For the 3rd time: in this thread, the British are aware of the incoming war. They are experimenting with an novelty, an SP gun for their artillery arm, with intent to use it in indirect fire role (the A9 'stug' is to be used in tank units, instead of historical CS tanks). As an experiment, it uses an affordable chassis and an already produced artillery piece. If the experiment fails, it was not costing them too much. If it works, they would produce more examples, either same type, or improved, or substantially better designs. The 18pdr is an useful piece, and implying it's 'substandard' is way out of mark.
Sorry but the substandard was in relation to 12cm mortars, however it applies to some extent to the 18pdr depending on model and year. There are 2 different 18pdr barrel and recoil mechanisms and 3 rather different carriages. there is also a modernized HE shell. AS to the carriages I am not referring to the the type of wheels or brakes but wither it had the pole trail carriage, the box carriage or the split rail carriage. The carriage affects the elevation and traverse limits for a simple conversion ( cut the wheels off, cut trail/s down and mount on/in vehicle) Building new elevation/traverse mechanisms tends to run up the cost. The problem here is that the most desirable carriages for conversion to SP guns (the MK IV box trail and MK V split trail) are also the most desirable for the British to convert to 25pdrs as towed artillery. as an example 704 of the converted 18/25pdr guns were lost in France along with 216 18pdrs. The least desirable guns for conversion were the pole carriage guns. These had an elevation limit of 16 degrees with rather limits the range. They also had a total of 8 degrees of traverse. the box trail offered 30 degrees of elevation and the Split trail offered 37.5 degrees. The box trail equipment was sometimes given a turntable like the 25pdr for easier large arc traverse movement.
There were 90 of the 25pdr MK II (the "standard 25pdr")in England in May of 1940 and none are supposed to have gone to France.
For your experiment the 25pdr MK I (18/25pdr) is as good as it gets (from 1937 on), the guns/mounts to be turned into the 25pdr MK I are second best and perhaps spoken for but available in small numbers. The older guns with pole carriage, recoil cylinders on top of the barrel and so on are the "cheapest" they are also slated for scraping or training commands, have limited range about 6000 meters (the change from 16 degrees to 30 degrees was worth 2600yds) have a different breech mechanism ( a slower two motion breech instead of a single motion breech).
The Experimental Birch guns used the later 18pdr barrels, breeches and recoil systems and that was in 1925. there were experimental gun carriers in the First World War based on the Big British tanks. The British played with the Birch guns fot 6 years.
the French had built 8 different prototype SP guns by 1919 and the US had built 12 different models by 1922. The Idea was not novel but exact doctrine and technique needed a lot of work.
Thanks for the information. BTW, any info about the max elevation of the early StuG-III gun?
It's obvious that LT-based SP gun would need observation posts/units, they can use the 'Bren' carrier, or maybe another LT based vehicle.
Stug elevated to 20 degrees.
The OP unit needs to mount the standard OP optics (not much of a problem) a small map area, (not much of a problem) and a decent radio set ( a bit more of a problem). The First German OP unit mentioned Sd Fkz 253 actually had thicker armor on the front than the standard half track. It might be better to use the LT chassis rather than go cheap with the "Bren" carrier.
Think I've covered this before, but anyway:
*Not yet (prior Sept 1939).
** Yep, the A9 based vehicle, firing both HE smoke shells.
***That's one of the aims, LT-based SP piece being sorta proof of concept.
an A9 "Stug" doesn't really have the armor to take part in the direct fire battle, the A9 itself didn't have the armor. A10 maybe.
If you have this kind of influence (
) get the British to make and issue an HE round for that 3.7in smoke mortar
and an HE round for the 2pdr.
The concept is already somewhat proven, what is needed is a "practical" vehicle to carry it to the next step. Small vehicles with limited ammo storage, limited firing arcs (if used with 8-9 degree traverse mounts) limited working room and some what limited cross country performance (step and trench) are NOT needed in any numbers. The MK VI light tank also had a primitive steering system. It used the clutch and brake system which was OK on the level and climbing hills, it would reverse steer descending a hill unless the engine was under load (accelerating). To steer the 'inside' track was de-clutched and if needed was braked as the outside track continued to be powered causing the tank to slew (turn). going down hill on a trailing throttle as soon as the 'inside' track was de-clutched it ' free wheeled' (free tracked ?
) and the normally driven track held back causing the vehicle to turn in the opposite direction intended. Not great in any vehicle, in a top heavy SP gun??
Part of the British resistance to SP guns in the late 30s was not so much cost but mistaken tactical beliefs. Like the tank was invulnerable (even with 30mm or less armor) and so didn't need artillery support to suppress enemy defenses.
