The Devil's Chariots
Page 38
Armament
Front plate: 1 Hotchkiss MG
Rear plate: 1 Hotchkiss MG
Engine
Ricardo 6-cyl. 150hp
hp per ton: 4.05hp
Est’d endurance: 9.75 hrs
Max speed: 4.3mph on level
Transmission
4-speed forward and 4-speed reverse
Epicyclic gear in final drive to each track, in permanent mesh
Dimensions
Length: 34ft 2.5in
Width; 12ft 4in
Height: 10ft 3.5in
Track width: 20.5in
Fighting weight etc.
37 tons laden
27 tons unladen
Max trench crossing: 12ft 6in
Medium A ‘Whippet’ Tank
The Medium series of light tanks was introduced in 1918. It was a slow-motion but still deadly mechanical cavalry designed for pursuit and exploitation after a breakthrough. Speeds of 6–8mph in this class do not impress today, but the so-called ‘chasers’ were twice as fast as the heavy tanks and highly rated. The ‘A’ Type was an iron boot in shape. Its low-profile armoured chassis with almost continuous mud chutes along the track frames was topped by an angular fixed turret at the rear, providing a cramped fighting space for a commander, driver and one – or theoretically two – machine-gunners. A rear door gave entry. Ahead and below them between the independently driven tracks were twin commercial Tylor 4-cylinder 45hp engines, each with its own gearbox powering a track. The driver contended with a mass of controls. He had two sets of clutch pedals, gear change and hand-brake levers, plus a magneto control, a steering wheel of sorts and a master throttle which uniformly governed both engines. Turning the steering wheel automatically closed the throttle of the engine on the inside of a turn and opened the other’s – but naturally this risked an engine stall if the master throttle had been set either fully open or ‘idle’. The method worked for slight turns; for bigger swings the driver could select differing ratios in the two gearboxes, even spinning the tank on its axis by reversing one and staying in forward on the other. Alternatively, he could drive round a turn on one track while declutched and hand-braked on the other.
A machine gun mounting was fitted in each of the four faces of the turret, which rotated only in pre-production designs. The army had wanted a 2-pdr gun for destroying Maxim positions but it was impracticable in the small turret. An antiaircraft MG mounting was fitted in April 1918. Some inevitable weaknesses emerged. Overall height exceeded the rail loading gauge, necessitating a part dismantling of the turret for transportation. Two engines doubled the chances of a failure, and stalling was a regular event. The crew could restart engines from inside the tank but anything else meant exposure to fire outside. If one engine failed, the clutch system could only deliver 24hp which might just move the machine in a straight line, but steering was unlikely with half that power going to each track through the locked differential. Ventilation was poor; 3rd Battalion’s War Diary recorded on 21 August 1918 that some of its Whippets were neutralized in two recent actions when one hour’s running with the door closed in summer heat left them weaponless save for revolver fire. Ammunition swelled and jammed the guns. In several cases rounds exploded in the tanks. Guns and driver controls were too hot to grip. Nevertheless the Whippets gave most valuable service until the Armistice.
Origination
Design began: October 1916
Designed by: W.A. Tritton
First builder: Wm Foster & Co., Lincoln
Prototype first moved itself: 3.2.17
First series production tank completed: October 1917 (first five machines in mild steel)
First trials
4.1.17. Prototype’s factory trials
3.3.17. Took part in the Oldbury transmission trials. Coolant repeatedly boiled. Fan belt problems
April 1917. Ran 120 miles on test with overheating problems
WD serial numbers
A 200–399
Outline Specification
Crew: 3–4
Commander
1 driver
1–2 gunners
Armament
4 Hotchkiss MG
Anti-aircraft mounting added April 1918
Engine
2 Tylor JB4 4-cyl. each 45hp
hp per ton: 6.43hp
Est’d endurance: 10 hrs
Max speed 8.3mph on level
Transmission
A gearbox serving each engine provided 4 forward speeds and reverse
Dimensions
Length: 20ft
Width: 8ft
7in Height: 9.0ft
Track width: 20.5in
Fighting weight etc.
