History of the M18 Gun Motor Carriage (Hellcat)

The M18 "Hellcat" was a typical representative of the US Army's tank destroyer during World War II. This type was fast, maneuverable, well-armed, and in sufficient numbers to fight the armored forces of the Wehrmacht throughout Europe. An improvement over the previous M10 series, the M18 proved to be just as powerful as the M36 "Slugger" series, playing a role in overthrowing the ground success needed for Germany's postwar advance.

Hellcats served until the end of the war, and were even included in the lists of several countries in the postwar world.

The original M10 became the most definitive American tank destroyer of World War II, with nearly 7,000 produced for the U.S. Army and its allies. However, the type was based on a modified chassis of the M4 Sherman and lacked armor protection. As the war progressed, its main gun eventually proved largely inadequate.

The M36 "Slugger" was subsequently developed from the M10 series line to feature a more powerful 90mm main gun, a design also based on the classic M4 Sherman tank chassis. Production reached 1,400 units, capable of dealing with the latest German tank offerings, but coming towards the end of the war.

The design of the M18 Hellcat was already in development as early as December 1941. The Japanese attack on Pearl Harbor that month brought the United States into full-scale war with the Japanese Empire, with Germany and Italy declaring war on Japan.

British Prime Minister Churchill persuaded US President Roosevelt that fighting Hitler and Mussolini in Europe and Africa was a priority, so resources were allocated for that.

The U.S. Department of Ordnance has released design specifications for the "Fast Tank Destroyer", which focuses on the placement of the 37mm main gun mount.

The vehicle will be powered by a Wright Continental R-975 C-Series 9-cylinder radial engine with a suspension system based on the famous Christie arrangement. This makes the new tank destroyer design the first U.S. vehicle designed specifically for the tank kill role, rather than a design with modifications to the existing hull to fit that role.

In mid-1942, the T49 GMC ("Gun Car") prototype appeared for review. By that time, operations in North Africa had shown that, given the quality of the armor of the latest German tanks, the 37mm weapons originally intended for a tank-killing role were far below that.

Prototypes instead use 57mm caliber weapons and now feature a more versatile torsion bar suspension. The assessment continued, and soon, as the German army's influence had grown beyond the deployment points of the Panzer III and Panzer IV, the need for more powerful armament became apparent - the superb Panther and Tiger I heavy tanks soon became The Bundeswehr is the backbone of all operations and is at the forefront.

These German tanks featured powerful main guns and thick armor that surpassed all Allied tanks of the time. Therefore, the future development of the new American tank destroyer chose the 75mm M3 main gun.

These changes soon led to the "T67 GMC" pilot vehicle design, a lighter, smaller vehicle with a 75mm M3 main gun. The idea to mount the 76.2mm main gun resulted in the "T70 GMC" prototype model, which became the pre-production design known as the "M18 GMC".

Serial production began in July 1943 and continued until October 1944, when 2,507 prototypes from the U.S. factory entered service. Combat readiness was achieved in the summer of 1944, and the M18 duly received the unofficial nickname "Hellcat".

In this field, the M18 proved to be an excellent vehicle for the expected task. Its power-to-weight ratio allows the vehicle to reach a top speed of 55 to 60 mph in ideal conditions - faster than any other armored fighting vehicle in the war. The Continental powerplant allows for excellent acceleration, while the combination of the engine and the chosen hull design allows for a fairly flexible installation.

This is the speed of the vehicle, often used as an inherent defense whose armor protection could prove dubious, allowing the M18 crew to fire on the enemy and then retreat quickly before reacting. Given the relentless nature of the war, her powertrain was considered a reliable and important asset. The M18 is much smaller in profile and size, and weighs half the weight of the previous M10 series. This makes them a harder target to spot and attack. Its armor is improved over the M10, but it's still not adequate when going head-to-head with enemy main battle tanks - a task best left to the M4 Sherman and hidden anti-tank guns.

