PzIIIH: Layered vs Single Plate Armour - why not in succedding variants?

[Wol]

Why would anyone think that there is some rule of similitude such that because a 2pdr round failed at two 30 mm FH plates (where it might be expected to penetrate 1 60mm Hom plate) other rounds (with no regard for shell geometry, velocity, hardness, cap size etc etc) should perform the same?

can someone indicate where the test results of this experience are to be found. I would like to compare it with other results.

BTW T/D and velocity certainly do affect shatter. even at T/D (indeeed especially) of .75

[Bastables]

Originally posted by Bastables:

[

There were only ever 4 to 5 PIII ausf H in Africa at any one time. The capture of ausf H tac number 1102 on the 14 April was one of the few of these rare panzers that were "killed" by guns from the front. That being said 1102 was only penetrated with a front turret hit (3cm armour) at around 500yds from a 25pdr after proving impervious to 2pdrs and 25pdr hull hits.

[/QB]

I was wrong, only a hand full of ausf H ever saw service with Pz regt 5. Pz regt 8. a "newly created" (or recently transfred unit) unit had 2/3rds of its Panzer III componate as ausf H, around 51 out of 71, the other 20 were 3cm armoured ausf G. Because Pz regt 8. recived factory fresh and ordance depot Pzs (Pz II were the only Panzers with their bolted armour applied at the ordinace depots). all of its PII and PIV componate sported bolted FH plates to the front. Pz regt 8. arrived in time for the Commonwealth attack; Operation brevity in may 1941.

Production of PIII ausf H ended on April '41 with 308 produced (chassis numbers 66001-66650) out of the 759 ordered before the switch to ausf J.

[rexford]

Originally posted by Wol:

Why would anyone think that there is some rule of similitude such that because a 2pdr round failed at two 30 mm FH plates (where it might be expected to penetrate 1 60mm Hom plate) other rounds (with no regard for shell geometry, velocity, hardness, cap size etc etc) should perform the same?

can someone indicate where the test results of this experience are to be found. I would like to compare it with other results.

BTW T/D and velocity certainly do affect shatter. even at T/D (indeeed especially) of .75

Did you read my recent post where I explained all of the guns and ammo that was fired during the British tests in Cairo during 1942.

In the British tests against PzKpfw IIIH front hull, which we have in a U.S. report:

2 pdr AP

broke up and failed at 200 yards

6 pdr AP

clean penetration of driver plate at 600 yards

clean penetration of nose armor at 500 yards

37mm APCBC

3 partial penetrations at 200 yards vs driver plate

1 complete penetration at 300 yards vs driver plate

75mm Grant AP

1 complete penetration at 500 yards vs driver plate

partial penetration at 600 yards with damage to main armor

75mm Grant APCBC

Clean penetration at 1000 yards, little remaining energy after penetration

Firing Test against PzKpfw IIIH side hull

2 pdr AP clean penetration at 1500 yards

[Bastables]

Originally posted by Wol:

Why would anyone think that there is some rule of similitude such that because a 2pdr round failed at two 30 mm FH plates (where it might be expected to penetrate 1 60mm Hom plate) other rounds (with no regard for shell geometry, velocity, hardness, cap size etc etc) should perform the same?

can someone indicate where the test results of this experience are to be found. I would like to compare it with other results.

BTW T/D and velocity certainly do affect shatter. even at T/D (indeeed especially) of .75

Only if the T/D ratio is enough that it allows uncapped rounds such as the 7,62cm, 2pdr and 25pdr to defeat the "boosting" of equivalent thickness that FHing a plate causes (versus uncapped rounds).

[JasonC]

There are many guns tested, Rexford, but the only one that fails is the 2 pdr. Even the 37mm gets in, albeit "partials" at close range and against the driver's plate. The conclusion about effective thickness then depends on marginal guns succeeding and failing, and thus on the failure of the 2 pdr against a thicker, face hardened plate. It is not like they kept shooting at Pz III H fronts out to 1500m (or whatever it is) until the US 75mm failed, and then read out "69mm".

It even says the close range 2 pdr failures were "shell broke up" results. Fits perfectly the 53-57mm effective thickness, plus shatter theory.

[ May 28, 2003, 11:58 AM: Message edited by: JasonC ]

[Little_Black_Devil]

So - is it possible then, that the PzIII Ausf H was equipt with the layered plates on account of battle experience, freshly gained in France?

