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Cruiser tank A.C. Mark IV
General characteristics
4 peopleCrew
26.4 tWeight
5 forward
1 back
Gear box
76 mm QF 17-pounder cannonWeapon 1
50 roundsAmmunition
-10° / 20°Vertical guidance
7.7 mm Vickers machine gunWeapon 2
4 250 roundsAmmunition
250 roundsBelt capacity
390 shots/minFire rate
2 980 Ge icon.pngPurchase
Sl icon.png4 730/3 390/2 560Repair
10 000 Sl icon.pngCrew training
270 000 Sl icon.pngExperts
630 Ge icon.pngAces
x 2.60 Rp icon.pngReward for battle


GarageImage A.C.IV.jpg

The Cruiser tank A.C. Mark IV, also known as the AC IV Thunderbolt or the AC IV Sentinel, is a premium Rank III British medium tank on the British tree with a battle rating of 5.3 (AB/RB/SB). It was released some time after Update 1.55 "Royal Armour". Armed with a 17-pounder gun, it has a high firepower for the battle rating it is in, able to effectively fight any other tanks at the battle rating. The Thunderbolt is also a small and maneuverable tank able to exploit harsh terrain to target the enemy.

The AC IV is a relatively small medium tank in comparison to the common mainstay of the other countries, especially when compared to the American Sherman tanks. The Sentinel also has a good maneuverability and power-to-weight ratio for the propulsion, able to accelerate to its max speed of roughly 30 km/h quickly and stay there on stable terrain. The tank has a great advantage of a decent reverse speed in comparison to other medium tanks of its caliber, with a reverse speed almost the same speed as forward. The addition of the 17-pounder gun also gives this tank a whopping high firepower for the size, so it can stand a chance against tanks of the same tier despite being out of the league in terms of armour.

The tank in the game is the version planned for serial production, so it has the hull of the AC III; unlike the actual prototype design developed, which used the hull from the AC I version.

General info

Survivability and armour

The AC IV Thunderbolt's armour have a high tendency to bounce shells. This is obvious with the extreme slope on the from of the tank, and turret design. The armour itself is not think, but due to the angle it is put at this tank is very fierce competition.

Armour type:

  • Cast homogeneous armour
  • Rolled homogeneous armour (Hull roof)
Armour Front Sides Rear Roof
Hull 50.8 mm (66-67°) Frontal glacis
50.8 mm (30°) Driver's port
50.8 mm (7-68°) Lower glacis
44.45 mm (0-12°) 22.22 mm (78°) Top
44.45 mm (21-52°) Bottom
22.22 mm
Turret 63.5 mm (4-47°) Turret front
25.4-63.5 mm (1-68°) Gun mantlet
63.5 mm (0-88°) 63.5 mm (1-53°) 35 mm
Armour Sides Roof
Cupola 63.5 mm 35 mm


  • Suspension wheels and bogies are 20 mm thick, tracks are 20 mm.
  • The rear bottom area has a track placed there, providing 20 mm of extra armour.
  • The commander cupola is extended outwards from the left side of the turret, creating a vulnerable unsloped area vulnerable to weaker guns.


Mobility characteristic
Weight (tons) Add-on Armour
weight (tons)
Max speed (km/h)
26.4 N/A 53 (AB)
48 (RB/SB)
Engine power (horsepower)
Mode Stock Upgraded
Arcade 615 757
Realistic/Simulator 351 397
Power-to-weight ratio (hp/ton)
Mode Stock Upgraded
Arcade 23.29 28.67
Realistic/Simulator 13.29 15.04


