Defense against Hypersonic Glide Vehicles

Pioneer said:
I think this is the best thread for this:

https://armyrecognition.com/focus-a...erful-machine-gun-to-stop-hypersonic-missiles
Regards
Pooneer
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The problem with intercepting hypersonics with guns is that the smaller caliber guns simply have too short range. You NEED a kill zone at least a few miles out, because even the debris of a successful intercept will be moving at mach 5. And thus will be a danger.

There's a reason most navies are going to RAM or even CAMM type weapons and dropping low caliber gun type CIWS.

The only gun type CIWS that seems worth a damn against hypersonics might be something like the 76 mm type with guided ammo.
 
MihoshiK said:
The problem with intercepting hypersonics with guns is that the smaller caliber guns simply have too short range. You NEED a kill zone at least a few miles out, because even the debris of a successful intercept will be moving at mach 5. And thus will be a danger.

There's a reason most navies are going to RAM or even CAMM type weapons and dropping low caliber gun type CIWS.

The only gun type CIWS that seems worth a damn against hypersonics might be something like the 76 mm type with guided ammo.
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Or a rail gun. The US did look at using GAU-8's to defend missile silos but all they had to do was damage the RVs and let the silo deal with the fragments. As long as it didn't detonate that's all that mattered.
 
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Forest Green said:
Is this actually any better or cheaper than air-bursting rounds? This would actually spread out the fragments, whereas electronic firing mechanisms fire out a shed load of rounds really fast in the same direction unless you use air-burst rounds with it I guess.
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Good question, one that I'm not qualified to answer.
I'm wondering if a fragment from an air-burst would have the density and kinetic energy to damage a hypersonic system?

Regards
Pioneer
 
Forest Green said:
Is this actually any better or cheaper than air-bursting rounds? This would actually spread out the fragments, whereas electronic firing mechanisms fire out a shed load of rounds really fast in the same direction unless you use air-burst rounds with it I guess.
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I'm assuming if it's found difficult to accurately calculate the optimal detonation time, then a cloud of bullets is not a bad alternative.
 
Pioneer said:
Good question, one that I'm not qualified to answer.
I'm wondering if a fragment from an air-burst would have the density and kinetic energy to damage a hypersonic system?

Regards
Pioneer
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Don't know the answer to that. Given the range of gun-type systems and the speeds involved, we're really talking about the last second before impact here. Is anything that doesn't completely obliterate the missile outright sufficient at that point?
 
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Forest Green said:
Don't know the answe to that. Given the range of gun-type systems and the speeds involved, we're really talking about the last second before impact here. Is anything that doesn't completely obliterate the missile outright sufficient at that point?
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Depends on impact velocity.

For example, ICBM RVs have slowed down to Mach 2 at about 20,000ft, just because of the dense air.

Hypergliders will have the same problem.

You don't get into "packing its own weight in TNT in kinetic energy" until 3km/s. Mach 10. And you need that Mach 10 at impact, despite the dense air.

Thus far, there hasn't been mention of a rocket boosted hyperglider or RBA for pure kinetic force.

Long story short, yes a gun that doesn't obliterate a hypersonic is still sufficient as long as the hypersonic's impact velocity is below Mach 10.
 
Scott Kenny said:
For example, ICBM RVs have slowed down to Mach 2 at about 20,000ft, just because of the dense air.
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A lot higher than that even for depressed trajectories. Someone has a pdf somewhere on this very subject already posted in some thread.

EDIT: Well crap, that took ages to find but finally. :cool: For MET (Minimum Energy Trajectory) it's ~2.75km/s (Mach 8+) at impact (0ft) and you can see from the DT (Depressed Trajectory) lines that lifting body RVs can come down significantly faster than standard. Sadly there is no line for lifting body MET speed but it's ~3.3km/s even for DT which is about Mach 10.

Post #206 GBI Thread.
https://www.secretprojects.co.uk/threads/ground-based-interceptor-gbi.18293/post-575521https://scienceandglobalsecurity.org/archive/sgs28tracy.pdf
1743447580271.png
 
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NMaude said:
For example the Mk-1 RV used by the Polaris A1 and A2 had a terminal velocity of M1.2 (It was barely supersonic).
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I was reminded of this fun fact, that the terminal velocity of the Mk-2 RV (Carrying the W49 and was used by early Atlas Ds) was only 350mph, a high-performance piston-engine fighter in the right location could've intercepted a Mk-2.
 
NMaude said:
I was reminded of this fun fact, that the terminal velocity of the Mk-2 RV (Carrying the W49 and was used by early Atlas Ds) was only 350mph, a high-performance piston-engine fighter in the right location could've intercepted a Mk-2.
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Crud, I think an old "Slow but deadly" SBD Dauntless dive bomber could have caught one!
 
