2017/05/20

Lightweight warhead direct fire projection


The title looks awfully technical, but it's precisely on topic, for I see a gap in the available hardware.

I began to compile a list of lightweight equipment to see how much weight could be saved from the infantryman's load over a year ago, and identified a gap. There was no satisfactory device to propel a substantial grenade forward in direct fire.


All military off-the-shelf solutions appear to be deficient in one way or another.

The anti-tank weapons and munitions are often meant to penetrate heavy passive protection and are much too heavy for almost everything. The PzF 3 is one of the few good ones, but it's awfully heavy at 13.3 kg + sight unit.

There's a wide range of mid weight solutions with calibres of around 80-90 mm, but they are too weak against tanks from any but the best angles and still needlessly heavy (often about 6 k per round) for most other purposes.

The supposedly lightweight bazooka and RPG category solutions such as M72 and RPG-26 are terribly short-ranged. It's hard to hit a stationary tank at 200 m with these (unless you know the distance), and 300 m is an entirely impractical distance.

Rifle grenades overcame most of the old criticism with bullet traps and aren't that much slower to use than a stand-alone grenade launcher if the latter is not the primary weapon (extending a buttstock and flipping up sights costs time as well). Still, their dismal effective range and terrible dispersion in range at it disqualify rifle grenades. The calibre of rifle grenades varies form about 35-76 mm, with disclosed RHAeq penetration values of up to 275 mm RHAeq. The IMI BT/AT-44 HEDP round is a good representative at 41 mm calibre; 160 mm RHAeq penetration and 490 g weight. Still, its effective range of something around 100-150 m is very unsatisfactory in my opinion.

30 to 45 mm grenade launcher rounds need not apply. All of them have a small calibre and spin stabilisation, which degrades HEAT effect and thus penetration. The highest penetration claim for a 40x46 mm HEDP grenade that I ever found was the 90 mm RHAeq claim of the DM 12. That's theoretically enough to penetrate a BMP-3's frontal protection (~ up to about 60 mm RHAeq). The effective range of such a round is still dismal at a mere 76 m/s muzzle velocity (barely good for 100 m), and medium velocity models would have increased spin (=less penetration) and little more effective range.

Millions of "Panzerfaust" have been produced in WW2, most were used - but a mere few ten thousand were expended against tanks. Such "anti-tank" munitions are needed and used as grenade projectors beyond throwing range. This was observed in all wars ever since. All but dedicated anti-MBT munitions of man-portable grenade weapons should thus be HEDP (high explosive dual purpose = shaped charge with fragmentation liner outside) munitions or have no shaped charge at all.

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The effective range of man-portable warhead projectors doesn't need to be huge against infantry because competent adversary infantry will hardly ever be detected beyond 100 m distance. The effective range against vehicles (including lightly armoured vehicles like BMP, BTR and BMD series) on the other hand should be fine. This should at least equal the 300 m effective range of small arms against soft targets, but 400 or 500 m would be better because no-one wants to dismount infantry from BMPs or BTRs 500 m distant from the next cover.

Having voiced my dissatisfaction with all the available hardware I'd like to present a hypothetical and certainly feasible design:

  • A simple launch tube with a 45-60 mm calibre
  • The sight accepts a standard night vision monocular device (such as taken from a helmet)
  • A rocket inside with a charge that expels the entire rocket forward at low speed with a slow spin, so indoors use is possible.
  • The rocket ignites and accelerates to a high subsonic speed (about 300 m/s) which it sustains.
  • Accelerometer chips measure the rocket's movements in four dimensions and a microprocessor calculates the fusing of minute charges to correct the trajectory against wind drift, gravity and so on.
  • A fuse which can be set to a short delay (enough to penetrate doors, windows and soft vehicles) or point detonation super quick modes by electromagnetic induction.
  • The HEDP warhead deals the damage (penetration and graze fusing sufficient to defeat a BMP frontally).  Its shaped charge should not use an expensive liner (no tantalum), and should be optimised for much effect behind thin armour plates.*
  • The accelerometers can be used to correct unsteadiness of the user, but they can also be used to observe the movement of a target which was tracked with the launcher's sight for two seconds prior to launch. The missile could then fly an intercept course based on the extrapolation of the movement.
There's but one weapon and munition that comes close: The Israeli IAI Picket. It's so very obscure and unknown I had to scan pages of my Jane's Weapon Systems 1984/85 book to show it, for there's almost nothing about it in the internet.


