I'll agree for the most part..though I'll respectfully point out that the X-15 was rocket powered, not jet-powered;)
Everything else is spot-on for the most part...even the venerable F-15 has a "public" top-speed of Mach 2.5:) Although getting upwards of Mach 4 is a practical limit for turbojets due to the drag issues of slowing down the stream to subsonic via a "tuned" shockwave ala the SR-71 "cones". That's where SCRAMjets come in...they can sustain combustion with a supersonic stream flowing through the engine from inlet to outlet, thus they don't have the same "upper" limit.
As has been addressed in prior comments, as well as TFA...the new device will have 160GB, which is a 90GB loss in comparison to the current Series-3. A literal reading of the summary gives that information as well, though I can see where a quick skimming would lead one to the wrong conclusion if s/he couldn't be bothered to actually read the article before commenting on it.
It wasn't shocking to me personally...but it was shocking to a lot of folks in the West who fancy themselves "experts" in the capabilities and motivations of the Chinese...including the authors of the article cited. The same pundits who think China is still a land of rice farmers and bicycles when it is in actuality becoming quite the economic and military powerhouse paid for in large part by the generosity (or stupidity?) of the completely insane trade policies between China and the U.S. Personally, I'm surprised it didn't happen sooner...technologically it's not that difficult for a nation that has already figured out ICBMs and, as I stated previously, such an accomplishment really only takes money and will since the rocket technology is well-known and suitable guidance systems are practically commodities these days. I think the timing was chosen to coincide with a time of American weakness around the world...to usher in an era of "Here we are, take notice" by the Chinese.
In the end, it's more shocking that it is shocking to anyone...shows the level of ignorance that permeates the folks whose job it is to actually know about this kind of stuff. But that seems to be a re-occurring theme as of late here the States...*sigh*
Heh, no. There are no air-to-air missiles in the U.S. inventory with enough energy to do it "accidentally"...the AIM-54 (phoenix) would be the only one that would *remotely* have a snowball's chance in hell of making it that high, and you'd have to put the plane into a ballistic profile at max attainable altitude to do it..hardly an "accidental" scenario. Even then, there's no way the phoenix would have enough umph to go the additional 100+ miles straight up (I'd have to do the calcs to figure it's max altitude, and I'm feeling lazy tonight...but since it only has a max *horizontal* range of a little over 100 miles it's pretty clear that traveling 100 miles vertically against gravity isn't going to happen)...especially considering it only has aerodynamic surfaces for guidance so there'd be no way for it to maintain course at extreme altitude and would corkscrew wildly like an inflated balloon that's been let go to fly about the room while the solid booster was burning. Not to mention the F-14 (the only plane that carried the missile) doesn't have an optimal thrust/weight ratio that would provide best initial energy to the missile. The YF-12 was to carry a predecessor phoenix called the AIM-47 that had a bit longer range, but it's basically the same story besides the fact that both were very short-lived projects. The Soviets, on the other hand, had a couple of missiles that might have come closer...the ones that were designed to kill the SR-71. A decent write-up on several of these missiles can be found here though I haven't cross-checked all the facts for accuracy.
Instead, I think you are referring to the ASAT tests conducted by the Air Force using a F-15 in the 1980's (I linked it in my post above, but here it is again: http://en.wikipedia.org/wiki/Anti-satellite_weapon ). That was a specially-made missile for the task..and its success was no accident.
we would call it history We yanks have had the demonstrated ability to shoot down satellites for more than 20 years.
What's shocking about the Chinese effort is that most folks tend to underestimate them in the progress they've made in their space program. What they don't take into account is that they are able to stand on the shoulders of giants...they won't need nearly as much time to develop theirs as we did since most of the "hard work" of basic designs and calcs has already been done and is readily available in textbooks. All it takes is money and will at this point...something they have plenty of due to the trade imbalance and their desire to be taken seriously as a world power.
Well, yes and no. It's true that the majority of the thermal energy is removed after the turbine stage..but that doesn't mean that 75% of the initial energy is lost uselessly to the environment. Rather, the act of condensing the steam back into water drastically reduces the exhaust pressure and increases overall flow rate through the turbine...causing substantially more mechanical energy to be produced than would otherwise be made. The effect can be calculated quite accurately using 2nd Law analysis. It's the fact that the water-steam volume difference is so great that makes the Rankine cycle so successful. Even at quite high pressures, an exhaust stream of steam can become nearly a vacuum (or at least 1 atm) practically on-demand simply by cooling it to the condensation point. That's the job of the big cooling lakes and/or nearby natural bodies of water that Rankine-based power generation plants are built near.