If German tankers could target the thinly armored M18, they actually enjoyed a big advantage. The rifle group still operates in the open turret position. While this exposes her to unnecessary danger on the battlefield and the elements, it provides an unobstructed view of the action and plenty of room to control main battery functions in the heat of battle. The 360-degree rotation of the turret also allows the M18 to engage targets in any direction without turning the entire vehicle around to counter the threat.

By contrast, other TD contemporaries used in the war had their guns mounted in fixed superstructures - requiring the entire vehicle to be aimed at the enemy. The M18 was versatile, tough and effective throughout the war, making it in many ways the best American tank destroyer in conflict and the proven war winner.

In combat operations with the M18, it traveled through the European countryside and its many villages to the German border. The new German Panther and Tiger I tanks displayed enviable armor protection and excellent artillery placements, but what they lacked was agility - an advantage of the M18 itself. The M18 could often maneuver and engage weaker side and rear armor (via "flanking" maneuvers) before German tanker crews rotated their turrets to counterattack. This helped the M18 crew to achieve excellent initiative and to some extent limit their losses on the battlefield.

The M18's 76mm main gun wasn't exactly unified, but it worked. The only German tank target that the M18 crew couldn't hit was the heavier Tiger II series - but few Allied tanks could stand up to this beast, and wartime Germany's shortage of fuel and resources was the biggest threat.

In July 1944, the US 630th Tank Destroyer Battalion provided no fewer than 53 Panther Medium and Tiger I Heavy Tanks in the ensuing battle. The group also managed to capture no less than 15 German self-propelled tracked vehicles during the same period.

Notably in these totals, only 17 Hellcats were killed by enemy actions or other factors. It was this kill/loss ratio that the M18 crew enjoyed as the war went on.

The development of high-velocity armor-piercing projectiles (HVAP) late in the war was only to make their 76.2mm guns more powerful and to increase their penetration value against German targets.

Like the M10 before it, the M18 continued to advance in its tank destroyer battalion until it became apparent that with the general progress in anti-tank combat, a dedicated tank destroyer was no longer needed. Future tank warfare will rely entirely on tank-to-tank combat, which itself does not require the intervention of specialized tank destroyers.

As a result, U.S. tank destroyers are increasingly being used as part of direct armored forces, rather than remaining in a reserve role, but entering into action when needed. This brings these units closer to the role of assault and self-propelled artillery, which function alongside infantry operations and are further supported by air cover.

The Allies enjoyed air superiority at the end of the war, which limited the range of German attacks, especially on clear days. The concept of a dedicated tank destroyer all but died out by the end of the war, and has since been eliminated from U.S. Army doctrine.

The success of the M18 hull and power system led the US Army to rapidly develop other useful battlefield roles for the type. A post-war development was the installation of a 150mm field howitzer on the M18 chassis to create the prototype "T88 Howitzer Motor Carriage". This self-propelled artillery platform was tested at the end of the war and never went beyond prototype stage production. The "90mm Cannon Motor Gun Carriage" attempted to mount a high-speed 90mm main gun on the M18's turret, but the end of the war stopped its progress. The "T41E1" prime mover and the "M39" fast infantry carrier were also developed - each without the turret of the original M18 - although the T41E1 was cancelled at the end of the war, and the M39 (more formally known as the "M39 Armored Multifunction") was also developed.

Vehicle ") ") built from about 650 examples, the M39 can carry up to 8 people, is equipped with 1 x 12.7mm Browning M2HB heavy machine gun for self-defense, and served in the upcoming Korean War, "T65 Flame "Tank" and "T86", "T86E1" and "T87" all failed to enter production. Other prototypes tested included a mobile command post.

The design of the M18 was very traditional, following the tracked vehicle practice common in the United States at the time. The power unit is installed in a compartment at the rear of the vehicle, and the drive sprocket is located at the front of the fuselage. Track idlers are set at the rear, and four track idlers manage the upper part of the track system by themselves.

