Countermeasures for hypersonic weapons

[boneh3ad]

For some number n = (cost of missile)/(cost of projectile), the limitations of a gun launched system are outweighed by the number n of projectiles.

Sure, but clearly the shells for SLRC won't be "just shells." What sort of scaling up is required to hit that range and how does that adjust the denominator in your $n$? I don't know the answer to that.

 

[etudiant]

No argument that

First, ICBMs are indeed faster than the hypersonic weapons currently in development, but it seems you are dramatically overestimating their maneuverability. They have some, sure, but they still follow a more or less ballistic trajectory. They aren't really easy to intercept, but they are easy to track and model, which makes the job somewhat easier. It's doable, if not a 100% success rate.

The bigger issue with the above as it relates to weapon systems currently in development is that you assume that forthcoming hypersonic weapons are using the same booster for the same mission as other weapon systems currently in the arsenal, specifically ICBMs, which is not accurate. At least here in the US, there are no plans to arm hypersonic weapons with nuclear warheads or to employ them in strategic roles. All of the systems currently in development and foreseen for the future are intended to serve a conventional tactical or theater role, performing long-range stand-off strikes in airspace that is denied to our current forces (e.g. by sophisticated air defenses or by shore-based anti-ship missiles that keep carriers out of striking distance).

Furhter, if they did come in nuclear variants, there would be no way to safely use the conventional variants for fear of an adversary mistaking it for a nuclear launch. There is then a likelihood that they would launch their own nuclear counterattack, and obviously no one wants that. The Pentagon has stated that their goal is to have thousands of these available for conventional use, so arming them with nukes would be counter-productive.
I don't know a ton about the SLRC (1000 mile cannon), but based on what I have seen, there doesn't seem to be a lot of room for concern just yet. It's largely on hold for the moment while the National Academies Study it and create a feasibility report, so to me it sounds like they know it's a big risk and are getting outside opinions. Based on what's public, it seems that it would use some combination of traditional artillery shell explosive propulsion to get it going followed by a rocket booster. My major question is why would this need to be a gun instead of just using a missile, especially since the Army is working on fielding its own ground-based hypersonic missiles.

Either way, if you don't dream big, you don't make big technological leaps. The key is to dream big but pull the plug if it becomes obvious that the program is not feasible. DoD is not always the best at doing the latter part of that on time.
This is not an accurate statement.
Do we know that the majority of its range comes from a shell propulsion system? I haven't seen that but that would definitely be eye-raising if true.

The question of why not simply a missile is clearly central.
Afaik, even the rail gun efforts only deliver about Mach 6 at launch, deteriorating thereafter from air drag.
I'm unaware of any gun system that delivers a faster projectile and obviously sustaining that speed requires on board propulsion, plus guidance for targeting, because it becomes a non ballistic trajectory.

Separately, while there has been progress in hypersonic propulsion, the reported gains to date remain modest.
There has been no publicly reported long range self propelled US hypersonic flight since the last X-51 demonstration in 2013. The various projects such as the Lockheed AGM 183 are boost/glide vehicles, rocket propelled and then aerodynamically steered. That greatly cuts the available payload and adds costs.
The rationale for building hugely expensive small conventional strike systems remains questionable to me.

 

[Rive]

...when the vast bulk of the range comes from a shell propulsion system that robs whatever payload the gun may have provided.

At hypersonic speed a simple kinetic impact carries considerable damage potential.
On the other side, I'm not really sure that (chemical, still safe) explosives has enough time to detonate in such circumstances or you simply get the payload only splattered around the target upon impact.
Just think about the discarding sabot type ammunitions.

Ps.: of course, a payload may have it's own use: if you are considering missiles, then you need a pack of explosive to have a fragment field. But that's a different story.

 

[boneh3ad]

The question of why not simply a missile is clearly central.
Afaik, even the rail gun efforts only deliver about Mach 6 at launch, deteriorating thereafter from air drag.
I'm unaware of any gun system that delivers a faster projectile and obviously sustaining that speed requires on board propulsion, plus guidance for targeting, because it becomes a non ballistic trajectory.

