KV-2 and 150mm Inf gun Questions

[Michael Emrys]

Originally posted by Michael Dorosh:

</font><blockquote>quote:</font><hr />Originally posted by flamingknives:

Looking about the web, I find that the British 25pdr weighed in at 1800kg, had a range of up to 13,000yds and was most certainly used for DF.

Not after North Africa. </font>

[Michael Dorosh]

Originally posted by Michael Emrys:

</font><blockquote>quote:</font><hr />Originally posted by Michael Dorosh:

</font><blockquote>quote:</font><hr />Originally posted by flamingknives:

Looking about the web, I find that the British 25pdr weighed in at 1800kg, had a range of up to 13,000yds and was most certainly used for DF.

Not after North Africa. </font>

[Michael Emrys]

Originally posted by Michael Dorosh:

My error; I hadn't even considered the Pacific.

You're in good company: Neither has BFC.

Michael

[Andreas]

Originally posted by Michael Emrys:

Andreas, I am inclined to agree with you on the sIG33, that it was probably used IDF more often than not (until it was put on a tracked carriage; I don't know what followed that, although I would be inclined to expect to see it used a bit more up front as assault gun).

I would tend to think that the Grille variants were just attempts to create a more mobile gun for the identical purpose of the towed variety, whatever that was. The sIG33 on Pzkpfw. I chassis I believe to be more of an assault gun - one reason for this is that the latter came in special companies, while the former was just given to Panzergrenadier regiments in replacement for the towed variety.

Originally posted by Michael Emrys:

As for the lIG18, I'm assured that it could be used either way. As to which was its primary mode of employment, I am still up in the air. So far, as I say, the bulk of pictorial evidence is heavily on the side of DF, but I don't give that a whole lot of weight by itself as there could be factors that biased the taking and selection of photos in that direction. There are other factors that point in the direction of its use DF, but so far nothing conclusive.

Stay tuned.

Michael

The IG18 is a whole different kettle of fish, being far more mobile at only 400 or so kg weight.

Who needs horses?

Try doing this with a sIG33...

[Andreas]

25-pdr DF: I think what we are discussing here are the design properties, and what they tell us about actual use of the gun. My point would be that having a shield is not a sign that a gun was intended primarily for DF. It is however a sign that the design requirements considered the likelyhood/risk of DF employment as high enough to warrant the extra weight, and expense, of fitting a shield for crew protection.

[Michael Dorosh]

Originally posted by Andreas:

25-pdr DF: I think what we are discussing here are the design properties, and what they tell us about actual use of the gun. My point would be that having a shield is not a sign that a gun was intended primarily for DF.

Exactly my point as well, which you beat me to it. I didn't bother to edit after reading your remarks.

It is however a sign that the design requirements considered the likelyhood/risk of DF employment as high enough to warrant the extra weight, and expense, of fitting a shield for crew protection.

There is no evidence of that; outside of asking the original designers. It is possible the original intent was merely to protect the crew from shrapnel during counter-battery attacks and the use of the gun in a DF role was never given a second thought. Given some of the odd design choices made by British engineers on various bits of equipment, I'd be loathe to assign too much meaning to the addition of various equipment.

The 25 pounder was a very good AT weapon in the desert - was this out of design, or necessity? I seem to recall it being the latter but can stand to be corrected. We all know the story of the FlaK 88.

Perhaps I'm reading too much into the fact that by 1944, the employement of the 6 pounder and 17 pounder - in the closed spaces of Italy and France - meant that the 25 pounder never got within a few miles of the shooting.

It's significant, though, that the vehicle mounted Sexton was not used as an "assault gun" but simply as "self propelled artillery". One would be inclined to use the all-round protection and tracked carriage as incorrect evidence of intent for a DF role in that case, also, no?

[Michael Emrys]

Originally posted by Michael Dorosh:

There is no evidence of that; outside of asking the original designers.

I suppose with sufficient research, one could turn up the original documents that discussed specifications and intent. I admit that for my part, that research is likely to be purely hypothetical though.

