Countermeasures for hypersonic weapons

[FactChecker]

It has everything to do with the wing-loading [pounds of lift per square foot of wing area]. Jets have relatively much larger wings for their size than missiles, so they can maneuver out of it\s way and the missile can't follow the arc of the aircraft's turn.

It is wrong to judge the maneuverability of a missile the same as an airplane. A modern fighter airplane can get much greater aerodynamic forces than thrust forces and turn at up to 9 Gs from its aerodynamics. It could never get 9 Gs of acceleration from thrust. Some missiles can get much greater thrust/weight from their propulsion and can achieve up to 20 G maneuvers. They just need to turn their thrust in the right direction. They don't need to rely on wing-loading and aerodynamics.

 

[nsaspook]

As an info point the US has a long history of hypersonic countermeasures for hypersonic weapons (ABM systems). I would be surprised if the old technology couldn't be adapted for modern use.


http://www.astronautix.com/s/sprintabm.html

 

[boneh3ad]

As an info point the US has a long history of hypersonic countermeasures for hypersonic weapons (ABM systems). I would be surprised if the old technology couldn't be adapted for modern use.


http://www.astronautix.com/s/sprintabm.html

I don't know how many times we have to say it, but existing countermeasures (including tracking) are designed for ballistic trajectories. They kill an incoming threat either exo-atmospheric, in the midcourse phase, or in the terminal phase. In both cases, they aren't maneuvering. The newer class of threats come in inside the atmosphere and are maneuverable. There may be a way to adapt existing interceptors to the task (e.g., SM-3) but it's not feasible at the moment.

 

[nsaspook]

I don't know how many times we have to say it, but existing countermeasures (including tracking) are designed for ballistic trajectories. They kill an incoming threat either exo-atmospheric, in the midcourse phase, or in the terminal phase. In both cases, they aren't maneuvering. The newer class of threats come in inside the atmosphere and are maneuverable. There may be a way to adapt existing interceptors to the task (e.g., SM-3) but it's not feasible at the moment.

Sure, it won't work directly but we do have an existing framework to work with. Use hypersonic interceptors to generate a flak (static kinetic, EM or nuclear) box the maneuvering device must pass through to hit the target in the last 5 to 10 seconds. In the case of ships that are also moving forcing last second changes in course might reduce a kill shot to a near miss. In the case of the Sprint it used neutron flux to neutralize the incoming nuclear threat, not to destroy it directly.

 

[boneh3ad]

Sure, it won't work directly but we do have an existing framework to work with. Use hypersonic interceptors to generate a flak (static kinetic, EM or nuclear) box the maneuvering device must pass through to hit the target in the last 5 to 10 seconds. In the case of ships that are also moving forcing last second changes in course might reduce a kill shot to a near miss. In the case of the Sprint it used neutron flux to neutralize the incoming nuclear threat, not to destroy it directly.

The issue with things like a nuclear interceptor is the altitude. The incoming threat is at a much lower altitude than an ICBM RV, so you'd be detonating nukes at a level that would pose serious risk to whatever is below. I once sat in a meeting where something like this was proposed and it was dismissed outright as unworkable.

Some version of flak may well be one of the options being developed. Details about hypersonic countermeasures are held even more closely than the offensive hypersonic systems currently under development.

Having said that, I'm skeptical that you could simply try to force something like this into a certain flight path filled with flak. They are more maneuverable than I think you're giving them credit for being. However, if you do manage to hit a maneuvering vehicle with a point defense, it makes the likelihood of an outright miss far greater than if it was flying directly at the target, so it's not all bad.

 

[shjacks45]

It has everything to do with the wing-loading [pounds of lift per square foot of wing area]. Jets have relatively much larger wings for their size than missiles, so they can maneuver out of it\s way and the missile can't follow the arc of the aircraft's turn.

Missile fins are at the rear. A high speed plane making a sudden vertical stabilizer only turn leads to a flat spin. At hypersonic speed a flat spin at mach 5 is probably destructive to the missile.

