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British Aorg Report On Tank Effectiveness In Wwii


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#1 Markus Becker

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Posted 29 August 2017 - 0755 AM

Cross posted from TBO-verse:


I was rereading Armored Champion by Zaloga, (Great book, I highly recomend it) and I noticed a very interesting study done by the UK on WWII tanks. It was published in 1952. Its listed as follows.

E. Benn and R. Shephard, Tank Effectiveness: A Comparision of the Theoretical Measure with Observed Battle Performance (AORG Report No. 6/52; Byfleet: UK 1952.

Per Zaloga, the Effectiveness of a tank was defined as "the reciprocal of the number of tanks required per enemy tank to achieve parity in battle." So a tank rated at .5 means you only need half as many tanks as a enemy tank rated at 1. Note this was purely a tank vs tank analysis, for example the Churchill was not rated since that was not really its goal. Having said that, I thought some aspects of it were very interesting.

Specifically, the chart reproduced for the book compared the Panther, PzKpfw IV, Tiger I and the King Tiger. I've tried to attach the file here. Some things of note.

Panther and Tiger I are virtually Identical when compared against the Cromwell and the Sherman 75mm (Tiger I is about ~3% better at various ranges.) Against the 17pdr Firefly, the Firefly is actually rated a bit better then the Tiger I (.9 Firefly to match 1 Tiger I at 600 and 1000 yards.) while the Panther is slightly better then the Firefly (1.2 Fireflies to match 1 Panther.) Panther would have a 33% advantage over the Tiger I when facing Firefly Shermans. Interesting so far.

The comparison between the Cromwell, Sherman and PzKpfw IV is where it gets interesting. From my armchair general perspective, I would expect all these tanks to be very similar and overlap in capabilities. Specifically, while the 75mm Sherman and the PzKpfw IV are very close, I would expect the relative advantage to be more with the PzKpfw IV at long range and the Sherman at close range. Basically at long Range the flatter trajectory and better penetration of the PzKpfw IV gun would seem to be at the best advantage, and at least a portion of the hull was well protected against the 75mm Sherman gun. At long range the value of quick turret traverse is lessened as well. At close range I would expect the advantage to shift to the Sherman. The unity periscope sight with wider field of view, the faster turret traverse and under certain circumstances the stabilized sight would all be useful. At close range the advantage in penetration of the German gun would not matter since both tanks could penetrate the other. That is what the seems logical to me.

The interesting thing is that is not what the study concludes. Per the Study, the PzKpfw IV is better at medium range (1.1 Sherman to match 1 PzKpfw IV at 1000 yards.) and actually inferior at long range (.9 Sherman to match 1 PzKpfw IV at 1500 yards.) Note this is the opposite of the relationship between the Sherman and the heavier German tanks.

Also noteworthy is the difference between the Sherman and the Cromwell. I've always viewed the Cromwell as a acceptable tank, its primary problem being mechanical reliability but if it actually got to the fight was basically a Sherman with better mobility but inferior ergonomics (Extrapolating that based on the Chieftain's hatch video on the Comet.)

But per the study, it would take 135 Cromwells to achieve parity with 100 PzKpfw IV at 1000 yards. It would take 110 Shermans, so the Cromwell is at a 18.52% disadvantage compared to a Sherman against PzKpfw IV. Here is where I'm scratching my head, at 1500 yards it would take 150 Cromwells to match 100 PzKpfw IV, while it would take 90 Shermans, here the Cromwell is a 40% disadvantage, and I have no idea why, why would the relative ratio change so much at longer range? Grasping at straws, perhaps this is a narrow range band where the sloped glacis of the Sherman can actually deflect some rounds, but 40% seems way too high for that, considering the difference between a 75mm Sherman and a Firefly is only 22% against a Tiger.

