Vulnerability of external sensor on new AFVs'

[DE1083]

All the new design proposals for MBT's and some other AFV's focus on un-manned turrets and have numerous "cupolas" with various types of optical sensors, as well as TV cameras localed elsewhere on the chassis. It would seem these installations would be extremely vulnerable to light weapons fire and could cause a "mission kill'. What options are in place to protect these exposed systems?

 

[dan_inbox]

See on an early Merkava Mk4:

 

[stealthflanker]

Make them smaller thus harder to hit. Or make them retractable.

Problem with both options are that it doesnt answer the artillery threat, as we see in recent conflict, artillery seems killed more tanks than anything else now. The blast and fragmentation from even conventional shell can shred every single thing on turret. Guided artillery rounds added more problem as it's top attack by default and they are relatively common, like for example Russians have guided shell for practically every single caliber of their artillery.

addition of Drone jammers exacerbated the problem as they are more than often an omnidirectional antenna which shaped like whip and this poke out of vehicle, protecting the tank from the drone but also serve as potential beacon to enemy ESM's. Can't really armor those antenna.

The other option is somehow make sensor that can see through armor. This might not be practical for optical sensor, but Radiometric sensor, this could be an option. God knows tho what kind of dielectric material available today which meet the requirement of being an armor and radome at the same time.

 

[A Tentative Fleet Plan]

The alternative is the commander sticking his head out to have a look, multiple cameras offer better redundancy, no matter how vulnerable.

 

[Kat Tsun]

All the new design proposals for MBT's and some other AFV's focus on un-manned turrets and have numerous "cupolas" with various types of optical sensors, as well as TV cameras localed elsewhere on the chassis. It would seem these installations would be extremely vulnerable to light weapons fire and could cause a "mission kill'. What options are in place to protect these exposed systems?

As far as individual protection concerns go, optics are typically already bulletproof, so "light weapons" are not huge concerns to begin with? If by a light weapon you mean a 30mm cannon I guess then every tank is seriously vulnerable to that and there's no real protection measure to be taken. You're just gonna have to deal with losing optics. The Bradley for instance has ballistic plate covering its optics and such protected against .30 caliber AP rounds. Modern solutions might be aluminum oxide windows.

The only real option for protection is having enough replacement units whether whole turrets or simply replacement optics stockpiled, and sufficient industrial capacity to produce new ones, when the time comes to finish a war. Stockpiles might be more important than factories in the age of intercontinental bombardment too, but that's an untested hypothesis.

Reducing vulnerability isn't that important though, if only because tanks will be destroyed en masse regardless of individual characteristics (as shown in every major war since tanks were introduced), and things like general strategic mobility and weight concerns matter more for support infrastructure than statistical loss rate concerns tbh.

The actual issue at hand is that concerns for individual tank protection measures might result in a tank so heavily protected, and so costly to produce, that it cannot be made in sufficient quantities to affect the course of a war overall. The land version of the Chinese Junk and Super Battleship paradox. Given that modern tanks aren't produced in anywhere near sufficient numbers to finish a major, protracted war, besides maybe the T-72, there's serious cause to believe that we're already well past this point too.

God knows tho what kind of dielectric material available today which meet the requirement of being an armor and radome at the same time.

The easiest/most obvious solution for this is a fiberglass-silica composite tbh. It would be ballistic against small arms fire and little else. That's what FCS was supposed to have I think?

https://apps.dtic.mil/sti/pdfs/ADA481721.pdf

I'm not sure if this would be protected against 14.5mm but I'm sure the radar and its antennae could be incorporated into the protection scheme. It's very likely that protection of sensors against 155mm splinter and 14.5mm API rounds is a fantastical notion, at least with current materials science, so eating the losses by having sufficient amounts of battle damage and repair parts stockpiles on hand is most important.

The armor facing panels which were supposed to be incorporated into the APS radar array, rather than SATCOM carriers like this one, were pure silica panels possibly backed with Kevlar. Both of those would be transparent at the types of energies used (35 GHz?).