All that said, there's no indication from the article that the powerplant is based on the Rankine cycle. Steam power generation plants can achieve thermal efficiencies well in excess of 30%...with some of the newer designs pushing the 50% mark. This particular article is claiming a bit over 5.5%. A lot of that can be attributed to scale (smaller heat engines typically have lower thermal efficiencies)...but I hope there's a typo in there somewhere else color me underwhelmed.
First, the drone is going Mach 6-ish, not Mach 3. Second, there's a big difference between a cylindrical missile body and a hypersonic recon plane in regards to ability to withstand the aerodynamic forces involved in high angle of attack at such high speeds. Third, as an air-breathing craft, engine flameout is a very distinct possibility at hypersonic speeds in any flight regime that deviates from straight ahead (careful shockwave management is part of the propulsion system)...further limiting its ability to execute a high-g turn.
If the drone did manage to turn around, it means that the missiles were fired too soon. It's like a deer in the road that pops in front of you at the last second...at 30mph you can swerve or stop in time. At 100mph it's going to be sitting in the front seat with you no matter what you try. And even if the drone did escape, it was denied the airspace so mission accomplished.
The array of missiles I'm thinking about are equilateral triangle formations with perhaps 75 miles between each individual missile site (I haven't run the calcs to optimize it). Batteries would be stacked in a truss formation along the edge of the airspace you want to deny the enemy. With enough early warning and tracking, it's trivial to time the missile firing to ensure that the drone can't escape...it will be heading towards at least one of the 3 (or more, if the drone's turn takes causes it to overlap multiple batteries) missiles no matter what it does once it enters the kill zone (which is not inside the geometrical confines of the missile triangle, but off to the side of the drone's approach perhaps 10 miles or so...like I said I haven't run the optimization calcs). My previous calculations didn't take into consideration the closing speed of the missiles in relation to the drone...which will actually drastically reduce the amount of time the drone has to turn. In those 47 seconds of flight of the interceptor missile to reach altitude at a 45 degree angle, the closing speed would be in excess of Mach 8 by the initial "head-on" missile...lets call it 2500m/s. The "containment" missiles start off with a very small close-rate, but if the drone turns, it increases up to a maximum of Mach 8 close rate. With proper firing timing and geometry of launchers, it would be simply impossible for the drone to escape since the drone would necessarily be inside the geometric "triangle of death" no matter what because it simply can't turn around before it breaches that 10 miles from the time the missiles fire and the time it's inside the triangle as it would take over 30 seconds to just turn 90 degrees at 10-g's and Mach 6) Now..the missiles might very well *miss* (hitting a bullet with a bullet can be hard)...but that's another matter.
It wouldn't be all that expensive...CCD IR detectors in automated arrays are practically commodity products...you could buy hundreds of them and stick them everywhere. The hard part is the software that pulls it all together. The missile batteries aren't all that bad either, considering you only need a group of 3 every 75 miles or so (or whatever the optimal triangle size ends up being)...it's all what you figure your strategic "privacy" is worth. Of course, any fixed structures are subject to destruction by strike forces...that's the nature of war. But in a situation of a Cold War...you generally don't have that happen very often.
BTW...small correction on my prior math...a 10g turn results in a turn radius of about 24 miles, not 240 miles..and 2.8 degrees/second turn rate. Damned decimal point (how embarrassing!)...serves me right for doing stuff in my head instead of writing it all down (though you didn't call me on it..which is even worse..always check the numbers yourself!). Using that outside number to design the triangles...easy day to make a trap for such a drone (or cause it to abandon its mission by "chickening out" before it reaches the contested airspace) All of that depends on the tracking and fire control systems that I mentioned before..it would
Well, I'm glad you finally agree that it is possible. That was my point. I never said it would be easy. I just hate blanket statements that are obviously false when compared to facts. When you issue an absolute, you have to be right in 100% of all cases. To disprove such a statement, you only need to be right once.
As for your drone doing a 10g turn...good luck at 100,000 feet. If it did manage to pull it off with some sort of vectored thrust (and didn't disintegrate or stall the engines from a high-alpha flight path at Mach 6), it would bleed off so much speed it would be easy prey for missiles. Your post indicates to me you don't have much formal education in aeronautics. That's not a dig..just an observation. I have to deal with lay-people a lot who need a crash-course in compressibles and aerodynamics in order to understand why things work the way they do versus what seems intuitive. I've done significant supersonic and hypersonic research in a University setting...I know what works in that regime of flight. Your "thought experiment" simply doesn't reflect the physics of flight in that regime. You are thinking of fighter-like maneuverability when the altitude and speed simply won't let that happen.