 

[nsaspook]

The issue with things like a nuclear interceptor is the altitude. The incoming threat is at a much lower altitude than an ICBM RV, so you'd be detonating nukes at a level that would pose serious risk to whatever is below. I once sat in a meeting where something like this was proposed and it was dismissed outright as unworkable.

Some version of flak may well be one of the options being developed. Details about hypersonic countermeasures are held even more closely than the offensive hypersonic systems currently under development.

Having said that, I'm skeptical that you could simply try to force something like this into a certain flight path filled with flak. They are more maneuverable than I think you're giving them credit for being. However, if you do manage to hit a maneuvering vehicle with a point defense, it makes the likelihood of an outright miss far greater than if it was flying directly at the target, so it's not all bad.

If they are tossing nukes (Russian hypersonic anti-ship weapons for example are expected to have nuclear warheads) at you then detonating warhead deactivating nukes at a danger close levels to defend won't be a issue because ships at sea are ready for nuclear decon operations. I don't think that forcing a kill path will be the point. If they can dance then make them dance till they drop or at least fall out the kill window.



50 years ago we did this so I'm pretty sure a technical solution will be found.

Our adversaries have every incentive to exaggerate and say hypersonic missile defense is impossible and we ("Details about hypersonic countermeasures are held even more closely") have a big incentive to publicly agree with them while holding a set of Aces, just in case.

 

[DaveC426913]

...a 400kt fighter jet can out-maneuver a machine 3 missile.

That's a heckuva fighter jet!

 

[FactChecker]

That's a heckuva fighter jet!

They do it either by running away so that the missile runs out of fuel or by timing a last-second maneuver to side-step the missile. Either method takes a lot of nerve and luck. But it is doable.

 

[DaveC426913]

They do it either by running away so that the missile runs out of fuel or by timing a last-second maneuver to side-step the missile. Either method takes a lot of nerve and luck. But it is doable.

Oh my God.
I honestly thought Russ was talking about the mass of the jet.

 

[FactChecker]

Oh my God.
I honestly thought Russ was talking about the mass of the jet.

Then you are right -- that IS a hell of a jet! :-)

 

[berkeman]

Yeah, another example of Imperial tonnes versus sailing/aero knots. Lordy.

 

[Rive]

It seems that conventional interceptor missiles would have to be hypersonic themselves, and even more nimble, to be able to intercept incoming hypersonic missiles.

Yes. No.
Yes, they have to be fast. But that 'fast' is about doing the job 'farther the better' and not really about the speed of the target.
Since the job is actually about laying a nice debris field in the right moment at the right place, the speed of the incoming missile is actually not that important (except, that higher speed will do a slightly better headbang on that debris field).

The following part about the sensors is more important.

there will undoubtedly be issues with mounting sensors for terminal guidance on interceptors.

That debris field must be at the right place, in the right moment. This requires a quite fast and accurate response. That's the real challenge.

 

[FactChecker]

Since the job is actually about laying a nice debris field in the right moment at the right place, the speed of the incoming missile is actually not that important ...
That debris field must be at the right place, in the right moment. This requires a quite fast and accurate response. That's the real challenge.

The required speed of the response is a function of the speed of the approaching target. A slow target allows a slow response and a fast target requires a fast response.

 

[Rive]

The required speed of the response...

Speed has a secondary meaning here as 'low response time' // 'low delay'.
For any intercepting device the 'fast' as 'high speed' is not necessarily better since the high(er) relative speed makes it harder to respond (to any direction change).

 

[FactChecker]

Speed has a secondary meaning here as 'low response time' // 'low delay'.
For any intercepting device the 'fast' as 'high speed' is not necessarily better since the high(er) relative speed makes it harder to respond (to any direction change).

The post I commented on was referring to the speed of the incoming missile, not the defense system. The speed of the incoming missile has a very direct influence on the required reaction speed of the defense.

 

[boneh3ad]

Speed has a secondary meaning here as 'low response time' // 'low delay'.
For any intercepting device the 'fast' as 'high speed' is not necessarily better since the high(er) relative speed makes it harder to respond (to any direction change).

