In article ,
David Pugh -cay wrote:
Of course, how hard would it be to add GPS guidance to a Katyusha rocket?

You can't do it with a civilian 'one chip' GPS, they don't like high
speed.

Since the rockets rotate (I think) the antenna is going to be a problem.

You'll need a gyro in the rocket so it can know where 'down' and 'north'
is since the GPS gives its outputs as long/lat.

Then the guidance has to translate this data into steering commands,
taking into account the altitude and the speed of the rocket so that it
can fly a sane trajectory. And while you *can* get altitude and speed from
the GPS, they won't be especially accurate. If that is a problem, and
I think it is (Imagine the the poor rocket thinking it is 200m west
of the target at 50m and 300m/s, and the altitude from the GPS is in
error by 50m high. Oops) you'll need a pitot and barometric altimeter,
or a radar altimeter.

The guidance is doable, but hard.

If
you could bring the CEP down to 10m or so and still have a warhead of 10kg
(the 122mm Katyusha has a 20kg warhead so this is at least plausible), you'd
have a very, very nasty weapon for insurgents (target checkpoints, the
people trying to evac the victims of the latest road-side bomb, etc.) or
terrorists (target parked commercial aircraft at a gate, the 50-yard line at
the Super bowl, etc.).

If everything went right in the R&D and it was as lean as lean can be
each round would still be as expensive as a MANPADS.

If it was fatter: Copperhead.

-bertil-
--
"It can be shown that for any nutty theory, beyond-the-fringe political view or
strange religion there exists a proponent on the Net. The proof is left as an
exercise for your kill-file."