Considering that the Ausf H began production in October of 1940 (three months after the Battle of France) perhaps its reasonable to surmise that there was not enough time to re-tool factories and what not to produce PzIII's with an original or factory built single plate, 50mm in thickness.

Surely, some time must have been used to compile after action reports, and then derrive the lessons learned. Some of these lessons (like armour thickness) would have then had to have been administratively initialized into reality in the form of changes/upgrades.

If thats the case, it would seem logical that the plates bolted/welded onto the PzIIIH were indeed a stop gap measure.

The PzIII Ausf J, began production in March 1941 - so the Germans must have seen the layered plates, as a stop gap measure and a liability - therefore they were to be replaced by original factory produced armour as thick as 50mm to protect the tanks frontal surfaces.

Considering that "production" of the PzIII H ended in April of 1941, I wonder if other earlier Ausfs, refitted were part of its total production run of 308, or if they were a production, or rather refit run unto themselves?

In any event it would seem that the additional plating put on the PzIIIH was indeed a stop gap measure, to bring the tanks ability to take hits more on par with what they could expect (primarily) on western battlefields.

Perhaps indeed the required time/effort to produce or upgrade PzIII's with the layered plating was excessive - when compared to factory produced PzIII's with thicker armour.

Maintenance, and the possibility of shearing would also seem to make the practice of layered plating a band-aid solution and not a conventional means of providing their tanks with additional armoured protection.

I guess, despite the two face hardened layers, the Germans must have worked out its overall effectiveness to 50mm - otherwise it does seem somewhat contradictory to move from a collective 60mm (or 62mm) of layered armour to a single factory produced 50mm plate.

I guess this must reflect on the differenes between layered faced hardened plates and a single face hardened plate.

It would seem logical that a layered plate, exposing incoming projectiles to two face hardened layers AND and additional 10mm of armour would provide additional protection over that of a single 50mm face hardened plate.

However, in light of some of the things I've seen covered in this thread - it doesn't appear to be quite that "simple".

Perhaps, as has been mentioned here also, it is partially dependant on the penetrating projectile in question.

Food for thought anyways.

[rexford]

In response to Jason's post (see quotes that follow my statements):

Since the firing report against PzKpfw IIIH left out the side angle I believe that they also left out many of the hits that failed to penetrate, and only mentioned the unusual partial penetrations or notable outright failures.

There also was a short discussion of 75mm M72 AP failures at 600 yards, with significant damage to the main armor after the rounds pierced the outer plates. No complete penetrations at that range by 75mm M72 AP.

When 75mm AP failed to completely penetrate at 600 yards it either broke up or ricocheted.

The 75mm APCBC that penetrated did so with little remaining energy, which suggests that the armor resistance was very close to the penetration of the projectile.

Contrary to British info on PzKpfw IIIH, the firing test report indicates that the outer 32mm plate was face-hardened and the interior main armor was homogeneous. This FHA/RHA combo is mentioned in two places, at the beginning of the test results and in the description of 75mm AP damage.

I would guess that visual damage to a homogeneous plate might be different than a face-hardened plate, where the homogeneous plate would show ductile movement of armor while face-hardened armor would show a shatter effect on the surface.

Changing subjects, why would they fire the 75mm APCBC at 1000 yards against PzkPfw IIIH front armor and only fire the 6 pdr AP at 500 yards against the nose armor and 600 yards against the driver plate?

Weren't they curious as to whether the 6 pdr AP would penetrate the driver plate at 600 yards? I find it hard to believe they took the 6 pdr gun to 600 yards, penetrated the driver plate on PzKpfw IIIH, then took the gun to 500 yards, penetrated the nose, and then went on to another tank. Only fired two shots and they were happy with a test which resulted in partial information on the actual maximum penetration ranges?

By the way Jason, I am still waiting to see the reference and exact words regarding combat reports that you had from Africa where 25 pdr guns penetrated the front armor on PzKpfw IIIH's at 1000m. I don't believe that the report from DAK that you referred to specifically mentioned PzKpfw IIIH. Can you prove me wrong?

Originally posted by JasonC:

There are many guns tested, Rexford, but the only one that fails is the 2 pdr. Even the 37mm gets in, albeit "partials" at close range and against the driver's plate. The conclusion about effective thickness then depends on marginal guns succeeding and failing, and thus on the failure of the 2 pdr against a thicker, face hardened plate. It is not like they kept shooting at Pz III H fronts out to 1500m (or whatever it is) until the US 75mm failed, and then read out "69mm".

