AHC: design an ideal WW2 division with hindsight

[ShadowArxxy]

Problem with rifled barrel HEAT shells is that it reduces their penetration by something like 50%. 105mm howitzer infantry support Shermans would be better.

That's true, but WWII-era HEAT rounds were fired from rifled barrels -- smoothbores firing fin-stabilized rounds were a later development -- and typically achieved penetration levels of 150% to 250% the caliber. For the 25-pounder, even the weakest end of that range yields penetration well in excess of five inches, sufficient to defeat a Tiger 1 everywhere but the very thickest parts of its gun mantlet.

Introduce "down-time" knowledge of slip rings (which isn't even ahistorical; the Germans had them) and more refined shaped charge geometries, and the 25-pounder would easily defeat any WWII tank ever made; even the vaunted King Tiger's armor only requires about 200% penetration, which isn't even outside the range of a WWII shaped charge.

 

[sillygoose]

That's true, but WWII-era HEAT rounds were fired from rifled barrels -- smoothbores firing fin-stabilized rounds were a later development --

There were WW2 smoothbore fin stabilized HEAT shells in WW2, though later than 1939 AFAIK.
One of the earliest:

https://en.wikipedia.org/wiki/No._68_AT_grenade

Later:

8 cm PAW 600 - Wikipedia

en.wikipedia.org

https://en.wikipedia.org/wiki/3.7_cm_Pak_36#Stielgranate_41

I suppose technically the British PIAT also counted:

https://en.wikipedia.org/wiki/PIAT

The first rifled projectile only entered service in 1940 with the German 75mm L24 cannon.

https://en.wikipedia.org/wiki/7.5_cm_KwK_37

and typically achieved penetration levels of 150% to 250% the caliber. For the 25-pounder, even the weakest end of that range yields penetration well in excess of five inches, sufficient to defeat a Tiger 1 everywhere but the very thickest parts of its gun mantlet.

That is not accurate, see the above link as the 75mm shell actually produced only about 75% penetration relative to its width initially:

Gr.38 Hl (HEAT)	450 m/s (1,500 ft/s)	52 mm (2.0 in)
Gr.38 Hl/A (HEAT)	450 m/s (1,500 ft/s)	81 mm (3.2 in)
Gr.38 Hl/B (HEAT)	450 m/s (1,500 ft/s)	87 mm (3.4 in)
Gr.38 Hl/C (HEAT)	450 m/s (1,500 ft/s)	115 mm (4.5 in)

Only the last variant (in service January 1944) produced 150% penetration relative to width. AFAIK the rifle British and American HEAT shells weren't any better.

Introduce "down-time" knowledge of slip rings (which isn't even ahistorical; the Germans had them) and more refined shaped charge geometries, and the 25-pounder would easily defeat any WWII tank ever made; even the vaunted King Tiger's armor only requires about 200% penetration, which isn't even outside the range of a WWII shaped charge.

Again not with the rifle variants. I'm not sure where you're getting the rifled ones penetrating over 150% of their caliber width. That is smoothbore HEAT shells.

 

[Buba]

I recommended something like that in the OP and in a separate mortars thread.

I fully agree with you on the light and medium stuff (as apparent in my suggestions), but not on the heavy mortars. As attractive as they are - a 15cm shell from a weapon in the weight class of a medium MV 75mm weapon - they simply lack the range to be Divisional artillery. At 6km (and consdering that they are NOT on the frontline) they do not cover the whole front of an InfDiv.
I consider such 16cm mortars to be Corps/Army troops, allocated to InfDiv for an assault.

As to HEAT - I'm with @ShadowArxxy - even with poor early war HEAT, at 150% calibre penetration, a 25pdr with such ammo is good until '42 or '43.
Meh, considerign the armour of (almost all) the opposition, even c. 100% Heat or HE will be enough. With HEAT - a "come early" IG37 would rule the field.

If HEAT not available in 1939, then the problem is non existent
In 1939 a 37-47mm HV/MV AT cannon is enough. If a B-1 or Matilda (the latter not exaclty being an infantry mower) comes calling, then pray and call for heavy AA from Corps/Army

Also - I misused the term APDS - I was thinking of the arrow/spindle shaped shells/shot.

Russian 45mm Anti-Tank Rounds (WWII) - Inert-Ord.net

www.inert-ord.net

My go-to solution for tank killing and infantry support in the 37-41 period

Stealing a concept from alternate history discussion forum.

Linky? Cannae find it ... but it is possible that the OP is one of the commies/misspelling cunts I have on ignore.

 

[sillygoose]

I fully agree with you on the light and medium stuff (as apparent in my suggestions), but not on the heavy mortars. As attractive as they are - a 15cm shell from a weapon in the weight class of a medium MV 75mm weapon - they simply lack the range to be Divisional artillery.

