American PT-ACS since the war (part of 2) - M18 Hellcat

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M18 Hellcat (English witch) - 76 mm self-propelled artillery fighter class tanks times of the second world war. This American tank destroyer is light in weight, unlike most self-propelled guns of that time, was created not on the basis of the tank, but on a specially designed chassis. For all the time of mass production from July 1943 to October 1944, 2507 self-propelled guns left the factory workshops. During the war, self-propelled guns were actively used by Americans in the years 1944-1945 in battles in Italy and in North-Western Europe. Shortly after the war ended, the M18 Hellcat tank destroyer was decommissioned by the U.S. Army, but was used in other countries for a long time. As of 2007, there were 8 and 75 M18 Hellcat in South Korea and Venezuela respectively.

History create

At the very beginning of World War II, the US military was heavily inclined to develop a light highly mobile tank destroyer. 2 December 1941, the General Staff sent a memorandum to the G-4 department recommending the creation of a tank destroyer with an 37mm gun and Christie suspension. Guided by this concept, the 8 December 1941 Ordnance Department published a recommendation to develop a tank destroyer that would have high speed, Christie suspension, and an 37-mm gun.

Enterprise General Motors Buick Division received an order for the release of 2-x pilot models of ACS. Meanwhile, by the spring of the 1942, the Ordnance Department (Artillery Department) conducted an analysis of the fighting of the British army in North Africa and came to the idea of ​​installing a more powerful 57-mm anti-tank gun on the SAU. 18 April 1942 was agreed to create 2-x prototypes, called T49 Gun Motor Carriage. Future PT-ACS should have high mobility with a weight of about 12 tons, speed at the level of 50 miles / h, crew in 5 people. Reservations for the turret, forehead hull and sides should have been 7 / 8 inches, and the bottom and top of the hull should be 3 / 8 inches.
American PT-ACS since the war (part of 2) - M18 Hellcat

By the middle of 1942, the 2 of the first T49 GMC prototypes were ready. In July, 1942 began testing self-propelled guns at a special site in Aberdeen. It turned out that the T49 could not develop a given speed, but the car’s suspension showed itself quite well when driving on rough terrain. Despite this, the work on the car were curtailed, because again there was a need to strengthen the armament of the machine. The self-propelled gun was planned to install 75-mm gun, created for the tank M4 Sherman.

The second prototype of the machine with the new instrument received the designation T67 GMC. For placement on the ACS 75-mm guns decided to borrow the tower from the T35 GMC, this tower was round with an open top. The frontal part of the car was changed, the course machine gun disappeared from here, the reservation of the hull's forehead was brought up to an inch, the bottom and upper horizontal surfaces, as well as the stern and sides of the self-propelled guns were made thinner opposite.

In November, 1942 began testing T67 GMC at the same Aberdeen Proving Ground. The tests demonstrated that the car was a success, but it needs a transition to a torsion bar suspension, as well as the replacement of the power plant with a more powerful engine. The first and second prototypes were equipped with two Buick 330 hp carburetor engines, but the car went into the series with a radial 9-cylinder carburetor air-cooled engine with a power 400 hp. Upon completion of the tests, the T67 GMC was recommended for standardization, but the military again intervened and asked to replace the 75-mm cannon with a new 76-mm M1 gun. The new gun was distinguished by the best armor-piercing characteristics, which for the tank destroyer had one of the most important values.

In January, 1943, General Motors received an order for the production of 6 pilot machines of the new modification which received the designation T70 GMC. The first prototype was ready in the spring of 1943. The car was equipped with a radial engine Continental R-975-C1. For the sake of better balancing, the 900T Torqmatic transmission was moved forward, an individual torsion suspension was used. The two front and final track wheels of the vehicle chassis were equipped with shock absorbers. In order to keep track of the tracks when moving over rough terrain, the engineers equipped the guides and drive wheels with track tension compensators. Another notable technical solution was the installation of the engine and transmission on special rails, on which in case of repair or dismantling they could easily roll out. The body and turret of self-propelled guns were made of rolled homogeneous armor, the front of the tower was cast, the connection of the elements of armor was carried out by welding.

The T70 GMC prototypes passed combat tests in Italy and in February 1944 were standardized under the designation M18 Gun Motor Carriage. This PT-ACS received the unofficial designation "Hellcat" (witch). Total General Motors Buick Division produced 2 507 PT-SAU M18 at 57 500 dollars per unit.

Project Evaluation

American PT-ACS were defensive weapons. But the M18 could not be used to support the advancing infantry. She had very weak armor, which at close range could even break through with shrapnel or 7,62-mm armor-piercing bullets. Also, the self-propelled gun did not have a machine gun installed in the hull and paired with a gun. Its tower had an open top, which certainly improved visibility, greatly simplifying the task of tracking the enemy during the battle. At the same time, the open tower made the crew of the vehicle vulnerable to enemy mortar and artillery fire, as well as enemy infantry in melee combat. All of this spoke of the narrow role of the PT-SAU М18 - the hunt for enemy tanks from ambushes.

The most outstanding feature of the car was its speed. The self-propelled cruising speed was more than 70 km / h, and the maximum, according to some evidence, even reached 95 km / h. M18 crews compared driving ACS with driving a racing car. Such an outstanding speed strengthened the crew’s faith in surviving combat with fairly slow German cars.