The responding countermeasure needs to be fast enough to adequately respond to any lateral/vertical maneuvering of the attacking vehicle, but it certainly doesn't need to be able to chase it down from behind (though perhaps that would make for an easier interception if you could actually pull it off). However, speed buys more time for additional intercept attempts in the event that the first one fails.

For what it's worth, though, existing terminal ABM systems (at least in the US) sort of fall all over the place in terms of Mach number, but are often themselves slower than the target. Essentially all of the current US, Russian, and Chinese terminal ABM systems fall in the Mach 3.5 to 4.5 range as far as publicly released data shows, with the exception of THAAD, which can hit Mach 8.2. They still all have a fairly low probability of success with a single missile against ballistic targets, which are faster but more predictable than the current batch of maneuvering hypersonic systems. That's why it's not uncommon to launch multiple interceptors at a single incoming threat.

It's generally easier to intercept before the RV re-enters the atmosphere, but that's not an option with the current batch of hypersonic missiles in development.

 

[Klystron]

Countermeasures and counter-countermeasure deployment in an integrated battle space depend on mission objectives of the attacking force versus resource conservation and allocation of the defenders.

Position; therefor, change of position over time, while important and impressive remain another input set. Attacker stealth to avoid detection including unexpected approaches such as nap-of-the Earth and extreme altitudes, radial closure toward emitters, coordinated attacks combining tactics, coupled with anti-radar and other CCM; contribute to successful missions surpassing incoming velocity.

Relying on extremely high incoming velocity for penetration of an area risks creating a virtual "Maginot Line" in space. Game changing innovations and ultimate weapons rarely survive first contact. Defenders learn to adapt.

 

[boneh3ad]

Relying on extremely high incoming velocity for penetration of an area risks creating a virtual "Maginot Line" in space. Game changing innovations and ultimate weapons rarely survive first contact. Defenders learn to adapt.

But that's just it; this is effectively the case with existing ICBM tech. That hasn't changed a whole lot in recent years and most countries invested in ABM systems have decided that interception in space is the highest-probability approach. If that fails, the RVs re-enter and have very limited maneuverability so there's a shot at hitting them with a terminal defense system like THAAD, Patriot, or Aegis. In effect, that Maginot line in space is what we have now.

The new breed of hypersonic missiles avoid those problems by simply not flying into space and remaining maneuverable up until the very end of the flight (a link back to the previous CRS report I cited). The figure from the CRS report pasted below is a good, simplified visual.

Figure 1 from the CRS report

Over time, I am confident all parties will concoct appropriate defensive measures, but substantial challenges remain. The original poster, @neanderthalphysics, correctly pointed out some of the major challenges associated with various methods that have been considered to defeat these weapons and was flamed out of his own thread for it for not already being an expert on the solutions (which, again, no one is).

 

[shjacks45]

But that's just it; this is effectively the case with existing ICBM tech. That hasn't changed a whole lot in recent years and most countries invested in ABM systems have decided that interception in space is the highest-probability approach. If that fails, the RVs re-enter and have very limited maneuverability so there's a shot at hitting them with a terminal defense system like THAAD, Patriot, or Aegis. In effect, that Maginot line in space is what we have now.

The new breed of hypersonic missiles avoid those problems by simply not flying into space and remaining maneuverable up until the very end of the flight (a link back to the previous CRS report I cited). The figure from the CRS report pasted below is a good, simplified visual.

View attachment 275339
Figure 1 from the CRS report

Over time, I am confident all parties will concoct appropriate defensive measures, but substantial challenges remain. The original poster, @neanderthalphysics, correctly pointed out some of the major challenges associated with various methods that have been considered to defeat these weapons and was flamed out of his own thread for it for not already being an expert on the solutions (which, again, no one is).

I am a bit confused. The hypersonic tests that I've heard of fly these hypersonic devices in higher altitude thinner air. So with this hypermaneuverability hypersonic missiles will travel 50 feet above the ground like cruise missiles? Since the hypersonics are tested at high altitude, do we know what happens to a mach 6 hypersonic device hitting a rain squall? And active radar targeting that is unjammable?