14 tons
Max trench crossing: 7ft
Medium B Tank
The Medium A had proved its value as a chaser but was hard to handle, more liable to breakdown with twin engines, and lacked protected access to them. Maj Wilson’s ‘B’ Type aimed to overcome these defects. It was effectively a scaled-down Mk V with separate crew and engine compartments. In place of sponsons a coffer-shaped door on either side formed a mini sponson projecting 9in, with a mounting for a single machine gun plus a revolver port. A large full-width turret on the forepart of the roof provided five further MG mountings to give all-round fire, and an anti-aircraft mounting. The turret’s position almost on the nose ensured that the commander and the gunners got the earliest possible view ahead when the tank crested a rise. Track width was increased from the ‘A’ Type’s 20.5in to 22.5in. Unfortunately, access to the engine and the transmission beyond it was so cramped that the 100hp Ricardo had to cool down for at least an hour before attempting even a plug change. Roof plates had to be removed in order to change inlet valves. A novel smokescreen generator injected sulphonic acid into the engine exhaust. As smoke could only be produced with a running engine, thirty smoke grenades were carried in case of engine failure under fire.
The introduction of the ‘B’ Type was delayed by repeated design changes and then a shortage of armour plate. The tank was 4 tons heavier than the Whippet, and with its 100hp engine its power-to-weight ratio was actually inferior. Gen Elles wanted production postponed until Ricardo’s 150hp engine became available. The first 100hp Medium B was delivered in mid-October 1918, coinciding with a very adverse report from Col Fuller who had inspected the trials machine at Dollis Hill. The Tank Board decided to accept the type primarily as a training machine and to concentrate on the Medium C.
A male version of the ‘B’ Type with a 2-pdr gun was planned, but was abandoned in March 1918 because production of the gun would have seriously compromised Armstrong’s output of 6-pdrs for the heavy tanks.
Origination
Design began: March 1917
Design by: Maj W.G. Wilson
Design still in early stages in October 1917 when priority switched to Mk V working drawings
Design completed: January/February 1918
First builder: The Patent Shaft & Axletree Co. Ltd
Build started: prototype completed July 1918
First series production tank completed: 9 September. Delivered c. 15 October to tank experimental ground, Dollis Hill
First trials
September 1918: a short run with No. 1201 at Oldbury. Minor alterations only. October 1918: 1,000-mile trial. Track brakes failed and mud entered epicyclics. Gearbox overheated. Trials recommenced using 1202. Gearbox still overheating
WD serial numbers
Patent Shaft 1201–1450
Coventry Ordnance 1501–1600
North British Loco 1601–1700
Outline Specification
Crew: 4
Commander
1 driver
2 gunners
Armament
4 Hotchkiss MG
Engine
Ricardo 4-cyl. 100hp hp
per ton: 5.5hp
Est’d endurance: 12 hrs
Max speed: 6.1mph on level
Transmission
<
br /> 4-speed forward and 4-speed reverse
Epicyclic gear to each track, in permanent mesh
Dimensions
Length: 22ft 9.5in
Width: 9ft 3in
Height: 8ft 4.75in
Track width: 22.5in
Fighting weight etc.
18 tons
Max trench crossing: 8ft
Medium C ‘Hornet’ Tank
When the working drawings for Maj Walter Wilson’s much delayed 18-ton Medium B were nearing completion in February 1918, Gen Hugh Elles, the Tank Corps commander, complained that it was going to be too slow and should be shelved pending a more powerful engine from Harry Ricardo. Sir William Tritton was asked on the 5th to complete a rival design. He had been working on his 19.5-ton Hornet for several months. The tank resembled the ‘B’ Type externally and in its internal layout, but there was more superstructure above the tracks, it was 3ft longer (only 7in shorter than the Mk V heavy tank) and it was planned to take the forthcoming Ricardo 150hp engine with conventional Mk V-type transmission, giving a top speed of nearly 8mph against the 6.1 of the ‘B’. The engine was highly accessible in a rear compartment, and the driver sat right up front. Immediately behind his lookout a full width turret covered the crew compartment, fitted with two forward-firing machinegun mountings and one each side and to the rear. The commander could perch on a small, hinged platform and observe through a rotating mini turret set on the rear of the main turret’s roof. The usual massive starting handle bisected the compartment at knee height but was demountable – a necessary innovation. A newly designed 2-pdr gun was planned for the female version to deal more effectively with Maxim positions but Gen Elles thought it inadequate and wanted a 6-pdr. Neither gun was installed.