The crew of the PT-ACS M18 consisted of 5 people. The driver was located in the car body on the left, next to the transmission, the driver's assistant was in the front right. The commander of the SAU was in the left rear of the tower, the gunner in the left front part of it, and charging in the right side of the tower.

The pre-production versions of the self-propelled guns were armed with the 76-mm M1 cannon, the serial modifications of the self-propelled guns were armed with the M1А1, М1А1С and М1А2 guns, while the first two guns were almost identical. М1А1С differed by the presence of a thread at the end of the barrel to install the muzzle brake. The M1А2 besides this was distinguished by modified barrel cutting, which gave the projectile greater stability and slightly increased armor penetration. All guns used the same projectiles - PC-T M62 and HVAP-T M93. The first of these had an initial speed of 790 m / s, the second - 1040 m / s. The ammunition of the gun consisted of 45 shots, 9 of them was located in the right front corner of the machine, the rest were distributed among the sponsors of the self-propelled gun body. As a defensive armament used 12,7-mm machine gun МХNUMXНВ, mounted on the rear left side of the tower.

In the troops PT-SAU M18 Hellcat almost immediately fell in love for the convenience of operation and maintenance, as well as reliability. The transmission and the engine, if necessary, could be replaced in record time, and the high speed of movement even over rough terrain along with a fairly low silhouette added to the machine survivability in battle. M18 Hellcat entered into service with the anti-tank battalions of the infantry and tank divisions of the American army, sometimes the ACS served as an artillery tractor or reconnaissance vehicle.

Despite this, the role of the tank destroyer M18 Hellcat was not convincing enough. Even at the stage of prototyping, its armament evolved from 37 to 76-mm guns, but the increase in the power of the gun did not correspond to the ever-increasing booking of German tanks. Initially, the 76-mm gun was created as a weapon of high armor-piercing, but its creation was fully influenced by uncertainty, bureaucratic confusion and the inferiority of the American concept of the development of tanks and their guns.

In the American army, it was widely believed that for a gun, the survivability of the barrel was a more important criterion than broken penetration. Guided by this principle, the prototype 76-mm guns were shortened from 57 to 52 calibers, however, it was assumed the use of a small powder charge - 3,6 pounds. For comparison, the English 17-pdr. the gun with a barrel length in 55 calibers used a powder charge weighing 9 pounds. According to its armor-piercing characteristics, the English 76-mm cannon surpassed even the famous German gun 75mm KwK 42. In an effort to increase the life of the gun, the Americans were satisfied with the pressure of the powder gases in the gun chamber in 38.000 psi, while in the long-barreled German KwK 42 the pressure was 48.000 psi. High gas pressure during the shot led to rapid barrel wear, but the Germans and the British reasonably believed that if a tank was destroyed, then it simply would not need a long tool life.

It is safe to say that the 76-mm gun M1A1 PT-SAU M18 Hellcat was poorly suited to combat the enemy's heavy tanks and the new Panther medium tanks. In order to remedy this situation, the tungsten HVAP (High Velicity Armor Piercing) tungsten sabot shells appeared in the army in 1944, which had fairly good armor penetration. But in the troops of these munitions was not enough, but at great firing distances they gave a high dispersion and did not radically change the situation. Taking into account the rather low-power cannon and weak booking, the crews of the M18 Hellcat self-propelled guns used the hit and run tactics (hit and run). In general, this tactic justified itself, as the M18 Hellcat had more victories over the enemy than losses.

Performance characteristics: M18 Hellcat
Mass: 17,7 t.
Dimensions:
Length 6,655 m., Width 2,87 m., Height 2,565 m.
Crew: 5 people.
Reservations: from 5 to 38 mm.
Armament: 76,2-mm threaded gun M1A1
Ammunition: 45 shots
Engine: radial 9-cylinder carburetor air cooling, power 400 hp
Maximum speed: on the highway - 72 km / h
Power reserve: on the highway - 160 km.

Used materials sites:
www.vn-parabellum.com/us/m18-art.html
www.rus-wot.ucoz.ru/publ/tanki_ssha/protivotankovaja_sau_m18_quot_hellcat_quot/9-1-0-68
www.weltkrieg.ru/tanks/1090-m18-hellcat.html
www.all-tanks.ru/content/samokhodnaya-artilleriiskaya-ustanovka-m18-hellcat
www.aviarmor.net/tww2/tanks/usa/spg_m18_hellcat.htm
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5 comments
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  1. +1
    21 March 2012 09: 27
    That's where Hamer's legs grow ...
  2. +3
    21 March 2012 09: 43
    World of Tanks will have a Firefly PT Yes
  3. 755962
    +1
    21 March 2012 10: 56
    Radial 9-cylinder air-cooled carburetor. Greetings from aviation wink
  4. AlexMH
    +1
    21 March 2012 11: 59
    The Su-76 is similar in parameters (except for the tower and speed). But ours used mainly for long-range support of the infantry ..
    1. +2
      21 March 2012 21: 07
      AlexMH, used to be used in tank battle formations !!! and direct fire !!!

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