It is wrong to judge the maneuverability of a missile the same as an airplane. A modern fighter airplane can get much greater aerodynamic forces than thrust forces and turn at up to 9 Gs from its aerodynamics. It could never get 9 Gs of acceleration from thrust. Some missiles can get much greater thrust/weight from their propulsion and can achieve up to 20 G maneuvers. They just need to turn their thrust in the right direction. They don't need to rely on wing-loading and aerodynamics.

I'm in space and turn my thruster, firing the thruster (offset from its center of gravity) makes me tumble in space. Same with the missile with low drag fuselage, except tumbling would be suboptimal for continued mach 5.5 flight, likely including structural degradation. A few videos of supersonic aircraft disintegrating in flight after maneuvers. Maneuvering jets at front of craft could be used instead of larger drag inducing wing surfaces. But there is always new tech around the corner. Who would have thought 200mph cavitating torpedoes were possible, a few years ago.

 

[boneh3ad]

I am a bit confused. The hypersonic tests that I've heard of fly these hypersonic devices in higher altitude thinner air. So with this hypermaneuverability hypersonic missiles will travel 50 feet above the ground like cruise missiles?

It doesn't need to be sea-skimming at 50 feet to not be in space like an ICBM RV. One of these hypersonic missiles will be picked up on radar before something that flies extremely low like a Tomahawk would for sure. But a hypersonic system is moving so quickly that there is considerably less time to acquire, track and engage the target than with existing systems. They are also simply harder to hit because they are moving so quickly.

Since the hypersonics are tested at high altitude, do we know what happens to a mach 6 hypersonic device hitting a rain squall?

We know a bit, but this is still an active area or research both at the basic and applied level. There are some really cool experiments out there using ballistic ranges, too.

And active radar targeting that is unjammable?

I don't think anything exists that is absolutely unjammable, whether hypersonic or not. I admittedly am not a radar guy, though.

I'm in space and turn my thruster, firing the thruster (offset from its center of gravity) makes me tumble in space. Same with the missile with low drag fuselage, except tumbling would be suboptimal for continued mach 5.5 flight, likely including structural degradation. A few videos of supersonic aircraft disintegrating in flight after maneuvers. Maneuvering jets at front of craft could be used instead of larger drag inducing wing surfaces.

Planes are not missiles and are designed entirely differently. A missile essentially just needs to point itself in the right direction and then close distance as quickly as it can and doesn't need to worry about the physiological limitations of a pilot.

But there is always new tech around the corner. Who would have thought 200mph cavitating torpedoes were possible, a few years ago.

Plenty of people considering that the Soviet VA-111 Shkval torpedo was introduced in 1977.

 

[FactChecker]

I'm in space and turn my thruster, firing the thruster (offset from its center of gravity) makes me tumble in space.

I'm in space and turn my thruster slightly to rotate the missile toward the desired orientation. When the desired orientation is nearly obtained, I turn my thruster slightly in the opposite direction to slow the rotation. As the rotation is stopped at the desired orientation, I have centered the thruster. Admittedly, there are a lot of additional complications that need to be addressed, but all control systems are fundamentally like that.

 

[berkeman]

Plenty of people considering that the Soviet VA-111 Shkval torpedo was introduced in 1977.

Interesting! I was wondering how in the world you would guide something that was in a cavitation bubble, but Wikipedia says that the initial versions used inertial guidance only. They do go on to say that later versions included terminal guidance, but I'm still wondering how you do that. Would they need some sort of an extension out in front of the bubble to try to use sonar?

https://en.wikipedia.org/wiki/VA-111_Shkval

 

[boneh3ad]

Interesting! I was wondering how in the world you would guide something that was in a cavitation bubble, but Wikipedia says that the initial versions used inertial guidance only. They do go on to say that later versions included terminal guidance, but I'm still wondering how you do that. Would they need some sort of an extension out in front of the bubble to try to use sonar?

https://en.wikipedia.org/wiki/VA-111_Shkval

View attachment 275421

I don't actually know. I think it's a pretty un-maneuverable weapon in general, though, and relies on speed and surprise to sink a target before it can dodge. It would definitely be nontrivial to steer it, though. Fins operating in a bubble of water vapor would be pretty much useless, and fits that are longer such that they extend out of the bubble will increase drag dramatically and have to endure substantial forces. The Wikipedia article states that the fits would steer the torpedo by just touching the edge of the bubble and using that massive drag to create a moment that turns the vehicle. That seems reasonable.