A male version was designed but never built. It was to be a tank destroyer with a single Hotchkiss 6-pdr in the bows. The gun would have reverted to the longer 40-calibre barrel because muzzle blast from the current 23-calibre gun could have injured the driver directly beneath. The Medium C was unquestionably the best of the light tank series to date and promised to be one of the outstanding tanks of the war. When it was chosen to spearhead the breakout in the following year’s offensive, its production orders leapt in September 1918 from 600 machines to 3,230. The Armistice halted almost all Hornet construction but the handful that were built remained in service for five or six years until the Vickers Medium Mk I with its sprung bogies and 30mph top speed replaced them.
Origination
Design began: possibly August/September 1917 but contemporary records also state
December
Designed by: Sir Wm Tritton
First builder: Wm Foster & Co. Ltd
Mock-up built: 4.4.18
Design approved: 19.4.18
First tank moved itself: 16.8.18, possibly a mild steel version
First series production tank completed: 3.9.18, female
Delivered: January 1919
First trials
16 August 1918. Tests began at Lincoln. Gearbox troubles, stripped pinions.
3 September. Generally satisfactory but coolant boiled and gearbox overheating threatened a possible box redesign.
6 October. Completed 1,000-mile test and ran the last 150 miles non-stop at 7.5mph. Gearbox redesign avoided
WD serial numbers
Female: 1801–2000
No male tanks built
Outline Specification
Crew: 4
Commander
1 driver
2 gunners
Armament
Male (none built): 1 Hotchkiss 40-cal. 6-pdr; 3 Hotchkiss MG
Female: 4 Hotchkiss MG; A 2-pdr QF gun was planned but not installed
Engine
Ricardo 6-cyl. 150hp
hp per ton: 7.5hp
Est’d endurance: 16 hrs
Max speed: 7.9mph on level
Transmission
4-speed forward and 4-speed reverse
Epicyclic gear in final drive to each track, in permanent mesh
Dimensions
Length: 25ft 10in
Width: 8ft 10.5in
Height: 9ft 7in
Track width: 20.5in
Fighting weight etc.
19.5 tons
Max trench crossing: 10ft
Mks I & II Gun Carriers and Salvage variants
By spring 1916 it was clear to some at least that if newly gained ground was to be held by exhausted and lightly armed infantry, then heavy artillery must be brought forward into range at speed to continue to give fire support before the enemy counter-attacked. On 7 March, the day of his promotion to major, Walter Wilson began design of a tracked and lightly armoured gun carrier with Maj John Greg of the Metropolitan Company, whose idea it was. GHQ in France formally requested the machine in May but the Ordnance Board raised objections and a hiatus ensued. Lloyd George the Minister of Munitions authorized construction of 50 machines without army sanction. The first machine successfully completed firing trials from the vehicle in January 1917. The dual self-propelled gun/gun carrier was finally approved by the army at the end of May, a year after its initial request.
