A.C.IV

A.C.IV

A.C.IV

Britain

III Rank

Battle rating:

AB	RB	SB
5.3	5.3	5.3

Class:

PREMIUM

Medium tank

Purchase:3 410

Description

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 thick, but thanks to the angle of it this tank can be a 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

Notes:

• 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

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

Armaments

Main armament

76 mm OQF 17-pounder
Capacity			Vertical guidance	Horizontal guidance	Stabilizer
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	_.__	_.__	_.__

Ammunition

Penetration statistics
Ammunition	Type of warhead	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 warhead	Velocity in m/s	Projectile Mass in kg	Fuse delay in m:	Fuse sensitivity in mm:	Explosive Mass in g (TNT equivalent):	Normalization At 30° from horizontal:	Ricochet:
								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	Projectile 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

Full ammo	1st rack empty	2nd rack empty	3rd rack empty	4th rack empty	5th rack empty	6th rack empty	7th rack empty	8th rack empty	9th rack empty	Visual discrepancy
50	XX (+X)	XX (+X)	35 (+15)	45 (+5)	10 (+40)	14 (+36)	31 (+19)	39 (+11)	1 (+49)	Yes

Machine guns

7.7 mm Vickers
Coaxial mount
Capacity (Belt capacity)				Fire rate (shots/minute)	Vertical guidance	Horizontal guidance
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

Pros:

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

Cons:

• 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.

History

Development

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 along with the incorporation of a suspension system of horizontal rubber cylinder springs seen on many early-war French tanks notably the H.39 and H.35. 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. The entire hull being casted would be the first in history as many tanks of the era did not use such techniques. Although originally specified for a 2-pounder, it was then asked for a 6-pounder armament but due to the manufacturing of such guns not begining at the time in Australia they would have to use the 2 pounder for the first 65 produced. Two Vickers machine gun were used as the coaxial and hull machine gun the later having an armoured mount to protect its water sleeve resulting in a rather lewd looking front of which is made fun of to this day. 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. However it would be the only commonwealth tank ever to mount such a gun.

Termination

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.

Survivors

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.

Media

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

• [Devblog] AC IV Thunderbolt