US Airpower in this Global Thermonuclear War scenario

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jetblast16

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Unread post17 May 2017, 01:47

X-rays..

In low-to-moderate altitudes, the X-rays produced from the uncontrolled nuclear explosion, are absorbed within yards of the burst point. Due to their energies, rapid transfer of energy and number, the surrounding air is heated to a very high temperature. This phenomenon is sometimes referred to as the "X-ray fireball". The point being, the majority of these "photons" are absorbed by the air near the burst point. Some having higher than average energies escape past this fireball (plasma sphere), and propagate outward, eventually being absorbed by air or other particles, perhaps even adjacent structures.

At high altitudes, the X-rays propagating upward, away from the Earth, escape into space, while those traveling downward, are largely absorbed by a layer of air called the "X-ray pancake", which becomes incandescent (glows) from the ionizing effects of the rays.
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Unread post17 May 2017, 13:11

arian wrote:Shauraya is the one that has about 200 miles of "glide", in its maximum range configuration (1,900km with a small warhead).


Which is WAYYYY more than a Pershing II type RV. All those (and other maneuvering RVs) do is minor course corrections for accuracy and evasion. They don't in any way, shape, or form glide for several hundred miles.

arian wrote:In short range profile (its 700km max range) it spends all of its time inside the atmosphere, but that is irrelevant to this discussion. No way is it the same "boost-glide" as what we're talking about.


You seem to be under the mistaken impression that only ICBMs can be boost gliders or that "boost glider" has some mandatory range requirement. This is incorrect. The term "boost glider" applies to the flight profile for which Shaurya definitely fits the bill.

arian wrote: It is still little different than Pershing type profile, in its long-range configuration


You clearly have no idea what a "Pershing type" flight profile is.

arian wrote: and a longer-ranged SRBM in its short-range configuration.


Wrong again. It's not flying a ballistic trajectory, which is to say it's not a BALLISTIC missile. It gets up to speed, while staying relatively low, and GLIDES the rest of the way. It's under hypersonic glide for so long it has to do the "rotisserie" thing to spread the heat across its body evenly.

arian wrote:Its relevant in the trade-off made between avoiding exo-atmospheric and endo-atmospheric interceptors. If you try to avoid exo-atmospheric interceptors (which something like that Indian missile really can't do with only a 200 mile glide, since it will still be within reach for majority of its flight profile), but end up slowing down to Mach 5 or some other similar figure, then you're now potentially well within the engagement envelope of something like SM-6 and THAAD and PAC-3 (and even SM-3 at high enough altitudes). So have you really made the right trade-off? This Indian missile is nothing new in its capabilities that our targets don't already mimic.


Name a target that mimics the Shaurya profile. Hell, we can't even manage to create a Sizzler analog. (The first tests were failures so we quit.)


arian wrote:On the other hand, if you can do that, and maintain Mach 20 (for thousands of miles), then you're outside of both exo and endo interceptors. That's relevant.


We're debating what is or isn't a boost-glider. Speed has SFA to do with whether or not a missile is a boost glider.
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Unread post17 May 2017, 13:23

arian wrote:Here's what the Indians claim of their missile:
Image

So they claim that in its long-range version (with a small 140kg warhead), it can "glide" between about 1,300 and 1,800km (so 300 miles).


You must be using one of those new Chinese calculators. My HP-48 says 1800km is 1118 miles. :wink:

arian wrote: While this is good, it isn't in the same class as what is needed to counter interceptors involved here: SM-3 would still be able to intercept it in the long ballistic flight, and terminal defenses would still be able to intercept it because it has to slow down considerably.


Only if it happened to still be in space when SM-3 arrived. THAAD ER would be better (or just wait until it's near the target and hit it with a PAC-3) but Shaurya might have more divert capability than even THAAD ER with it's upper stage.

arian wrote:To achieve HTV-2 type of "boost-glide", you need either much better aerodynamic lift or multiple boost phases.