The 30ft machine’s low-profile track frames stood some 5ft high. Between and above them a tall armoured box body filled the rear half, straddling the tracks, the upper run of which passed through a tunnel at that point. The remaining space was an open well. Up front a narrow armoured cab perched above each track for the commander and driver. The machine was designed for a 6in howitzer or a 60-pdr Field Gun Mk II. The artillery piece was winched backwards up a ramp between the two cabs and into the open well in a firing position before securing against a recoil beam. Its wheels were removed and chained to either side of the box body, inside which was a compartment for a detachment of eight gunners, a Daimler 105hp engine and transmission similar to the Mk I tank’s system, and two gearsmen. Mud and stones regularly built up in the tunnel trackways through the body, bursting the undersides of the left- and right-hand radiators above. The tunnels also prevented the use of track spuds. The first machine, No. 100, arrived in France complete with a steering tail in time for Third Ypres, which opened on 31 July 1917. Its intended role was overtaken by events and the tail soon disappeared. The carrier brought several hundred tons of ammunition forward, and a few 60-pdr guns. Once, at least, ‘sniping’ was accomplished by taking up a 6in howitzer and moving about during the night, firing it from the vehicle, which harassed and puzzled the enemy. Gun-carrying companies were formed, the first drawing its machines in France on 6 September. They were soon relegated to a supply role conveying gun ammunition and infantry stores for which they were invaluable. A carrier with its four-man crew could shift a 7-ton load which would otherwise require a carrying party of 290 men. The surviving vehicles were fitted at Central Workshops with cranes for salvage work in the spring of 1918.
The order for 50 carriers was altered in October 1916 to 48 plus two variants for salvage work. These recovery machines were not built until June/July 1917. The two forward cabs were omitted and the well was decked over for a hand operated crane to lift 3 tons in jib form or 10 tons with sheerlegs. A winding drum for wire rope haulage was mounted on the box body, in front of which was a cab. A third machine was fitted that December with a large Priestman steam-powered grab.
A GC Mk II was designed but only a mock-up was built. The general principles of the Mk I were retained but the hull occupied two-thirds of the machine’s length and the open well lay at the rear. The front end was built on similar lines to Mks IV and V fighting tanks, with sufficiently angled track to enable the machine to climb. A Ricardo 150hp engine would drive through epicyclic gears. The guns were to board from the rear, retaining their wheels, but could not be fired from the machine.
Origination (MK I)
Design began: 7.3.16
Designed by: majs J. Greg and W.G. Wilson
Outline design approval by GHQ only: 17.4.16
Construction order authorized unilaterally by Minister of Muniti
ons: 16.6.16
Construction order formally confirmed by War Office: 29.5.17
First builder, prototype: Metropolitan Carriage, Wagon & Finance Co. Ltd
Prototype completed: 1.1.17
First builder, production machine: Kitson & Co. of Leeds
First series production tank completed: June 1917
First trials: c. 2.2.17. Prototype at Shoeburyness ranges fired 60-pdr (5in) gun from the carrier’s well
WD serial numbers
Began at GC 100
Outline Specification
Crew: 4 + 8
1 Commander
2 driver
gearsmen Detachment of 8 gunners
Armament:
1 machine gun for defence.
GC carried 1 6in howitzer Mk I + 60 rounds, or 1 60-pdr 5in Field Gun Mk II/L + 60 rounds
Engine
Daimler 105hp hp
per ton: 3.9hp
Est’d endurance: 11 hrs
Max speed: 3.7mph on level
Transmission
Primary box: 2 forward and 1 reverse
Secondary gears: 2-speed to each track
Dimensions
Length overall with tail and 60-pdr gun: 43ft
Length without tail and gun: 30ft
Width: 11ft
Height: 9ft
4in Track width: 20.5in
Weight etc.
With 60-pdr and ammunition: 34 tons
With howitzer and ammunition: 31 tons
No gun: 27 tons
Max trench crossing: 11ft 6in
APPENDIX 2
Production Histories of Principal British Tanks, 1916–19
Mk I Heavy Tank
Builders (of first tank in bold type) First orders February 1916 Revisions April 1916 Revisions June 1916 Total Built
Wm Foster & Co. Lincoln 25 M
12.2.16 30 M
i.e. extra 5
M c. 21.4.16 37 M
i.e. 7 M transferred from Robey’s probably early June 37 M
Robey & Co. Canwick Rd. Lincoln - 75 M c. 21.4.16 Cancelled, probably early June Nil
Metropolitan Carriage, Wagon & Finance Co Ltd.
Birmingham (built at Oldbury factory) 75 M