At 6km (and consdering that they are NOT on the frontline) they do not cover the whole front of an InfDiv.
I consider such 16cm mortars to be Corps/Army troops, allocated to InfDiv for an assault.

Sure, which is why I said in my version of a division in this thread that they should be used in battalion strength attached to a brigade due to their size and weight as well as range. They be primary used to bunker bust and attack units in the open if there were a worthwhile target.

For longer range as I said in the artillery mortar thread a smaller caliber very long, aerodynamic shell could be used with full bore fins instead of caliber matching ones and a cup sabot. That should give it the range close to the 25 pounder. For a 150mm mortar I'm thinking a 105mm mortar shell, but with the shell body being 7 caliber lengths long in a V-2 missile style aerodynamic configuration with fins for a 150mm shell instead of a 105mm one. The cup sabot could attach in the middle and discard at the muzzle of course.

For division level artillery I'd still suggest something in the 200-240mm range for special use when dealing with fortifications. The weapons would be easier and cheaper to make than even a 150mm howitzer, so you get a lot more fortification busting power or ability to smash infantry targets in the open defensively.

As to HEAT - I'm with @ShadowArxxy - even with poor early war HEAT, at 150% calibre penetration, a 25pdr with such ammo is good until '42 or '43.

If HEAT not available in 1939, then the problem is non existent
A 37-47mm HV/MV AT cannon is enough. If a B-1 or Matilda comes calling, then pray and call for heavy AA from Corps/Army

They didn't exist in 1939 by a long shot then it is a moot issue, but several points of order:

Problem is the 150% penetration HEAT wasn't available until 1944 and IIRC only for the Germans. AFAIK the only HEAT shells the British produced were PIAT and rifle grenade versions, not rifled projectile ones.

Besides, per this forum discussion on the 25 pounder shell the reason it was cancelled in 1944 was that it simply wasn't very good:

Hollow Charge (HEAT) for the 25 Pounder

According to this link, http://www.canadiansoldiers.com/weapons/ordnance/25pounder.htm a hollow charge round was developed for the 25 Pounder but never...

ww2talk.com

Development started 1940, but little was known about HEAT warhead design then, plus there was a lot of trouble in developing a suitably sensitive base fuze, so a looong time was spent in R&D. By the time they were getting it sorted, they discovered that HEAT didn't work too well with a spun shell, and that the Wallbuster (HESH) approach seemed more promising, so they cancelled the HEAT in 1944.

The HESH rounds actually were enhanced by the spin imparted by rifling.

Linky? Cannae find it ... but it is possible that the OP is one of the commies/misspelling cunts I have on ignore.

Oh this particular AHC is not on that website AFAIK. I meant I was stealing the concept of an AHC for this forum, since I haven't seen any.

 

[ShadowArxxy]

Besides, per this forum discussion on the 25 pounder shell the reason it was cancelled in 1944 was that it simply wasn't very good:

Hollow Charge (HEAT) for the 25 Pounder

According to this link, http://www.canadiansoldiers.com/weapons/ordnance/25pounder.htm a hollow charge round was developed for the 25 Pounder but never...

ww2talk.com

That is exactly why I said taking advantage of down-time knowledge is the critical step there. With slip rings and a proper shaped charge geometry, we can easily field 25-pounder HEAT rounds that will pierce even a Maus.

 

[sillygoose]

That is exactly why I said taking advantage of down-time knowledge is the critical step there. With slip rings and a proper shaped charge geometry, we can easily field 25-pounder HEAT rounds that will pierce even a Maus.

Outside this OP though. This is about division design in 1939, not about directing research for 1944.

 

[sillygoose]

Based on the war lessons from Ukraine how might a 1939 division make use of those lessons? It seems firepower via artillery/rockets really is the way to go, but networkings and mobility were nowhere near what existed on average in 1939. How important is manpower vs. firepower when it comes to calculating how many divisions to field for a given task? By that I mean is too much firepower a liability in 1939 relative to communications technology and availability for huge armies over 100 division? Especially without drones for spotting and computerization making everything much easier and requiring less time and manpower.

 

[Buba]

Based on the war lessons from Ukraine how might a 1939 division make use of those lessons?

The way I see things the lessons are either eternal and thus nothing new, or impossible with 1939 tech. Not sure if anything falls in between.

 

[ATP]

Poland in 1939 used 75mm french and russian guns - both used anti-bunker ammo which could go through 70mm of armour at 500m.Good enough for everything in 1939.
And here,would be used in new 75mm guns,with better velocity.

 

[sillygoose]

The way I see things the lessons are either eternal and thus nothing new, or impossible with 1939 tech. Not sure if anything falls in between.