It even says the close range 2 pdr failures were "shell broke up" results. Fits perfectly the 53-57mm effective thickness, plus shatter theory.

Bulloney. Projectiles generally fail against face-hardened armor by breaking up unless they stick in the armor.

[ June 01, 2003, 03:54 AM: Message edited by: rexford ]

[Bastables]

Originally posted by Little_Black_Devil:

So - is it possible then, that the PzIII Ausf H was equipt with the layered plates on account of battle experience, freshly gained in France?

Not quite, I've spoken about it before but...

The Pz III ausf H was initially to be the first Pz III with the 5cm KwK gun. Reports from Poland noted that the 3cm armour basis of Pz IIIs was insufficient (relative to 3,7cm antitank guns), a program was instituted to double the front armour. Bolted plates increased the weight and changed the centre of mass to the extent that the ausf H required a new reworked strengthed suspension and wider tracks.

Reports from france on the ineffectiveness of the 3,7cm versus Somu tanks forced a Wa Pruf crash program to fit the 5cm KwK to the ausf G and F. Wa Pruf achieved the fitting of the 5cm KwK through the expedient of cutting the mantel and front turret face off and replacing it with one already designed for the ausf H.

Bolting 3cm plates to the ausf F and G could only be carried out during factory rebuilds since it required a new suspension, it was apparently quite a difficult procedure as only 1/3 of Pz III rebuilds left the assembly areas as ausf H the other 2/3rds returning to combat units with 3cm armour basis.

[ June 01, 2003, 05:18 AM: Message edited by: Bastables ]

[Bastables]

Originally posted by Little_Black_Devil:

The PzIII Ausf J, began production in March 1941 - so the Germans must have seen the layered plates, as a stop gap measure and a liability - therefore they were to be replaced by original factory produced armour as thick as 50mm to protect the tanks frontal surfaces.

Considering that "production" of the PzIII H ended in April of 1941, I wonder if other earlier Ausfs, refitted were part of its total production run of 308, or if they were a production, or rather refit run unto themselves?

otherwise it does seem somewhat contradictory to move from a collective 60mm (or 62mm) of layered armour to a single factory produced 50mm plate.

Not really, the most expedient method of up armouring the Pz IIIs front hull armour is just using the 3cm FH plates already manfactured and in stock.

Moving down to 5cm armour on the subsequent J model had more to do with an earlier decision to settle on 5cm after meeting British AP weapons in Africa 1941, therefore the steel mills had not manufactured any stocks of 6cm armour by 41/42. Plus it was cheaper; remember this is the same bureaucracy that went for the 5cm L/42 KwK as opposed to mounting the more powerful 5cm L/60 KwK prior to 1941 because of costs and manufacturing bottlenecks.

[rexford]

As mentioned in the highly edited version of my last post, the PzKpfw IIIH which was fired upon by the British had a 32mm face-hardened plate bolted onto 30mm homogeneous, according to the report.

Other British information on PzKpfw III armor type indicates that the main armor on PzKpfw IIIF and IIIG was face-hardened, and PzKpfw IIIH used two face-hardened plates in a layered combo.

Some material I recently read indicated that the PzKpfw IIIH was a stop gap answer to the need for improved armor on the PzKpfw III hull front, and was not going to be the ultimate response. A single 50mm plate was envisioned but it took time to convert production and it was easier, at first, to add 32mm atop production vehicles.

Given the problems involved in building tanks with 32mm/30mm front and rear hull armor, and in converting PzKpfw IIIG (only 1/3 could be successfully converted), 50mm plates might have been simpler from a production and maintenance standpoint.

If the British firing tests were conducted at 30 degrees side angle, than adding 20mm to the 30mm main armor would have provided less than 50mm resistance. 30mm may have been chosen on the basis of who knows what criteria.

Using a 30 degree side angle results in about 57mm effective face-hardened resistance for the 32mm/30mm combo on PzKpfw IIIH front.

============================================

British 2 pdr guns would have been recovered in France, as well as tanks with that weapon. 2 pdr AP penetrates a 57mm face-hardened plate at 250m on half the hits without a side angle, which might have been satisfactory to the panzer planners.