As for your intercept scenario....you are making an assumption that the launch site would be the only sensor. It's likely that a huge array of sensors would be employed to give significant heads-up (and thermal-based triangulation) to set up an interceptor shot (more likely, multiple simultaneous shots from different angles to bracket the target). Hell, the missile doesn't really need much of a seeker of its own if precise enough positional/trajectory data is being fed to it real-time (and optical tracking can be *very* precise from fixed locations). Just a terminal-phase seeker to fine-tune the kill collision/detonation. A missile just has to be at altitude and heading head-on to the target. The drone won't be making any sharp turns...that darned physics thing precludes it. The drone, at that speed and altitude, would have a turn radius measured in hundreds of miles if it wanted to maintain said speed and altitude. If it didn't..well, it would be that much easier to shoot it down with subsequent shots since it would be traveling significantly slower and probably lower. So, you're right...a maneuvering target at Mach 6 & 100k feet would be a nightmare intercept target. Problem is...it won't be maneuvering that much. Best bet for the drone is to just put the hammer down and hope that you are out of the kill zone before the systems can react to your presence...or better to just avoid the kill zone to begin with by having adequate intel that allows you to plan a flight path that keeps your drone out of trouble. The reaction time of detection, triangulation, decision to launch, and time to climb for the missiles compared to the sheer speed of the drone's straightline flight path is what will keep the drone alive...not any sort of uber maneuvering capability.
And to comment on your statements on missile performance and the associated "ugly numbers". An average speed of 1100mph is not a big deal for an intercept missile. Patriot missiles are supersonic within 20ft of the launch tube. So, let's assume that some new intercept missile will have at least the same performance as the Patriot..and go a step further and let's give it an average speed of 2000mph during its climb. A missile would need 34 seconds to climb to 100kft. At a 45 degree angle, it would need 47 seconds. The drone will travel 57 miles in that time. Lets say that some magical technology allows it to pull a *20g* turn at constant speed and altitude (and I do mean magical). At 4400mph (~2000m/s) a 20g turn will yield a 1.75 degrees/second turn rate (and a turn radius of about 120miles). Times 60 seconds (47 seconds plus the automated reaction time...nice round minute to make the numbers pretty)...That's a maximum of 105 degrees of turn. Only 3 missiles, launched from different (and appropriately located in conjun
yes, really. Mach 1 = the speed of sound in the current density of air. So, Mach 1 at 80,000 feet is significantly slower than Mach 1 at sea level. So, you do not recall correclty. I think you'll find that 2200mph is well above Mach 2.8 @ operational altitude as previously posted if you'll look up the standard atmosphere tables and do the math.
IMHO, recon assets are probably the best bang-for-buck that the taxpayer gets from the defense budget. You don't always have a satellite where it needs to be to see something *when* you want...that's where these come in. Good recon can prevent wars...or at least help keep wars small (dependent on the cowboy factor in the whitehouse, of course). Far different from the nuclear stockpile...recon assets have immediate benefit and impact on national security while being used in an active role. As others have surmised...I'd be surprised if this thing wasn't already operational. I never bought the story that the air force was going to rely 100% on satellites for strategic recon...especially since the Soviets demonstrated ASAT weapons decades ago. The recent tests by the Chinese in that arena have only refocused the public on a long-existing threat to our global surveillance capabilities via our satellite systems.
Actually the Mach number is higher than that when you consider the altitude that the SR-71 was flying. The speed of sound goes down as altitude goes up..so a given absolute speed will yield a different Mach number depending on the altitude.
True..that's why no SR-71 was ever shot down..although the Soviets got close a few times with their SAMs-as-flak approach. However, that also highlights the necessity of having some sort of intelligence built into the auto-pilot. If it doesn't even attempt to turn, shooting it down with the ballistic approach would be fairly straight-forward. That was the point I was trying to make.
Never said it would be easy...just that it can be done. Current prototypes of theater defense systems that can shoot down everything from mortar shells to ballistic rockets show what is possible...and almost always on the 1st shot. Repeated shots won't have the effect on the atmosphere that you claim, since each shot will be through a very different column of air due to the high speed of the target and the subsequent change in angular position from the firing station. Finally, the stealth factor won't make a bit of difference on an optical system. Just aim for the bright spot in the sky, let the LIDAR system hone in on the hard bit, and fire the main shot. Adaptive optics systems developed during the Reagan-era Star Wars program have already proven quite effective in being able to focus laser light through a disturbed atmosphere. All the pieces are here today except the laser with enough power and capability of multiple shots and some semblance of portability. The theater-defense system is a good start, but they'll have to scale it up for anti-aircraft duty when the target would be something along the lines of a SR-72-type plane. I agree..that might be 10 years away depending on funding..but that's really the last piece of the puzzle. Everything else is working in some fashion today in various military research projects that have been publicized. In any case..it's a far cry from your original statement of "lasers through the atmosphere don't work"....blanket absolute statements such as that are rarely accurate.
