F-35 Cancelled, then what ?
"Rules don't apply to me". OK, now we know where you stand.
Depending on aspect, some weapons and pylons might be an order of magnitude (0.5 m2 vs 5 m2) less than a clean MiG. But not "multiple" (either 0.05 m2 or 0.005 m2) which is what you originally claimed, and then changed to the meaningless "some order of magnitude".
But in any event, you can't consider them in isolation because the weapons and pylons create multipath scattering and dihedrals relative to the airframe. These effects and the RCS of the weapons and pylons can be adjusted with treatments and shaping, but I have seen no evidence that it can create multiple-order effects.
And the statement "LO combat platforms with external stores are still multiple orders of magnitude more stealthy than non-LO platforms with the same external stores " still appears to rest on the assumption that stealthy airplanes magically cause things attached to them to have lower RCS.
Depending on aspect, some weapons and pylons might be an order of magnitude (0.5 m2 vs 5 m2) less than a clean MiG. But not "multiple" (either 0.05 m2 or 0.005 m2) which is what you originally claimed, and then changed to the meaningless "some order of magnitude".
But in any event, you can't consider them in isolation because the weapons and pylons create multipath scattering and dihedrals relative to the airframe. These effects and the RCS of the weapons and pylons can be adjusted with treatments and shaping, but I have seen no evidence that it can create multiple-order effects.
And the statement "LO combat platforms with external stores are still multiple orders of magnitude more stealthy than non-LO platforms with the same external stores " still appears to rest on the assumption that stealthy airplanes magically cause things attached to them to have lower RCS.
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This forum appears to have turned into a farce. More name calling and school girl squabbling than discussion.
Between the sniping, there seems to be some disagreement about RCS. I think you are trying to make comparisons based on assumptions that are ill-founded. RCS is not an additive process and is far more complicated than you seem to be suggesting. For example, a bare pylon can have a far larger reflectivity than a pylon with an adapter and/or weapon(s) fitted. A thousand pound bomb in freefall does not have the same effective RCS as the same weapon being carried and the effect the weapon has on total RCS depends greatly on the aircraft carrying it due to reflections between the weapon and the airframe.
External carriage certainly makes a huge difference to RCS; if that were not the case, no one would have spent all that time and money working out how to carry everything internally, with all the limitations and complications that brings. But it is almost impossible to speculate the degree of difference any external weapon would make to the total RCS of a VLO aircraft and it is somewhat pointless to try to do so, especially in public and with the attendant squabbling.
Between the sniping, there seems to be some disagreement about RCS. I think you are trying to make comparisons based on assumptions that are ill-founded. RCS is not an additive process and is far more complicated than you seem to be suggesting. For example, a bare pylon can have a far larger reflectivity than a pylon with an adapter and/or weapon(s) fitted. A thousand pound bomb in freefall does not have the same effective RCS as the same weapon being carried and the effect the weapon has on total RCS depends greatly on the aircraft carrying it due to reflections between the weapon and the airframe.
External carriage certainly makes a huge difference to RCS; if that were not the case, no one would have spent all that time and money working out how to carry everything internally, with all the limitations and complications that brings. But it is almost impossible to speculate the degree of difference any external weapon would make to the total RCS of a VLO aircraft and it is somewhat pointless to try to do so, especially in public and with the attendant squabbling.
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Mach 2 I agree and it was never the intention. I merely wished to make the point that a stealth aircraft with external stores is still considerably stealthier than its non-stealth equivalent with the same set of pylons and stores attached. There's no magic involved.
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Originally Posted by KenV
"Generally Understood?" Is that the same as "It is rumored that...."
@MSOCS: "Disposable" UAS are going to happen, in fact, basic vehicles are already in service - MALD, CHAMP, etc. Development of stealthy loitering platforms launchable from aircraft and ships is inevitable. There's going to be a blurring between cruise missiles and more autonomous vehicles with actual AI. They even want to make B-21s and future F-X / F/A-XX "optionally manned" for the most difficult missions (a concept that I think you and I would agree is would be very expensive.)
Last edited by Maus92; 27th Mar 2016 at 00:30.
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I can see the appeal of the lightweight, tactical UAV as a disposable asset. The weightier, stealth UAVs I see more as a loiter, sensor fortress, comm node platform. If you add a B-2esque weapons bay to that mix then you've pretty much ended up with a B-21. So, if you're going to chance losing one, you'd probably want to be able to take a whole load of hurt to the enemy in the process.