No comment on the Mach number from a rail gun, but you are correct that a typical shell is several times slower. Presumably you could pack enough explosive behind it to get it going faster but at what cost? At some point the cost starts to approach that of a missile and the complexity is probably greater than a missile. If it's a ramjet-powered shell, as I've seen reported, then that solves some of the problems but introduces others. That's probably why they paused it pending the outcome of an independent feasibility study.

Separately, while there has been progress in hypersonic propulsion, the reported gains to date remain modest.
There has been no publicly reported long range self propelled US hypersonic flight since the last X-51 demonstration in 2013. The various projects such as the Lockheed AGM 183 are boost/glide vehicles, rocket propelled and then aerodynamically steered. That greatly cuts the available payload and adds costs.
The rationale for building hugely expensive small conventional strike systems remains questionable to me.

To the best of my knowledge, there hasn't been a flight test since X-51, though several are imminent. However, the advances in things like materials, flameholding/combustion, and ground test in the past decade have been pretty significant. Air-breathing weapons are absolutely expected to be the more challenging variety to develop (compared to boost-glide), but it's not insurmountable (or at least doesn't seem to be).

On the other side, I'm not really sure that (chemical, still safe) explosives has enough time to detonate in such circumstances or you simply get the payload only splattered around the target upon impact.

Sure it does. You just have to known when to initiate the process.

 

[ardnog]

The rationale for building hugely expensive small conventional strike systems remains questionable to me.

One can indeed debate the need for more weapons but if one assumes they are necessary, no current "hard kill" system is designed to engage a maneuvering hypersonic target such as a hypersonic cruise missile. Current ballistic missile interceptors are by design intended to engage targets on ballistic trajectories. EDIT: But ballistic missiles are already hypersonic, so I take hypersonic missile to imply airplane-like flight characteristics.

 

[etudiant]

No comment on the Mach number from a rail gun, but you are correct that a typical shell is several times slower. Presumably you could pack enough explosive behind it to get it going faster but at what cost? At some point the cost starts to approach that of a missile and the complexity is probably greater than a missile. If it's a ramjet-powered shell, as I've seen reported, then that solves some of the problems but introduces others. That's probably why they paused it pending the outcome of an independent feasibility study.
To the best of my knowledge, there hasn't been a flight test since X-51, though several are imminent. However, the advances in things like materials, flameholding/combustion, and ground test in the past decade have been pretty significant. Air-breathing weapons are absolutely expected to be the more challenging variety to develop (compared to boost-glide), but it's not insurmountable (or at least doesn't seem to be).
Sure it does. You just have to known when to initiate the process.

The detonation speed of high explosives such as TNT is close to 10,000 meters/sec, 2-3x that of the fastest shells at over 20,000mph. Harnessing the full explosion speed without tearing the gun apart is an unsolved problem afaik, but could allow much longer range guns.
Aiming such a gun is challenging, the 80 mile range WW1 Paris guns fired by the Germans at best hit Paris somewhere. So terminal guidance becomes essential, which requires some ability to course correct. The military benefit of such a 'golden bullet' is questionable imho.

 

[ardnog]

Aiming such a gun is challenging, the 80 mile range WW1 Paris guns fired by the Germans at best hit Paris somewhere. So terminal guidance becomes essential, which requires some ability to course correct. The military benefit of such a 'golden bullet' is questionable imho.

Price will come down as technology improves. While they may not be exconomical now, a weapon system lasts 30 or more years. Such a gun if it existed today would be a significant threat to a warship, or high value land target like an air defense radar or command center.

Now, if we're talking about smaller, shorter-range guns, missile interception and armor penetration would benefit greatly from the increased velocity of a hypersonic projectile. Whether or not this will be better than a laser is another open question.

 

[berkeman]

If it's a ramjet-powered shell, as I've seen reported, then that solves some of the problems but introduces others.

Wow, that's pretty interesting. I hadn't heard about that concept before:

https://www.thedrive.com/the-war-zo...llery-round-for-the-armys-new-super-howitzers

"The tactical 155mm XM1155 will be able to strike moving and stationary high-value targets on land and at sea," according to Raytheon's press release. "The maneuverable, extended-range airframe will be compatible with legacy and future 155mm artillery systems."

