The Medium Mark B Whippet was designed to replace the Medium Mark A Whippet but arrived too late for service in the First World War and saw limited service after the war.
The Medium Mark B was designed by W.G. Wilson, one of the co-designers of the Mark I Tank and of the much improved epicyclic steering used in the Mark V Tank.
The Medium Mark B was a much more conventional looking design than the Mark A Whippet although the basic concept was similar, with the engine in the long lower fuselage and a fixed turret forming the fighting compartment above it. However while the Mark A had the turret at the rear and an unusual shaped fuselage, the Mark B had the turret at the front and a standard looking rhomboid fuselage.
It was significantly smaller than the original Mark I heavy tank, being ten feet shorter and four feet narrower. It was actually slightly taller, but a sizable part of that was the fighting compartment – the main rhomboid hull was several feet shorter than that of the Mark I.
Internally the vehicle was split in two, with the crew of four in the fighting compartment at the front and the engine and transmission at the rear. There wasn’t room for a full sized six cylinder Ricardo engine, so a smaller 100hp four cylinder version was used. This powered a four speed gearbox with epicyclic steering similar to that used in the Mark V Tank.
In the crew compartment the driver sat in a central position at the front with a small viewing hood at the foot of the turret. The were five machine gun positions in the turret walls and one in each of the hull doors, which jutted out like smaller sponsons. The tank commander didn’t have a dedicated viewing position.
The prototype was completed in September 1918 by the Metropolitan Carriage, Waggon and Finance Company. By this point an order for 459 machines had been placed, later expanded to 700 machines, to be built by Metropolitan, the Coventry Ordnance Works and the Patent Shaft and Axle-tree Company of Wednesbury. Sources differ on how many were built, possibly 45 before the end of the war and 102 in total.
Once the Medium B reached the Tank Corps after the war it was found to be rather cramped. The biggest problem was the crowded engine compartment, which soon became too hot for anyone to work in. Given how often the early tanks broke down and needed repairs this would have been a major problem if it had ever seen battle.
While Wilson was working on the Medium B his colleague on the Mark I, Sir William Tritton, had been working on his own design, the Medium Mark C Hornet. This was a similar but larger design, and like the Medium B didn’t enter in service in time to fight in the First World War.
After the war the Medium B saw less use than the Medium C. Seventeen were sent to Russia during the British intervention in the Russian Civil War, and some ended up in Soviet service. Others were used for experiments at Bovington in 1919-21 and one may have been given a 2-pounder gun in a rotating turret.
Hull Length: 22.75ft
Hull Width: 8.84ft
Weight: 18 tons
Engine: 100hp Ricardo gasoline engine
Max Speed: 6.1mph
Armament: Four machine guns