Of course, "considerably stealthier" is not the same as "multiple orders of magnitude" stealthier, and is far harder to define.
I believe MSOCS and KenV may be distantly descended from the same ancient military engineer, given their mastery of the motte-and-bailey argument.
http://slatestarcodex.com/2014/11/03...-in-the-motte/
I believe MSOCS and KenV may be distantly descended from the same ancient military engineer, given their mastery of the motte-and-bailey argument.
http://slatestarcodex.com/2014/11/03...-in-the-motte/
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Thanks LO, though I'm not an engineer by trade or qualification. KenV may be, I don't know.
Of course, you cannot prove me wrong and I cannot prove you wrong. Though the reasons for each couldn't be more different. M2 was entirely correct. Alas, our disagreement can't conclusively be settled on an unclassified and open forum. I stand by my original statement so guess that's the dead end reached.
Of course, you cannot prove me wrong and I cannot prove you wrong. Though the reasons for each couldn't be more different. M2 was entirely correct. Alas, our disagreement can't conclusively be settled on an unclassified and open forum. I stand by my original statement so guess that's the dead end reached.
Alas, our disagreement can't conclusively be settled on an unclassified and open forum.
not an engineer by trade or qualification.
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Or, you incorrectly assume that only engineers know or understand such things. One could assert the signature of a Russian fighter as, say, 10dbsm clean and 15dbsm with a set of stores. Now take a generic stealth fighter with -20dbsm clean, for example. Add the same stores and let's say it becomes -10dbsm or -5dbsm. That's still a multiple order of magnitude lower than the 15dbsm Sukhoi.
As I said earlier, Mach 2 is entirely correct. Without proof - which is highly guarded - it's a road to nowhere when the cognoscenti demand evidence that isn't 'out there'. LO's figures from his earlier argument are just as indefensible as those in the example above.
As I said earlier, Mach 2 is entirely correct. Without proof - which is highly guarded - it's a road to nowhere when the cognoscenti demand evidence that isn't 'out there'. LO's figures from his earlier argument are just as indefensible as those in the example above.
Last edited by MSOCS; 27th Mar 2016 at 23:49.
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Or, you incorrectly assume that only engineers know or understand such things. One could assert the signature of a Russian fighter as, say, 10dbsm clean and 15dbsm with a set of stores. Now take a generic stealth fighter with -20dbsm clean, for example. Add the same stores and let's say it becomes -10dbsm or -5dbsm. That's still a multiple order of magnitude lower than the 15dbsm Sukhoi.
As I said earlier, Mach 2 is entirely correct. Without proof - which is highly guarded - it's a road to nowhere when the cognoscenti demand evidence that isn't 'out there'. LO's figures from his earlier argument are just as indefensible as those in the example above.
As I said earlier, Mach 2 is entirely correct. Without proof - which is highly guarded - it's a road to nowhere when the cognoscenti demand evidence that isn't 'out there'. LO's figures from his earlier argument are just as indefensible as those in the example above.
As has been pointed out I believe you do not understand RCS when expressed in decibels. We use decibels (dB) because radar respond to a reduction in RCS in a logarithmic manner.
The decibel (dB) is a logarithmic unit used to express the ratio of two values of a physical quantity, often power or intensity. One of these values is often a standard reference value, in which case the decibel is used to express the level of the other value relative to this reference. The number of decibels is ten times the logarithm to base 10 of the ratio of two power quantities or of the ratio of the squares of two field amplitude quantities.
Radar Cross Section (RCS) is measurement whose units are surface area, typically recorded in square meters. Since RCS is a quantity that can change several orders of magnitude as the angle between the radar and the target varies, usually the base 10 logarithm of the linear RCS is used to show the RCS in plots. It is routine to see the RCS represented this way in dBsm, or decibel square meters.
Even a small panel that's not properly installed can destroy an aircraft's low signature. If a tanker were to damage the surface of a stealth aircraft, it could also spell trouble.
To put it another way, if I use your math I could put eight weapons each with a 1 square meter RCS (1 m2 = 0 dBsm) and not change the signature of the system at all. Or even better, I could mount a very small sphere with a -50 dBsm RCS to an aircraft with a -30 dBsm signature and have a system with a -80 dBsm signature.