Well, I didn't mean "evade" in the sense of a fighter would..but rather controlling speed to make ballistic projectiles miss (the "hit the brakes and he'll fly right by" theorem of Maverick) and minor course corrections as appropriate. Similar to what the SR-71 pilots would do...mostly it's just grit your teeth and hope for the best but there's a little room for "helping".
The Soviets would send up SAM's in salvos in an almost flak-like manner...sending them on ballistic paths hoping that the SR-71 would just run into them. That's where a little pilot skill and the use of what little evasive capabilities of the plane come in handy.
But you're right..there's only so much you can do at that speed and altitude...the proposed/rumored SR-72 would probably have a turn radius literally the size of Texas (or more) at operational speed and altitude.
You obviously didn't follow my suggestion to research hypersonic IR seekers. Come back when you learn to read. Further, try learning a little about compressible fluid dynamics before trying to comment on such a topic. THAAD is just one "famous" application for such technology, but there are numerous other projects around the world for lower-tier interception that use IR for final stage guidance that would be applicable. Finally, THAAD does not operate in a "vacuum"...and it must deal with the same thermal envelope problems due to its speed. Such heating has more to do with Mach number than the density of the surrounding air...altitude is largely irrelevant since the Mach number "auto-adjusts" to the altitude due to the relationship of the speed of sound to density. THAAD is not just a out-of-the-atmosphere interceptor..it is designed to engage targets both endo- and exo-atmospherically including short-range ballistic missiles. The IR seeker was designed to function in a an environment exceeding Mach 7 inside the atmosphere...
In any case...as I said before...this proves the concept...it *is* possible despite the previous poster's assertions...but I doubt a missile-based defense system would be the most viable against the proposed "SR-72"...energy weapons from perhaps an airborne platform would be my first choice for flexibility and probability of kill.
Try doing a little research before calling someone stupid, next time. Your comment drips with ignorance in the subject.
Actively denying a program gives valuable information (that it doesn't exist). By "neither confirming nor denying" the existence of any such program...inadvertent transfer of viable intelligence through confirming the existence or the lack of existence of a program/vehicle/weapon/capability. They can't control rumors..but they can control the release of concrete information (in either the affirmative or negative) by simply saying nothing.
Auto-Pilot with inertial/ring-laser guidance system solves the no-satellite thing. The interesting part is imparting enough smarts to the autopilot to evade interception attempts.
You don't need to fly at Mach 8 to intercept a Mach 6 vehicle...simply standing still and letting it fly into you is enough. Besides, I wasn't trying to insinuate that THAAD would be used...merely that IR-sensors in high-speed interceptor missiles was possible and feasible (contrary to your assertion). The fact that THAAD exists proves my point...IR guidance is feasible against such a target with a high-speed kill vehicle that generates it's own thermal envelope via supersonic slipstream compression. In addition, for further education I suggest you begin by googling "hypersonic IR seeker"...you'll see there is a wide body of research in the field for just this type of scenario.
I'll correct your statement: It's very difficult to make lasers work through the atmosphere. It's unlikely that our probable adversaries would have such a system in place that could challenge the proposed/rumored reconnaissance plane in a reasonable timeframe.
Gosh, ARM cores are hardly considered cutting-edge are they? I could probably make one with a piece of doped silicon and a butter knife. And when was the last time you bought an ARM-based core for your PC (where the highest level of competition and time-to-market factors are seen in the industry)?
If AMD wants to go back to the days of being a "value" cpu provider who is at least an entire generation behind Intel, but sells relatively slow chips on outdated processes for half of what Intel sells it's last-generation chips..then sure this is a great plan! And that would be a closer analogy to your ARM example in any case.
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I'll agree for the most part..though I'll respectfully point out that the X-15 was rocket powered, not jet-powered ;)
:) Although getting upwards of Mach 4 is a practical limit for turbojets due to the drag issues of slowing down the stream to subsonic via a "tuned" shockwave ala the SR-71 "cones". That's where SCRAMjets come in...they can sustain combustion with a supersonic stream flowing through the engine from inlet to outlet, thus they don't have the same "upper" limit.
