Landships II

The Vickers 1921 tank's claim to fame is it was the first British tank with a revolving turret. This is obviously not the case, as the prototype Whippet had a rotating turret. However, the Vickers 1921 was in fact the last of the rhomboids. From a side view, its track shape has a great deal in common with the Mk.I through V, aswell as the Medium C.

Was the Vickers 1921, in specific the Number 2 vehicle, superior to the Medium Mk.I series that Britain eventually ordered?

Vickers 1921:

Height: ~ 7 feet.
Length: ~ 16 feet.
Width: ? ? ?
Engine: 86hp water cooled.
Speed: 15 mph
Weight: 8.75 tons
HP per Ton: 9.8
Armor: .5 inch (12.7 mm)
Armament(No.2): One 3pdr in turret, 3 mountings for Hotchkiss MGs, as well as another in the turret roof for Anti Aircraft work.
Crew: 5
Note: All the power train was housed in a seperate compartment in the rear, similar to the Medium Mk. B, and C. Steering was accomplished by the use of Williams-Janney infinitely variable hydraulic units.

Vickers Medium Mk.I:

Height: 9 feet 3 inches
Length: 17 feet 6 inches
Width: 9 feet 1 & 1/2 inches.
Engine: 90hp air cooled Armstrong-Siddeley V-8
Speed: 15 mph
Weight: 11.7 tons
HP per ton: 6.9
Armor: .25 inch (6.5 mm)
Armament: One 3 pdr, 4 mountings for Hotchkiss MGs, aswell as 2 vickers MGs.
Crew: 5
Note: The whole of the drive mchanism was scattered about the tank: Gone was the rear power compartment as used in the Medium B, C, and Vickers 1921. Steering was accomplished either by the two 2 speed epicyclic gear boxes, one for each track, or clutch-brake steering.

The Vickers 1921 was deemed mechanically unreliable, and the Medium Mk.I was developed and put into production instead. Was this the right choice?

Both vehicles had the same crew size, and similar armament, but that's where the similarities end. The 1921's hydraulic power unit seems very advanced for the time. The Mk.I in comparison, had its drive taken to a multiple dry-plate clutch, to a four-speed gearbox without synchromesh, to a propeller shaft running to the bevel box at the back of the tank, and then to the two epicyclic gear boxes. Maybe it was more reliable than the hydraulic units on the 1921, but it seems more complicated.

The armor of the 1921 was .5 inches thick. The turret, and much of the front of the vehicle, was rounded or curved. The Mk.I in comparison, had .25 inch armor, half the thickness of the 1921, and was far more boxy in shape.

The 1921 had more power, had thicker armor, could deflect bullets easier, and had its engine seperated from the crew. All of this while being a substantially smaller more compact vehicle.

---Vil.

The No.1 Lincoln Machine had a round turret, yes - but could it revolve? I thought it was a fixed structure, designed to mock-up a possible revolving turret on a production vehicle.

A picture showing some detail of the turret is found in Richard Pullens "The Landships Of Lincoln", a fine little book. I am enclosing that picture.

But as for the topic at hand,

I would like peoples comments on my comparison of abilities for the 1921 and Medium Mk.I Vickers vehicles though. On paper, the 1921 seems to be the superior vehicle.

It is often that a vehicle will be rejected because it tries to be too different. Could it be that military personnel simply weren't ready to have a tank with a hydraulic transmission, instead wanting the traditional mess of metal gearing to accomplish the same task?

It is never mentioned what part of the 1921 was mechanically unreliable. These days infinitely variable hydraulic transmissions are common on agricultural tractors because they're extremely versatile and low maintenance. Was the technology just simply not polished enough in 1921 to make a reliable heavy-duty hydraulic transmission?

---Vil.