 

[riggerrob]

Thirdly, what-if you make external sensors cheap and quick to replace?
Instead of mounting expensive optical sensors on top of an extensor pylon, what if you mount those sensors internally, then make the external pylon more like a long periscope: just a tube with a mirror on the end. That configuration also lends itself to retractable sensors. Retractable sensors are less vulnerable to being knocked off by trees or passing trucks. A key point is that retractable sensors need to be quickly operated - by one hand - by a few member who stays inside the armour.

 

[Kat Tsun]

Thirdly, what-if you make external sensors cheap and quick to replace?

If the sensors are cheap they are bad. They are already fairly easy to replace though. It's a bolted cover and some screws and plugs. Given that electronics need to be replaced periodically just in general, either because a circuit board or something fails, or a capacitor leaks, or a tube is going out, or whatever, just having direct access is not only a good thing but a actually necessary one when it comes to tasks like boresighting a main gun's primary sight.

The hard part is swallowing the apple of knowledge that having large stockpiles of expensive B-kits of FLIRs means war is just expensive.

 

[Scott Kenny]

If the sensors are cheap they are bad. They are already fairly easy to replace though. It's a bolted cover and some screws and plugs. Given that electronics need to be replaced periodically just in general, either because a circuit board or something fails, or a capacitor leaks, or a tube is going out, or whatever, just having direct access is not only a good thing but a actually necessary one when it comes to tasks like boresighting a main gun's primary sight.

The hard part is swallowing the apple of knowledge that having large stockpiles of expensive B-kits of FLIRs means war is just expensive.

Depends on type of sensor.

A basic CCD video camera, like on your phone, is easily able to be 4k or higher resolution and will see from NIR to UVA. And those are cheap imagers these days, my phone has at least 4 camera chips on it and cost less than $150.

 

[Firefinder]

Like most things this is a scale between the trade off of Visibility and Protection.

And right now that standard is to keep the commander head out of the hatch to see around.

Some nations tankers go around with just their head out, others go all the way up to their belly button. Either wat

You big, watermelon size, squishy head with the tanks primary computer out in the open.


Any thing better then that.

Also these sensors should be pretty damn small, like IR/color/night vision with 8x zoom at most. Like basically need something twice the size and length of a standard cell camera. You just need to see some as good as you can with the Mark 1 but under the Armor.

The gunner sight and commanders optic should be the big ones with all the toys. And either be colocated with the gun or in their own heavily armor turret on top of the... turret. Basically as it is now.

Be good enough to spot and slew the big optic around to get the close in.

 

[Kat Tsun]

Depends on type of sensor.

A basic CCD video camera, like on your phone, is easily able to be 4k or higher resolution and will see from NIR to UVA. And those are cheap imagers these days, my phone has at least 4 camera chips on it and cost less than $150.

Good sensors are LWIR FLIRs, at minimum. Nothing else is particularly useful. This has been rather amply demonstrated in the Donbas.

The sensor cost itself is not the problem, though. It's labor and the manufacturing capacities of Western military industries. A cell phone camera would still need to be shock hardened, armor plated, and be protected against nuclear weapon flash, among other things.

The cost of such things is mostly because these have to be done by hand and there are no assembly lines in China or Vietnam for such products, nor has anyone mechanized the process, because it's not like anyone buys enough for it to matter. A simple, commercially available CCD sensor for backing up that is compatible with the M1 would probably be somewhere in the five digits cost for a module and six digits for a whole vehicle installation. A good FLIR can easily breach a million.

 

[Scott Kenny]

Good sensors are LWIR FLIRs, at minimum. Nothing else is particularly useful. This has been rather amply demonstrated in the Donbas.

The sensor cost itself is not the problem, though. It's labor and the manufacturing capacities of Western military industries. A cell phone camera would still need to be shock hardened, armor plated, and be protected against nuclear weapon flash, among other things.

The cost of such things is mostly because these have to be done by hand and there are no assembly lines in China or Vietnam for such products, nor has anyone mechanized the process, because it's not like anyone buys enough for it to matter. A simple, commercially available CCD sensor for backing up that is compatible with the M1 would probably be somewhere in the five digits cost for a module and six digits for a whole vehicle installation. A good FLIR can easily breach a million.

The "situational awareness" cameras getting fitted to Abrams and things like the Ripsaws are all automotive grade or phone grade CCDs. I can buy a low rez LWIR camera that plugs into my phone for $500. It's maybe 640x480 and 30hz, but that's plenty for the purpose of not running over your infantry support. Automatic welder's hoods can cover the nucflash issue for $500 a sensor set.