Anyone have access to the raw study? Any ideas on this?



http://www.tboverse....ile.php?id=3977

#2 Stuart Galbraith

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Posted 29 August 2017 - 0810 AM

Was cromwell that unreliable? Ive not read that. If anything it seems to have been quite an advance on Crusader, which is admittedly not saying very much.

 

Im struggling to see a Cromwell as significantly inferior to Panzer IV, not at short range anyway. At long range engagements I could see the German tank having superior optics and a better gun probably being decisive.



#3 bojan

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Posted 29 August 2017 - 1037 AM

At 1500m later Sherman glacis ([email protected] IIRC) would be pretty resistant to 7.5cm kwk 40. IIRC vs Pak 40 penetration limit was about 1100-1200m give or take.


Edited by bojan, 29 August 2017 - 1555 PM.


#4 Markus Becker

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Posted 29 August 2017 - 1550 PM

Was cromwell that unreliable? Ive not read that. If anything it seems to have been quite an advance on Crusader, which is admittedly not saying very much.


Compared to an M4 yes as our very own Nick Moran found out:

https://worldoftanks..._Hatch_Dracula/

#5 demosthenes

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Posted 29 August 2017 - 1619 PM

So we don't know the ratio of empirical vs theoretical data?



#6 Manic Moran

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Posted 29 August 2017 - 2140 PM

In fairness, look at the date of the

 

 

Was cromwell that unreliable? Ive not read that. If anything it seems to have been quite an advance on Crusader, which is admittedly not saying very much.


Compared to an M4 yes as our very own Nick Moran found out:

https://worldoftanks..._Hatch_Dracula/

 

 

In fairness, they had some time in between that test and the invasion of France to fix the problems, I don't think I would use Dracula as a source for Cromwell reliability in battle.



#7 Stuart Galbraith

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Posted 30 August 2017 - 0202 AM

I read an account of a Cromwells crew in battle from 1944 to the Rhine, and they didnt find it unreliable. Mind you, as it turned out they had accidentally been issued a mild steel training tank which had a bit more 'go' than the other ones.

 

That said, ive listened to an account of a British tank crew using M4A4 and they had little argument about its reliablity either. Apparently they were supposed to turn the engine over by hand each morning, but that was a little too much like hard work so they never bothered. As it turned out it didnt make any difference to the vehicles reliablity.



#8 Markus Becker

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Posted 30 August 2017 - 0521 AM

Until now I too hadn't come across information that labeled the Cromwell as unreliable but as much better than the preceding cruisers. And not just because some of those were really bad. It was actually reliable, maybe just not as reliable as an M4.

Speaking of, you mixed something up. The M4A4 had the Chrysler Multibank (three car engines), not the Wright radial that needs to be turned over before starting. Both were liked for their reliability though.

#9 Stuart Galbraith

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Posted 30 August 2017 - 0532 AM

Im pretty sure in thinking the British Army only used M4A4, or at least in the Normandy campaign. The crewman questioned seemed assured that they were told to turn them over each morning, but maybe that was incorrect instruction left over from using M4A1s, which I think we might have used in the middle east.

 

 

I was interested to note reading the Dakota Manual, that they have to electrically turn over the engines before they start them for exactly the same kind of sump problem with a radial engine.



#10 Tim the Tank Nut

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Posted 30 August 2017 - 0851 AM

pretty much all radial engines are like that



#11 Stuart Galbraith

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Posted 30 August 2017 - 0854 AM

I never stopped to think about If Im honest. I do remember the WW1 engines required someone to turn them over manually, but I thought that was just for priming.

 

 

Incidentally, the recording was 'The Sherman Experience Tapes' which you can probably still find online somewhere. It was really interesting, had an interview with Trooper Joe Ekins in it, the man who was thought most likely to have killed Wittmann.



#12 R011

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Posted 30 August 2017 - 1359 PM

Mr. Neihorster's execellent site gives tank strength by type for 21st Army Group for June 1944. About 300 of the approx. 2200 Sherman's were M4 (Sherman I) and M4A1 (Sherman II) with the radial engine. The rest were A4 and A2 versions.