Main armament

76 mm OQF 17-pounder
Capacity Vertical
47 -6°/+20° ±180° N/A
Turret rotation speed (°/s)
Mode Stock Upgraded Prior + Full crew Prior + Expert qualif. Prior + Ace qualif.
Arcade 10.7 14.8 _.__ _.__ _.__
Realistic 10.7 12.6 _.__ _.__ _.__
Reloading rate (seconds)
Stock Prior + Full crew Prior + Expert qualif. Prior + Ace qualif.
7.60 _.__ _.__ _.__
Penetration statistics
Ammunition Type of
Penetration in mm @ 90°
10m 100m 500m 1000m 1500m 2000m
Shot Mk.6 AP 160 157 133 112 96 86
Shell Mk.1 HE 9 9 9 9 9 9
Shot Mk.4 APC 165 160 138 108 94 81
Shot Mk.8 APCBC 171 168 156 143 130 120
Shell details
Ammunition Type of
in m/s
Mass in kg
Fuse delay

in m:

Fuse sensitivity

in mm:

Explosive Mass in g
(TNT equivalent):
Normalization At 30°
from horizontal:
0% 50% 100%
Shot Mk.6 AP 883 7.7 N/A N/A N/A -1° 47° 60° 65°
Shell Mk.1 HE 883 7.0 0.4 0.5 580 +0° 79° 80° 81°
Shot Mk.4 APC 883 7.7 N/A N/A N/A -1° 48° 63° 71°
Shot Mk.8 APCBC 883 7.7 N/A N/A N/A +4° 48° 63° 71°
Smoke characteristic
Ammunition Velocity
in m/s
Mass in kg
Screen radius
in m
Screen time
in s
Screen hold time
in s:
Explosive Mass in g
(TNT equivalent):
17pdr Shell SS Mk.1 754 8.4 13 5 20 50
Ammo racks
Ammo racks of the AC IV Thunderbolt
rack empty
rack empty
rack empty
rack empty
rack empty
rack empty
rack empty
rack empty
rack empty
50 XX (+X) XX (+X) 35 (+15) 45 (+5) 10 (+40) 14 (+36) 31 (+19) 39 (+11) (+49) Yes

Machine guns

Main article: Vickers (7.7 mm)
7.7 mm Vickers
Coaxial mount
Capacity (Belt capacity) Fire rate
4,250 (250) 390 N/A N/A

Usage in battles

Exploit the A.C. IV's maneuverability against the heavier tanks, plus the 17-pounder tank allows for a penetration through the enemy's armour to cause internal damages. The fast reverse speed makes the "shoot-and-scoot" tactic a viable method against the enemy, and should be the prime one as the armour of the Sentinel is not exactly the most durable at only 50 mm flat. However, the sloping nature of the armour could give the bouncing capability of the tank comparable to the T-34, it's even arguably much better. So while the weight class is definitely against the Sentinel, a chance is always there to take out the opposition.

"Shoot-and-scoot" tactics are the best tactics to use with this vehicle. The Sentinel's armour does not let the tank be a brawler, so it must be more "sneaky" against the enemies. Another thing to note is the driver's hatch at the front of the tank. To avoid a frontally penetrating shot, always angle the driver's hatch away from the enemy.

Pros and cons


  • Good sloped armour.
  • High penetration solid shot rounds.
  • Good manoeuvrability.
  • Fast reverse speed.
  • Small profile.


  • Sloped armour only on the front.
    • Susceptible to large caliber HE.
  • Only 44mm (4.4cm) of side armour.
  • Cannon lacks armour-piercing rounds with high-explosive filler.
  • No APDS rounds, unlike other British medium tanks at this rank.



Australia began designing a tank in November 1940 as the AC I, and was intended to be a cruiser tank weighing between 16 to 20 tons with a 2-pounder gun. With no prior experience in producing a domestic tank, Australia sent a task force to the United States to study the M3 Medium design to understand the in-and-outs of a tank. They also received the aid of Colonel W.D. Watson MC in December 1940 from Britain, who has many years of tank designing experience. The overall mission ended up having the tank design to have a similar concept as the Canadian Ram tank, being based off the the M3 Medium chassis and mated with a domestic design of their choice for the upper part. The Australian attached the chassis with a hull and turret with design similarities to the British Crusader tanks. The design started to become less of a cruiser tank and more of a medium tank by American specifications due to the attempt to up-armour and up-gun the tank to keep up with German armour development.