But yes, for the primary sensor you want to get the best you can afford.

 

[dan_inbox]

Increasingly, a tank's primary sensors for commander and gunner will not necessarily be on the tank itself.
It is somewhere nearby and networked. On a UAV or even a mini-UAV (the kind that can fly near/into buildings to check for snipers), on any other vehicle (IFV or obs like Hummer Racoon), or even on an infantryman.

The original question is valid in low-intensity conflict (like Hamas sending children to damage the optics in the hope that the crew will hurt them and give propaganda-useful photos), but in full-scale conflicts it is much less relevant, because the would-be destroyer of optics will be busy with the accompanying infantry.

 

[Kat Tsun]

The "situational awareness" cameras getting fitted to Abrams and things like the Ripsaws are all automotive grade or phone grade CCDs. I can buy a low rez LWIR camera that plugs into my phone for $500. It's maybe 640x480 and 30hz, but that's plenty for the purpose of not running over your infantry support. Automatic welder's hoods can cover the nucflash issue for $500 a sensor set.

Yet each module will still cost tens of thousands of dollars, because it's literally not about the sensor. It's about the fact that it's ensconced in armor grade steel, which are hand made in an artisan workshop in the United States, to pay a ballistic welder $40/hour, which an increasingly important and increasingly scarce skillset...

Also running over infantry is something that just happens, with or without cameras, because if they can't get out of the way when I reverse that's on them. Being able to look around in a tank is more for the commander's benefit than the surrounding infantrymen, but given how bad DAS is, and how glacially slow Western arms conglomerates move, I'm not sure we're close to full virtual transparency in tanks yet. Modern commercial VR headsets are still extremely novel almost a decade after their introduction.

But yes, for the primary sensor you want to get the best you can afford.

A big sensor is only useful if you don't hope to survive a hit and can engage the enemy at a tactically useful range, though.

Ukraine's weird "duct tape the camera to the back of the tank" wouldn't survive a light mortar near miss or small arms hit, let alone a major barrage in a dug in position. It's very clever for what it is but it's not very robust nor is it suitable for a military that has the luxury of peacetime to make procurement decisions. They probably don't need super FLIRs more than they just need any FLIRs at the sub-1 km distances they fight, though.

Almost all sensors on a main battle tank are bulletproof, or so redundant as to be essentially bulletproof, and the majority can't be stripped by artillery splinter. Things like atmospheric sensors and radio antennae come to mind as most vulnerable with no real easy solution for them. A FLIR's window is typically ballistic rated ceramics that can stop small arms fire, although the optic might not be able to see outside of the cracked glass very well, and the backup gunnery sights are usually buried inside the mantlet.

The best option is to simply have large amounts of sensors, apertures, or ballistic plate on hand to repair as many tanks as possible. Important wars will consume tanks by the hundreds or thousands no matter how good they are, so focusing on individual protection measures is bad if it's detrimental to the mass production, and mass field repair, of armor.

If that means skimping on a sensor then that's fine. No one complained much about the Hughes TIS in Desert Storm. It's better to have some thermal capability, even if it's poor, than to have literally nothing at all. The advantages of a cooled dual-band 720p MWIR/LWIR FLIR over a simple uncooled 240i LWIR staring array are far less than the staring array over parachute flares and image intensification.

 

[1635yankee]

The alternative is the commander sticking his head out to have a look, multiple cameras offer better redundancy, no matter how vulnerable.

I would also suspect that having an electroptical sensor destroyed would be less traumatic to the crew than dealing with a corpse -- or part of a corpse -- in the turret.

I wouldn't hold my breath waiting for sensors that can look through armor. A thick enough block of kevlar-reinforced plastic is probably going to block quite a few interesting frequencies, and graphite-reinforced plastic is going to be opaque at many electromagnetic frequencies, as graphite is conductive.

 

[Alexandre Julião]

I was really wondering about this issue when I logged in. This thread is very informative indeed. Great conversation guys!

 

[Kat Tsun]

I would also suspect that having an electroptical sensor destroyed would be less traumatic to the crew than dealing with a corpse -- or part of a corpse -- in the turret.

