Airborne lasers

Allen Thomson wrote:

Pat Flannery wrote



The ideal time to hit it would be by firing virtually straight up at it
as it reaches the apex of its trajectory...and its lowest velocity.




The present version of the ABL has a fairly specific CONOPS and
damage mechanism in mind. See slide 5 in
http://www.defenselink.mil/news/Jul2...-6570C-001.pdf .


Now that's interesting...it implies that they assume that the missiles
they are going to be shooting at are liquid-fueled.
I wonder how long of a laser illumination they need to destroy a
solid-fueled one?
Also, this technology would be hard pressed to defeat a High G
Acceleration/Short Burn Time solid-fueled missile (like a
surface-to-surface variant of the Sprint), as the motor burn would be
over before the aircraft could detect, target, and engage it effectively.
The thick motor casing of a solid-fuel missile of any sort would mean
that the laser would have a hard time heating its contents in comparison
to the thin tank walls of a liquid-fueled missile.

Pat

"Pat Flannery" wrote in message
...
Also, this technology would be hard pressed to defeat a High G
Acceleration/Short Burn Time solid-fueled missile (like a
surface-to-surface variant of the Sprint), as the motor burn would be over
before the aircraft could detect, target, and engage it effectively.
The thick motor casing of a solid-fuel missile of any sort would mean that
the laser would have a hard time heating its contents in comparison to the
thin tank walls of a liquid-fueled missile.

Perhaps burning through the casing would be feasible at a distance.

Pat Flannery wrote

Now that's interesting...it implies that they assume that the missiles
they are going to be shooting at are liquid-fueled.

Yes, but much of the current TBM threat is composed of Scud-like
liquid-fueled missiles, so that's ok.

I wonder how long of a laser illumination they need to destroy a
solid-fueled one?

Also, this technology would be hard pressed to defeat a High G
Acceleration/Short Burn Time solid-fueled missile (like a
surface-to-surface variant of the Sprint), as the motor burn would be
over before the aircraft could detect, target, and engage it effectively.
The thick motor casing of a solid-fuel missile of any sort would mean
that the laser would have a hard time heating its contents in comparison
to the thin tank walls of a liquid-fueled missile.

It isn't clear that the ABL Mod 1 is intended to defeat things like
the SS-21 or M-9/M-11, all of which are harder and burn faster than
Scudish missiles.

Perhaps that's for Mod 2 and beyond.

In sci.space.policy Neil Gerace wrote:
"Pat Flannery" wrote in message
...
Also, this technology would be hard pressed to defeat a High G
Acceleration/Short Burn Time solid-fueled missile (like a
surface-to-surface variant of the Sprint), as the motor burn would be over
before the aircraft could detect, target, and engage it effectively.
The thick motor casing of a solid-fuel missile of any sort would mean that
the laser would have a hard time heating its contents in comparison to the
thin tank walls of a liquid-fueled missile.

Perhaps burning through the casing would be feasible at a distance.

A really neat idea comes to me.

On the front of a liquid fuelled rocket, you put a heat exchanger, and
run the fuel through it first.
Add some really big jettisonable aero surfaces, so that it can point
accurately at the laser, jettison the aero surfaces.
Ride the beam in.

Allen Thomson wrote:

Pat Flannery wrote



Now that's interesting...it implies that they assume that the missiles
they are going to be shooting at are liquid-fueled.



Yes, but much of the current TBM threat is composed of Scud-like
liquid-fueled missiles, so that's ok.


At the moment, yes...but what about the timeframe when this system
becomes operational...say in ten years or so?

It isn't clear that the ABL Mod 1 is intended to defeat things like
the SS-21 or M-9/M-11, all of which are harder and burn faster than
Scudish missiles.

Perhaps that's for Mod 2 and beyond.


The Russians laser armored their SS-18 mod 5 according to this:
http://www.astronautix.com/lvs/r36m2.htm
Putting polyurethane foam over the rocket body would mean that the laser
would have to burn it off before heating the structure of the missile's
fuel tanks.
Two other techniques come immediately to mind for defeating laser attack
on a missile; spinning it on it's axis to spread the illumination over a
wider area, and enveloping the missile in a smoke cloud during ascent
via a smoke generator on its nose.
The laser would heat the smoke, not the missile's body.

Pat

Ian Stirling wrote:

A really neat idea comes to me.