There are five rubber tire wheels on each track side and little side armor for protection against direct side impacts. The turret was mounted amidships forward of the main guns and housed the long-barreled main guns sealed by double sliding muzzle brakes (used on the M1A2 guns). The sides of the hull superstructure have clean edges and slope inwards for ballistic protection. The open-top turret is elongated from the top profile and has an overhang at the tail for maximum internal loading.

The turret also features sloping sides and armored front panels for maximum protection within the required design weight constraints. The short-range heavy machine gun is mounted on a flexible ring mount at the rear of the turret, which can be operated by any turret crew.

The M18 is powered by a Continental R-975C 9-cylinder radial air-cooled gasoline engine rated at 340-400 hp. This gives the vehicle a top speed of 55 mph and a range of 150 miles. She had a crew of five, including a driver, a co-pilot, a full-time gunner, an ammunition handler and a tank commander. Primary armament is a 76mm (3in) M1A1 or M1A2 main gun and secondary armament - mainly for defensive purposes - is provided by a 12.7mm Browning machine gun. The main gun was developed from the main armament of the previous M10 tank destroyer, but improved.

The main gun of the M1A2 version is identified by its muzzle brake, which the M1A1 did not have. Machine guns are capable of targeting (or suppressing) enemy infantry, lightly armored vehicles, and low-flying attack aircraft. The aircraft carries a 45 x 76.2mm projectile, which may be a mix of armor-piercing (AP) and high-explosive (HE) ammunition types, to suit almost any need on the battlefield. Armor protection thickness is between 6mm and 25mm.

The car is 7 feet 9 inches tall and weighs 16.76 tons.

Surprisingly, the M18 Hellcat was still in service with the Yugoslav army in the early 1990s - a sign of either the excellent design of the M18 Hellcat series or the lack of modernization by the Yugoslav authorities. These M18s were fought by Serbia in the ensuing Yugoslav War. Taiwan became another postwar user of the genre, as did the rebuilt "Western" German army. The U.S.

Army M18 served from 1944 to 1957.

M18 Gun Motor Carriage (Hellcat) Specification

Basic

Year:
1943
Staff:
5
Manufacturing:
General Motors Corporation / Buick - USA
Production:
2,507 units

Roles

- anti-tank/anti-tank

Dimensions

Length:

6.65m

Width:

2.87m

Height:

2.58m

Weight:

41 tons (37,557 kg; 82,799 lb)

Performance

1 x Continental R-975 C-Series radial engine, 340-400 hp, driving a conventional track and wheel arrangement.

Performance

Maximum Speed:

55mph (89km/h)

Maximum range:

105 miles (169 km)

Armor

1 x 76mm main gun (M1A1 or M1A2), mounted in an open-top turret.

1 x 12.7mm Browning M2HB Heavy Machine Gun (HMG) (AA or Infantry) on the turret.

Ammo:

45x76mm projectile.

800x12.7mm ammo.

Changes

T49 GMC - first prototype; 57mm gun; torsion bar suspension.

T67 GMC - second prototype; 75mm gun

T70 GMC - third prototype; 76. 2mm gun

M18 GMC "Hellcat" - Production code for the base series.

M39 - High-speed APC or supply vehicle platform based on the turretless T41 design; 650 copies made.

T41 - M6 anti-tank gun/turretless personnel carrier.

T41E1 - Fast reconnaissance vehicle based on the turretless T41 design.

Heavy Artillery Tractor - proposed variant

Mobile command and communications rear car - proposed variant.

T65 Flame Pot - Flamethrower Conversion Model; upper hull modified to fit flame throwers.

T88 Howitzer Motor Carrier - Experimental 105mm howitzer platform; never produced.

90 mm CMGC - Gun motor mount for the 90 mm main gun; never produced.

T86 - Proposed amphibious howitzer tank; rail powered.

T86E1 - proposed amphibious howitzer tank; propeller for propulsion.

T87 - Proposed amphibious howitzer tank; 105mm T12 gun; rail powered.

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