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#462
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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
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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
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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
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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
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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
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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
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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
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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
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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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