External store signature will overwhelm the total signature of the aircraft. While I don’t have a good reference for the RCS of various external stores I will look at a theoretical example. For a given radar with an effective radiated power of x-watts, a low signature aircraft with external stores having a very small signature of 0.1 m² RCS would be detected at 112 NM and a stealth fighter of 0.001 m² (-30 dBsm) RCS would be detected at 36 NM. If you put the external stores on the aircraft the radar will see the 0.1 m2 and the 0.001 m2 aircraft is inconsequential.
Also, when looking at external stores please note that the measurement of RCS in meters squared does not equal geometric area. A perfectly conducting sphere of projected cross sectional area 1 meter square (i.e. a diameter of 1.13 m) will have an RCS of 1 square meter. However, a square flat plate of area 1 square meter will have an RCS of σ = 4π A2 / λ2 (where A=area, λ=wavelength), or 13,982 square meters at 10 GHz if the radar is perpendicular to the flat surface. So external stores with a 0.1 square meter is very small indeed.
Last edited by Bevo; 28th Mar 2016 at 04:03.
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Bevo, in your example above, the 0.1m2 stealth aircraft (with external stores) is still much more stealthy than a 10m2 Sukhoi with external stores, by 2 OOM in fact. I really do appreciate the non-additive, non-linear relationship of such things. On balance, external stores will affect a stealth platform in a much more severe way than a non-stealth platform. The former are optimised against LO requirements, whereas the latter are either blissfully inconsiderate of it or treated to make a design as good as one can.
Thankfully, aerodynamic shaping on weapons fortuitously means that Rayleigh scattering/specular reflection prevents ~14000m2 being seen at the radar in reality; well, at the more offensive aspects anyway.
A stealth aircraft with external stores is still more stealthy than a non-stealth aircraft with external stores. It isn't as doom and gloom as some people like to make out. Of course, if I were LockMart I'd be developing pylons and weapons that were optimised to the F-35 and not just bolt-on bits of orthogonal metal.
Thankfully, aerodynamic shaping on weapons fortuitously means that Rayleigh scattering/specular reflection prevents ~14000m2 being seen at the radar in reality; well, at the more offensive aspects anyway.
A stealth aircraft with external stores is still more stealthy than a non-stealth aircraft with external stores. It isn't as doom and gloom as some people like to make out. Of course, if I were LockMart I'd be developing pylons and weapons that were optimised to the F-35 and not just bolt-on bits of orthogonal metal.
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Perhaps you would like to explain how “Rayleigh scattering/specular reflection” will change the radar cross section expressed in either square meters or dBsm as it relates to the radar range equation. Never mind. I tried to explain.
Of course, if I were LockMart I'd be developing pylons and weapons that were optimised to the F-35 and not just bolt-on bits of orthogonal metal.
Brilliant insight, but a concept invented and flight-tested >25 years ago - and one that has to be built-in, in practice, at the earliest design stage.
Brilliant insight, but a concept invented and flight-tested >25 years ago - and one that has to be built-in, in practice, at the earliest design stage.
Of course, if I were LockMart I'd be developing pylons and weapons that were optimised to the F-35 and not just bolt-on bits of orthogonal metal.
Actually, all that can be done is to speculate, as anyone who knows the technical details sure isn't posting them on a public forum. (And if there were, they ought to be charged and jailed ...)
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I believe MSOCS and KenV may be distantly descended from the same ancient military engineer, given their mastery of the motte-and-bailey argument.
Indeed, if anyone is guilty of motte and bailey arguments, it is those (like LO) who devoutly embrace the anti-F-35 orthodoxy. They routinely make very specific claims about how terrible the airplane is (motte) and then when pressed for facts, they fall back on the usual and very typical hard data is classified and not available and my statement was based on the "generally understood" failures of the program. (bailey).
Ecce Homo! Loquitur...
IIRC in most scenarios the empty pylon has a higher signature than the pylon+weapon due to the exposed face/catches. It would seem more desirable to have one-use eject able pylons - the same way Colt had hundreds of reinforced cardboard/tinfoil tanks for the Jag - and at an even more horrendous cost to the taxpayer.
Mind you, if you hung disposable tanks on the 35B/C and jettisoned them on the edge of enemy cover, they'd might have a chance of making a target beyond the littoral before having to turn for home.
Roll on the UCAV tanker.........
Mind you, if you hung disposable tanks on the 35B/C and jettisoned them on the edge of enemy cover, they'd might have a chance of making a target beyond the littoral before having to turn for home.
Roll on the UCAV tanker.........