The first design was completed in February 1942 as the Cruiser Tank Mark 1 (AC I) and designated the "Sentinel". The design was simplified by using existing parts of current tanks and using a cast hull and turret. Though originally specified for a 2-pounder, it was then asked for a 6-pounder armament. Two Vickers machine gun were used as the coaxial and hull machine gun. With the power of three Cadillac V8 Petrol engines. It was unorthodox, but powerful enough to propel the vehicle. 65 of these tanks were made by June 1943 before being succeeded by a more advanced design known as AC III, also known as the "Thunderbolt". It had better armour and an improved firepower in the form of the 25-pounder howitzer. Despite the bigger gun, the 54-inch turret ring was never expanded to accommodate for the gun's larger size, so the crew experienced a slightly cramped turret interior for the benefit of having a better high-explosive charge and armour-piercing capability. Other differences in the design was the removal of the hull machine gun and a different set-up of the three Cadillac engines. One pilot model was built and plans were made for a production for 25 tanks for further trials, but the program was terminated.

Another attempt was made to increase Australian tank firepower with the AC IV design. It first started when the designers check to see if the turret could mount the massive 17-pounder in use by the British to fight the heavier and more protected German tanks. When the tests proved successful, the 17-pounder was chosen to be the gun for the AC IV, with a new and larger turret and 70-inch turret ring to improve crew comfort. These tanks were only made for evaluation purposes only and were never mass-produced for equipping the armoured units.


The AC IV design, along with the entire Australian Cruiser tank program, was terminated in July 1943, ending with only 65 tanks produced and a few prototype models. The reason was that the funds were better spent improving the infrastructure than building new tanks due to the large number of American tanks such as the M4 Medium that were being supplied to Australia. The AC "Sentinel" were all put into storage and kept until the end of the war. The only use the Sentinel saw was in the film The Rats of Tobruk in 1943 when a squadron of AC I tanks were modified to resemble German tanks.


After the war, the Australian government disposed most of the tanks in 1945, most were sold off by the Commonwealth Disposals Commission. Today, about six Sentinels survive in intact conditions across the world. One notably in the Bovington Tank Museum, and three in Australia in the RAAC Tank Museum, Treloar Technology Centre, and one in the United States in the Collings Foundation.


Excellent additions to the article would be video guides, screenshots from the game, and photos.

See also

Links to the articles on the War Thunder Wiki that you think will be useful for the reader, for example:

  • reference to the series of the vehicles;
  • links to approximate analogues of other nations and research trees.

External links

Britain medium tanks
Valentine  Valentine Mk I · Valentine Mk IX · Valentine Mk XI
Cromwell  Cromwell I · Cromwell V · Cromwell Mk.V (RP-3)
Based on Cromwell  A30 Challenger · Comet I · Iron Duke IV
Foreign  Grant I · Sherman II · A.C.IV · Strv 81 (Rb.52)
Firefly (M4)  Firefly "Scorpion" · Sherman Firefly
Centurion  Centurion Mk 1 · Centurion Mk 3 · Centurion Mk.5 AVRE · Centurion Mk 10 · FV4202
Chieftain  Chieftain Mk 3 · Chieftain Mk 5 · Chieftain Mk 10 · Vickers MBT
Challenger  Challenger Mk.2 · Challenger Mk.3 · Challenger 2

Britain premium ground vehicles
Light tanks  A13 Mk.I (3rd RTR) · Mark IV A13 Mk II · AEC Mk.II
Medium tanks  Cruiser Tank Grant I · Cromwell Mk.V (RP-3) · Sherman IC 2nd "Warsaw" Armoured Division · Cruiser tank A.C. Mark IV · A34 Comet I Iron Duke IV · Strv 81 (Rb.52) · Centurion Mk.5 AVRE · Sho't Kal Dalet
Heavy tanks  A1E1 Independent · A.33 Heavy Assault Tank "Excelsior" · A.43 Black Prince
Tank destroyers  Achilles (65 Rg.)