German vs. British tanks during Crusader

[ClintHardware]

There are several elements so far missing from this topic. The following are just tasters because they each need a page or more of explanation.

1) Shatter due to internal stresses on impact - especially occured with 2-Pdr A.P. Shot at various velocities and angles of impact. Shatter did not necessarily follow with a failure to penetrate. And also partial penetrations upto 90% of armour depth could induce spalling from the inner plate surface causing crew wounds/fatalities.

2) Jump
Brigadier George Davy, who took command of the 7th Armoured Brigade in September 1941, discovered that the 2-Pdr guns in the tanks of his three armoured regiments (7th Hussars, 2nd and 6th Royal Tank Regiments) all had telescopic sights that had not been corrected during manufacture to provide an allowance for ‘Jump’. The phenomenon of Jump occurs where a gun barrel mounted below its recoil mechanism tends to fire low. Brigadier Davy was had been a Royal Artillery officer and he used his knowledge to test the extent of the problem after becoming aware of various complaints of shot firing short. He discovered that the sights supplied for every tank mounted 2-Pdr were causing shot to land 11 minutes below the point of aim so that if the point of aim was in the middle of a tank at 500 yards the point of impact would be with the ground at 300 yards. The tank crews were compensating for this by using the first round to judge range and adjusting accordingly, or aiming high, but until this error was eliminated with new sights, it gave the panzers an initial advantage in a fire-fight.

3) Elevation and range
Whereas the gun sight of the 7.5 cm Kw.K. 37 L/24 of the Panzer IV was graduated to 1200 metres for panzergranaten (APHE), and 2000 metres for Sprenggranaten (H.E.) and Hohlraum (H.E.A.T.) and that of the Panzer III was graduated to 1500 metres for panzergranaten and 3000 metres for Sprenggranaten. The 2-Pdrs were graduated to 1800 yards (1645 metres) in 100 yard increments for A.P. Shot. The Light Tank’s .5-inch machine gun was similarly graduated out to 1500 yards for AP W rounds.

The respective -15 degree and -20 degree elevations of the 2-Pdr mountings in the A13 and Matilda would have given both an edge over the Panzer III and IV in laying onto targets from higher ground whilst being able to expose less of their armour to return fire, although such opportunities may have been rare.

4) Residual kinetic energy at the point of impact and after penetration.
The Panzer III and IV crews were at a distinct advantage in respect of residual kinetic energy and therefore potential penetration of their armour piercing rounds at all combat ranges. These figures are indicatively only and use velocities at the muzzle.
................................................Joules...........Foot lb
2-Pdr (40 mm)...........A.P. Shot........ 338317.........250859
5 cm Kw.K 38 L/42.....Pzgr & Pzgr 39...482954.........358275
7.5 cm Kw.K 37 L/24...K. Gr. Rot Pz....503965.........373942

In respect of quality of armour plate the British and German pre-war qualities were very close in quality. The edge given in using Face Hardened instead of Homogenous Hard was not always present under certain conditions of impact.

5) Overmatch (Calibre greater than Depth of armour struck). The 7.5 cm projectile had the advantage of overmatching the A10, A13 and A15 front plates. The 87.6 mm 25-Pdr and the 8.8 cm Flak 18 or 36 overmatched everything.

[Urmel]

4) Residual kinetic energy at the point of impact and after penetration.
The Panzer III and IV crews were at a distinct advantage in respect of the penetration of their armour piercing rounds at all combat ranges. These figures are indicatively only and use velocities at the muzzle.
................................................Joules...........Foot lb
2-Pdr (40 mm)...........A.P. Shot........ 338317.........250859
5 cm Kw.K 38 L/42.....Pzgr & Pzgr 39...482954.........358275
7.5 cm Kw.K 37 L/24...K. Gr. Rot Pz....503965.........373942

You are comparing apples and oranges here. The 75mm round is the Tungsten variety in your list, it would be very unusual for it not to be far superior in energy. Furthermore, when measured at the muzzle you are giving it another advantage, given that it was a low-velocity gun. Compared to the 5cm Kw.K. 38 it had a penetration of 43% (PzGr.40) at 100m and 70% at 500m. You needed to go beyond 1,000m before the additional energy made itself felt in better penetration, but that far out the lower MV would lead to added problems actually hitting. So in short you'd probably be better off with either of the high-velocity guns.

[ClintHardware]

Well I was not looking at penetration in detail with the figures but was interested in stored energy. The figures are only starting figures at the muzzle and to some extent the proportional differences would widen as range increased because the heavier projectiles would retain more energy over longer ranges than lighter projectiles. So crews firing the 5 cm and 7.5 cm projectiles were already with a advantage even before impact.