I suppose with today's technology such a rocket weapon could be reasonably cheap and weigh about 2.5 kg including a simple launcher. An effective range of 400 m should be feasible against 1x1 m target areas, even if the target is moving steadily. That's enough to choose where to hit a non-moving target instead of having an unsatisfactory chance to hit at 200 m distance at all as with RPGs. The Raytheon's Pike has shown how very small guided missiles can be made nowadays. Accelerometer chips of sufficient quality are what enables the flight stabilisation of all those cheap quadcopter toys. We don't need a gyroscope as the Picket had.

This goes beyond mere hardware. The ability to equip the infantry with well-ranged grenade projection and anti-BMD firepower at lightweight would enable a very different behaviour by infantry. It would be more agile than with legacy weapons and munitions, while having a much better punch against all but MBT targets than without or with few legacy weapons and munitions. Keep in mind, I don't trust even the heavy man-portable munitions against modern MBTs.


We could equip an infantry squad with a couple such munitions and be confident in their ability to deal with opposition in thin-skinned AFVs and adversaries behind walls or inside buildings up to the effective range of their small arms. They wouldn't need to carry a few super-heavy anti-MBT rounds just in case some thin-skinned BTR shows up and opens fire at 300 m distance, degrading their choice of evasion routes.
A squad of 8 with six 2.5 kg weapons (15 kg total) instead of three Panzerfaust 3-IT (42.2 kg with basic sight unit) would save 27.2 kg - that's 3.4 kg on average per infantryman. This makes a huge difference, especially since the three men who carry the rounds would be MUCH more agile and have much better endurance. The break-even is actually at six rounds of my concept and a single Panzerfaust 3-IT !
I suppose there's no question about the relative effectiveness compared to the cheaper LAW-style weapons (M72, Miniman, SARPAC, RPG-18/-22/-26, RPG-75) - they cannot compete in accuracy or range and most of their versions lack a fragmentation liner.

S O
defence_and_freedom@gmx.de

P.S.: One could in theory - if the infantry or scouts use a stand-alone grenade launcher such as AG36 anyway - use a different approach to the same end.  A muzzle-loaded overcalibre munition for such a launcher could do the same. Again, calibre 45-60 mm and fin stabilised, and the launch would merely provide a low muzzle velocity. The rocket would need to accelerate itself after this launch beginning at a safe distance so the rocket doesn't affect the user. I'm not in favour of stand-alone 40 mm grenade launchers, so I favoured the more bazooka-like approach.

P.S. next day: BTW, this kind of autopilot guidance is immune to quick reaction smoke, and the short time of flight (less than 2 seconds) has the same effect. The short time of flight isn't really a necessity, although it reduces the problem of gravity (the missile has to fight gravity mostly with minute charges in order to fly the programmed straight line).

*: This isn't trivial. Shaped charges in part rely on turning the armour plate into fragments for behind armour effect (spalling). The thinner the plate, the less they have to work with. Spall liners, fibreglass plating and highly ductile plates reduce the spall effect further. Finally, BTR type vehicles usually don't carry much inside that's good for secondary fires or even explosions. To penetrate them is the easy part of defeating them for good.
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19 comments:

  1. Why not a mini-EFOGM missile of 2.5 kg?
    It only needs a mobile like camera and actuators attached to a conventional bazooka round with 300-400 meters range.
    Also would be possible to record the attack for intel
    Maybe you can shoot it like a mortar round instead. That would do the training cheaper by recovering and reuse the round.

    Rex

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    1. High angle launch does not really fit together with direct fire at short ranges.

      A missile seeker adds to the costs, for the missile would still require what my concept makes necessary, or substitutes.

      A missile with seeker would have the seeker in front of the shaped charge, so the seeker would function as spaced armour, necessitating a bigger warhead.

      The simple "mobile like camera" would be worthless at low light conditions, so the procurement agency would be tempted to ask for a more expensive uncooled infrared seeker.

      Actuators are more likely to fail technically than redundant minute charges.

