2015/03/15

Battlefield missile artillery from the blackpowder age to the 21st century - Part II

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LARS with original,
protected cabin vehicle
Interest in multiple rocket launchers dwindled in the West after the Second World War.Their nature as short-ranged area effect weapons seemed obsolete during the 1950's when nuclear warheads of 0.1 to 10 kt TNT equivalent strength launched by single shot V2-like missiles, very heavy howitzers and ultimately heavy howitzers of 155 mm calibre became the new battlefield artillery munition for area effect.



It's likely not by pure chance that the West Germans - who had good reason to expect to call the target area of such munitions  their home -created and used one of the few major MRLs of the West from the 1960's.
They stuck to the spin stabilization and the LARS (Leichtes Artillerieraketensystem - light artillery rocket system) was similar to the Soviet post-WW2 BM-21 MRL.

Technical advances in fire control became available during the Cold War: Now you could launch a rocket, track its trajectory by radar and self-destruct it in flight. The deviation of the trajectory from the intended one could be used to compute an improved firing solution for the full salvo. This preserved the element of surprise against the targeted troops which did not notice the tracking rocket and would usually receive no timely warning by friendly artillery radar operators.

Drag rings* were applied to increase the rocket's drag and to thus decrease its minimum range. This largely solved a relevant problem for MRL crews because they could not add the propellant in increments to the warhead as do mortar and howitzer crews.

The 1970's were an era of revival for MRLs in the West: The unrestricted use of nuclear artillery had become understood to be undesirable, even improbable. Nuclear artillery was no reliable area effect artillery any more, and MRLs were available to meet the demands. Jane's Weapon Systems editions from the 1970's present a great many rocket artillery projects, often times with photos of prototype launches instead of finished products. Fin-stabilized short range MRLs were proliferating and became quite popular as simple development projects in Third World Military forces such as Brazil's or Egypt's.
There were late in the Cold War also projects to make meaningful use of aerial rockets such as 70 mm Hydra as short range artillery rockets. The results were impressive (the RD-MRWS trailer holds 114 70 mm rockets), but didn't become popular owing to the short range.
 
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RS-80 prototype
The Western MRL project which announced the late Cold War face of MRLs was an (over)ambitious one by comparison:
The tri-national (FRG/UK/ITA) RS-80 MRL was supposed to launch heavy and long 280 mm rockets out to well beyond 40 km. The calibre was wasteful for unitary high explosive warheads because little area could be covered with fragments, but the MRL was meant to employ DPICM (shaped charge + fragmentation bomblet) warheads anyway. This and the long range approach were later used in the successful MLRS program's concept (227 mm, range greater than 155 mm L/39 howitzers'). RS-80 became too elaborate and was given up, and MLRS became the de facto NATO standard MRL (and increasingly multi-national) in the 1980's.
Nowadays many people mistake "MLRS" as the "MRL" category name just as they say "AWACS" when they think of "AEW&C". MLRS was successful enough to become a synonym, just as the Soviet MRLs never really shed the "Katyusha" title fully.

Some long-range MRL such as MLRS had rather expensive launcher vehicles, the weapon or its upgrades were often rather expensive and the ammunition was always expensive. A rocket of this kind needs to be produced with tight tolerances to keep dispersion** under control and the large amount of solid rocket fuel is expensive in itself. DPICM warheads are furthermore more expensive than HE. Another popular warhead category for such MRL is capable of scattering anti-tank mines, which could be used to fix a tank company in place or to stall its advance. It's curious that NATO countries used this approach so much since it was the Warsaw Pact that lead in mineclearing equipment for tanks.

MLRS reloading
MLRS uses an unusual ammunition concept: "sixpack" containers with six rockets (or a single large ATACMS missile) can be lifted  up, loaded and disposed of by the launcher itself. The transport packaging includes the launch tubes, which burdens the production of ammunition with tight tolerances for accuracy**.
Nobody has to push individual rockets into the tubes, but on the other hand it's (AFAIK) not possible to add drag rings for reduced minimum firing range since the containers are sealed.
The M26 rocket thus had a range of 10-32.5 km and the later extended range version of 13-45 km (figures from field manual XST 6-60).
A 10 km minimum range (probably more in mountainous terrain) disqualifies MLRS as standard artillery system. It was merely able to complement the 155 mm heavy field howitzers and self-propelled guns. Its core competencies were the scattering of mines and the delivery of much DPICM over long ranges on short notice - particularly for artillery counterfire on artillery batteries found by artillery radars.
The inability to reload individual rockets (except subcalibre practice rockets) reduced the versatility further; one couldn't (even if it was developed) load a single radio jammer rocket into a launcher. The choice of the calibre made rocket too heavy for reloading even only individual rockets with manpower only anyway.

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BM-21
The Warsaw Pact's Cold War MRL developments centred a lot on the ubiquitous BM-21: 122 mm calibre, launch tubes, spin stabilized, range initially 20 km growing into MLRS range territory. Czechoslovakia even produced a derivative (RM-70) based on a bigger truck with a full set of quick reload rockets in place - capable of two salvoes for a total of 80 rockets or six hectares devastation per shoot & scoot cycle (2-3 minutes quick reload, BM-21: almost 10 minutes).


Russian BM-21- 'bringing freedom' to Ukrainians

The Soviets developed some interesting munitions for their multiple rocket launchers, including radio jammer rockets which - stuck in the ground - jammed radio communications on about one square kilometre.***

Later, the Soviet Union introduced contemporaries to MLRS; particularly the BM-27 Uragan. They sensibly used trucks instead of more expensive and more maintenance-intensive tracked carriers for these vehicles.

The Operational Manoeuvre Group (OMG, no really: "OMG") concept became the terror of NATO war defence planners during the Cold War; it was essentially a rebranded Panzerkorps, meant to push through the thinly manned defensive line of NATO and to exploit the breakthrough in brazen dashes forward. It's interesting that the Soviets equipped the divisions of such OMGs with MRL artillery: The bulk and weight of rocket ammunition is much greater than with howitzer artillery of comparable firepower. The propellant is used less efficiently because the rocket is recoilless: The propellant gasses cannot push against some solid object to propel the warhead forward and thus much more propellant is required. It's similar to the difference between swimming in water with legs working only and being able to push off the pool wall with the legs.

An interesting Soviet development from the early 1980's was TOS-1: A short range, heavy rocket MRL meant to deliver thermobaric or incendiary warheads that defeat entrenched troops or troops in settlements. The launcher vehicle was a tank hull owing to the risks associated with going within a few kilometres of the target area. This was a revival of a German concept from the Second World War and is lacking a Western equivalent.

later Part III: the early Post-Cold War era, the Cluster munitions ban and the rise of PGMs for MRL

S O
defence_and_freedom@gmx.de

*: A drag ring (or spoiler ring, nose ring) can be mounted on the narrow rocket nose. Its additional drag reduces a 127 mm Valkiri rocket's minimum range from 15 to 8 km, for example (maximum range without is 22 km).
**: "accuracy": Difference between aim point and centre of the group of impacts
"dispersion": Differences between centre of the group of impacts and the impacts. Dispersion in length is usually larger than to the sides.
Accuracy is a fire control and launcher quality challenge, dispersion is a rocket/shell/mortar bomb design challenge.
***: I'm not sure whether this was a Cold War or post-Cold War development.
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