Raytheon did not offer any specific details about its design, but the ramjet will be at its core. The projectile will have to first get to an appropriate velocity for this engine to function optimally. Past ramjet artillery round designs have used rocket boosters or large conventional propelling charges to provide this initial burst of speed. The sustained supersonic flight, coupled with the fact the engine is actually pulling the projectile through the air, which helps reduce drag, are at the core of the significantly extended range capabilities.

 

[Klystron]

Detection and tracking are related but distinct problems. Detection and early warning (of attack) can be achieved with coarser methods than track; such as audio, IR and mass detectors, atmospheric disturbance and minimally processed RF; not to mention old-fashioned visual.

Tracking cruise missiles at any speed even with look-down, synthetic (images built from multiple returns) and mobile systems such as AWACS remains a nifty problem in applied physics.

When combatting cruise missiles with radar designed to track aircraft, I would recite that old poem about the 'little man upon the stairs'.

"He wasn't there again today. Oh how I wish he'd go away!"

 

[FactChecker]

So terminal guidance becomes essential, which requires some ability to course correct. The military benefit of such a 'golden bullet' is questionable imho.

How can that be questionable? Am I misreading what you mean here? IMHO, hitting the exact target has great military value and has been convincingly proven by today's smart weapons.

 

[Rive]

How can that be questionable?

I think it's about the price. There are those GPS-guided artillery shells already. But even if there were a few pieces at hand 'everywhere', as far as I know it was always kind of a celebration (with spectators!) to actually fire them.

 

[boneh3ad]

Aiming such a gun is challenging, the 80 mile range WW1 Paris guns fired by the Germans at best hit Paris somewhere. So terminal guidance becomes essential, which requires some ability to course correct. The military benefit of such a 'golden bullet' is questionable imho.

We have the technology for guided artillery right now. To me, that isn't the hard part (anymore). The quoted range combined with cost effectiveness is the big question for me.

The military value of being able to land a shell exactly on a specified target with minimal risk of collateral damage (i.e. low CEP) is unequivocally valuable. The question is just whether it's economical given the system requirements.

 

[boneh3ad]

I think it's about the price. There are those GPS-guided artillery shells already. But even if there were a few pieces at hand 'everywhere', as far as I know it was always kind of a celebration (with spectators!) to actually fire them.

It's a fairly new technology so, sure, it's not currently something you see used at scale on the battlefield. The question is whether or not it has the potential to become feasible after accounting for the the economy of scale from full-scale production. Lots of people get paid comfortable but not amazing government salaries to answer that question.

 

[FactChecker]

I think it's about the price. There are those GPS-guided artillery shells already.

Although the reliability of GPS in a war might be a current issue.

 

[boneh3ad]

Although the reliability of GPS in a war might be a current issue.

I believe we created a whole new branch of the military over this issue.

 

[Stormer]

Going on the offensive is always applicable. Weapons are the tip of the spear, there is a lot of infrastructure to support any weapons operation even if you can't directly target the weapon. You kill the builders of the weapon, kill the operators, then bomb the logistics, crater the roads, etc.. This all has an effect on the amount of defensive countermeasures needed at the targeted end.

Might be pretty difficult to find and strike the infrastructure when that can be any normal looking shipping container on any ship or semi truck.

 

[ardnog]

A reminder that development into hypersonic may not even your own choice. The "me too" crowd is quite influential and Russia continues tests.

https://www.navalnews.com/naval-new...inue-tsirkon-hypersonic-missile-tests-in-2021

In October 2020, the frigate ‘Admiral Gorshkov’ launched the Tsyrkon missile against a target at a range of 450 km. The weapon covered this distance in 270 seconds, reaching a speed of some Mach 8.0 and a top altitude of 28 km.

EDIT: This missile is known in the west as SS-N-33 (link) and is a hypersonic cruise missile.

EDIT: It is my opinion that the US has lost the lead in missile technology.

 

[boneh3ad]

A reminder that development into hypersonic may not even your own choice. The "me too" crowd is quite influential and Russia continues tests.

https://www.navalnews.com/naval-new...inue-tsirkon-hypersonic-missile-tests-in-2021
EDIT: This missile is known in the west as SS-N-33 (link) and is a hypersonic cruise missile.