Against a 50mm face-hardened plate angled at 10 degrees from vertical (PzKpfw IIIJ driver plate), 2 pdr AP penetration range for 50% success is limited to 500m.

From a German perspective, the loss in effective resistance which changed the vulnerability from 250m to 500m penetration range against 2 pdr AP may have been acceptable (32mm/30mm to single 50mm), due to the many advantages it bestowed.

[JasonC]

Rexford, reported 75mm failures certainly strengthen the case for a higher figure for the layered plate. It is however surprising in itself, particularly if there is supposed to be no side angle. At 500m CMBB gives the Sherman 83mm of penetration flat, and 75mm at 1000m. Which should be enough against either figure for the III H.

The German reports I've read about meeting Grants in North Africa give the effective range of the US 75 as much farther than 600m. I've seen statements they were effective beyond 1000m even with highly angled hits, and others that the Grants were appreciated because they outranged DAK Panzers. Indeed, I'd expect 500-600m failures with the US 75 against IV Hs, not III Hs, if the side angle is suppose to be zero.

For a citation, I have to refer you to Rune. It is his book (by the German DAK chief of staff, so he knows which one), I saw it at his place during one of the Chicago get togethers. No, I don't think it specifies Pz III H, but it is talking about the Gazala period fighting (May 1942), when I believe the DAK fleet mix was short IVs (I think mostly Es), a few III Js with long 50s, and the bulk III Hs with short 50s.

[rexford]

Originally posted by JasonC:

Rexford, reported 75mm failures certainly strengthen the case for a higher figure for the layered plate. It is however surprising in itself, particularly if there is supposed to be no side angle. At 500m CMBB gives the Sherman 83mm of penetration flat, and 75mm at 1000m. Which should be enough against either figure for the III H.

The German reports I've read about meeting Grants in North Africa give the effective range of the US 75 as much farther than 600m. I've seen statements they were effective beyond 1000m even with highly angled hits, and others that the Grants were appreciated because they outranged DAK Panzers. Indeed, I'd expect 500-600m failures with the US 75 against IV Hs, not III Hs, if the side angle is suppose to be zero.

For a citation, I have to refer you to Rune. It is his book (by the German DAK chief of staff, so he knows which one), I saw it at his place during one of the Chicago get togethers. No, I don't think it specifies Pz III H, but it is talking about the Gazala period fighting (May 1942), when I believe the DAK fleet mix was short IVs (I think mostly Es), a few III Js with long 50s, and the bulk III Hs with short 50s.

The CMBB figures for 75mm M72 AP are not face-hardened penetration data, which is what we are interested in, and the Grant gun fired at a much lower velocity than the Sherman.

If a Sherman gun penetrates 83mm at 500m and 75mm at 1000m, that is the homogeneous armor penetration for 2030 fps/619 m/s muzzle velocity and APCBC ammo.

The British firing test results published by the Americans show 75mm M72 AP failing on several hits at 600 yards against the front armor on PzKpfw IIIH, and then that ammo obtains a complete penetration of the driver plate at 500 yards. The 500 yard penetration is "not clean".

My penetration calculations for the Grant 75mm AP have 67mm of vertical face-hardened armor at 500m.

[ June 01, 2003, 08:16 PM: Message edited by: rexford ]

[rexford]

How many of the PzKpfw III used by the DAK during the Gazala battle were IIIG and how many were IIIH?

Avalon Hill's TOBRUK game had all PzKpfw III as Ausf H models, which seems wildly optimistic.

I don't have the data anymore, but it would also be interesting to see how many AP and how many APCBC rounds were carried by the Grant in those initial combats.

[Bastables]

Originally posted by JasonC:

(May 1942), when I believe the DAK fleet mix was short IVs (I think mostly Es), a few III Js with long 50s, and the bulk III Hs with short 50s.

Really? From Dec '41 all PzIII replacements were ausf J. Remember ausf H production had ended in april 1941.

Beginning in July-august '42 the ausf L ( 5cm+2cm) were received by DAK (76 ausf L).

How can ausf H been the major subtype in use with DAK in Gaza 42 when all replacments were ausf J with 5cm armour? How can the ausf H have been the major subtype in 42 when only 71 ausf H were ever issued to DAK in 41? No ausf H were issued in 42. By Jan 42, 71 ausf J were in Africa, doubling the numbers in the two Pz regts. With these sort of figuers your attempts to paint the ausf H as the main, never mind half of Panzer III subtype in Africa is problomatic to say the least. (1996 Jentz).