...the use of the gun in a DF role was never given a second thought. Given some of the odd design choices made by British engineers on various bits of equipment, I'd be loathe to assign too much meaning to the addition of various equipment.

While I do not cite it as absolute proof of the argument, it seems to me that the platform on which the gun was placed and on which it could be rapidly rotated is suggestive in that direction. Granted it could be useful in relaying the gun through a wide arc when firing indirectly, it would be even more useful when engaging moving targets over open sights. Again, as I say, not conclusive of itself, but strongly suggestive.

The 25 pounder was a very good AT weapon in the desert - was this out of design, or necessity?

Well, they did have solid shot ammo for it. That requires a certain lead time for production and distribution. The gun crews didn't snatch it out of thin air. The question is when did this ammo reach the batteries? Did they have it in France? A likely date would have been in late '40 when the Brits were preparing to repel an invasion, but I simply don't know.

Lastly, what does Ian Hogg have to say about all this?

Michael

[ August 19, 2003, 11:24 AM: Message edited by: Michael Emrys ]

[Michael Dorosh]

As far as evidence goes, the circular platform would be a far better case for an intention on the part of the designers to allow for DF than the gunshield. Though as rightly pointed out, not absolute proof by any means.

My dad was a gunner on 25-pounders in the late 50s. No doubt doctrine had changed by then and his reminiscences are irrelevant, but for what it's worth, his reserve unit only trained in indirect firing.

[Bastables]

Originally posted by Michael Dorosh:

[

The 25 pounder was a very good AT weapon in the desert - was this out of design, or necessity? I seem to recall it being the latter but can stand to be corrected. We all know the story of the FlaK 88.

[/QB]

Not quite the same as experience with 8,8cm/2cm FlaK in Spain and then Poland meant a reclassification as a dual-purpose gun and the issue/manufacture of AP cartridges expressly for penetrating tanks. By North Africa FlaK guns were an integral part of Stuetzpunkt (best described as defensive hedgehogs) and assorted doctrine for destroying planes and tanks, in order to by time for Panzer counter attacks. The Commonwealth attacks during battle axe where stopped precisely because FlaK of both Infantry regts and the FlaK regts guns were sited to DF on Tanks and Infantry.

You'll also note that as the war went on the Heer 2cm and 8,8cm FlaK were gradually fitted with gun shields (Practice began in FlaK units before the invasion of France) because they were expected to be sited at times on the front line for DF. FlaK that was expressly used for anti aircraft and never issued to the heer such as the 12,8cm and 8,8cm Flak 41

even in 44/45 did not have gunsheilds fitted.

I (and the FlaK example) also agree with Emrys that 25pdr having solid shot designed, manufactured and then issued well before combat versus Italian tanks began, is pretty indicative that 25pdrs were expected to be used in the DF role. Even the old 18pdr that the 25pdr was to replace had AP-shot pre war.

[ August 19, 2003, 10:13 PM: Message edited by: Bastables ]

[JonS]

25-pr. Firing Platform: While useful for rapid engagement of moving targets in a DF role, it has many uses in an indirect role too.

1) It supports the weight of the gun better,

2) and provides a stable mounting point on all types of ground,

3) it also transmits recoil to the ground more efficiently, helping with the stable mount thing,

4) it allows the rapid swithing between targets at long ranges, a attribute that is important for the rapid massing of fires from multiple batteries (a key characteristic of the RA Doctrine).

It that regard, it's worth noting that the L-118 Light Gun, designed in the 1970s and prominent in the Flaklands, Bosnia, and most recently in GW2, was designed with a box trail carriage and a firing platform, just like the 25-pr. Unlike the 25-pr., it doesn't have a sheild. The L-118 is definately not intended for direct fire, although it does have an A/Tk round available (HESH). Weird things happen in war, and the ever practical gunners figure it is better to have something and not use it, rather than need something and not have it.

Also, if the firing platform is such a wizard idea for DF, why didn't more guns that were intended to fire DF (6-pr, 17-pr, German guns, French guns, American AT guns, etc) have one?

AP Shot for 25-pr.: I don't know for sure, but was the early stuff really proper AP shot, or just HE-plugged*?