The 5 cm Kw.K 38 L/42.....Pzgr & Pzgr 39 carries roughly about 47% more energy than the 2-Pdr A.P. Shot measured at the muzzle.

I believe the following might be a battlefield eye witness account of 2-Pdr A.P. Shot shattering on the targets induced by angle of impact and strike velocity:

Lieutenant Llewellen-Palmer 7th Queen’s Own Hussars
“The enemy came on slightly across us...we halted at 900 yards and opened fire. My gunner Sgt Carpenter fired two rounds slap into the side of the first one, then two, and into a total of sixteen tanks. It did them little harm - our shells too light.” (31)

Both the 5 cm and 7.5 cm projectiles would have shattered at some point under the right conditions but those conditions may never have been encountered on the battlefield. I have never seen any indication of German or Italian rounds shattering.

[Urmel]

I doubt that the quote is about shatter. Against the sides the 2-pdr should not shatter, only against the front. This sounds more like they actually missed each time. Maybe the maladjusted sights?

My point on the stored energy was that you were looking at a Tungsten round in the 7,5cm against normal rounds in the 5cm and 2-pdr guns.

[ClintHardware]

You may well be right. BUT what surprises me is: 1) that he saw no pyrophoric effect or tracer indicating Shots ricocheting away on any of the 16 panzers struck, and 2) there were rare incidents of panzers seemingly disabled at up to 2000 yards with very lucky impacts of 2-Pdr A.P. Shot and therefore at 900 yards side armour should have been penetrated at least to a point of spalling from the internal face or some penetration. I think I have two eye witness reports in my book of 2000 yard knockouts (IIRC) BUT I do not have great faith that any thing more than some repairable damage was achieved at the target with the residual kinetic energy available.

Here is some stuff on shatter and what they were thinking in May 1942 (the APCBC 2-Pdr projectile arrived in the field in September 1942):

On the 26th May 1942 the Metallurgy Committee of the Ministry of Supply met to discuss the issue of the 2-pdr AP Shot shattering on enemy armour. The Minutes of the meeting was to be shared with the Controller of Chemical Research.

Quote
Minutes of the Metallurgy Committee 26th May 1942
The behaviour of 2 pdr. shot when fired at increasing velocities against thick plate is indicated in the accompanying diagram. It will be noted that at a velocity of about 2600 ft./sec. the shot no longer makes a clean hole but breaks up into small fragments leaving a dent only on the plate. At still higher velocities perforation occurs but the hole is quite different in appearance from normal hole. There is a range of about 200 ft./sec. In which perforation is not achieved.

It is desirable to lift the minimum shatter velocity now round about 2600 ft./sec. on homogenous armour to at least a value exceeding that of the muzzle velocity of the gun, viz, 2850 ft./sec.

Various ways have of achieving this object have been considered by the A. P .P. Sub Committee at the Board’s request and one suggestion made is that improvement would be obtained if a stronger and/or tougher steel were available for use in A. P. Shot manufacture.

Arising out of this suggestion arrangement have been made to test shot manufactured from 4¼% nickel-chromium steel and a 5% nickel steel, both having high carbon content. It is realised that highly alloyed steels of this type may not be forthcoming even if successful in view of the supply position, but the information obtained will help in the further study of the problem. (WO 195/2122)
End Quote

The minute noted that the effect of compression on 2 and 25-pdr projectiles was to be tested and then stated the following.

Quote
At the present time the 2 pdr. shot is the only shot where shatter in good shot gives rise to a tactual disadvantage, and even in this case the effect only appears at short ranges. In view of the fact that an improvement over present performance may be expected from modification of the shape of the head, it is clear that even with present materials, shatter against homogenous armour with present muzzle velocities is not likely to give rise to a serious tactical disadvantage. On the other hand, as there is a tendency to increase muzzle velocities further improvements in A. P. shot compositions should be sought. (WO 195/2122)
End Quote

[Don Juan]

Interesting Soviet evaluation of the 2 pdr here:

http://tankarchives.blogspot.co.uk/2013 ... tanks.html

The Russians conclude that the main weakness of the gun was the poor quality of the ammunition.

My suspicion is that there were quality issues with 2 pdr ammo that were manufacturing-related rather than design-related i.e. how good your 2 pdr shell was depended on who was making it. Proving that will not be an easy job to say the least....

[sitalkes]

One difference that rarely gets mentioned is the number of crew per tank. The Pz III and Pz IV had three men in the turret and five men in the tank. This meant that it was easier and quicker to find a target and lay a gun on it, then load and fire it, as well as to move the vehicle around and co-ordinate its movements with other vehicles. That ties in with the doctrine difference intimately. Many of the British tanks had four man crews and two man turrets.