Stop pulling "numbers" and unsupported personal beliefs out of your hat to support your arguments. You've been doing this since the infamous Sherman firefly thread.

[ June 02, 2003, 12:42 AM: Message edited by: Bastables ]

[rexford]

Originally posted by Bastables:

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

(May 1942), when I believe the DAK fleet mix was short IVs (I think mostly Es), a few III Js with long 50s, and the bulk III Hs with short 50s.

Really? From Dec '41 all PzIII replacements were ausf J. Remember ausf H production had ended in april 1941.

Beginning in July-august '42 the ausf L ( 5cm+2cm) were received by DAK (76 ausf L).

How can ausf H been the major subtype in use with DAK in Gaza 42 when all replacments were ausf J with 5cm armour? How can the ausf H have been the major subtype in 42 when only 71 ausf H were ever issued to DAK in 41? No ausf H were issued in 42. By Jan 42, 71 ausf J were in Africa, doubling the numbers in the two Pz regts. With these sort of figuers your attempts to paint the ausf H as the main, never mind half of Panzer III subtype in Africa is problomatic to say the least. (1996 Jentz).

Stop pulling "numbers" and unsupported personal beliefs out of your hat to support your arguments. You've been doing this since the infamous Sherman firefly thread. </font>

[Michael Emrys]

Originally posted by rexford:

Avalon Hill's TOBRUK game had all PzKpfw III as Ausf H models, which seems wildly optimistic.

Possibly done to simplify the counter mix.

It also had a smattering of Js. ISTR that the PzKpfw IVs were all Ausf Ds in that game. Perhaps also to simplify the counter mix.

Michael

[Bastables]

Originally posted by rexford:

T Do you have any figures on DAK breakdown of PzKpfw III Ausf G models during May 1942?

If 300 or so PzKpfw IIIH were built and about 70 were sent to DAK, the rest went where? Russia? France?

As an aside, how many PzKpfw IIIG, IIIH and IIIJ started Barbarossa? Russian reports indicate that 45mm anti-tank guns failed beyond 500m against PzKpfw III, and seeing the split might help put that statement in perspective.

Thanks for putting things right. [/QB]

That is a bit harder, nay impossible for me to quantify. DAK when first shipped over had 71 ausf G, most concentrated in Pz regt 5. The problem is I don?t know if the mini replacement shipments during 1941 (5 to 10 tanks shipped over on 3-4 separate occasions) contained ausf G or J (Or were even PzIIIs at all). I do know the first major ausf J shipment occurred in dec 1941 with an entire kompanie worth of them (17) were delivered on the build up to the Gaza counter attacks.

I?d suggest getting in contact with Jentz he seems to have a great deal of info on the tanks in north africa for both sides, he mentions that north africa has the largest amount of surviving records referring to tank combat, deployment etc.

Unfortunatly for Barbarossa I just don't have the figures for PzIII sub type make up.

[JasonC]

Hs is what I thought. I'm not the only one. But it may be an oversimplification of a more complicated picture.

Samuel Mitcham in "Rommel's Greatest Victory", pp. 43-44, gives the type mix before Gazala as Pz IIs, III Hs, III Js with long 50, IV Es, and a few IV F2s. Only 19 of the long 50s and 4 of the long 75s. "The Panzer III H was Rommel's workhorse; he had 220 of them. Wt 23 tons, short 50mm gun, 62mm max armor." But that is far too many to all be factory built Hs.

I suspect he was using the H as representative of all the short 50 IIIs. Short and long Js, both, might have confused him. But a more basic reason may simply be that "H" is being used not as a designation of a factory model, but of an armor and gun combo, however it was arrived at. If an original G had bolted armor added, it is "effectively" an H.

There wasn't a period when the British 2 pdr was effective, followed by one where it became ineffective - as you might expect with plain Gs, not uparmored, for 1941. There are reports of the 2 pdr being ineffective in the very first engagement by Panzer Regiment 5 early in 1941, that it "could do the Pz III hardly any damage", from the front anyway.

Greene Massignani in "Rommel's North Africa Campaigns" states positively that the III Gs and IV Ds were uparmored. In his table of tank specs on page 238, a caption reads "IIIG and IV D were given improved armor as soon as they arrived and later ones shipped over had already been uparmored by 30-35mm".

