The underrated genius gun

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World War II artillery lessons learned pointed at four desirable main improvements:

+ all-round fire capability on short notice

+ anti-tank self-defence capability

+ ability to shoot in the upper angle group* (43-70° elevation)

+ more range

A greater shell weight was not emphasised much; 149-155 mm was identified as practical calibre limit for standard artillery. 87-105 mm howitzers had proved their effectiveness. Soviet 122 mm howitzers had proved to be an excellent compromise between the 10 cm and 15 cm main calibres.

The bigger howitzer calibres (149-155 mm) justified their existence primarily with test results that showed a greater overhead cover penetration in firing missions against entrenched troops. It was proved again and again in both world wars that such firing missions were slow, expensive in terms of ammunition and in effect usually inferior to a smarter artillery use with suppressive and surprise fires.

You can bombard entrenched troops into oblivion, but operationally you can achieve much more if you overrun them with support by surprise, suppressive and blinding (smoke) indirect fires.

The need for improved shell effectiveness was afaik rated lowly in German WW2 artillery lessons learned. The first use of radio proximity fuses against land targets in late 1944 had already promised an effectiveness boost against soft targets in the open. These fuses favoured medium calibres, for small ones did initially not justify the fuse price for ground combat uses and large ones offered little additional fragmentation radius over medium ones.

The dominance of the 152 and 155 mm calibres came into being only later (1970's), when they replaced dedicated field cannons with their improved range and proved to be most suitable for cargo (bomblet) shells. The effectiveness ratio between impact-fused 105 and 150 mm HE shells was about 2:3 (at most about 1:2) and it jumped to almost 1:4 for 105 and 155 mm bomblet cargo ("ICM", "DPICM") shells.

The optimal WW2 lessons learned standard artillery piece would thus be a medium calibre gun (till the early 70's) somewhere between 105 and 149 mm. NATO countries did not use medium calibre field howitzers of larger calibre than 105 mm; the last ones in the West (120 mm howitzers) were pre-WW2 vintage, if not pre-WW1 vintage and played no role during the Cold War.

The Russians on the other hand had a great WW2 122 mm howitzer, and developed the wet dream of WW2 artillerymen in 122 mm calibre: The 122 mm 2A18 (called "D-30" by Westerners).

Serbian D-30JA1 (or D-30J)

It had
+ an unusually good range (it outranged even the standard U.S. 155 mm howitzers and self-propelled howitzers in 1965-1972!),
+ improved accuracy
+ all-round traverse
+ secondary anti-tank capability with a shaped charge shell, a low profile and a small shield
+ 70° maximum elevation
+ de facto no limit on towing speed (80 kph maximum on roads)

Its emplacement and displacement times are normal for towed howitzers. Its shell effect was significantly better than with 105 mm shells and in regard to HE with proximity fusing close to 152/155 mm shells (the Soviets were famous for having mostly ancient ammunition in their stocks, though).

Its one exceptional element is the three-legged carriage.

Three points are necessary to define a plane in math, and three are necessary to give a gun a stable position. Three relatively equal trails allowed for an unlimited traverse - unlike with the ancient box or the early 20th century split trail designs. A four-legged trail would be one more than necessary, and lead to issues during emplacement as the fourth could float in the air (have you ever seen a three-legged stool to wobble? How about a four-legged one?).

Unlimited traverse is important because it enables a quick reaction to all calls for fire (not just in a 60° arc) - and to a sudden demand for self-defence fires, as against tanks.
 

The first guns to make use of all-round traverse on land were as far as I know anti-air guns, especially those in 37 - 128 mm calibre (albeit not all of them). The flat four-legged (cruciform) design was apparently the dominant one for AAA.

Some anti-tank guns with a 360° traverse feature were employed as well, albeit it was quite unnecessary for up to 76.2 mm calibre because such AT guns were 'light' enough to be traversed by their crew. The French had a 47 mm SA modèle 39 TAZ prototype on three legs and the British 40 mm two-pounder AT gun had a different three-trail design, too. Both were essentially over-engineered, as much heavier AT guns were very well man-handled during WW2 (the limit for this was somewhere in the 1,000 - 1,200 kg range). The French gun can be considered to be the first one with such a system as later employed in the 2A18, though. The same three-trail concept was also used in a French 75 mm AT gun prototype before the French armaments industry quitted WW2 involuntarily.

Germany employed four-legged designs for the 8,8 cm Pak 44 / 8,8 cm K 44, for the 12,8 cm Pak 44 prototypes (two designs), the 10,5 cm FH 43 Skoda prototype and the two 15 cm FH 43 prototypes - all during WW2.

The Swedes did pick this up (post-WW2) with their Bofors 105 mm howitzer 4140 on a four-trail carriage.

Then came the Russians (Soviets) with their 2A18 design that became the dread of Central European Cold War armies (not the least due to its insurmountable quantity), a dominant artillery piece of the Soviet Pact, a prime export weapon in the Third World and a much-copied design overall. Afaik the Chinese are still manufacturing it, amongst others.

There is one drawback, though: The breech type (vertically-sliding, wedge-type breechblock) does afaik typically not allow for bag-type propellants due to imperfect sealing. Cases are apparently necessary, and this violates a specific German WW2 lesson; cases become expensive and problematic once you need to produce many millions of artillery cases per month while experiencing material shortages...

I was irritated that such a 'great' gun design never seemed to get the kind of attention and 'admiration' that even mediocre main battle tanks received. Or does "D-30" ring louder in your ear than "T-62"?


The 2A18/D-30 design was phenomenal during the 60's, great during the 70's and is still a very good choice for all ground forces that don't need to care much about the counter-artillery radar problem. It's a true classic that begins to exceed the French Soixante-Quinze in its longevity in accomplished service.

S O

*: The upper angle group was important both for firing positions in woods, for better overhead cover penetration and most importantly for a greater fragmentation effect.

Detail photos of a 2A18 gate guard. 

edit Oct 2011: There was also a three-legged 25 pdr mock-up from Woolwhich for the design competition of the famous 25 pdr gun (pre-WW2 !). A prototype of a U.S. 75 mm "Divisional Gun" with three strangely long legs existed as well - it was meant to double as field artillery and heavy AAA.  Source: Hogg, "British & American Artillery of World War Two"

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