Part of the reason the 25-pr. got to do A/Tk work so often in the desert wasn't because it was such a great A/Tk gun, but because it was better than the 2-pr., and there were lots of 25-prs. around. Also, the nature of the fighting from mid-1941 till about August 1942 (open flanks, broad brush movements, strongpoints, etc) virtually ensured that the 25-pr. would often be caught up in the thick of the fighting.

Gun Shields and Counter-Battery Fire: Gun sheilds would be nearly useless at protecting the guns or gunners on the receiving end of counter-battery fire, unless of course the CB was being fired direct. With indirect CB, the incoming rounds will fall anywhere in a 360° circle around the bty posn, not convieniently out to the front.

Definition of Direct or Indirect Fire: is what Andreas(?) said on page 1. Any situation in which the gunner observes and adjusts his own fall of shot is Direct Fire. Thus, mortars can quite happily conduct direct fire, even though their rounds are doing high, looping trajectories to the target.

Any situation in which the target cannot be seen through the gun's sights - and therfore the adjustments are done by a third party - is Indirect Fire. Indirect fire may be observed (controlled by an FO) or predicted (target information obtained from map inspection). See here and here for a better and more detailed description than I can give.

Regards

JonS

* an HE round with an inert fuze, which is the way they are delivered from the factory. The fuzes come seperately.

[ August 19, 2003, 11:41 PM: Message edited by: JonS ]

[Bastables]

Originally posted by JonS:

AP Shot for 25-pr.: I don't know for sure, but was the early stuff really proper AP shot, or just HE-plugged*?

18pdr AP Shot Mk 3T

25pdr fired a 20pd AP Shot Mk 3T

5,5inch fired HE with shipping plug in place in lieu of a proper AP shot, presumably this could be done with the 25pdr HE round but there was already a proper shot for that gun.

[Michael Emrys]

Originally posted by JonS:

25-pr. Firing Platform: While useful for rapid engagement of moving targets in a DF role, it has many uses in an indirect role too.

1) It supports the weight of the gun better,

2) and provides a stable mounting point on all types of ground,

3) it also transmits recoil to the ground more efficiently, helping with the stable mount thing,

4) it allows the rapid swithing between targets at long ranges, a attribute that is important for the rapid massing of fires from multiple batteries (a key characteristic of the RA Doctrine).

But I wonder how much you need to swing the whole gun to bring that part of the enemy line that is within range under fire? Most artillery seems to have enough traverse to do the job when firing indirectly.

Also, if the firing platform is such a wizard idea for DF, why didn't more guns that were intended to fire DF (6-pr, 17-pr, German guns, French guns, American AT guns, etc) have one?

I thought of that, but I'm not sure that's such a fruitful line of argument. Turn it around and ask if it was such a wizard idea for IDF, how come it wasn't adopted for other artillery pieces clearly intended for the IDF role? The only other examples I've been able to locate so far from the WW II period are the German 17cm K18 and 21cm Mrs 18.

AP Shot for 25-pr.: I don't know for sure, but was the early stuff really AP shot, or HE-plugged* ?

I can't find anything definite at the moment, but my impression from what I'd read in the past lead me to believe that it was a purpose-built solid shot. Chamberlain & Gander in WW2 Fact Files do mention that when firing AP a larger propelling charge was used.

Definition of Direct or Indirect Fire: is what Andreas(?) said on page 1. Any situation in which the gunner observes and adjusts his own fall of shot is Direct Fire. Thus, mortars can quite happily conduct direct fire, even though their rounds are doing high, looping trajectories.

I believe I was the one who said that, although nothing prevents Andreas from saying it too.

Michael

[Michael Emrys]

Originally posted by Michael Emrys:

</font><blockquote>quote:</font><hr />Originally posted by flamingknives:

I'm pretty sure that the 75L11s fire indirect...

This is a question I have yet to resolve in my own mind. It was certainly a high-angle weapon, yet whether this was utilized to fire indirectly or not I don't know yet. Did it have dial sights?</font>

[JonS]

Originally posted by Michael Emrys:

But I wonder how much you need to swing the whole gun to bring that part of the enemy line that is within range under fire? ...