EDIT: It is my opinion that the US has lost the lead in missile technology.

You are not alone in that assessment, though I think China is considered the more worrisome of the two other major countries developing these weapons.

https://www.airforcemag.com/article/catching-up-on-hypersonics/

There was a quote recently by a Russian academic in the field that said, in effect: "Russia has a great deal of experience in this but no money. China has a great deal of money but little experience here. The US has both, but has lacked the will." I thought it was a good encapsulation of the situation (even if it's a bit more complicated than just lacking the will).

 

[berkeman]

https://www.airforcemag.com/article/catching-up-on-hypersonics/

Interesting article. I hadn't considered the propulsion testing difficulties...

Propulsion testing is especially problematic. For a combined-cycle engine—one that uses conventional, turbine-like propulsion to get to high velocity, and then transitions to a scramjet for hypersonic speed—“we really don’t have anything that will let us do that adequately on the ground,” Lewis said. For any wind tunnel work in the U.S., “you have very limited choices. … So that’s an area that needs investment.”

Availability of flight-test ranges is another problem. Again, programs are competing for range time, not only with each other but with “all the other things we want to do flight-testing on,” Lewis said.

“We’ve got some amazing [test] infrastructure, but it’s very old,” said Maj. Gen. Christopher P. Azzano, commander of the Air Force’s Test Center at Edwards Air Force Base, Calif. “We’ve put sustainment money into it over the last few years, but it needs more.”

 

[Frabjous]

Interesting article. I hadn't considered the propulsion testing difficulties...

I have met old timers from several places who remember the day the blow torches came to turn their wind tunnels to scrap.

Ignoring disinformation and media misunderstanding, it can be hard to compare programs from different countries from media reports because each country has a different design cycle where testing and system namings are performed at different points in the cycle.

 

[Klystron]

Illuminating articles. NASA tends to separate system tests even for scale models. Thermal materials were tested in blow-down wind tunnels where the 'air' is super heated in a pressure vessel then blasted through various enormous nozzles fitted into thick pipes. Difficult to stimulate 1000 km flights, one imagines, using blow down instead of recirculation.

Even back in the 1980's the 8x7 hypersonic wind tunnel cost a bundle to run and maintain.

 

[boneh3ad]

I have met old timers from several places who remember the day the blow torches came to turn their wind tunnels to scrap.

Ignoring disinformation and media misunderstanding, it can be hard to compare programs from different countries from media reports because each country has a different design cycle where testing and system namings are performed at different points in the cycle.

Every country has different strategic goals as well, so the systems are not 1-to-1 counterparts.

 

[boneh3ad]

Illuminating articles. NASA tends to separate system tests even for scale models. Thermal materials were tested in blow-down wind tunnels where the 'air' is super heated in a pressure vessel then blasted through various enormous nozzles fitted into thick pipes. Difficult to stimulate 1000 km flights, one imagines, using blow down instead of recirculation.

Even back in the 1980's the 8x7 hypersonic wind tunnel cost a bundle to run and maintain.

Blow down tunnels are actually far more able to simulate high altitudes than recirculating tunnels.

EDIT: I misread that. Recirculating can certainly simulate long flights but you can get a lot of data in short times in blow down tunnels.

 

[ardnog]

Ignoring disinformation and media misunderstanding, it can be hard to compare programs from different countries from media reports because each country has a different design cycle where testing and system namings are performed at different points in the cycle.

is NASA still dependent on Russian rocket engines? I haven't been keeping up to date.

 

[boneh3ad]

is NASA still dependent on Russian rocket engines? I haven't been keeping up to date.

As far as I know, no. Congress passed a law forbidding it in 2014. The exception was allowing ULA to use up the rest they had on hand but not order any new ones.

 

[Klystron]

Illuminating articles. NASA tends to separate system tests even for scale models. Thermal materials were tested in blow-down wind tunnels where the 'air' is super heated in a pressure vessel then blasted through various enormous nozzles fitted into thick pipes. Difficult to stimulate 1000 km flights, one imagines, using blow down instead of recirculation.

