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asymetric warfare



 
 
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  #462  
Old December 31st 03, 03:58 PM
Arved Sandstrom
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"Chad Irby" wrote in message
om...
In article ,
"Damo" wrote:

I was under the impression (mistaken?) that the F-22 can only carry 4
air-to-air missiles, if it carries more it loses what stealth it had and

you
might as well send in F-15s??


Six AIM-120C in the center bay plus two Sidewinders in the side bays.

Or two AIM-120C + 2 JDAMs in the center bay and two Sidewinders in the
side bays.

If they go with external tanks and missiles, they get another four
AIM-120s and another 1200 gallons of fuel, but they lose stealth if they
do that.


Just out of curiosity, why were they not able to design conformal external
fuel tanks that also are fairly stealthy? I find it difficult to believe
that it could not be done.

AHS


  #463  
Old December 31st 03, 04:14 PM
Kevin Brooks
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"Arved Sandstrom" wrote in message
...
"Chad Irby" wrote in message
om...
In article ,
"Damo" wrote:

I was under the impression (mistaken?) that the F-22 can only carry 4
air-to-air missiles, if it carries more it loses what stealth it had

and
you
might as well send in F-15s??


Six AIM-120C in the center bay plus two Sidewinders in the side bays.

Or two AIM-120C + 2 JDAMs in the center bay and two Sidewinders in the
side bays.

If they go with external tanks and missiles, they get another four
AIM-120s and another 1200 gallons of fuel, but they lose stealth if they
do that.


Just out of curiosity, why were they not able to design conformal external
fuel tanks that also are fairly stealthy? I find it difficult to believe
that it could not be done.


I think it is not that it could not be done--it is more a factor of not
being required. The F-22 already has a pretty good range (reportedly
superior to all other current and near-future competitors). Of course it can
also carry its conventional external tanks as required--I would think that
dropping those before entering into the threat envelope would clean it back
up to a pretty stealthy profile (the point being that stealth is not
required for the full flight profile--only during the
ingress/attack/egress).

Brooks


AHS




  #464  
Old December 31st 03, 04:46 PM
Fred J. McCall
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"Arved Sandstrom" wrote:

:Just out of curiosity, why were they not able to design conformal external
:fuel tanks that also are fairly stealthy? I find it difficult to believe
:that it could not be done.

Because the weapons carriage is internal. You can't launch weapons
through a conformal tank. It would also make the tank quite expensive
(rather than just steel). There is also the issue of changing the
shape of the airframe with conformal tanks (all those join lines),
which makes this a lot more difficult than you apparently think.

All this means you might as well just design the volume into the
airframe in the first place (which is what they did).

--
"Millions for defense, but not one cent for tribute."
-- Charles Pinckney
  #465  
Old December 31st 03, 05:24 PM
Chad Irby
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In article ,
"Arved Sandstrom" wrote:

Just out of curiosity, why were they not able to design conformal external
fuel tanks that also are fairly stealthy? I find it difficult to believe
that it could not be done.


Money.

Once the F-22 makes it into the inventory on a serious basis, someone's
bound to come up with something like that. They built in enough extra
pieces to make it easier when they *do* get around to it (like the wing
pylons that could, if they wanted, let them hang eight AIM-120Cs under
the wings for a total of ten).

--
cirby at cfl.rr.com

Remember: Objects in rearview mirror may be hallucinations.
Slam on brakes accordingly.
  #466  
Old December 31st 03, 07:19 PM
Arved Sandstrom
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"Fred J. McCall" wrote in message
...
"Arved Sandstrom" wrote:

:Just out of curiosity, why were they not able to design conformal

external
:fuel tanks that also are fairly stealthy? I find it difficult to believe
:that it could not be done.

Because the weapons carriage is internal. You can't launch weapons
through a conformal tank. It would also make the tank quite expensive
(rather than just steel). There is also the issue of changing the
shape of the airframe with conformal tanks (all those join lines),
which makes this a lot more difficult than you apparently think.


I know it's not easy. I do have a physics degree and some electrical
engineering under my belt. Yes, the tank would cost a few bucks - compared
to the price of the a/c itself I don't know how worried I'd be about that.
And I know a bit about antenna theory, so I am not oblivious to the fact
that it would have to be carefully done. But I suspect it would be less
difficult to do than you suggest.

All this means you might as well just design the volume into the
airframe in the first place (which is what they did).


Resulting in yet other compromises.

AHS



  #467  
Old December 31st 03, 07:31 PM
William Baird
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LukeCampbell wrote in message
My prediction is that laser weapons will really take off when a
practical, high efficiency, high repetition rate short pulsed
(nanosecond or less) laser with a reasonable energy per pulse (say about
a joule) is available.


FWIW, the LLNL solid state laser is a pulsed one. The flash lamps are
supposed to be followed on with LEDs as well.

Ah, here we go:

"The project scientists are also investigating several diode
cooling and packaging techniques for optical pumping using
laser diodes. A 10-bar prototype monolithic diode array is
operational and delivers 300 W at 940 nm. When complete, the
HELSTF laser will deliver 100-kW-to-MW output power under burst
mode for the duration of several seconds."