Forest Green said:
A lot higher than that even for depressed trajectories. Someone has a pdf somewhere on this very subject already posted in some thread.

EDIT: Well crap, that took ages to find but finally. :cool: For MET (Minimum Energy Trajectory) it's ~2.75km/s (Mach 8+) at impact (0ft) and you can see from the DT (Depressed Trajectory) lines that lifting body RVs can come down significantly faster than standard. Sadly there is no line for lifting body MET speed but it's ~3.3km/s even for DT which is about Mach 10.

Post #206 GBI Thread.
https://www.secretprojects.co.uk/threads/ground-based-interceptor-gbi.18293/post-575521https://scienceandglobalsecurity.org/archive/sgs28tracy.pdf
View attachment 765221
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Surely the terminal velocity is dependent on the specific missile/fuel stack?
 
Forest Green said:
A lot higher than that even for depressed trajectories. Someone has a pdf somewhere on this very subject already posted in some thread.

EDIT: Well crap, that took ages to find but finally. :cool: For MET (Minimum Energy Trajectory) it's ~2.75km/s (Mach 8+) at impact (0ft) and you can see from the DT (Depressed Trajectory) lines that lifting body RVs can come down significantly faster than standard. Sadly there is no line for lifting body MET speed but it's ~3.3km/s even for DT which is about Mach 10.
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Except that IIRC from stuff that's been posted on this forum, a Trident II's depressed trajectory range is under 6000km, with ONE warhead.



Josh_TN said:
Surely the terminal velocity is dependent on the specific missile/fuel stack?
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I don't think so. The equations only care about distance flown, weight of "projectile", and I'm not sure those numbers included atmospheric drag at low altitudes.
 
Scott Kenny said:
Except that IIRC from stuff that's been posted on this forum, a Trident II's depressed trajectory range is under 6000km, with ONE warhead.
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Possibly but that has little bearing on the conversation. Clearly for an ICBM warhead (like Minuteman) on an MET, the speed is nearer Mach 8+ at impact and would be significantly higher with a lifting body RV and at 20,000ft it's 4.5km/s or about Mach 12-13 for a standard ballistic MET at 8,600km range (actual MMIII range is 13,000km), which is slightly above Mach 2.

A Trident D5 MET range with 4 warheads is >6,000nm, think it was 6,100nm (11,500km) from memory, so again well over Mach 2 even at impact.
 
Forest Green said:
Possibly but that has little bearing on the conversation. Clearly for an ICBM warhead (like Minuteman) on an MET, the speed is nearer Mach 8+ at impact and would be significantly higher with a lifting body RV and at 20,000ft it's 4.5km/s or about Mach 12-13 for a standard ballistic MET at 8,600km range (actual MMIII range is 13,000km), which is slightly above Mach 2.
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Except that DT drag is so high that impact velocity drops to under 1km/s at the practical DT range. And at 5km altitude is about 1.6km/s. (This is all straight off the chart you posted for 6100km range.)


Forest Green said:
A Trident D5 MET range with 4 warheads is >6,000nm, think it was 6,100nm (11,500km) from memory, so again well over Mach 2 even at impact.
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Per the charts you posted, about 2.75km/s at zero elevation.
 
My take away from all this is that intermediate or short ranged weapons are largely supersonic at their terminal engagement ranges…something not too surprising. Hypersonic seems to often be used to describe top speed at burn out for any missile design to hit the ground (a lot of SAMs and AAMs could be described as ‘hypersonic’).
 
Scott Kenny said:
Except that DT drag is so high that impact velocity drops to under 1km/s at the practical DT range. And at 5km altitude is about 1.6km/s. (This is all straight off the chart you posted for 6100km range.)
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Why are we even talking about DTs again? We were discussing the use of a gun-type system against hypersonic objects, which implies lifting body warheads and scramjet weapons. You mentioning that the speed of an ICBM warhead at 20,000ft is only Mach 2 with no reference to DTs or range. As regards D5s, the DT ranges looked at for those seem to be 1,850-3,000km when dealing with a 7,400km MET configuration, which is 8 warheads.
https://www.nuclearinfo.org/wp-cont...vid_C_Wright_Science_Global_Security_1992.pdf
Also, whilst the DT velocity drops below 1km/s at impact for a 6,100km DT, it's ~2km/s at 6km, which is Mach 6.
Scott Kenny said:
Per the charts you posted, about 2.75km/s at zero elevation.
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That's for an 8,600km MET, 3km/s for a 6,100km MET. Add a hypersonic lifting body warhead and it's even higher, even for DT. So the bottom line is that with a gun you get exactly 1 go at obliterating it then you're done, all inside a second.
 
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