No you don't. Go read up on BGRV.

arian wrote:In the short-range profile, it is little different from all the other contemporary theater ballistic missiles.


Not sure if you're just willingly ignorant or have some dogmatic reason for not accepting that Shaurya is a boost glider. (Because it is. It's definitely NOT flying a ballistic profile like "all the other contemporary theater ballistic missiles".)


arian wrote: Theoretically, they are all "hypersonic glide" weapons since they all use some aerodynamic lift and don't follow a ballistic trajectory and are inside the atmosphere and are hypersonic. So that's just BS word games from the Indians.


Wrong again. Neither ATACMs nor Iskander (both non-traditional semi-ballistic missiles) are boost gliders. SCUD damn sure isn't.

arian wrote:Speed, range, time to endo-flight etc are all the really important parameters to consider here. Not whether something can "glide". Theoretically, most contemporary theater ballistic missiles can and do.


Really? Name one that glides for 400+ miles.
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Unread post19 May 2017, 22:23

sferrin wrote:You must be using one of those new Chinese calculators. My HP-48 says 1800km is 1118 miles. :wink:


Seriously? I'm going to let you contemplate for a while where the "glide" is in that profile.

Only if it happened to still be in space when SM-3 arrived.


Which is why you wouldn't randomly position a ship to intercept ballistic missiles.

sferrin wrote:but Shaurya might have more divert capability than even THAAD ER with it's upper stage.


It certainly doesn't, however.

No you don't. Go read up on BGRV.

BGRV was a aerodynamically shaped re-entry vehicle testing spacecraft re-entry. So, yes it does. And how long did it glide in tests?

Not sure if you're just willingly ignorant or have some dogmatic reason for not accepting that Shaurya is a boost glider. (Because it is. It's definitely NOT flying a ballistic profile like "all the other contemporary theater ballistic missiles".)


I'm not sure if you understand that virtually NONE of modern SRBMs follow a ballistic profile either. SRBM doesn't mean it flies ballistic. Iskander, ATACMs etc. None of them do. They also are under controlled "hypersonic glide" profile as well. So yes, "boost glide" only in the sense as in every other SRBM is also a "boost glide" as well.

Wrong again. Neither ATACMs nor Iskander (both non-traditional semi-ballistic missiles) are boost gliders


Neither of them follow a ballistic profile. Both of them are under controlled aerodynamic flight. Both of them retain the ability to maneuver. Either they are all "boost glide", or none of them are. (hint, none of them really are, in the context of what we're talking about, and for the purposes for which it matters, which is as a defense against exo-atmospheric interceptors)

Really? Name one that glides for 400+ miles.

Well, none, actually. Neither does this Indian thing. It "glides" for 300 miles. And, hasn't actually ever been tested in doing so :wink:
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Unread post19 May 2017, 22:37

sferrin wrote:Which is WAYYYY more than a Pershing II type RV. All those (and other maneuvering RVs) do is minor course corrections for accuracy and evasion. They don't in any way, shape, or form glide for several hundred miles.


Neither does this Indian thing since it hasn't been tested in doing so. It's just conjecture and internet BS :wink: But, my point is the principles and methods are the same, and its utilizing the same method as Pershing II. Pershing II didn't do so not because it couldn't. It probably (certainly) could. But it's return to aerodynamic flight was aimed at a specific goal: to allow for guided flight to target. Not to avoid interceptors or extend range.

You can use the same principle and method for different goals, and hence achieve different results.

You seem to be under the mistaken impression that only ICBMs can be boost gliders or that "boost glider" has some mandatory range requirement. This is incorrect. The term "boost glider" applies to the flight profile for which Shaurya definitely fits the bill.


Technically, ANY projectile which is "boosted" by a rocket or other means, and then aerodynamically "glides" to a target fits the definition of a "boost glide" projectile. Probably, there were projectiles in WW1 that fit this bill.