Everything else is spot-on for the most part...even the venerable F-15 has a "public" top-speed of Mach 2.5
As has been addressed in prior comments, as well as TFA...the new device will have 160GB, which is a 90GB loss in comparison to the current Series-3. A literal reading of the summary gives that information as well, though I can see where a quick skimming would lead one to the wrong conclusion if s/he couldn't be bothered to actually read the article before commenting on it.
Since you've taken to the jack-assery of correcting someone's grammar, here's a tip for you:
"published articles are not one of them" is grammatically incorrect. A plural noun cannot be "one" of anything.
"published articles are not among them" would be one correct way to express that thought.
It wasn't shocking to me personally...but it was shocking to a lot of folks in the West who fancy themselves "experts" in the capabilities and motivations of the Chinese...including the authors of the article cited. The same pundits who think China is still a land of rice farmers and bicycles when it is in actuality becoming quite the economic and military powerhouse paid for in large part by the generosity (or stupidity?) of the completely insane trade policies between China and the U.S. Personally, I'm surprised it didn't happen sooner...technologically it's not that difficult for a nation that has already figured out ICBMs and, as I stated previously, such an accomplishment really only takes money and will since the rocket technology is well-known and suitable guidance systems are practically commodities these days. I think the timing was chosen to coincide with a time of American weakness around the world...to usher in an era of "Here we are, take notice" by the Chinese.
In the end, it's more shocking that it is shocking to anyone...shows the level of ignorance that permeates the folks whose job it is to actually know about this kind of stuff. But that seems to be a re-occurring theme as of late here the States...*sigh*
Heh, no. There are no air-to-air missiles in the U.S. inventory with enough energy to do it "accidentally"...the AIM-54 (phoenix) would be the only one that would *remotely* have a snowball's chance in hell of making it that high, and you'd have to put the plane into a ballistic profile at max attainable altitude to do it..hardly an "accidental" scenario. Even then, there's no way the phoenix would have enough umph to go the additional 100+ miles straight up (I'd have to do the calcs to figure it's max altitude, and I'm feeling lazy tonight...but since it only has a max *horizontal* range of a little over 100 miles it's pretty clear that traveling 100 miles vertically against gravity isn't going to happen)...especially considering it only has aerodynamic surfaces for guidance so there'd be no way for it to maintain course at extreme altitude and would corkscrew wildly like an inflated balloon that's been let go to fly about the room while the solid booster was burning. Not to mention the F-14 (the only plane that carried the missile) doesn't have an optimal thrust/weight ratio that would provide best initial energy to the missile. The YF-12 was to carry a predecessor phoenix called the AIM-47 that had a bit longer range, but it's basically the same story besides the fact that both were very short-lived projects. The Soviets, on the other hand, had a couple of missiles that might have come closer...the ones that were designed to kill the SR-71. A decent write-up on several of these missiles can be found here though I haven't cross-checked all the facts for accuracy.
n ). That was a specially-made missile for the task..and its success was no accident.
Instead, I think you are referring to the ASAT tests conducted by the Air Force using a F-15 in the 1980's (I linked it in my post above, but here it is again: http://en.wikipedia.org/wiki/Anti-satellite_weapo
we would call it history We yanks have had the demonstrated ability to shoot down satellites for more than 20 years.
What's shocking about the Chinese effort is that most folks tend to underestimate them in the progress they've made in their space program. What they don't take into account is that they are able to stand on the shoulders of giants...they won't need nearly as much time to develop theirs as we did since most of the "hard work" of basic designs and calcs has already been done and is readily available in textbooks. All it takes is money and will at this point...something they have plenty of due to the trade imbalance and their desire to be taken seriously as a world power.
Well, yes and no. It's true that the majority of the thermal energy is removed after the turbine stage..but that doesn't mean that 75% of the initial energy is lost uselessly to the environment. Rather, the act of condensing the steam back into water drastically reduces the exhaust pressure and increases overall flow rate through the turbine...causing substantially more mechanical energy to be produced than would otherwise be made. The effect can be calculated quite accurately using 2nd Law analysis. It's the fact that the water-steam volume difference is so great that makes the Rankine cycle so successful. Even at quite high pressures, an exhaust stream of steam can become nearly a vacuum (or at least 1 atm) practically on-demand simply by cooling it to the condensation point. That's the job of the big cooling lakes and/or nearby natural bodies of water that Rankine-based power generation plants are built near.
All that said, there's no indication from the article that the powerplant is based on the Rankine cycle. Steam power generation plants can achieve thermal efficiencies well in excess of 30%...with some of the newer designs pushing the 50% mark. This particular article is claiming a bit over 5.5%. A lot of that can be attributed to scale (smaller heat engines typically have lower thermal efficiencies)...but I hope there's a typo in there somewhere else color me underwhelmed.