On the front of a liquid fuelled rocket, you put a heat exchanger, and
run the fuel through it first.
Add some really big jettisonable aero surfaces, so that it can point
accurately at the laser, jettison the aero surfaces.
Ride the beam in.


Hey, I _like_ that! They wouldn't be expecting that, would they?

Kim Jong-Il

Pat Flannery wrote:


Allen Thomson wrote:

Pat Flannery wrote


Now that's interesting...it implies that they assume that the
missiles they are going to be shooting at are liquid-fueled.



Yes, but much of the current TBM threat is composed of Scud-like
liquid-fueled missiles, so that's ok.


At the moment, yes...but what about the timeframe when this system
becomes operational...say in ten years or so?

It isn't clear that the ABL Mod 1 is intended to defeat things like
the SS-21 or M-9/M-11, all of which are harder and burn faster than
Scudish missiles.

Perhaps that's for Mod 2 and beyond.


The Russians laser armored their SS-18 mod 5 according to this:
http://www.astronautix.com/lvs/r36m2.htm
Putting polyurethane foam over the rocket body would mean that the laser
would have to burn it off before heating the structure of the missile's
fuel tanks.

If part of the polyurethane foam is burned off, wouldn't that make the
missile's mass distribution asymetrical? I think that'd chinger the
missile as the thrust vector needs to point through center of mass.

Two other techniques come immediately to mind for defeating laser attack
on a missile; spinning it on it's axis to spread the illumination over a
wider area, and enveloping the missile in a smoke cloud during ascent
via a smoke generator on its nose.
The laser would heat the smoke, not the missile's body.

How about a highly reflective, mirror surface?

Reflectors on bicycles or roadside warning signs employ three sets of
mirror fragments, each set perpendicular to the other two. Looking into
a triplet of mirror fragments would be like looking into a box corner.

Any beam hitting such a corner is bounced back in the direction it came.


Pat



--
Hop David
http://clowder.net/hop/index.html

On the front of a liquid fuelled rocket, you put a heat exchanger, and
run the fuel through it first.
Add some really big jettisonable aero surfaces, so that it can point
accurately at the laser, jettison the aero surfaces.
Ride the beam in.



The ABL isn't a continuous-fire weapon, it fires short bursts.
Not long enough for something to home in on.

The 'rangefinding' laser paints the target for a longer period
before the weapon fires, but I doubt even that is long
enough.

Eric P.

Eric Pawtowski wrote:

On the front of a liquid fuelled rocket, you put a heat exchanger, and
run the fuel through it first.
Add some really big jettisonable aero surfaces, so that it can point
accurately at the laser, jettison the aero surfaces.
Ride the beam in.

The ABL isn't a continuous-fire weapon, it fires short bursts.
Not long enough for something to home in on.

Sorry, but that's hogwash. If you can get the instantaneous direction
of the incoming pulse, then the same for several following pulses,
then you can derive the track of the firing unit by working from that
data. If you can derive the track, you can send a weapon to
intercept.

D.
--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL

Pat Flannery wrote:

Allen Thomson wrote:

Pat Flannery wrote

Now that's interesting...it implies that they assume that the missiles
they are going to be shooting at are liquid-fueled.


Yes, but much of the current TBM threat is composed of Scud-like
liquid-fueled missiles, so that's ok.

At the moment, yes...but what about the timeframe when this system
becomes operational...say in ten years or so?

Probably still liquids as big solids are difficult to do. Even if the
threat vehicle is solid fueled, burning a hole in the side of it will
do it no favors.

The Russians laser armored their SS-18 mod 5 according to this:
http://www.astronautix.com/lvs/r36m2.htm

Mark needs to change his drug dosages.

Putting polyurethane foam over the rocket body would mean that the laser
would have to burn it off before heating the structure of the missile's
fuel tanks.

Handwaving away the problems of keeping the foam in place, and of the
weight of the foam.

Two other techniques come immediately to mind for defeating laser attack
on a missile; spinning it on it's axis to spread the illumination over a
wider area,

Handwaving away the enourmous problems this causes in guidance.

and enveloping the missile in a smoke cloud during ascent
via a smoke generator on its nose. The laser would heat the smoke, not the
missile's body.

Hanwaving away the problem of creating a dense enough smoke cloud.

Pat; stick to cute personality filled monkeys. At least there you
have a clue what you are talking about.

D.

--
Touch-twice life. Eat. Drink. Laugh.

-Resolved: To be more temperate in my postings.
Oct 5th, 2004 JDL