But we're not arguing semantics here: we're arguing a distinct method for a specific purpose. The short-range profile of this Indian missile is similar to other modern SRBMs (which also do this). The long-range profile of this Indian missile is what we're...actually...talking about. But the issue there is 2 fold: 1) it's never been tested, and 2) it is so limited as to, perhaps, not be useful against most interceptors.

I'm not saying the long-range profile of this Indian missile isn't "boost glide" in the exact way we're describing. I'm saying, for the purposes for which it is intended, it is not sufficient. To truly avoid exo-atmospheric interceptors you need much longer glide, and to truly be able to avoid endo-atmospheric interceptors or terminal defenses, you need much higher speed.

There are too many trade-offs involved against different threats, for anyone to have actually come up with a viable weapon at all at this point (the closest thing was HTV-2, if it had worked)

You clearly have no idea what a "Pershing type" flight profile is.


You're clearly interested in playing semantics here, rather than discussing the actual mechanisms involved here.

Wrong again. It's not flying a ballistic trajectory, which is to say it's not a BALLISTIC missile. It gets up to speed, while staying relatively low, and GLIDES the rest of the way. It's under hypersonic glide for so long it has to do the "rotisserie" thing to spread the heat across its body evenly.


Again, semantics games. Simply because they are called SRBMs doesn't mean they fly ballistically either.

Name a target that mimics the Shaurya profile


A low hypersonic maneuverable ballistic missile target? All of them?

We're debating what is or isn't a boost-glider. Speed has SFA to do with whether or not a missile is a boost glider.


YOU are debating whether something is or isn't boost-glide. I am debating whether something has the ability to counter defenses or not. I'm not interested in debating semantics, because that is what most of the distinction between the various different types are. The mechanisms are the same or similar among different missiles spanning decades. They simply use the mechanisms for different purposes. So whether something works or not, given its performance, for the purposes given, is what matters.
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Unread post19 May 2017, 23:06

To go back to your earlier comment armedupdate about Atlas ICBM re-entry vehicle and speeds. Finding pictures of Atlas warheads is difficult, but I managed to find one. Here is a person standing next to the Mk.2 re-entry vehicle for Atlas:

Image

And here is a person next to a modern re-entry vehicle. You can see the vast difference.
Image

Here's another one with models (not to scale) of the evolution of warheads. The first one to the left is the Atlas warhead (blunt end is the front):
Image
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Unread post20 May 2017, 23:08

To expand further on this discussion of what is or isn't "boost-glide", and what are the mechanisms involved:

The term "boost glide", if we want to play semantics, is really only applicable to ballistic missiles which intend to use aerodynamic lift to extend range following re-entry. Range-extension is the primary defining characteristic of these systems, NOT the mechanism of flight.

The mechanism of flight is similar for both "boost-glide" and maneuvering re-entry vehicles which rely on aerodynamic lift. It is also similar for theater/tactical/short-range ballistic missiles, but these never re-enter the atmosphere, and have very different speed and maneuvering requirements. Also, not all maneuvering re-entry vehicles rely on aerodynamic lift for maneuvering: some use thrusters, some use shifting center of gravity (internal mass moves and shifts the cg), or some use bent-nose configurations (the nose is bent to provide lift, which is controlled by speeding up or slowing down spinning in order to direct the lift in certain directions. Technically this last one also relies on aerodynamic lift, but is very different).

Boost-glide and aerodynamic maneuverable re-entry vehicles (ie Pershing II-type) all operate under the same principles. First tested in 1959 under Alpha Draco program:
Image

The shape look familiar?

I.e., some form of lifting-body design. They typically have the same sharp-nose, long body and aerodynamic control surfaces. However, the means of achieving aerodynamic lift matter here. All these systems (Alpha Draco, Pershing, the Chinese systems, the Indian systems etc.,) rely on the nose-cone lifting effect. Other systems like HTV-2 rely on a very different lifting body design, for important reasons discussed below.

The difference between the two types comes about because of the trade-off made in terms of range, speed and maneuverability.