Heh, no worries. Any day we learn (or re-learn) something, is not a wasted day :)
First, the drone is going Mach 6-ish, not Mach 3. Second, there's a big difference between a cylindrical missile body and a hypersonic recon plane in regards to ability to withstand the aerodynamic forces involved in high angle of attack at such high speeds. Third, as an air-breathing craft, engine flameout is a very distinct possibility at hypersonic speeds in any flight regime that deviates from straight ahead (careful shockwave management is part of the propulsion system)...further limiting its ability to execute a high-g turn.
If the drone did manage to turn around, it means that the missiles were fired too soon. It's like a deer in the road that pops in front of you at the last second...at 30mph you can swerve or stop in time. At 100mph it's going to be sitting in the front seat with you no matter what you try. And even if the drone did escape, it was denied the airspace so mission accomplished.
The array of missiles I'm thinking about are equilateral triangle formations with perhaps 75 miles between each individual missile site (I haven't run the calcs to optimize it). Batteries would be stacked in a truss formation along the edge of the airspace you want to deny the enemy. With enough early warning and tracking, it's trivial to time the missile firing to ensure that the drone can't escape...it will be heading towards at least one of the 3 (or more, if the drone's turn takes causes it to overlap multiple batteries) missiles no matter what it does once it enters the kill zone (which is not inside the geometrical confines of the missile triangle, but off to the side of the drone's approach perhaps 10 miles or so...like I said I haven't run the optimization calcs). My previous calculations didn't take into consideration the closing speed of the missiles in relation to the drone...which will actually drastically reduce the amount of time the drone has to turn. In those 47 seconds of flight of the interceptor missile to reach altitude at a 45 degree angle, the closing speed would be in excess of Mach 8 by the initial "head-on" missile...lets call it 2500m/s. The "containment" missiles start off with a very small close-rate, but if the drone turns, it increases up to a maximum of Mach 8 close rate. With proper firing timing and geometry of launchers, it would be simply impossible for the drone to escape since the drone would necessarily be inside the geometric "triangle of death" no matter what because it simply can't turn around before it breaches that 10 miles from the time the missiles fire and the time it's inside the triangle as it would take over 30 seconds to just turn 90 degrees at 10-g's and Mach 6) Now..the missiles might very well *miss* (hitting a bullet with a bullet can be hard)...but that's another matter.
It wouldn't be all that expensive...CCD IR detectors in automated arrays are practically commodity products...you could buy hundreds of them and stick them everywhere. The hard part is the software that pulls it all together. The missile batteries aren't all that bad either, considering you only need a group of 3 every 75 miles or so (or whatever the optimal triangle size ends up being)...it's all what you figure your strategic "privacy" is worth. Of course, any fixed structures are subject to destruction by strike forces...that's the nature of war. But in a situation of a Cold War...you generally don't have that happen very often.
BTW...small correction on my prior math...a 10g turn results in a turn radius of about 24 miles, not 240 miles..and 2.8 degrees/second turn rate. Damned decimal point (how embarrassing!)...serves me right for doing stuff in my head instead of writing it all down (though you didn't call me on it..which is even worse..always check the numbers yourself!). Using that outside number to design the triangles...easy day to make a trap for such a drone (or cause it to abandon its mission by "chickening out" before it reaches the contested airspace) All of that depends on the tracking and fire control systems that I mentioned before..it would
Well, I'm glad you finally agree that it is possible. That was my point. I never said it would be easy. I just hate blanket statements that are obviously false when compared to facts. When you issue an absolute, you have to be right in 100% of all cases. To disprove such a statement, you only need to be right once.
As for your drone doing a 10g turn...good luck at 100,000 feet. If it did manage to pull it off with some sort of vectored thrust (and didn't disintegrate or stall the engines from a high-alpha flight path at Mach 6), it would bleed off so much speed it would be easy prey for missiles. Your post indicates to me you don't have much formal education in aeronautics. That's not a dig..just an observation. I have to deal with lay-people a lot who need a crash-course in compressibles and aerodynamics in order to understand why things work the way they do versus what seems intuitive. I've done significant supersonic and hypersonic research in a University setting...I know what works in that regime of flight. Your "thought experiment" simply doesn't reflect the physics of flight in that regime. You are thinking of fighter-like maneuverability when the altitude and speed simply won't let that happen.
