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Posted by David McMillan on December 19, 2008, 2:40 pm
Ben Bradley wrote:
> On 15 Dec 2008 08:02:02 GMT, curt@kcwc.com (Curt Welch) wrote:
>
>>> On Mon, 15 Dec 2008 03:37:16 +0000, steamer wrote:
>>>> --This thing's been around in one form or another for over a decade;
>>>> it's old Reagan era tech but it's looking a little more sophisticated
>>>> now. IIRC it's intended to be an *orbital* kill vehicle; i.e. if fired
>>>> into the right orbit all it's gotta do is line itself up and, at a
>>>> closing velocity of several miles per second, achieve a 'kinetic kill';
>>>> no explosives needed. Supposed to be launched in swarms, too.
>>> If it is intended to ram into its target, then why did it appear to be
>>> firing guns in multiple directions? The flame from the underside
>>> appeared to be a rocket engine; the brief flames going in other
>>> directions looked, and sounded like, gunfire.
>> Nah, I don't think so. The flames elsewhere were just stabilizer rockets
>> keeping it pointed upright and making it move right and left. They were
>> pulsing like that because they probably can't be adjusted for thrust. They
>> are either on (full thrust) or off (no thrust) so the control system has to
>> pulse them like that to keep the device stable.
>
> I wonder why the main engine wasn't put on a gimbal and it
> controlled that way, though perhaps the multiple rockets and on/off
> valves are more reliable.
Faster. Reaction times are far lower. Plus, no rotational inertia to
deal with. Note that each thruster is mounted to thrust directly
through the center of gravity of the vehicle. Given that it's intended
to attack a target via hit-to-kill at truly ludicrous closing speeds,
the guidance system needs to be capable of making lots of very small
velocity vector changes *very* rapidly.
In a real scenario, it would be be operating in a free-fall
environment, so there wouldn't be any "hover" thrust going continuously.
All the thrusters would be pulsing as needed to keep the target in the
crosshairs. Conceptually, it's a very simple guidance system, but
getting it to work dependably and quickly enough must have been a huge
challenge.
>> The film was called "hover
>> test" so it's clearly just a prototype to test to see if the control system
>> could make it hover and move back and forth - which it did very nicely
>> until it was turned off (or maybe just ran out of fuel).
>
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