Boost-glide try to maximize range. This comes about at the expense of maneuverability and speed (much lower for boost-glide). Pershing II types try to maximize maneuverability, at the expense of glide range. This does involve differences in design (materials, structural, length, diameter etc.), but the mechanism is the same.

Theater/tactical/short-range ballistic missiles from the late 70s onward are all similar in mechanism:

Image

Shape look familiar?

They all rely on aerodynamic lift to achieve flat trajectories where the missile retains aerodynamic control during its entire flight path. ATACMs is similar. Lift from the conical nose, cg position etc. The Indian missile tested out to 700km is also similar. Although they all use the same mechanism as 'boost glide", these are clearly not the types of weapons we are discussing. The altitude, speed etc are all different. None of these are relevant here.

Now, to go back to strategic missiles where the term "boost glide" really applies, since it involves atmospheric re-entry and is tasked with a SPECIFIC purpose of range-extension for the purposes of defeating detection and interception.

The specific threat they are aimed at matters in so far as which of these variables of speed, range and maneuverability (and altitude) should be emphasized, or whether they are worth doing it.

The US tested all of these different configurations (over 30 different types of vehicles were tested), and eventually decided that it was preferable to focus on small ballistic re-entry vehicles and countermeasures as a more desirable approach to defeating defenses. The reasons are many (one primary one being size, these other alternatives are MUCH larger. The second being that no defenses existed at the time that required such an investment)

If you're going for boost-glide for the purposes of achieving a flat trajectory to go below radar horizon, and thus minimize detection time, and below exo-atmospheric interceptor range, you need extreme glide range of several thousands of miles. BGRV-3 was the only test the US conducted in 1967 which achieved (supposedly), something like this. There is a BIG problem, however. Speed. These conical nose lifting bodies achieve their best lift at relatively slow speeds: around Mach 5-7). At higher speed, it deteriorates. This makes them vulnerable to terminal defenses, and thus defeats the purpose. Also this means much longer flight time due to much lower speed. HTV-2 was the radical departure in this regard in that it achieved both extreme glide range, AND extreme speed of Mach 20. This is not trivial....as you make it sound. This is a critical factor. All other prior US projects were abandoned because of the speed issue being too slow. HTV-2 was a by-product, or eventual product, of 1980s projects.

The second type of missile relying on the same mechanism, the Pershing-II type (ie maneuverable re-entry vehicle using aerodynamic lift), were designed not for range but for maneuverability. They also suffer from speed loss during re-entry pull-up, again slowing them down to the point where terminal defenses can intercept them. However, they were designed for extreme maneuverability to counter systems like Gazelle and Sprint. Here again, how maneuverable they are does matter. The only US system to make it into production was Pershing II. Chinese and Indian projects are all extremely similar to Pershing II design, and for the same purposes. Howe good they are in comparison matters, and is unknown. But they are categorically not in the same league as the "boost-glide" systems designed for range extension. (they are ALL capable of range extension...however how much IS the entire point)

Yet another class of re-entry vehicles relying on the SAME mechanism were designed for extreme low-altitude glide to target below radar-horizon and ability of interceptors to reach them until the final approach. The US tested these systems in the 1960s, but advances in Soviet SAM technology made them irrelevant. The Russians, supposedly, tested a similar concept in their Topol-M where the warhead uses the same mechanism to glide at very low altitude for its final approach to target. How fast, how long is the glide etc., all matter as to whether it matters in terms of defeating defenses or not. That remains unknown.

The Chinese DF-21 warheads tested are also all in this family of maneuverable-reentry vehicles relying on nose-cone lift. Some Chinese designs shown appear to be of the bent-nose type (which are explicitly targeted at maneuvering). Others are similar to Pershing II (but appear to be much shorter and stubbier, implying almost no ability to glide at all but entirely aimed at maneuvering). So all the sensational "Chinese boost-glide" stuff on the internet is pure nonsense...until they can show which of these characteristics the Chinese DF-21 maneuverable warheads are emphasizing: speed, range, maneuverability (and altitude) etc. Without knowing this, calling everything that has aerodynamic lift "boost glide" is stupid. From what we've seen of designs, they are going for maneuvering, and is an evolution of their M-11 missiles (which were themselves copied from Pershing II) which would make sense for something intended to be terminally guided.

