Monday, 19 February 2018

Shermans in the Mud

Few people interested in WWII armoured warfare haven't seen this video depicting Swedish trials of a Sherman, a Churchill, and a Panther in difficult off-road conditions. Many people, after having seen this video, readily claim that the Sherman had inferior off-road mobility to the Panther. Certainly, it's hard to argue with the video, but there is a caveat. There were many different kinds of Shermans, and the video only tests one of them. I thought I'd take a look at some trials performed by the Western Allies in Europe to see if they arrived at the same results.

Very similar trials were conducted by the British, described in Mediterranean Area AFV Technical Report #27, Appendix D. The test consisted of the following conditions:

"
  1. Raised road. This involved the tanks having to climb 3 to 4 feet onto a road and descending a similar bank on the other side of the road into a ditch filled with water to an approximate depth of 2 feet. The ditch varied from 9 to 14 feet in width at the bottom. The far side of the ditch involved a climb of approximately 3 feet with a soft bank.
  2. The tanks then had to cross a stretch of grass field to a strip of plough, approximately 80 yards broad, half of which had previously been watered for three successive days. This represented the condition of a normal ploughed field encountered after rain.
  3. The soil was everywhere the same, classified as clay with a small proportion of silt and fine sand, and when wet of low supporting power."
Seven different configurations of Sherman tanks as well as a Churchill and a Panther participated in the test. Let's see how they did.

Tank
Tracks
Road
Ditch
Plough
Sherman (diesel)
Steel chevron
Success
Fail
Not attempted
Sherman (diesel)
Ditto with end connectors
Success
Success
Failed after 20 yards
Sherman (diesel)
Rubber tracks and platypus grousers
Success
Success (easy)
Success in second gear (easy)
Sherman (diesel)
Steel tracks with MWEE grousers
Success
Success (easy)
Success in second gear (easy)
Sherman (diesel)
Steel tracks with rat grousers
Success
Success (easy)
Success in first gear (easy)
Sherman (diesel)
Rubber track alternating standard and platypus grousers
Success
Success (easy)
Success in second and first gears (easy)
Sherman (radial petrol)
Rubber tracks
Success
Fail
Not attempted
Sherman (radial petrol)
Rubber tracks and platypus grousers
Success
Success (easy)
Success in second and first gears (easy)
Churchill IV
Standard
Success
Success
1st attempt stuck 5 yards from the end, reversed out. 2nd attempt crossed very slowly in first gear.
Panther
Standard
Success
Success
Failed after proceeding very slowly after considerable track slip.

The Panther does do better than at least some kind of Sherman. The basic diesel (M4A2) and radial petrol (M4A1) Shermans failed the ditch test, which the Panther succeeded in. However, the Sherman with extended end connectors performed as well as the Panther did, and all other Shermans were superior to the Panther. The kind of tank shown in the video, a Sherman Vc, was much heavier than any of these tanks, and had basic steel chevron tracks, so its performance was not surprising. 

The trials were followed by a race through the same terrain, but backwards. Unfortunately, the Panther could not participate, as its gearbox had broken. The winner of this race was tank #3 with platypus grousers, that went through the whole race in second gear and was even able to switch into third for some sections. Tank #6 (alternating grousers) came second, also able to use third gear a little bit. 

This sort of result isn't a fluke. Other trials show the same thing. For instance, trials at the Fighting Vehicles Proving Establishment in Surrey, which compared another heap of combinations of Shermans and tracks, comes to the following conclusions:
"Panther

Of the heavy vehicles, Panther had better flotation characteristics than the most successful combinations of special tracks tested. 

On traction, the results were substantially inferior to those of the Churchill, and only slightly better than those for the Sherman with standard steel chevrons."

Sources:
  • LAC RG 24 C 2 (Canadian Military Headquarters in London) 55/534/9/2 (AFV Technical Reports ME)
  • Fighting Vehicle Proving Establishment Report #FT1553/2 Comparative Trials of Somerset Coastal Sites with Various AFV Tracks in Soft Ground Conditions

1 comment:

  1. Platypus grousers? Almost never used.

    Normal extended end connectors were pretty common in 1944-45.

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