      The utility of a camera seeker guidance in a flight of few seconds (less than 5, maybe less than 2 seconds) is questionable.

      An additional display would be necessary (and be in need of battery power) for the user (this makes it less universally useful for the non-infantry, non-scout personnel who don't have their personal touchpad computer).

      Most training should be done with simulators (simulator device attached instead of night vision monocular). The smooth tracking from a minimal silhouette position can be trained by simply tracking cars, bicyclists etc over and over again with a dummy round.

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  2. What about Commando-Mortars with guided grenades ? The russians has even silenced ones in 82mm caliber and many versions in 60mm are available at the spot. Such a grenade could hit the top of the tank which is much more weaker in armour and with a guided version it could hit even a moving vehicle. Such a guided anti-tank grenade could be realised in a 60mm caliber.

    Moreover it could be used from infantry in defilace defence (full cover) which can be very advantougus especially when encountering tanks. Such Commando-Mortas could also be used for many other tasks from conventional blast ammunition against infantry to battlefield illumination to one-way uav´s and so on.

    Such a weapon would be very lightweight, very flexible and usable in many ways and could defeat many tanks from above. In combination with other kind of ammunition it could even beat hard-kill systems more easily than direct fire rockets.

    What do you think about this ?

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    1. Mortars are not really good for direct fires. They are not suitable against fast-moving targets and they are not really suitable against vertical targets (such as windows). Shots at small elevation are rarely feasible without extra weight for recoil management, such as in the Lacroix Samourai design.

      Defilade targets are usually not visible and will thus rarely be attacked.

      Mortars also cause high fixed costs in regard to weight. A 5 kg commando mortar weighs empty as much as two autopilot LAWs. Its munition would likely require extra packaging or pouches instead of a mere sling or snap hook.

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    2. Especially commando mortars can be fired in direct fires, especially against windows. The problem is fast moving targets but:

      what is was thinking of and perhaps did not pointed out enough is a kind of guided mortar ammunition which will give the mortar a kind of fire and forget anti-tank capability even against fast moving vehicles. Guided mortar ammunition would be fired in the area in which the moving vehicles are and then search for a target for itself and attack it.

      I was therefore talking about something like the KSTAM Ammunition but for mortars.

      And the excellence of a 60mm commando mortar is much higher in many aspects than that of and LAW. The reach is higher, the effects are higher and it can be used from defilade much more easily.

      Every direct fire from infantry with such small arms like LAW on armoured vehicles is today often nearly suicical because of the response of the board weapons of the vehicles and such vehicles did never come alone.

      So a indirect guided top-attack and fire-and-forget ammunition for a mortar would be a possibility to attack tanks form above even then they are fast moving.

      Such mortar ammunition exist since many years for mortars, like the STRIX (120mm) and Merlin (81mm) and i think it could be possible to get the same technology in a smaller caliber today.

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    3. Commando mortars can be substituted for by calling for indirect fires, though. A true lightweight approach 'outsources' everything that can be, so the infantry is burdened only by what it really needs to have.

      And guided munition that resists the launch acceleration of a mortar will cost a lot more than a tiny rocket with a dozen toy-grade accelerometers.

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    4. Infantry really really needs to have commando mortars, which are since the time of the immperial japanese army one of the most efficient and most underestimated weapons at all. Of cause one can follow an RMA Infantry approach and outsource the firepower, but to have such a flexible and versatile weapons in the company and even in the platoon offers so many possibilities to the infantry, even if there is other kind of indirect firepower available. That reaches from cheap dumb mortar ammo to one way uavs to battlefield illumination and smoke and so on and so on. And even to anti-tank and fighting fast moving vehicles.

      And the more expensive guided mortar munition you would only need against this moving vehicles - against other kinds of targets you can use other and much cheaper ammunition.

      Moreover it is a weapon system that will fit your ideas about an unspectacual advance beyond mutual cancellation

      http://defense-and-freedom.blogspot.de/2016/08/beyond-mutual-cancellation.html

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    5. It's not "RMA" to have fire support above company level. We had that in the 18th century already (regimental guns), and we had it a lot in WW2 and it's been standard to have 120 mm mortar support at battalion level throughout the Cold War.