Respectfully disagree. There were pretty substantial developments over the course of the war in organization as well as firepower enhancements; post-war things evolved even more with the dropping of things like infantry guns, the Soviets developing several new classes of mortars, the US opting to rely on air support over artillery (only a single battalion of artillery per brigade) while the Soviets focused on air defenses and artillery (one battalion or artillery/rockets per battalion in a brigade/regiment). In 1939 regiments were supported directly by infantry guns at best or mortars (if that) and 81mm mortars at the battalion level was considered and innovation. Things like automatic mortars did exist experimentally, but weren't developed until after the war. The US and UK basically lacked rocket artillery except in small numbers at the end of the war, something noted to be a major deficiency and they later dumped all their artillery over 155mm and went for light weight versions over those that could sustain fire. So it would seem to me that there were all sorts of things that could be done in 1939 to organize or equip better, though the question is whether extra firepower is a hindrance logistically and in terms of communications for what could be fielded in 1939.

One example I can think of, other than artillery mortars, would be the Soviet/Russian gun-mortar system that IMHO should have supplanted the infantry gun and was fully achievable with 1939 (or really earlier) tech.

 

[Buba]

I thought that you are asking about lessons from Ukraine 2022 that could be used for an InfDiv OdB in 1939 ...

the question is whether extra firepower is a hindrance logistically and in terms of communications for what could be fielded in 1939.

On a WWII board I learned my lesson:
"So, you'd like an extra 50/60/80mm mortar at company level? Well, the ammunition for it weights so and so. Which means so and so many more men using so and many horse carts/vehicles at company/battalion to keep it firing, plus so and so many men&vehicles at Division level. So, your one mortar barrel and 4 men crew adds up to 6 more men plus so and so many vehicles/horses/carts. If you go with a larger calibre then the numbers for the supply tail increase by XX. On a Divisional scale, that means so and so many men, which means another field kitchen and staff ... "

IMO a very nice example - the 60mm mortar as designed by Brandt (and used by US) and the cut-down 8cm mortar of German paratroopers weight more or less the same, 20-25kg. Similar (short) range too. But the 8cm jobbie fires twice the shell! So the choice should be simple ...
However, if you know that your logistics are/may be "not that good" then a 6cm mortar, even though with a lighter shell, may be a better choice than the more "powerful" weapon. Without ammunition a weapon is scrap metal ...

 

[sillygoose]

I thought that you are asking about lessons from Ukraine 2020 that could be used for an InfDiv OdB in 1939 ...

Yes I was/am. What sort of firepower, how much, and with what equipment and organization is pretty relevant IMHO.

On a WWII board I learned my lesson:
"So, you'd like an extra 50/60/80mm mortar at company level? Well, the ammunition for it weights so and so. Which means so and so many more men using so and many horse carts/vehicles at company/battalion to keep it firing, plus so and so many men&vehicles at Division level. So, your one mortar barrel and 4 men crew adds up to 6 more men plus so and so many vehicles/horses/carts. If you go with a larger calibre then the numbers for the supply tail increase by XX. On a Divisional scale, that means so and so many men, which means another field kitchen and staff ... "

IMO a very nice example - the 60mm mortar as designed by Brandt (and used by US) and the cut-down 8cm mortar of German paratroopers weight more or less the same, 20-25kg. Similar (short) range too. But the 8cm jobbie fires twice the shell! So the choice should be simple ...
However, if you know that your logistics are/may be "not that good" then a 6cm mortar, even though with a lighter shell, may be a better choice than the more "powerful" weapon. Without ammunition a weapon is scrap metal ...

Yeah that is sort of what I'm looking for.

Agreed about the 60mm mortar. Though arguably the same case then could be made for the 50mm mortar due to the lighter ammo at the squad level instead of the platoon or company level. A French or British style 50mm (or 2 inch) mortar would be light and effective enough for a squad and replace the need for something heavier at the platoon level. Or the Japanese Type 89 grenade launcher...which might be the best weapon in its class had it been pushed down to the squad level given the range limitations.

As an aside on this subject it is interesting to see the permutations of just mortar types, amounts, and arrangement the Germans went through during the war, as that is instructive about 'what works' given combat experience. I cite them because it is hard to find similar things for the Soviets, the next power with a lot of ground combat experience. However given that they introduced 120mm mortars at the battalion level in lieu of the 81mm mortar (or in addition and then devolved the 81s to the company level along with the battalion MGs) apparently the battalion/company supply trains could handle the heavier ammo without a reduction in effectiveness.

http://www.bayonetstrength.uk/GermanArmy/GerInfBn/Org%20of%20the%20German%20Inf%20Bn%201938-45.pdf