In his main text, pp 48-49, he says "The Panzer IIIs had been uparmored since the fighting in France, and most of the initial arrivals received 30mm face hardened plates to protect the vunerable points", also "The Panzer IVs were also being uparmored". After describing the arrival of the initial tanks from Panzer Regiment 5 and 8, he writes "After the first arrival from Europe, all later tanks came with the improved armor plating already attached."

In his discussion of the Crusader battle, he says on pp. 95-96 that the Brits "had no idea of the number of German tanks which had extra armor added to their hulls, though it was essentially all the Pz IIIs and IVs, and they did not know it was face hardened - which meant that the 2 pdr could only penetrate at short range."

He gives as effective ranges of the Grant's 75mm a figure of 700 yards, and for the 25 pdr with AP 600 yards. These are lower than the figures the DAK staff book gives. There are in action reports from the Gazala period that have 25 pdrs killing Panzers at 800 yards, and the DAK staff guy says 1000m was the "safety" distance they tried to stay beyond because of the 25 pdr threat.

Then there is the fact that the "Tp" designation, for tropical, is commonly given for the "G" series. The very first tanks sent do not seem to have had the desert filters and radiators that "Tp" designation signifies, however. Suggesting there were factory built Gs meant to DAK after the first tanks. Of course, being factory built as Gs does not mean they shipped from Italy as Gs - uparmoring could have been done before loading.

I looked at the some brief German unit histories of Panzer Regiment 5 and 8 to see about Panzer III shipment dates. The basic picture is 140 IIIs sent in the initial wave, Pz Rgt 5 in March and Pz Rgt 8 in May of 1941. Then after Battleaxe but before Crusader - thus late summer to early fall 1941 - roughly 75 additional IIIs seem to arrive.

In early December there are only about 35 runnings IIIs left in the theater after the post Crusader retreat to El Algheila. But at least 2 shipments of IIIs arrive to rebuild in late December, allowing the first counterblows. Some reports put that at 53 Pz IIIs, others at 42 or 45 - the difference may be the number of long 50 Js. These replacements mostly go to Pz Rgt 8. There are additional replacement received in January, which mostly go to Pz Rgt 5. All told, December and January about 75 Pz IIIs are added.

Then comes the big build up before Gazala, in the spring. This one is around 150 Pz IIIs. Some of that may be repairs and recoveries, though, because it is not based on shipments but on changes in running strength.

Summarizing - 140 initial, 75 late summer, 75 turn of the year, 150 spring of 1942.

What types? The initials were Gs, most agree. Some state they were uparmored in the field as soon as they reached the theater. The ~70 figure for true factory built Hs would fit the late summer wave, or the turn of the year wave. If the latter, then the late summer wave could be G Tps. If the former, the only spot for G Tps is Panzer Regiment 8's initial shipment (a little over half the "initial" above, by May of 1941).

It is unlikely from the calendar and number arriving, though, that the spring 1942 IIIs are factory built Hs, or old Gs still being uparmored. It is more likely they'd be factory built short Js. This conclusion is slightly complicated by the fact that repaired and recovered IIIs may form part of the spring build up total. Those would presumably be uparmored Gs or Hs still.

Then the Gazala era fleet would be mixed short J and "H equivalents", perhaps half Hs or uparmored Gs equivalent to Hs - plus or minus a sixth, because of uncertainty about recoveries in the spring 1942 total.

People calling all of them Hs would be collapsing the modified G and true H into the "H" designation. And then using the same term for short Js to avoid confusing them with long Js - or perhaps be unaware that short Js are running around to start with, and just assume since the longs are Js, the shorts are pre-J.

How does this square with the tactical range data? It would fit if the 1000m range the DAK staff guy gives were correct for the 50mm armor on the short III Js, while the 600m range Massignani gives were correct for the 30+32 on the Hs and uparmored Gs. That does imply lower penetration numbers for the 25 pdr than CMBO gives (it has 61mm at 30 degrees at 1000m).

I don't see evidence of Gs without added armor in the early engagements. The tactics are right for uparmored Gs from the get-go. By Gazala, short Js are probably more common that surviving Hs or uparmored Gs. Either remains effective vs. the 2 pdr or US 37mm at typical desert ranges. The Brits consistently think of 500 yards as "2 pdr range", while sometimes being disappointed with 2 pdr performance even when they get that close. Mid 1941, late 1941, mid 1942 - they think the same thing.