      Tiny commando mortars can do illumination, but this adds a lot of weight to the infantry platoon while calling for 120 mm IR-ILLUM costs a fraction of a battery's weight.

      Tiny commando mortars are NOT really effective HE deliverers. The dispersion and inaccuracy of the first shot is much greater than the lethal effect area. It's very training-intensive to get a man to aim well, and this is still uncertain under stress.

      Commando mortars cannot be used indoors, nor are they of much use in woodland.

      Commando mortars can deploy smoke, but MUCH less so than 120 mm fire support. S couple tiny (51-60 mm) SMK mortar bombs cannot really deliver the smoke wall needed by a squad to break contact in all but the easiest terrains. You need different means for this.

      Guided 51-60 mm mortar projectiles don't seem to be in the pipeline. Even 81 mm calibre doesn't seem to get PGMs and PGMs are still rare even among 120 mm mortars.


      An agile infantry has to be lightly loaded or use some exoskeletons. A lightly loaded infantry has to limit its need for munitions and 'outsource' indirect fires.

      To burden a platoon with 10-15 kg for commando mortar & its munitions means to deviate from the 'agile & elusive infantry' path.

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    6. To use commando mortars does not mean, to not have heavier mortars at bataillon level, but to have both. Moreover i would not scatter them amongst the platoons, but concentrate them in a support platoon/group at company level. The effect of one such mortar is not very impressive i agree, but several such mortars together can create really astounding effects.

      And 15 kg for a platoon is near to nothing, it would mean around 0,5 kg per soldier. Only the protection and armour (with helmet) weighs today between 20 kg and 25 kg per soldier. If you do not use such armour, you spare at least 600 kg per platoon.

      This mean, you can use your lightweight rocket launchers and a commando mortar both and the infantry would be still very lightweight and extremly agile and elusive.

      Even if you use ultralightweight boots instead of the heavy militarr issued you spare around 1 kg per soldier and the commando mortar is only 0,5 kg per soldier (and to save 1 kg on the foots is equivalent to spare around 3 kg on your back(pack)) so it reduces the strain more than one suggest.

      That is an important point: the strain is not only a result of the kg, but of the question where exactly you wear it and how it is fixed to your body.

      So i am not talking about a commando mortar instead of your lightweight rocket launcher and without bataillon fire support, but an infantry company with all three of them: commando mortars, lightweight rocket launchers and bataillon guns.

      This would make the unit much more flexible in every way. It could fire at targets which are in greater distance for itself, it could fire from defilade, call in bataillon gun support and could diversify its effects much more.

      By the way: there are many opportunities in a fight in which you should not use bataillon gun fire because of collateral damage, because the bataillon guns have not enough ammunition or you do not want to show their position and so on. So many cases i can think of in which i would not call in fire support from the bataillon but would try to find a solution on the company level. And then you need flexibility and the weapons to achieve the goal otherwise.

      To your critics of the concept in particular:

      Commando Mortars are extremly effective in woodland, the ija proved this in dense jungle for several years.

      The lethal effect area of several such mortars together is astoundingly high. Same for smoke and moreover if infantry need a big smoke screen to break contact something has gone terribly false. Smoke does not block bullets and explosions and is more useful for attacks then for breaking contact.

      The argument of the high training demands can be countered by modern aim-devices for such mortars which make it much easier to hit (and guided ammunition for moving vehicles).

      And the weight: seriously? Most infantry carries today around 30 kg to even 40 kg of equipment per soldier. Simply reduce the body armour and cancel the helmet and wear lighter shoes and a lighter backpack and so on and you have around 10 to 15 kg for free on every soldier and you need only 0,5 kg per soldier for the commando mortar.

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  3. Your description of the weapon sounds similar to the israeli Shipon FFE.

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    1. It's versatile, but it's also too heavy.

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  4. Predicted Line of Sight (PLOS) guidance, soft launch capability, 200 m/sec speed, disposable and 20-600 m range are features of the RB-57 / MBT LAW / NLAW anti-tank weapon.

    You'll probably find http://www.defense-aerospace.com/articles-view/release/3/6659/bae-wins-law-missile-subcontract-(sept.-24).html interesting in regards with the guidance package ( "typically package three SiVSG rate sensors with three silicon accelerometers, together with the associated processing" ).