I wouldn't hold my breath waiting for sensors that can look through armor. A thick enough block of kevlar-reinforced plastic is probably going to block quite a few interesting frequencies, and graphite-reinforced plastic is going to be opaque at many electromagnetic frequencies, as graphite is conductive.

AlON is transparent at ballistic thicknesses, thus that's the obvious choice, at least for the window. It will need mounting brackets, electronics, some sort of power system and connections to the rest of the tank, and all will need to be protected by ballistic steel. You don't need radars or anything for a simple all-aspect visual sensor because a CCD on a tank is backing camera not a serious detection system, but you'd need either goggles that could connect wirelessly to the sensors or through a cable to the tank's main computer.

If you did need an integrated radar system, the actual armor you'd use is a fiberglass impregnated with silica or something. FCS talked about ceramic antennae for Quick Kill, for instance, whereas a ballistic fiberglass sleeve might be used to cover a CREW Duke-type coil antenna.

All of this would stop small arms fire but be inadequate against 155mm splinter, which is the actual threat facing sensors on a tank.

 

[Scott Kenny]

AlON is transparent at ballistic thicknesses, thus that's the obvious choice, at least for the window. It will need mounting brackets, electronics, some sort of power system and connections to the rest of the tank, and all will need to be protected by ballistic steel. You don't need radars or anything for a simple all-aspect visual sensor because a CCD on a tank is backing camera not a serious detection system, but you'd need either goggles that could connect wirelessly to the sensors or through a cable to the tank's main computer.

If you did need an integrated radar system, the actual armor you'd use is a fiberglass impregnated with silica or something. FCS talked about ceramic antennae for Quick Kill, for instance, whereas a ballistic fiberglass sleeve might be used to cover a CREW Duke-type coil antenna.

All of this would stop small arms fire but be inadequate against 155mm splinter, which is the actual threat facing sensors on a tank.

Didn't that FCS paper mention making the radome proof against 155mm splinters?

 

[Kat Tsun]

Didn't that FCS paper mention making the radome proof against 155mm splinters?

No.

General requirements for radomes capable of
ballistic protection include minimal RF transmission loss,
ability to withstand standard environmental conditions,
vehicle mobility loads and costs. Ballistic protection
requirements range from NIJ III to NIJ IIIA, with
additional requirements on backface deflection (must not
damage antenna)

Flat 2 ft x 2 ft panels were fabricated for the
materials selected to evaluate ballistic performance at
NIJ III and NIJ IIIA levels. While standard V50 tests
were performed to evaluate the ballistic efficiency of
these materials, it should be noted that the ultimate
requirement is by necessity a V0 requirement (no
penetration), with a maximum backface deflection
requirement.

Energy absorption requirements are driven by the need to
protect the antenna system from small arms fire,
fragments from IED’s and backwash of active protection
systems.

The main threat was incoming projectile splinter.

Modeling shows that an APS system usually doesn't need more than two rounds per 90-degree axis or so because it will be destroyed by that time. FCS wanted a tougher APS that could resist small arms fire and shrapnel from the destroyed grenades and missiles. Later this evolved to include IED protection, which resulted in the vehicles being delayed by some months while an incredibly silly spaced armor scheme for the belly was devised. I think that scheme later went into the V-hull Strykers.

 

[Scott Kenny]

"Energy absorption requirements are driven by the need to
protect the antenna system from small arms fire,
fragments from IED’s and backwash of active protection
systems."

The main threat was incoming projectile splinter.

(forum wouldn't let me do that as a formal quote, sorry.)

Many IEDs have proven to be 122mm and 152mm shells, ergo protecting against those means protecting against 122-155mm shell splinters.

 

[Kat Tsun]

No, it doesn't?

The main threat from IED would be radome deformation and shock energy transmitted through the hull causing antenna damage, so the material had to be both rigid enough to resist deformation and ballistically capable enough to stop small arms fire, assuming the "IED" is "5kg blast land mine". The FSPs tested represented .30 cal ball and .223 ball ammunition.