Blow down tunnels are actually far more able to simulate high altitudes than recirculating tunnels.

EDIT: I misread that. Recirculating can certainly simulate long flights but you can get a lot of data in short times in blow down tunnels.

Upon reflection and rereading articles on new hypersonic flight, blow down tunnels should handle the stated ~10 minute experiments. Establish the simulated altitude and conditions then feed the fluid flow from multiple a/o ganged pressure vessels. My perception may be biased by blow down tests on thermal tiles and experimental ablation shields shortened by destruction of the material.

On the subject of hypersonic test range scarcity, I noticed no mention of West Coast facilities beyond Edwards. Could this be due to population expansion coupled with seismic activity?

I had migrated from wind tunnels to flight simulators when the 1989 Loma Prieta earthquake struck the Bay Area. Four gigantic very high-pressure, high-temperature vessels already prepared for major tests across the street from the sim building either ruptured or vented during the quake. I recall stumbling out of an ultra-cool computer room into a wave of heat and soot surpassing a desert dust storm.

 

[nsaspook]

Might be pretty difficult to find and strike the infrastructure when that can be any normal looking shipping container on any ship or semi truck.
View attachment 280622

The typical military response to that is to blow them all up during an actual war.

 

[boneh3ad]

Upon reflection and rereading articles on new hypersonic flight, blow down tunnels should handle the stated ~10 minute experiments. Establish the simulated altitude and conditions then feed the fluid flow from multiple a/o ganged pressure vessels. My perception may be biased by blow down tests on thermal tiles and experimental ablation shields shortened by destruction of the material.

On the subject of hypersonic test range scarcity, I noticed no mention of West Coast facilities beyond Edwards. Could this be due to population expansion coupled with seismic activity?

I had migrated from wind tunnels to flight simulators when the 1989 Loma Prieta earthquake struck the Bay Area. Four gigantic very high-pressure, high-temperature vessels already prepared for major tests across the street from the sim building either ruptured or vented during the quake. I recall stumbling out of an ultra-cool computer room into a wave of heat and soot surpassing a desert dust storm.

I don't know why they didn't mention other ranges. Maybe it just wasn't important to list them all. Really, Edwards isn't even testing these kinds of things as far as I know. It seems to be out over the Pacific run by Point Mugu.

 

[ardnog]

The typical military response to that is to blow them all up during an actual war.

The military often has an over-inflated view of what they can find and explode, or neither US or the Soviets would have got stuck in Afghanistan for 20 years trying to beat goat shepherds.

 

[nsaspook]

The military often has an over-inflated view of what they can find and explode, or neither US or the Soviets would have got stuck in Afghanistan for 20 years trying to beat goat shepherds.

The military knows well the limitations on the use of force. Decisions on the use of force and it's limitations are mainly political, not technical. Effective countermeasures to hyper-sonic weapons will be found IMO and used if deemed necessary.

What the US or the Soviets we couldn't find and explode in Afghanistan was (is) an idea not a military objective to destroy a military target. The Soviet military (I was off the coast of Iran and Afghanistan in 1980 and 1981) had no problems massacring entire towns and bouncing rubble to smaller and small rocks in an attempt to break the will of the 'rebels' by reducing much of the country to the stone-age. Fifteen thousand Soviet soldiers killed doing that broke the will of the USSR instead.

 

[FactChecker]

The military knows well the limitations on the use of force. Decisions on the use of force and it's limitations are mainly political, not technical. Effective countermeasures to hyper-sonic weapons will be found IMO and used if deemed necessary.

What the US or the Soviets we couldn't find and explode in Afghanistan was (is) an idea not a military objective to destroy a military target. The Soviet military (I was off the coast of Iran and Afghanistan in 1980 and 1981) had no problems massacring entire towns and bouncing rubble to smaller and small rocks in an attempt to break the will of the 'rebels' by reducing much of the country to the stone-age. Fifteen thousand Soviet soldiers killed doing that broke the will of the USSR instead.

The problem with trying to project power to the other side of the world is that we have to decide how long we want to keep soldiers away from home and family and how much money we want to keep spending, whereas they can just sit at home waiting for opportunities to take pot-shots.