As for your intercept scenario....you are making an assumption that the launch site would be the only sensor. It's likely that a huge array of sensors would be employed to give significant heads-up (and thermal-based triangulation) to set up an interceptor shot (more likely, multiple simultaneous shots from different angles to bracket the target). Hell, the missile doesn't really need much of a seeker of its own if precise enough positional/trajectory data is being fed to it real-time (and optical tracking can be *very* precise from fixed locations). Just a terminal-phase seeker to fine-tune the kill collision/detonation. A missile just has to be at altitude and heading head-on to the target. The drone won't be making any sharp turns...that darned physics thing precludes it. The drone, at that speed and altitude, would have a turn radius measured in hundreds of miles if it wanted to maintain said speed and altitude. If it didn't..well, it would be that much easier to shoot it down with subsequent shots since it would be traveling significantly slower and probably lower. So, you're right...a maneuvering target at Mach 6 & 100k feet would be a nightmare intercept target. Problem is...it won't be maneuvering that much. Best bet for the drone is to just put the hammer down and hope that you are out of the kill zone before the systems can react to your presence...or better to just avoid the kill zone to begin with by having adequate intel that allows you to plan a flight path that keeps your drone out of trouble. The reaction time of detection, triangulation, decision to launch, and time to climb for the missiles compared to the sheer speed of the drone's straightline flight path is what will keep the drone alive...not any sort of uber maneuvering capability.
And to comment on your statements on missile performance and the associated "ugly numbers". An average speed of 1100mph is not a big deal for an intercept missile. Patriot missiles are supersonic within 20ft of the launch tube. So, let's assume that some new intercept missile will have at least the same performance as the Patriot..and go a step further and let's give it an average speed of 2000mph during its climb. A missile would need 34 seconds to climb to 100kft. At a 45 degree angle, it would need 47 seconds. The drone will travel 57 miles in that time. Lets say that some magical technology allows it to pull a *20g* turn at constant speed and altitude (and I do mean magical). At 4400mph (~2000m/s) a 20g turn will yield a 1.75 degrees/second turn rate (and a turn radius of about 120miles). Times 60 seconds (47 seconds plus the automated reaction time...nice round minute to make the numbers pretty)...That's a maximum of 105 degrees of turn. Only 3 missiles, launched from different (and appropriately located in conjun
yes, really. Mach 1 = the speed of sound in the current density of air. So, Mach 1 at 80,000 feet is significantly slower than Mach 1 at sea level. So, you do not recall correclty. I think you'll find that 2200mph is well above Mach 2.8 @ operational altitude as previously posted if you'll look up the standard atmosphere tables and do the math.
IMHO, recon assets are probably the best bang-for-buck that the taxpayer gets from the defense budget. You don't always have a satellite where it needs to be to see something *when* you want...that's where these come in. Good recon can prevent wars...or at least help keep wars small (dependent on the cowboy factor in the whitehouse, of course). Far different from the nuclear stockpile...recon assets have immediate benefit and impact on national security while being used in an active role. As others have surmised...I'd be surprised if this thing wasn't already operational. I never bought the story that the air force was going to rely 100% on satellites for strategic recon...especially since the Soviets demonstrated ASAT weapons decades ago. The recent tests by the Chinese in that arena have only refocused the public on a long-existing threat to our global surveillance capabilities via our satellite systems.
Actually the Mach number is higher than that when you consider the altitude that the SR-71 was flying. The speed of sound goes down as altitude goes up..so a given absolute speed will yield a different Mach number depending on the altitude.
that's a hell of a set of lungs on that bird that can climb to 80,000 feet to make contact with a SR-71 at operational speed/altitude :P
True..that's why no SR-71 was ever shot down..although the Soviets got close a few times with their SAMs-as-flak approach. However, that also highlights the necessity of having some sort of intelligence built into the auto-pilot. If it doesn't even attempt to turn, shooting it down with the ballistic approach would be fairly straight-forward. That was the point I was trying to make.
Never said it would be easy...just that it can be done. Current prototypes of theater defense systems that can shoot down everything from mortar shells to ballistic rockets show what is possible...and almost always on the 1st shot. Repeated shots won't have the effect on the atmosphere that you claim, since each shot will be through a very different column of air due to the high speed of the target and the subsequent change in angular position from the firing station. Finally, the stealth factor won't make a bit of difference on an optical system. Just aim for the bright spot in the sky, let the LIDAR system hone in on the hard bit, and fire the main shot. Adaptive optics systems developed during the Reagan-era Star Wars program have already proven quite effective in being able to focus laser light through a disturbed atmosphere. All the pieces are here today except the laser with enough power and capability of multiple shots and some semblance of portability. The theater-defense system is a good start, but they'll have to scale it up for anti-aircraft duty when the target would be something along the lines of a SR-72-type plane. I agree..that might be 10 years away depending on funding..but that's really the last piece of the puzzle. Everything else is working in some fashion today in various military research projects that have been publicized. In any case..it's a far cry from your original statement of "lasers through the atmosphere don't work"....blanket absolute statements such as that are rarely accurate.