We still have a way to go to get lasers of this performance, however (or
if we don't, no one is talking about it). At the rate at which laser
technology is advancing, though, it will probably not be too long before
the military has these toys to play with.


The technologies are sufficiently advanced enough that the
Blue Beanies, ahem, USAF are talking about putting a SS-HEL
in the back of Lockheed's Air Force JSF version.

My bet is that within ten years we'll see each branch of the
military with one sort of laser or another as an offensive weapon.

Will

Luke


--
William P Baird Do you know why the road less traveled by
Speaking for me has so few sightseers? Normally, there
Home: anzha@hotmail is something big, mean, with very sharp
Work: wbaird@nersc teeth - and quite the appetite! - waiting
Add .com/.gov somewhere along its dark and twisty bends.
  #468  
Old December 31st 03, 08:04 PM
George William Herbert
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Fred J. McCall wrote:
"Damo" wrote:
:"John Schilling" wrote:
: Likewise, if your idea is that it doesn't matter how easy an individual
: missile is to find and kill because you are going to saturate US/NATO
: style air defenses with numbers, you don't match it against the present
: standard of an F-15 with four each AMRAAMs and Sidewinders but against
: an F-22 packed to the limit with air-to-air Stingers; fourty-five stowed
: kills at 0.8 Pk per shot, if my math is correct.
:
:I was under the impression (mistaken?) that the F-22 can only carry 4
:air-to-air missiles, if it carries more it loses what stealth it had and you
:might as well send in F-15s??

I think you're both wrong.

1) When did Stinger get cleared for carriage in an F-22 (and in such
ridiculous quantities, too)? That would be merely insane, since the
Stinger isn't even an air-to-air weapon (and you certainly couldn't
jam 45 of them in anywhere and be able to shoot them).

2) The F-22 carries 8 AAM rounds internally in pure air to air trim:
6 AIM-120C in the main weapons bay and an AIM-9X in each side bay.


The F-22 isn't cleared for Stingers. John is talking about
a hypothetical but reasonable design extension.

Stinger is used in air to air mode, there's a separate product
version for it even (ATAS Block 2). It's used and qualified on
US Army helicopters.

There exist multiple rocket pods firing rockets with similar
body diameter to Stinger; modifying the pods to actually fire
stingers would be a minor modification. Building a new pod which
volumetrically filled the F-22 weapons bay, was extended out
for firing and then retracted back in, is not trivial but
not a particularly difficult project. I am taking John's
count of how many missiles would fit in such pods on faith;
he knows how to do math.

Similar retractable rocket pods, firing unguided rockets then
but operationally very similar, have been used in USAF interceptors
of the past.


-george william herbert


  #469  
Old December 31st 03, 08:55 PM
LukeCampbell
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William Baird wrote:
LukeCampbell wrote in message

My prediction is that laser weapons will really take off when a
practical, high efficiency, high repetition rate short pulsed
(nanosecond or less) laser with a reasonable energy per pulse (say about
a joule) is available.



FWIW, the LLNL solid state laser is a pulsed one. The flash lamps are
supposed to be followed on with LEDs as well.

Ah, here we go:

"The project scientists are also investigating several diode
cooling and packaging techniques for optical pumping using
laser diodes. A 10-bar prototype monolithic diode array is
operational and delivers 300 W at 940 nm. When complete, the
HELSTF laser will deliver 100-kW-to-MW output power under burst
mode for the duration of several seconds."


Oh. My reading was that it could operate at full power (about 100 kW
CW) for several seconds, and then had to be shut off to cool. Since I'm
not actually working on the beasty, though, I can't say if my reading is
correct or not.

We still have a way to go to get lasers of this performance, however (or
if we don't, no one is talking about it). At the rate at which laser
technology is advancing, though, it will probably not be too long before
the military has these toys to play with.



The technologies are sufficiently advanced enough that the
Blue Beanies, ahem, USAF are talking about putting a SS-HEL
in the back of Lockheed's Air Force JSF version.

My bet is that within ten years we'll see each branch of the
military with one sort of laser or another as an offensive weapon.


Sounds about right. I would have guessed 10 to 20, myself, but I am
usually a bit conservative.

Luke

  #470  
Old December 31st 03, 09:02 PM
LukeCampbell
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Chad Irby wrote:

You also have some problems with ionization of the air in some
conditions, degrading the beam.


For visible or near IR, this is not so much of a problem as with mid IR
(or UV, for that matter). There is an ionization phenomena that can
actually help propagate the laser beam in some conditions. Very intense
light in air can lead to self focusing, and if there was nothing to stop
it, the laser would catastrophically self focus down to a point,
resulting in strong ionization and the total absorption of the beam. It
turns out however that before this occurs, the beam will cause weak
ionization of the air, forming a diverging lense and expanding the beam
again. The beam still has enough power to self focus in normal air,
though, so you go through a sort of leap-frog effect of focus, diverge,
focus, diverge, etc. This overcomes diffractive spreading of the beam,
and some researchers have managed to propagate millijoule, femptosecond
pulses of laser light for several kilometers through the atmosphere
using this method. It is not clear if this would be a good option for
weapons, but it might turn out to be a very effective means of
delivering pulsed laser energy to targets within a few kilometers.

Luke



 




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