 

[ardnog]

The problem with trying to project power to the other side of the world is that we have to decide how long we want to keep soldiers away from home and family and how much money we want to keep spending, whereas they can just sit at home waiting for opportunities to take pot-shots.

I think it's not just a case of living in caves and taking potshots, but the fact that they actually enjoy it.

Even if you blew the whole planet back to the stone age, they'd still be happy.

I think you have to evaluate very carefully what you mean by "win" in situations like this.

 

[etudiant]

The North Koreans demonstrated that it was quite possible to maintain a disciplined resistance in the face of truly overwhelming military pressure. Afaik, no North Korean city survived the war, yet the military effort remained uninterrupted.
I think the more recent US delusion that killing Al Qaeda leaders would cause the movement to fall apart should have been instructive, as all it did was clear the way for more ruthless and more effective successors.
So I'm deeply skeptical as to the value of 1000 mile golden bullets. It assumes someone in NYC can effectively target some place in Miami or Chicago and achieve some militarily significant result. I call it BS.

 

[nsaspook]

The North Koreans demonstrated that it was quite possible to maintain a disciplined resistance in the face of truly overwhelming military pressure. Afaik, no North Korean city survived the war, yet the military effort remained uninterrupted.
I think the more recent US delusion that killing Al Qaeda leaders would cause the movement to fall apart should have been instructive, as all it did was clear the way for more ruthless and more effective successors.
So I'm deeply skeptical as to the value of 1000 mile golden bullets. It assumes someone in NYC can effectively target some place in Miami or Chicago and achieve some militarily significant result. I call it BS.

I agree, so that's why I see the hypersonic weapon threat more as a trigger for starting a war, not as a useful weapon for ending one.

 

[boneh3ad]

The North Koreans demonstrated that it was quite possible to maintain a disciplined resistance in the face of truly overwhelming military pressure. Afaik, no North Korean city survived the war, yet the military effort remained uninterrupted.
I think the more recent US delusion that killing Al Qaeda leaders would cause the movement to fall apart should have been instructive, as all it did was clear the way for more ruthless and more effective successors.
So I'm deeply skeptical as to the value of 1000 mile golden bullets. It assumes someone in NYC can effectively target some place in Miami or Chicago and achieve some militarily significant result. I call it BS.

I think you are leaving out the part where the North Koreans were all but beaten but then the US crossed the 38th parallel and triggered Chinese intervention. Ultimately, that is what led to the stalemate. These are two very different examples in that the North Koreans fought a fairly conventional war and were propped up by a larger power. Al Qaeda is a very different, non-state entity that survives because, ultimately, it is an idea, not a physical state.

But this is all effectively irrelevant to the discussion of hypersonics. The hypersonic developments have been aimed at potential great power conflicts, not asymmetric warfare. I guess you could argue it would be easier to carry out a strike against fleeting command and control targets with a hypersonic weapon in an asymmetric engagement, but that's a pretty expensive way to do things considering that we already have that capability via drone strikes. The problem is that in a hypothetical conflict with a peer such as China or Russia, air superiority is not likely to be achieved over their territory, so you need something different to hold them at threat. That's the reason for all of the hypersonic developments.

I agree, so that's why I see the hypersonic weapon threat more as a trigger for starting a war, not as a useful weapon for ending one.

At some point it is all about deterrence and matching a peer adversary. If only one side develops a new weapon that changes the strategic balance and the other cannot similarly hold them at threat, it lowers the bar for that one side with the new weapons to use force since retaliation options are limited. If both sides have similar capabilities, it's a higher bar for either side to launch an attack because there is a degree of mutually assured destruction.

In both cases, it also fundamentally alters the other side's strategic decision making. One of China's chief goals is to assert dominance over the South China Sea, and to do that, they need to keep our carriers and other air power far enough away that they remain ineffective. This is why they are working to develop these weapons that can hit carriers and Guam. If we have similar capabilities, we can defeat that aim to some extent.

This is probably why you also see so much investment in the offensive systems compared to defensive ones. Offensive weapons are generally easier to develop, and both sides can achieve many of their strategic goals through offensive weapons and hope their deterrent value buys more time to build defensive weapons.