Well, I didn't mean "evade" in the sense of a fighter would..but rather controlling speed to make ballistic projectiles miss (the "hit the brakes and he'll fly right by" theorem of Maverick) and minor course corrections as appropriate. Similar to what the SR-71 pilots would do...mostly it's just grit your teeth and hope for the best but there's a little room for "helping".
The Soviets would send up SAM's in salvos in an almost flak-like manner...sending them on ballistic paths hoping that the SR-71 would just run into them. That's where a little pilot skill and the use of what little evasive capabilities of the plane come in handy.
But you're right..there's only so much you can do at that speed and altitude...the proposed/rumored SR-72 would probably have a turn radius literally the size of Texas (or more) at operational speed and altitude.
You obviously didn't follow my suggestion to research hypersonic IR seekers. Come back when you learn to read. Further, try learning a little about compressible fluid dynamics before trying to comment on such a topic. THAAD is just one "famous" application for such technology, but there are numerous other projects around the world for lower-tier interception that use IR for final stage guidance that would be applicable. Finally, THAAD does not operate in a "vacuum"...and it must deal with the same thermal envelope problems due to its speed. Such heating has more to do with Mach number than the density of the surrounding air...altitude is largely irrelevant since the Mach number "auto-adjusts" to the altitude due to the relationship of the speed of sound to density. THAAD is not just a out-of-the-atmosphere interceptor..it is designed to engage targets both endo- and exo-atmospherically including short-range ballistic missiles. The IR seeker was designed to function in a an environment exceeding Mach 7 inside the atmosphere...
- a&channel=s&rls=org.mozilla%3Aen-US%3Aofficial&hs= 4KB&q=thaad+ir+seeker&btnG=Search6 70
http://www.google.com/search?hl=en&client=firefox
http://www.arnold.af.mil/news/story.asp?id=123051
In any case...as I said before...this proves the concept...it *is* possible despite the previous poster's assertions...but I doubt a missile-based defense system would be the most viable against the proposed "SR-72"...energy weapons from perhaps an airborne platform would be my first choice for flexibility and probability of kill.
Try doing a little research before calling someone stupid, next time. Your comment drips with ignorance in the subject.
Actively denying a program gives valuable information (that it doesn't exist). By "neither confirming nor denying" the existence of any such program...inadvertent transfer of viable intelligence through confirming the existence or the lack of existence of a program/vehicle/weapon/capability. They can't control rumors..but they can control the release of concrete information (in either the affirmative or negative) by simply saying nothing.
Good point...
Auto-Pilot with inertial/ring-laser guidance system solves the no-satellite thing. The interesting part is imparting enough smarts to the autopilot to evade interception attempts.
You don't need to fly at Mach 8 to intercept a Mach 6 vehicle...simply standing still and letting it fly into you is enough. Besides, I wasn't trying to insinuate that THAAD would be used...merely that IR-sensors in high-speed interceptor missiles was possible and feasible (contrary to your assertion). The fact that THAAD exists proves my point...IR guidance is feasible against such a target with a high-speed kill vehicle that generates it's own thermal envelope via supersonic slipstream compression. In addition, for further education I suggest you begin by googling "hypersonic IR seeker"...you'll see there is a wide body of research in the field for just this type of scenario.
Um, there have been IR-guided weapons for decades. Most apropos being THAAD
http://www.wvi.com/~sr71webmaster/yf12~1.htm
Wow, these guys must really feel foolish having successfully tested a system that doesn't really work.i on/view/categoryid/2517/documentid/2488/history/3, 2360,646,2517,2488
:)
http://www.jinsa.org/articles/articles.html/funct
I'll correct your statement: It's very difficult to make lasers work through the atmosphere. It's unlikely that our probable adversaries would have such a system in place that could challenge the proposed/rumored reconnaissance plane in a reasonable timeframe.
Fixed
Gosh, ARM cores are hardly considered cutting-edge are they? I could probably make one with a piece of doped silicon and a butter knife. And when was the last time you bought an ARM-based core for your PC (where the highest level of competition and time-to-market factors are seen in the industry)?
If AMD wants to go back to the days of being a "value" cpu provider who is at least an entire generation behind Intel, but sells relatively slow chips on outdated processes for half of what Intel sells it's last-generation chips..then sure this is a great plan! And that would be a closer analogy to your ARM example in any case.