Re: Airborne lasers

From: Pat Flannery (flanner_at_daktel.com)
Date: 11/13/04 

Date: Sat, 13 Nov 2004 17:19:30 -0600

Mary Shafer wrote:

>A laser is no more of an electromagnetic emitter than is a landing
>light.
>

Light is a part of the electromagnetic spectrum, and a laser puts out
coherent light.
It's extremely directional in this case, but the idea was to turn the
missile into the beam and fly up it till the missile impacts the carrier
aircraft and destroys it.

>
>
>Maybe you could use the same kind of sensor they use on LGBs
>(Laser-Guided Bombs), since those are designed to home in on laser
>light.
>
They are designed to go after a spot on a target illuminated by a laser,
homing on the reflected light; this gizmo is so powerful that it can
melt things at over a hundred miles or so- trying to fly up its beam
into the carrier aircraft is going to get the sensor white hot, so I'm
pretty sure that optical homing devices are right out, as there is
simply too much energy to deal with.

>
>
>
>>>Smoke generators may have uses.
>>>Even relatively small impurities can cause a high intensity beam to
>>>generate plasma in the atmosphere.
>>>
>>>
>>>
>>The trick is to get the smoke far enough away from the missile's skin-
>>you'd want it a few feet away probably.
>>I get the feeling that the ABL is going to end up being like the
>>battlecruiser- it sounds good on paper, but... :-\
>>
>>
>
>I don't think smoke is going to do it, though. It's just too
>complicated to put a smoker on a missile.
>
I'm still playing around with my solid fuel rocket with exhaust nozzles
mounted on the _top_ of the fuel grain, and angled outwards- sheathing
the missiles' body in its own exhaust smoke cloud as it rises. This
would work fairly easily for a single staged missile, but gets pretty
involved for a multi-stage one, as the stages have to be mounted behind
the top (first) stage.
QuickBurn/High Acceleration missiles are still the best way to beat this
system though.
Sprint could hit Mach 10 within five seconds of launch. Asking a ABL to
spot, track, and successfully engage a missile within five seconds of
launch (especially if it's coming up out of cloud cover) is a very tall
order; and a warhead moving at Mach 10 is going to coast a very long way
on a ballistic trajectory after booster burnout.
Since the warhead is going to be thermally resistant already to protect
it during the boost an reentry phases of its flight, it will be able to
take a good deal of laser heating also; Sprint's warhead could deal
with very high heat loads:
http://www.paineless.id.au/missiles/Sprint.html
"Air friction alone during flight of the missile generated temperatures
of up to 3400°C (6200°F), and the ablative heat shield could dissipate
heat at rates up to 850 BTU/ft/sec. Sprint was also constructed to
withstand shocks up to 25,000Gs which meant it could handle nearby
nuclear explosions and their resulting blast (how hardened it was to EMP
and radiation is unknown). When in flight, the missile was surrounded by
a plasma sheath which the command signals from the MSR were able to
penetrate. This was achieved due to the sheer high power of the MSR (a
beam that was less than 1 degree wide, and had a power of at least 1MW)."
Because of its speed of ascent, Sprint was enveloped in a superheated
plasma sheath; this also may also have a departmental effect on a laser
beam trying to hit it.
(Anybody know how far something moving at Mach 10 is going to go if
fired on a 45 deg. ascent profile?)

Pat

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