[ClintHardware]

The Russian data is very interesting but would be more useful if it included Hardness data and information on the type of armour struck: Face Hardened etc. Did Britain send the least reliable ammunition to Russia? They were testing samples and the Hadfield process had been distributed to a group of manufacturers and quality checking was undertaken - but there may have been variations between manufacturers.

In his book Armoured Odyssey Stuart Hamilton describes reversing his Valentine towards the enemy to make use of his rear armour and the engine block for defence whilst the driver sat ready to drive the tank out of danger when given the order. Hamilton held three or more rounds in his left arm and loaded the 2-Pdr rapidly to pepper the Panzer IIIs and IVs coming at him. The 2-Pdr could be fired at 22 rounds per minute under test conditions and he saw the morale and doubt inducing effect of rapid hits on a panzer on several occasions. This proves nothing except that short and light rounds could be fired rapidly from a British two man turret if the crew wanted to do so and it is the sort of tactic that would have been mulled over by the officers most nights to get the best they could out of their Troops and kit.

IIRC the Valentine and Matilda had 2 turret crew but the A9, A10, A13 and Crusader had 3?

5th Crew member was definitely a bonus as you have described and could replace a wounded colleague to keep the tank in action.

[Don Juan]

A9, A10, A13, Crusader, Matilda and Valentine Mks.III and IV all had 3-man turrets.

Whether they had 4 or 5 man crews was down to having a hull machine-gun or not. A9 had a 6-man crew, A10 and Crusader Mk.I a 5-man crew, and the others a 4-man crew.

Valentine Mks.I & II, and 6-pounder equipped Crusaders (Mk.III) and Valentines (Mk.IX and X) had 2-man turrets. These all had 3-man crews.

[Dili]

Pz IV with 75mm short gun was more of a Stug with a turret = infantry support , than a tank. Hitting a tank with that gun over 500m would be difficult.

[phylo_roadking]

Well...its AP round could penetrate 43 millimetres (1.69 in) of armour, inclined at 30 degrees, at ranges of up to 700 metres...

But actually hitting the target was as much down to the sight and the gunner as it was the gun

5th Crew member was definitely a bonus as you have described and could replace a wounded colleague to keep the tank in action.

Clint....given that in the A9 and I think the early Crusader with the front MG turret, the gunner had to get out by his own hatch into the open to get into the main turret, or vice versa, I'm not sure this idea is as practical as you think!

Also - most British designs didn't have room to tuck a casualty away somewhere The space inside a Churchill was luxury for tankers; in most, the "fighting comparment" - the hull - was actually occupied by ammo racks, bits of various mechanisms, stowed kit etc....and the turret basket poking down below the top of the hull nearly to the floor.

[sitalkes]

I think the hull gunner was also the radio operator

[ClintHardware]

Well having a 5th crew member who could cover another role was useful however they might manage to move into the required position. Carrying or removing a wounded/dead crew member was another issue. Loader/Wireless Op was the common role and took place in the turret of most British tank designs with some exceptions.

The German bow machine gunner/radio op must have caused that role to need covering at all times leaving less choice to cover another crew member role. Perhaps the British crew roles were more flexible.

In terms of rapid fire (I love finding this stuff) there was an incident of a loader/wireless operator in the 5th RTR in a Cromwell in Normandy 1944 - who on encountering a Tiger at short range managed to load so rapidly that a crew member from another tank later described his Cromwell's 75 as behaving like a Bofors. Again - this proves nothing but it is interesting. The Tiger did not fire back but no one who saw the action could confirm it to be knocked out. I think the Loader/Wireless Op was Norman Smith and this incident was recorded from his own memoirs.

I have found only one reference to the Churchill spigot mortar/flying dustbin taking on a panzer (a Panther) the bomb was on course but hit a telegraph pole some yards from the Panther and detonated. However, there was no further movement or firing from the Panther. They must have been at least completely stunned and deafened.

Anyway I have come off topic too far. Sorry.

[Don Juan]

The only extra duties I've seen mentioned for the hull gunner in British accounts is that he was normally nominated to be the cook. It was the loader who was normally the radio operator.

As all the crew members were expected to engage in maintenance, an extra pair of hands would always have been welcome.

That said, an extra crew member is also a potential extra casualty, so I don't think there is any combat advantage in having additional crew who aren't materially adding to the combat efficiency of the vehicle.

[Urmel]

That said, an extra crew member is also a potential extra casualty, so I don't think there is any combat advantage in having additional crew who aren't materially adding to the combat efficiency of the vehicle.

I'd say the maintenance, guard duty, cooking, all materially add to the combat efficiency.