    Of course this is a significantly larger and heavier weapon but I guess it illustrates the sound reasoning behind your analysis.

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    1. Well, the guidance principle is known to work - there's no creative input of mine in it.

      NLAW is too heavy. It's one of those munitions with ambition to defeat MBTs.

      The use of only 3 accelerometers points at them not taking into account that moving targets may move downwards or upwards, which likely is suboptimal in mountains.
      I think it needs 4 accelerometer locations and orientations to get the full picture (up-down, left-right and two rotation axes).
      NLAW was designed before MEMS accelerometers became super-cheap and available in 25 € toys, of course. Maybe they wanted to save the expense of a fourth sensor (that would be negligible nowadays).

      Well, this or SAAB simply works with approximated movement data and found that to be accurate enough.

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  5. My understanding is that they use 3 accelerometers (X,Y & Z axis) AND 3 rate of rotation sensors (again, on X,Y & Z axis) so they can handle this case. The rate sensor along the axis of movement (roll axis) is needed to know one's attitude. The accelerometer on this axis may be used for estimating distance traveled instead of relying on a stored distance-vs-time function (which might not be enough when the movement is not horizontal and straight - this surely applies in the case of VL-Seawolf for which the technology was developed).

    I believe that when using the weapon you start by tracking the target for a short time so that the control unit calculates the relative angular rate of movement (i.e. I observe a tank moving 1/12th of a degree per second). This rate, if kept constant (i.e. the tank does not drastically accelerate/decelerate/change direction), along with distance to target should be enough to calculate the expected position of the target when the missile impacts it.

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    1. OK, separate rotation sensors works as well. I was thinking of using spaced accelerometers to measure the rotation. Then you should be able to get enough data from four accelerometers.

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    2. Maybe you can't get enough accuracy with such a setup.

      Now that I think of it, you don't even need to know the distance-to-target. You can just follow the trajectory that answers the question: where would the target be if impact was at time X for X>0.

      However, using in your calculations a rough ( and conservative ) estimate of distance would increase maximum range by following a ballistic trajectory until a point before the estimated distance, where the missile will switch to a level trajectory.

      And you only need to use such a mixed trajectory when the distance-to-target is large enough to require a ballistic section - otherwise you stick with the simpler level trajectory for the whole time. This means that the shooter has to provide an estimate of the distance-to-target only if it is, say, beyond 50% of maximum range.

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    3. There's not much of a ballistic trajectory to speak of in only 1.3 seconds. That's about 8 m drop only. After 200 m it would only be about 2.5 metres.

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  6. On the tactical and technical side your proposition is a breath of fresh air. Overladen infantry can't maneuver the way they're supposed to. When planning a defence and drawing circles of each of the jaegerplatoons weapons effective range it is very discouraging to draw the miniscule range of LAW72. Every encounter must be planned with that range in mind. APILAS offers some improvement but is heavy as F and not as numerous as LAW72. AT weapon with effective range of 300m that could be issued to every second or third soldier without slowing down the platoon would be a significant leap in combat power. This would bring versatility to attack because you can't always predict where the enemy will be and distances will vary. With LAW an enemy IFV over 250m away would halt my attack or deplete my stock of LAWs.

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  7. An example that matches your 1.3 sec time-of-flight is when the range is 400m and the missile speed is 300m/sec (0.87mach) for the whole duration of the flight. Of course the later isn't accurate because the missile briefly accelerates to that max speed and then continues with decreasing speed thus the real time of flight is greater.

    If we leave aside air-resistance, a missile capable of reaching 400m when aimed at a few degrees from the horizontal, surely can reach significantly greater ranges with a more ballistic trajectory. The reason this is not practiced with unguided anti-tank missiles on point targets is the insufficient accuracy but if the guidance system supports it ( as in your setup ) why not go for it?

    As an example RPG-7 ( from wikipedia ) has these: Muzzle velocity: 115 m/s (boost) - 300 m/s (flight)
    Effective firing range: 200 m
    Maximum firing range: 500 m (self detonates at ≈920 m)

    This means that it can reach further than 920 m but after 200 m its accuracy isn't enough to take advantage of that range. Your guidance setup can overcome this limitation and offer reasonable accuracies to much larger distances.

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