#13 Stuart Galbraith

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Posted 31 August 2017 - 0201 AM

Good lord, we had them that late then? I thought they had all gone to Italy.

 

Well I guess I had them mixed up then, It must have been an M4A1 he was talking about. Thanks for that.



#14 Getz

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Posted 01 September 2017 - 1451 PM

 

Was cromwell that unreliable? Ive not read that. If anything it seems to have been quite an advance on Crusader, which is admittedly not saying very much.


Compared to an M4 yes as our very own Nick Moran found out:

https://worldoftanks..._Hatch_Dracula/

 

 

Everything is unreliable compared to an M4.  It's not a very good yardstick...



#15 DB

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Posted 01 September 2017 - 1522 PM

On the contrary, if you have a gold standard, then it's the proper benchmark.



#16 Colin

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Posted 01 September 2017 - 2002 PM

I would have thought the M3 medium would have made them aware of the mechanical advantages of the US designs



#17 bojan

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Posted 01 September 2017 - 2100 PM

Early Lee was not particularly reliable.



#18 cbo

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Posted 02 September 2017 - 0512 AM

Cross posted from TBO-verse:

[SNIP]

But per the study, it would take 135 Cromwells to achieve parity with 100 PzKpfw IV at 1000 yards. It would take 110 Shermans, so the Cromwell is at a 18.52% disadvantage compared to a Sherman against PzKpfw IV. Here is where I'm scratching my head, at 1500 yards it would take 150 Cromwells to match 100 PzKpfw IV, while it would take 90 Shermans, here the Cromwell is a 40% disadvantage, and I have no idea why, why would the relative ratio change so much at longer range? Grasping at straws, perhaps this is a narrow range band where the sloped glacis of the Sherman can actually deflect some rounds, but 40% seems way too high for that, considering the difference between a 75mm Sherman and a Firefly is only 22% against a Tiger.

 

Without knowing how the study was conducted, it is difficult to make heads or tails of.

 

But it could be as simple as paper-scissors-rock.... :)

 

Basically: Vertical armour bad - high-velocity gun good.

 

Cromwell has vertical armour and a medium velocity gun, i.e. loose-loose

Sherman 75mm has sloped armour and a medium velocity gun, i.e. win-loose

Sherman 17-pdr has sloped armour and a high velocity gun, i.e. win-win

Panzer IV has vertical armour and a high velocity gun, i.e. loose-win

 

Conclusion, Cromwell is the worst, Sherman 75mm and Panzer IV about equal and Sherman 17-pdr superior

 

The Cromwell gets worse with range because its 75mm gun just does not have the firepower and the high velocity gun on the Panzer IV can still penetrate the Cromwells vertical armour

The Sherman 75mm has the same firepower problem as the Cromwell, but the sloped armour is starting to beat the Panzer IVs high-velocity gun at longer ranges.

The Sherman 17-pdr gains the advantage at the longer range, because it benefits from both sloped  armour and the ability of its gun to penetrate the Panzer IVs armour.



#19 Stuart Galbraith

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Posted 02 September 2017 - 0527 AM

M3 Stuart was well liked. They called it Honey because it was so reliable, or at least compared to British types.

 

Sounds to me this was operational analysis before they had computers powerful enough to come up with sensible conclusions. Maybe they should have got Solly Zuckerman on it.



#20 Getz

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Posted 02 September 2017 - 1113 AM

On the contrary, if you have a gold standard, then it's the proper benchmark.

 

Perhaps, but it's still not appropriate to call a tank unreliable simply because it is less reliable than the most reliable tank - and my experience is that good, serviceable tanks like the Cromwell and Pz IV get branded as "unreliable" simply because they were less reliable than the Sherman.

 

99% reliable is still pretty damn reliable, even if it's less good than 100% reliable.






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