EDIT: Actually, if you look at the tip of the Shkval more closely (large image attached below) that might be related as well. It looks like it tilts somewhat, so maybe they can shape the bubble in some way to aid with steering.

 

[BigDon]

FactChecker, you mention 9 g's in one of the above posts.

I spent much of my youth working on the avionics and fire control systems of F-14 Tomcats, in an elite outfit. A 25 ton bird that can do Mach 2.2 near sea level and burn their own paint off. ( Interception of a cruise missile from an unexpected direction in most cases.)

During a set of wargames vs the Airforce one of our pilots pulled and managed to stay conscious through a 12 g turn.

It freaking "bent" the airplane!

When he landed the wingtips were drooping three feet off the ground, instead of their customary 9 or so feet. Whizzing fuel all over hell and gone too. The central structural solid titanium I-beam that holds both wings together had to be replaced. It was bow shaped. A solid titanium I-beam, under bright hanger lights, is oddly beautiful, I must add.

Though the funniest example of how well Tomcats were engineered goes like this:

A lot of the places training and exercises take place are over the desert areas of Nevada and Arizona. Sometimes junior aircrews, and very much during training for low level tactics get lost and end up in Mexico, a very major faux pax as you can well imagine. And most aircrews would rather find their own way back than radio in their condition.

Most common way to find your way back? Stay low, find a highway, follow it head north.

Easy peasy, right?

So when we saw this one particular Tomcat land, after a brief thanks that it wasn't one of ours, we *knew* there was going to be a great story here.

I later learned it started with the Tower.

"Um, flight (whatever) is there something you'd like to tell us?"
"No, no, everything's fine. Had a great exercise!"

Without knowing, of course, that they had a full set of cross trees and two transformers from a telephone pole embedded in their port side horizontal stabilizer!

They never even knew they hit it! That's how tough those birds were.

(According to the serial numbers on the equipment the aircrew clipped off the transformers 20 miles south of the border.)

This was in fact what is referred to in military circles as a "Career limiting maneuver".

 

[berkeman]

During a set of wargames vs the Airforce one of our pilots pulled and managed to stay conscious through a 12 g turn.

With all due respect, I call BS. If this were true, it would be classified.

 

[Vanadium 50]

What's the difference between a fairy tale and a sea story? One starts out "Once upon a time, in a land far away" and the other starts out "No kidding, this really happened".

 

[Frabjous]

Wikipedia has an interesting article.
https://en.wikipedia.org/wiki/G-force

 

[Klystron]

Even so, @BigDon tells an interesting tale. Twin engine fighter planes going back to the near-transonic in a dive Lockheed P-38 Lightning can be difficult to target and track with anti-aircraft. Eccentric thrust and down low flying can leave fire control operators aiming where the aircraft was as opposed to will be.

USAF crews on the EW ranges always welcomed our Navy brethren in F-14 Tomcat, A-6 Intruder and EA-6B Prowler variants with relish and celebratory fireworks. I am certain the many near-misses by falling cement bomb, ECCM pod, chaff bundle, expended flare and detached aux fuel tank were kindly meant.

Grumman A-6 Intruder and the difficult to track Northrop Grumman EA-6B.

 

[DaveC426913]

What's the difference between a fairy tale and a sea story? One starts out "Once upon a time, in a land far away" and the other starts out "No kidding, this really happened".

"Even if you say it yourself, you wouldn't believe,
And I wouldn't trust a person like me, if I were you
I wasn't there, I swear I have an alibi
I heard it from a man who knows a fell who says it's true!"
- Johnny Tarr