Now none of this really matters in practice. What matters in practice if any of them can defeat modern defenses: PAC-3, THAAD, SM-6, SM-3, GMD. Each one would require a different prioritization and trade-off in design. GMD has extreme range, so if the intention is to go blow radar horizon and exo-atmospheric engagement envelope, would require extreme glide range of many thousands of miles. Same for SM-3, except SM-3 is mobile and therefore getting high apogee may put the ballistic missile in danger regardless of how long its glide is. SM-3 probably can also be effective at high atmospheric altitudes where a glide vehicle would be flying for the majority of its flight. So are any of these systems capable of defeating either? So far, certainly none come close. (which is why HTV-2 with Mach 20 is indeed a very different category, because at those speeds inside the atmosphere, it is outside the capabilities of endo-atmospheric interceptors)

THAAD has extreme maneuverability and very long range. Some sources claim 100g. This would make it quite capable of engaging these types of maneuvering vehicles, especially since most are traveling at low hypersonic at this point.

So is this worth the trade-offs made? Is it worth the development cost and time? Is it worth compared to more conventional means? Well, for terminally guided missiles there is little other alternative to begin with. But their ability to survive against modern defenses is also equally questionable. For strategic forces, the real threat is exo-atmospheric, where decoys, RCS, and other means of evasion may be more relevant or important, and hence re-rentry phase is much less so (especially given the absence of real endo-atmospheric ICBM defenses for things traveling at Mach 20)

So there are very good reasons to argue that unless one can come up with an HTV-2 type weapon, anything short of that is not worth doing for strategic weapons, when existing methods are more viable.

So this is all that matters, in my opinion:

1) The aerodynamic lift mechanism is the same. The difference is in which flight characteristic is emphasized, and for what purpose
2) They come with some very BIG trade-offs which may well make them irrelevant in terms of defeating interceptors of today
3) They are prevalent as a flight mechanism for most modern missiles which need terminal guidance, and that's why they are really used there.
4) But stretching the definition to "TRUE BOOST GLIDE!!!!! OMFG!!!!!" for something that certainly isn't at all in the same scale or category as what a real "boost glide" is, simply because it uses the same mechanism of generating lift...is a stretch of the imagination akin to saying that a V-2 rocket and a 7.62mm bullet are the same thing since they use the same flight mechanism.

5) And finally, as it matters in terms of suitability and effectiveness of the weapon, useful "boost glide" would be something in the class of HTV-2 since it maximizes two of the most important parameters needed: glide range and speed. None even come close. Of course, HTV-2 didn't come close either. But that's why these things are mostly pipe dreams.
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Unread post21 May 2017, 22:10

To continue on, as mentioned earlier these nose-cone lifting bodies have the disadvantage of being efficient at relatively low speeds. For those emphasizing glide range, speed could be a bit higher but the maneuvering capability was lower.

Unlike the military, NASA was focusing on winged glide designs for spacecreaft re-entry and of course the military applications of that were obvious. A winged design allowed for much higher speeds for gliders emphasizing range: speeds in the Mach 17-20 range. They experimented with these since the late 50s, such as project Hywards from 1957:

Image

Image

These winged designs eventually developed into the SGBV (strategic boost glide vehicle) of the 1980s which was envisioned to have a speed of Mach 18 and a glide range of 5,000 miles

Image

Sound familiar? This was what led to HTV-2

So this is why speed...does...matter. Speed is what separates these "true" boost-glide with strategic relevance, from nose-cone lift maneuverable re-entry vehicles, or even those with marginal gliding capability: they are designed for relatively slow glide flight, and are only capable of relatively short ranges. The winged designs are designed for very high speeds and extreme glide ranges.

And these actually do use a different mechanism of flight, at least.
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