"Fragments from IEDs" would be rocks, pebbles, and pieces of road surface, because a vehicle hit by an IED has a whole ass tank and crew between it and the antennae, and such small vehicles would be turned inside out anyway as was the case with M2s. FCS didn't have magic welds would resist such huge detonations as a bundle of 155mm or whatever. The vehicle was constructed along the lines of M8 AGS, after all, a thing that would have been notorious for popping like bubble wrap much like the M2.

The neighboring vehicles would be hit by a shotgun spread of small clods of dirt, aforementioned rocks, and whatnot pieces of crewmen and AFV that form the "fragments", all moving at relatively low velocities. This doesn't require a tremendous amount of armor to stop (Humvees and MRAPs did it fine), because it's not very fast moving. However, I'm not sure the radomes of the FCS tankettes would survive being stripped by nearby IED blasts, if only because FCS had some rather lofty ideas about how convoy ambushes worked. Iraqi militia ambushes were usually poorly planned, and more often than not weakly executed, beyond the initial surprise of a remote detonated landmine, so its applicability outside that specific theater is...dubious at best.

The direct IED protection for FCS came in the form of a spaced armor array in a sort of spider-y looking I-beam structure. The radome just has to stop rifle caliber .223 ball rounds as its top-end threat, and 155mm splinter is roughly comparable to 14.5mm BZ at 50 meters or 25mm APDS at 30 meters or 30mm APFSDS at 10 meters.

 

[Scott Kenny]

No, it doesn't?

The main threat from IED would be radome deformation and shock energy transmitted through the hull causing antenna damage, so the material had to be both rigid enough to resist deformation and ballistically capable enough to stop small arms fire, assuming the "IED" is "5kg blast land mine". The FSPs tested represented .30 cal ball and .223 ball ammunition.

The requirement for radome deformation was to prevent the radome from deforming enough to hit the antenna in the process of stopping the incoming (since expanding the radome causes issues with total size).

The goal in that paper was for materials that would stop 155mm splinters, because that is a very serious and very typical threat to strip antennas and vision blocks off a vehicle. The materials tested were a decent start in terms of cost, strength, and frequency transparency.

 

[Kat Tsun]

There is literally nothing about 155mm fragments in the paper. The stated requirements are right there: NIJ III i.e. .223 caliber ball, with a potential expansion to include blast (deformation) protection, presumably from nearby explosive detonations like a land mine or IED or explosive-reactive armor tile. The improved ballistic radome would have gone from a 50% chance of penetration by 9mm or .223 caliber ball ammunition to 0% chance penetration, which is not necessarily protection against 7.62x51mm steel-core AP either.

"Munition fragments" is vague but likely refers to light mortars (60-82mm) and ICM bomblets, not 155mm splinter, because 155mm splinter requires metal, and is probably the second most dangerous penetrator of armor besides medium cannons. Aluminum and titanium do not make a good RF transparent materials. Even the CAV-ATD had to use metallic foam composites in its armor and that was the baseline for FCS, and 14.5mm API approximates the 155mm threat at 30 meters, vehicles in a convoy are closer than 30 meters, and IEDs detonate within around 10 meters.

"Fragments from IEDs" do not mean the splinter itself, because the vehicle would either absorb the blast and keep moving (like the V-hull Stryker or the M1) thus the splinter would be lodged in the belly of the vehicle or its passengers and crew, or the only fragments would be pieces of road and maybe some bits of track, wheel and hull flying around at very low velocity. FCS tankettes weren't super strong in construction like the M1 tank, but they had decent mine protection, so they probably wouldn't implode into a hulk of melted aluminum like an M2. Maybe.

Of course FCS was so loosey goosey they may not have expected to take any artillery fire because counter-battery and GSRs would solve the problem. Either way, good thing land mines/IEDs direct all their splinter upwards into a vehicle's belly instead of sideways into a turret's SATCOM radome.

A ballistic radome is a bit of a silly goose requirement but this is for a fairly flush mounted communication/SATCOM antenna:



The ultimate placement of this radome would be the WIN-T SATCOM mount, maybe the JTRS SATCOM (GMR's is much lower profile though).

The MFRF face was ceramic, while everything else was encased in ballistic aluminum or titanium (such as the driver's LADAR, mmW radar, and Common EO/IR sensor), or a whip or coil antenna of a fairly low potential for damage to begin with due to small cross section.