Enough to make it worthwhile? Remember that the 25-pr. is generally regarded as the best gun of it's class in WWII. I would consider that the firing platform, the sight/gun-rule, and the breech design would go a fair way to explaining why.

Also, consider that having a firing platform means it takes longer to bring the gun in and out of action. Hardly a desirable trait for a DF gun to have.

Definition of Direct or Indirect Fire: is what Andreas(?) ... </font><blockquote>quote:</font><hr />I believe I was the one who said that, ...

</font>

[JonS]

Originally posted by Michael Emrys:

... "reciprocating dial sights". ...

The following is based on my experience from a different generation of equipment, a different doctrine, and a distance of 50-odd years. So take it with a grain of salt

The guns of a battery are brought into parallelism using a centrally located director (telescope attached to an accutrate compass and slip-ring marked out in ° " and ').

As each gun is brought into action the director lays on the gun dial sight, and the gunner lays his dial sight back on the director. Using a bit of tricky maths, the man operating the director is able to tell the gunner what bearing he should be laid on when he looks at the director. The gunner sets that, on his sight, re-lays on the director, and the alignment of that gun is set. Do the same for all the guns, and hey-presto, all the guns barrels are parallel to each other, which makes indirect shooting feasible and accurate.

Now, having a reciprocating sight on the gun means that the gunner doesn't have to do anything tricky like work out the back-bearing when the director dude gives him his angle. He just sets the bearing as given, and away he goes.

It removes a potential source of error and makes everyones life a little easier.

Regards

JonS

[Andreas]

Well, just checked Ian Hogg - 'The guns 1939-45' and he says that the infantry gun concept came from the use of mortars in WW I, which were seen as a useful power addition to the infantry in the frontline. Since mortars are by definition indirect fire (usually observed), one may guess that indirect fire was the main purpose of infantry guns, and that direct fire was a thrown-in bonus.

The sIG33 was an aberration by the way, nobody else used something as heavy in the role.

[Michael Emrys]

Originally posted by JonS:

</font><blockquote>quote:</font><hr />Originally posted by Michael Emrys:

But I wonder how much you need to swing the whole gun to bring that part of the enemy line that is within range under fire? ...

Enough to make it worthwhile? Remember that the 25-pr. is generally regarded as the best gun of it's class in WWII. I would consider that the firing platform, the sight/gun-rule, and the breech design would go a fair way to explaining why.</font>

[Michael Emrys]

Originally posted by JonS:

</font><blockquote>quote:</font><hr />Originally posted by Michael Emrys:

... "reciprocating dial sights". ...

The following is based on my experience from a different generation of equipment, a different doctrine, and a distance of 50-odd years. So take it with a grain of salt

The guns of a battery are brought into parallelism using a centrally located director (telescope attached to an accutrate compass and slip-ring marked out in ° " and ').

As each gun is brought into action the director lays on the gun dial sight, and the gunner lays his dial sight back on the director. Using a bit of tricky maths, the man operating the director is able to tell the gunner what bearing he should be laid on when he looks at the director. The gunner sets that, on his sight, re-lays on the director, and the alignment of that gun is set. Do the same for all the guns, and hey-presto, all the guns barrels are parallel to each other, which makes indirect shooting feasible and accurate.

Now, having a reciprocating sight on the gun means that the gunner doesn't have to do anything tricky like work out the back-bearing when the director dude gives him his angle. He just sets the bearing as given, and away he goes.

It removes a potential source of error and makes everyones life a little easier.</font>

[Andreas]

Originally posted by JonS:

slip-ring marked out in ° " and '.

I assume the German word for that is 'Richtkreis', in which case regimental cannon companies had someone in each of the Zugtrupps (Platoon HQs) to do this job.

[JPS]

Andreas, as per definitions used previously in this thread, also mortars can be considered direct fire. I do not know how they were used in practice in WW I, but your quote from Hogg by itself does not seem to solve the issue.