I hope this interests some...

[ June 03, 2003, 02:58 AM: Message edited by: JasonC ]

[Bastables]

Snip rambling fabrications

Originally posted by JasonC:

I don't see evidence of Gs without added armor in the early engagements. The tactics are right for uparmored Gs from the get-go. By Gazala, short Js are probably more common that surviving Hs or uparmored Gs. Either remains effective vs. the 2 pdr or US 37mm at typical desert ranges. The Brits consistently think of 500 yards as "2 pdr range", while sometimes being disappointed with 2 pdr performance even when they get that close. Mid 1941, late 1941, mid 1942 - they think the same thing.

I hope this interests some...

No Jason the G were not up armoured with 3cm plates by DAK engineers or any unit engineers, up armouring was a strictly a "factory" rebuilding concern especially with plates of such thickness. The factories had problems and slow ups in up armouring Gs and Fs to H standard, yet units can just casually up armour them off the cuff? If it was so easy why bother with factory upgrading, and why is there no waffenamt orders to carry out such upgrading? I?ll tell you why this upgrading never took place.

All DAK rear area troops and crewmen did do was festoon tracks and road wheels on the ausf G, additions that where glaringly absent on the 71 ausf H that DAK ever received.

But well without surreal reading of sources and information pulled out of his hat it would not be a Jason argument eh?

Again more unsupported statements in telling the Jason "story."

[rexford]

Jason posted "He gives as effective ranges of the Grant's 75mm a figure of 700 yards, and for the 25 pdr with AP 600 yards. These are lower than the figures the DAK staff book gives. There are in action reports from the Gazala period that have 25 pdrs killing Panzers at 800 yards, and the DAK staff guy says 1000m was the "safety" distance they tried to stay beyond because of the 25 pdr threat."

The above penetration ranges SUPPORT the conclusion that 32mm/30mm layered armor resists like a single 69mm thick face-hardened plate. ;o)

Grant 75mm AP penetrates about 63mm face-hardened at 700 yards, which would allow occasional defeats of 69mm face-hardened at 10 degrees from vertical.

25 pdr AP penetrates about 72mm face-hardened at 600 yards, and 68mm face-hardened at 800 yards. So 25 pdr AP would consistently defeat 69mm FHA/10 degrees at 600 yards and occasionally pierce at 800 yards.

1000m penetration of 25 pdr AP is 60mm face-hardened, which would usually be defeated by 69mm FHA at 10 degrees.

If 32mm/30mm face-hardened on PzKpfw IIIH resists like a single 69mm face-hardened plate, that would allow some 800 yard penetrations by 25 pdr AP and result in failures at 1000m after armor slope is worked in.

*************************************************

*************************************************

So the penetration ranges Jason just supplied for Grant 75mm and 25 pdr AP rounds support 32mm/30mm layered armor resisting like a single 69mm face-hardened plate. *************************************************

*************************************************

Against 50mm at 10 degrees face-hardened on Ausf J, Grant 75mm AP would penetrate on half the hits at 1100m and 25 pdr AP at 1200m.

Jason, please keep in mind that CMBO and CMBB present homogeneous armor penetration stats, and CMBO includes the 1944 25 pdr which fired at a higher velocity than the 1941-42 25 pdr.

[JasonC]

Bastables - tell it to Massignani. A factory rebuild would certainly be needed for the *suspension*, to get full mobility despite the extra weight. You are the first person I know who thinks it was hard to bolt on the plates themselves. Since they were sometimes sheered off by hits, I find it hard to credit. Do you think 2 pdrs are failing at 500 yards in the first half of 1941 against 30mm armor on unimproved Gs?

[JasonC]

Rexford, are those 25 pdr and Grant figures at 30 degrees? Tactical range calculations essentially have to be, because side angle of zero just doesn't happen on the battlefield. That gives just a tiny pencil at the end of a lobe shape, not an area most shooters will be in.

What ranges do you get for 57mm face hardened at 30 degrees of side angle? If I use a slope factor of 1.28 for 30 degrees then your 69mm RHA figure flat equals 54mm at 30. If I use a lower 1.2 I get 57.5mm. Either of them consistent with 30+30 resisting at less then full thickness as everyone else's layered analysis says.

