aegis system to detect smaller, slower
returns (I would expect that right now, those get filtered out so that
seabirds don't cause spurious readings on the radar scopes). If you
pick up a weak signal that doesn't belong there, just have AEGIS dump
all of its radiating power down a relatively tight beam and zorch a
little lightweight unshielded UAV right out of its electronic mind.
Shielding agains nuclear EMP might be tough (especially because it is
so non-trivial to check whether it works).

Shielding against a radar with known properties should not be a
problem. If you go to the pains of designing and building the UAVs, you
don't leave them vulnerable against such an obvious way to deal with
them.

Jeb wrote:
Airyx wrote:
Therein lies the problem with a UAV, the radar system ignores it
because its too slow.

That lasts only as long as it takes to recognize the potential threat
that little, slow UAVs could pose. I can't imagine that developing a
new algorithm to pick out non-avian flight patterns would be that
tricky. I doubt that there are many birds that follow as linear and
consistent a flight pattern as your average UAV, and a cheap
lightweight UAV won't be able to spoof the behavior of a seabird.


There is an upper limit on the number of targets a radar can track. A
thousand aircraft would be a large force but a thousand birds is a small
flock.

Andrew Swallow