Br,

Jukka-Pekka

[Michael Emrys]

Originally posted by JPS:

Andreas, as per definitions used previously in this thread, also mortars can be considered direct fire. I do not know how they were used in practice in WW I, but your quote from Hogg by itself does not seem to solve the issue.

Mortars, especially the ones found at the company level (45-60mm) were often fired directly. Everything bigger was more commonly fired indirectly even if it was a member of the mortar crew doing the spotting from only a few meters away. It's not too much of a stretch to suppose that the smaller inf. guns were used in the same way.

BTW, so far the discussion has been pretty much confined to German practice. In the British army at the time of WW II there was no equivalent to the regimental inf. gun although they had mortars on the same scale as other armies. In the US army the cannon companies were armed with 75mm and then later (in most cases) 105mm howitzers that were almost invariably used indirectly. The Soviet practice I am largely ingorant of, but I have been hearing lately that their regimental artillery was often used in a DF mode. I know next to nothing yet about Italian practice aside from their reputation as one of the army's better arms.

Michael

[ August 20, 2003, 01:24 PM: Message edited by: Michael Emrys ]

[JasonC]

Everyone is talking about the sIGs, I thought I'd address the KV-2 question. As others have already mentioned, the initial idea was bunker busting, based on experience tackling fortified lines in Finland. They weren't a big success operationally - too heavy, not mobile enough.

The replacement was the SU-152, based on the standard KV-1 hull with the same 152mm howitzer mounted without a turret. The SUs were quite successful, earning the title "animal killer" at Kursk for their ability to KO German heavies at range. Naturally they also performed the assault gun mission against bunkers and infantry positions. They were far more mobile and reliable than the KV-2.

(The much smaller SU-122 was based on the T-34 chassis and used a relatively low velocity howitzer, making it relatively ineffective for AT use. Although more HEAT ammo made it marginally capable in that role later on).

Late in the war, the ISU-152 and 122 became available, based on the IS series hulls. They were more heavily armored than their predecessors. The IS-122 used the 122mm gun (not the short howitzer), the same gun used in the IS-2, with high muzzle velocity giving good AP performance.

The heavy SUs were organized in independent "regiments", typically of 16-20 vehicles - thus more like the size of a western armor company. These were army level assets, although sometimes they were attached to a mobile corps (tank or mech). They thus wound up used in relatively small numbers tactically, either as reaction reserves on defense or in breakthrough fighting on offense.

All the SUs could be used for indirect fire in a pinch, but the standard use was for direct fire. Against soft targets that could be at relatively long range - a couple of kilometers, even. Because you don't really need direct hits. A whole battery can fire for a few minutes and just plaster the whole area with a large shell barrage. (Even though the fire is direct, that doesn't mean you have to hit with pinpoint accuracy). For AT work, closer would be better.

[JonS]

Originally posted by Michael Emrys:

</font><blockquote>quote:</font><hr />Also, consider that having a firing platform means it takes longer to bring the gun in and out of action. Hardly a desirable trait for a DF gun to have.

But again, that gets us into the tricky question of why then give it to the 2pdr? You would want to be able to get that in and out of battery even faster, I should think, yet with the 2pdr you even have to pull the wheels off! Admittedly, you don't have to do all that just to fire the gun, but apparently that was its preferred deployment.

Then again, it may have been a good idea in both cases, but for completely different reasons, and was omitted in other designs to simplify production...or something.</font>

[Michael Emrys]

I'm happy with that.

Now about those Italians...

Michael

[JonS]

Originally posted by Michael Emrys:

... the tricky question of why then give it to the 2pdr? You would want to be able to get that in and out of battery even faster, I should think, yet with the 2pdr you even have to pull the wheels off! Admittedly, you don't have to do all that just to fire the gun, but apparently that was its preferred deployment. ...

That's possibly why firing it Porté became so popular for a while. Sadly, having it sitting on the back of a truck turned a small, easily concealed target into a thumping great big one that couldn't really hide at all, and was terribly vulnerable. Eventually 8th Army had to order that the 2-pr. NOT be used en-porté.

Regards

JonS