Hypersonic Developments

Boagrius

Active Member
As I understand it, one of the engineering problems that hypersonics have encountered is that at certain point in the hypersonic regimen the air flowing around the hypersonic object becomes superheated and ionized, which in turn causes problems for missile guidance and telemetry. INS guidance might be able to target a stationary ground target so that hypersonic strikes against fixed targets of strategic value (buildings, fixed radar arrays, bridges, dams, power stations, transmission lines, transformer/relay stations, etc.) could be carried out. However, to target mobile targets either the hypersonic needs to have onboard sensors to provide guidance, or a datalink so that an offboard platform can provide the targeting and guidance information.

All that is needed even before any engineering difficulties relating to aerodynamics might be encountered, to permit a Mach 6+ missile the ability to maneuver sufficiently to strike a moving aircraft.
A recent article suggests that the plasma blackout issue may not be as big of a problem for hypersonics as first thought:

The US Department of Defense (DoD) is not concerned that its in-development hypersonic missiles could suffer from a communications blackout caused by a cocoon of plasma.

NASA spacecraft and intercontinental ballistic missiles have previously suffered from a communication interference caused by a layer of plasma forming around the vehicles when they re-enter the Earth’s atmosphere. Plasma forms when atmospheric gases are ionized – electrons are separated from their atoms – by the heat and compression caused by an object moving through the air at many times the speed of sound. The plasma layer blocks radio transmissions.

Many researchers and observers have thought that hypersonic missiles would also form a plasma sheath while flying more than five times the speed of sound through the atmosphere. That could make it difficult to communicate with the missiles. Radioing the high-stakes weapons could be critical, for instance, to abort a mission.

However, despite popular perception, the possibility is not a major concern, says Mike White, assistant director of hypersonics with the Pentagon.

“When we fly a missile for sustained hypersonic flight within the atmosphere, the plasma tends to not be so much of a problem,” he says. “We see plasma effects when we have relatively blunt bodies entering from space and the velocities they’re very, very high, and the shockwaves are very, very strong, so that heats the air even more severely than what we experienced in sustained flight.”

The DoD is developing two types of hypersonic missiles: boost-glide and air-breathing cruise missiles.
Interesting if true. I imagine you'd still be looking at INS + active RF based onboard guidance as the heating of the airframe would have to be prohibitive for IR based sensors.
 
Could EM railgun be used to defend against supersonic/hyper missiles ?

The closing speed of an incoming Kh-32 with an outgoing mach 6 weapon will be mach 11 or about 3.3km/s, but even the slightest change of trajectory by the Kh-32 after the EM gun round is fired means it will miss. and the Kh-32 could fly in a loose spiral trajectory and no rounds fired at it will connect.
 

ngatimozart

Super Moderator
Staff member
Verified Defense Pro
Could EM railgun be used to defend against supersonic/hyper missiles ?

The closing speed of an incoming Kh-32 with an outgoing mach 6 weapon will be mach 11 or about 3.3km/s, but even the slightest change of trajectory by the Kh-32 after the EM gun round is fired means it will miss. and the Kh-32 could fly in a loose spiral trajectory and no rounds fired at it will connect.
Possibly, because it would have the very high velocity and atpresent hypersonic missiles don't really have the luxury of sudden dramatic course changes. So even if it was programmed for a loose spiral trajectory, that can be predicted and the projectile aimed accordingly.
 

John Fedup

The Bunker Group
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Seems to be a difficult goal, especially for hypersonic missiles. Other considerations would include the frequency of changes to the missile’s flight profile and the rate of fire for the rail gun. Not sure if rail gun projectiles have explosive warheads and if they can be programmed.
 
Possibly, because it would have the very high velocity and atpresent hypersonic missiles don't really have the luxury of sudden dramatic course changes. So even if it was programmed for a loose spiral trajectory, that can be predicted and the projectile aimed accordingly.
How often to armies promote tanks with APFSDS rounds as anti aircraft weapons?

It's just like protecting tanks from penetrator rounds by using other penetrator rounds
 

Boagrius

Active Member
I think the question is less "how do you intercept a hypersonic weapon?", since systems like THAAD, SM3 and SM6 have been capable of that for some time, and more "how do you intercept HGVs and HCMs specifically?". These are the two technological breakthroughs that seem to be causing all the fuss.

To my mind, further evolution of weapons like THAAD and SM6 (in the west) make the most sense. The former is already a hypersonic system in its own right, as is/will be the Block 1B iteration of the latter. Note that I left SM3 out, as HGVs and HCMs have the potential to either under-fly its minimum effective altitude or simply outmaneuver it. This also leaves a gap in land based GBAD, as you probably want something that can provide cover below the altitude minimum for THAAD. Replacement or enhancement of Patriot is what you are probably looking at there(?).

As for railguns, AFAIK the technology is still significantly limited in terms of rate of fire and barrel wear. I am not confident that we will see a railgun capable of achieving much against credible HGV/HCM raids for quite some time yet. I suspect the same could be said for lasers, as the effective range of projected systems combined with the thermal blooming issue for head-on intercepts strikes me as pretty problematic.
 
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ngatimozart

Super Moderator
Staff member
Verified Defense Pro
How often to armies promote tanks with APFSDS rounds as anti aircraft weapons?

It's just like protecting tanks from penetrator rounds by using other penetrator rounds
It's part the cycle of offence and defence. One side will develop a new offensive (defence) weapon (system) and the other a counter to it. Spears & swords and shields / armour; guns and armour on the battlefield and at sea; radar and window etc.
 

Boagrius

Active Member
I was doing some trawling through the web on the topic of hypersonics recently and I came across this:

Hypersonic Missiles 2020.pdf

I thought it was an interesting overview that seems to compute with my understanding of the technical challenges associated with HGV, BM/ASBM and HCM development. An appropriately sized pinch of salt is probably warranted here given that it appears to have been produced in relation to the Harpoon series of naval strategy games BUT the author, Chris Carlson, is a former def pro with both naval and defence intelligence experience, so I am not inclined to dismiss his assessment out of hand.

He makes a few claims that I found interesting:

- RF blackout imposed by the plasma sheath becomes most pronounced above ~Mach 10. This would compute with the source I posted earlier (claiming the blackout problem wasn’t a big issue), which may have been referencing HCMs that would typically travel through the atmosphere somewhere between Mach 5 and Mach 10.

- Existing precision guided ballistic missiles need to use a "pull up" maneuver in terminal phase following atmospheric re-entry to decelerate the RV to Mach 10 or less so that the onboard RF seeker can function properly.

- He seems skeptical of the ability of existing ASBMs to hit moving naval targets, although work on this is obviously ongoing.

- Interception of hypersonics is not a new problem, since ballistic missiles – hypersonic weapons in their own right – have existed for over half a century. To my mind the real issue is that HGVs and HCMs (specifically) introduce a hypersonic target that can appear at lower altitude and on flatter and less predictable trajectories than existing ABM systems and their supporting ISR apparatus have been designed for.

That said, I am not sure that it is necessary to “wait” for lasers or railguns to mature before effective interception of HCMs or HGVs could be achieved. Perhaps an equally important (and challenging) task is the development of ISR apparatus capable of providing sufficient early warning and tracking of inbounds to effectively cue future (and possibly some current) missile-based interceptors.
 
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