I'd also be interested in the progression of 25 pdr AP muzzle velocities, if those changed between 1942 and 1944. The DAK staff guy is saying 1000m in 1942. The two different ranges quoted in 1942 sound to me like 2 different armor plates, not a muzzle velocity discrepancy.

But if all you mean is the CMBO figure is high because it is a better round by then, that is believable. What is the muzzle velocity difference? I've seen numbers spread over a pretty wide range for 25 pdr MV, but thought it was because some were for HE and some specifically AP.

50mm vs. 57.5mm is a 15% difference, consistent with the typical penetration drop of ~20% one sees for 500m vs. 1000m. 67mm or 69mm vs. 50mm, on the other hand, is a 34-38% difference, which I'd expect to give a larger range discrepency than 400 yards.

[ June 03, 2003, 11:37 AM: Message edited by: JasonC ]

[JasonC]

Speaking of carries and angles, incidentally, am I the only one who sees something a little strange in the 50L60 CMBB penetration chart, at the 1000m and 30 degree plain AP position? It gives 57, when the 500m figure is already 61. That means only a 7% drop over a doubled range. Similarly, the reduction for 30 degree slope seems way off. Interpolating from the rest of the chart, I'd expect a figure more like 48mm in that position - more like 50mm anyway. The 57mm figure is also suspiciously identical to the tungsten ammo figure for the same range and angle.

[rexford]

Jason C posted : " Rexford, are those 25 pdr and Grant figures at 30 degrees? Tactical range calculations essentially have to be, because side angle of zero just doesn't happen on the battlefield. That gives just a tiny pencil at the end of a lobe shape, not an area most shooters will be in."

Jason, your statement is speculation and incorrect when it is compared to the facts and some simple calculations. You always seem to squirm out of unpleasant conclusions by twisting around the ground rules.

British studies of impact angle on tanks showed that hits without side angle made up the single highest probability of any one angle, and if one is giving the safe range for frontal hits it would probably be based on zero side angle from firer to hull facing. Here's why.

A 10 degree angle from PzKpfw IIIH hull facing to a 2 pdr firing on the panzer introduces a 3% increase in effective armor resistance, which is nothing major and is not going to terribly influence the penetration range. A 2 pdr AP shot loses 3% of its penetration every 35m, a 25 pdr AP round loses 3% every 75m, at 500m range to 750m range.

So within a 0 to 10 degree arc from firer to hull facing, which is about one-third of the 0 to 30 degree arc, the armor resistance and penetration range is about the same as a shot with zero side angle. 33% of the hits within the 0-30 degree arc is a major portion, and that is a low estimate for 0-10 degrees since the hits are more heavily weighted towards lower angles.

The maximum quoted penetration range for battlefield combat would probably be based on zero side angle or close to it.

I have read MANY books where panzers in the desert moved directly towards 2 pdr guns, GUNS AGAINST TANKS is one such book that comes to mind.

Your range examples support the 69mm single plate equivalent resistance of 32mm/30mm. You just don't want to admit it.

==================================================

Early war 25 pdr AP was fired at 1550 feet per second, later war rounds at 1897 fps. 1942 battles probably used 1550 muzzle velocity.

When I use the early war 25 pdr AP muzzle velocity I am minimizing the penetration resistance of the the face-hardened PzKpfw IIIH hull front.

=================================================

I think the British use of a 30 degree side angle during their firing tests is not to estimate the typical penetration range, but to see how effective the gun is under very demanding conditions.

If the Sherman 75mm APCBC never hit the Tiger 82mm side armor at less than a 30 degree angle, no penetrations would be obtained, EVER!

Same for T34 hits on Tiger side armor.

Lorrin

[ June 03, 2003, 11:30 PM: Message edited by: rexford ]

[rexford]

The initial action of Tigers in Africa where 6 pdr ATG knocked em out includes impact angle data. The impacts on the side armor ranged from 15 degrees (measured from armor perpendicular) to 45 degrees.

The slope multiplier for 15 degrees impact angle is much closer to 0 degrees than 30 degrees.

The Americans, during the summer of 1944, conducted their penetration range tests against Panther tanks at 0 degree side angle, where the firing gun was lined up with the hull armor facing.

Combat reports for HVAP use against Panther front hulls suggest that there was little or no side angle from firer to glacis plate on many hits.

[ June 04, 2003, 07:10 AM: Message edited by: rexford ]