M18 Hellcat

Infobox Weapon
name=76 mm Gun Motor Carriage M18


caption=
origin=USA
type=Tank destroyer
is_vehicle=yes
length=6.68 m (21.9 ft) (with gun)
5.28 m (17.3 ft) (without gun)
width=2.87 m (9.4 ft)
height=2.57 m (8.4 ft)
weight=17.7 tonnes (39,000 lb)
suspension=Torsion bar
speed=88 km/h (55 mph)
vehicle_range=168 km (105 mi)
primary_armament=1× 76 mm (76.2 mm) M1A1 gun
45 rounds
secondary_armament=1× .50 cal M2HB machine gun
800 rounds
armour=5 to 25 mm (0.2 to 1.0 in)
engine=Continental R-975-C4, 9-cylinder, radial piston gasoline engine
engine_power=340 hp (253 kW)
pw_ratio=18.9 hp/tonne
crew=5 (Commander, gunner, loader, driver, co-driver)

The 76 mm Gun Motor Carriage (GMC) M18 was an American tank destroyer of World War II. It was given the nickname "Hellcat" and is recorded as being the fastest tracked armored fighting vehicle during the war with a top speed of over 50 mph. The M18 was built by Buick.

History

In December 1941, the Ordnance Corps issued a requirement for the design of a fast tank destroyer using a Christie suspension, the Wright Continental R-975 engine and a 37 mm gun.

In the light of experience gained in North Africa, the 37 mm gun was found to be inadequate and the design was changed to use a 57 mm gun. During the development process, the design was further upgunned to a 75 mm gun, and then finally to the 76 mm gun. The Christie suspension requirement was also dropped and replaced with a torsion bar suspension. The design was standardized in February 1943 and production began in July 1943.

As a new design, the M18 incorporated several innovative maintenance features. The Wright R-975 engine was mounted on steel rollers, which permitted it to be disconnected from the transmission, rolled out onto the lowered engine rear cover, serviced and then reconnected to the vehicle. Similarly, the transmission could be removed and rolled out onto a front deck plate to allow repairs and inspection.

The T70 prototype for the M18 first saw combat at Anzio, Italy, and production versions of the M18 were used in North-West Europe and Italy from the summer of 1944 onwards.

In contrast to the M10 Wolverine, which used the chassis of the M4 Sherman, the M18 Hellcat was designed from the start to be a fast tank destroyer. As a result it was smaller, lighter and significantly faster, but carried the same gun as the Sherman 76 mm models. The M18 carried a five-man crew as well as 45 rounds of main gun ammunition and an M2 Browning machine gun on a flexible ring mount.The main disadvantage of the M18 was its very light armor and the inconsistent performance of its 76 mm gun against the frontal armor of later German designs such as the Tiger and Panther. The open-topped turret (a characteristic which it shared with the M10) left the crew exposed to snipers, grenades and shell fragments. The doctrinal priority of high speed at the cost of armor protection thus led to an unbalanced design. The problem of the main gun performance was remedied with High Velocity Armor Piercing (HVAP) ammunition late in the war which allowed the 76 mm gun to achieve greater frontal armor penetration, but this was never available in quantity.

While the M18 was capable of high road speeds this attribute was difficult to use successfully in combat, but along with the high top speed was a commensurate ability to accelerate rapidly and change direction at the drop of a hat.Cite Sm|Military Channel, Program "Tank Overhaul" 22:51, Wednesday 13 August 2008 (UTC) "Current hour EDST", mixed documentary with interviews of WW-II veterans.] Although sustained travel at road speeds was hardly ever used outside of the allied response during the battle of the Bulge, most Hellcat crews found the higher speeds especially useful in a sprint to flank German tanks which had relatively slow turret traverse speeds, and such maneuvering allowed the tank destroyer crew a shot instead into the enemy's thinner side or rear armor. Interviewed veterans described the vehicle's ride as very smooth and generally comfortable, much akin to a ski boat with its tendency to skid turn such that the rear of the vehicle would slide when taking a turn at speed. Aiding the analogy, in earthen terrain, the hellcat frequently threw up "rooster tails" of dirt and turf from the rear of its tracks very similar to a boat's wake. In general, Hellcat crews were complimentary of their vehicle's performance and capabilities, but did complain that the open top created a cold interior in the Northern European winter of 1944-'45.

The only M18 variant which was produced in significant numbers was the Armored Utility Vehicle M39, a turretless variation used to transport personnel or cargo or as a gun tractor. This version was armed with a single M2 machine gun on a flexible mount.

The M18 continued in production until October 1944, when the war was nearing its end. 2,507 had been produced by that time at a unit cost of $57,500. Though all tank destroyer units were disbanded by the U.S. after the war, surplus M18s continued to see limited service.

Combat Performance

The M18 served primarily in Western Europe, but was also present in the Pacific.

On September 19, 1944, in the Nancy Bridgehead near Arracourt, France, the 704th Tank Destroyer Battalion was attached to the 4th Armored Division. Lt. Edwin Leiper led one M18 platoon of C Company to Rechicourt-la-Petite, on the way to Moncourt. He saw a German tank gun muzzle appearing out of the fog 30 feet away, and deployed his platoon. After five minutes, five German tanks of the 113 Panzer Brigade were knocked out, with the loss of one M18. The platoon remained in their position and destroyed a further ten German tanks, with the loss of another two M18s. One of the platoon's M18s, commanded by Sgt Henry R. Hartman, knocked out six of these and lived to fight another day. Most of the German tanks were Panthers. [ "Tank Action" by George Forty P195.ISBN 0-7509-0479-8 ]

The M18 Hellcat was a key element during World War II in the Battle of the Bulge. [ Military Channel, Tank Overhaul, "The Hellcat", (2006), aired October 5, 2007, 10:00am MDT] The 705th Tank Destroyer Battalion was attached to the 101st Airborne Division in Bastogne. By the end of the battle, the 705th had destroyed 43 German tanks, with the loss of only 6 of their Hellcats. [ "M18 Hellcat Tank Destroyer 1943-97", Steven J Zaloga, Osprey Publishing 2004]

Post War

After WWII, many M18s were given to other countries. These were rebuilt and refurbished by Brown & Root in northern Italy in the late 1940s and early 1950s and bear data plates that indicate those rebuilds. A primary user was Yugoslavia, which used them through the early 1990s. Most of these vehicles were later used by the Republic of Serbian Krajina army during the Yugoslav wars. One example was used on an armored train named the "Krajina Ekspres" (Krajina Express).

Taiwan also operated several M18s until their chassis and hulls were worn out, at which point the turrets were salvaged and mated onto the hulls of M42 Duster self-propelled anti-aircraft guns to produce Type 64 light tanks.

Prototype variants

*105 mm Howitzer Motor Carriage T88: M18 with the 76 mm gun replaced with a 105 mm T12 howitzer; canceled after the end of the war.
*76 mm Gun Motor Carriage T86 (Amphibious): M18 with a specially-designed flotation hull, using its tracks for water propulsion.
*76 mm Gun Motor Carriage T86E1 (Amphibious): Same as T86, but with the addition of propellers for propulsion.
*105mm Howitzer Motor Carriage T87 (Amphibious): This model had the 105 mm T12 howitzer of the T88, and like the T86, used its tracks for water propulsion. All work on the three amphibious models was canceled after the end of the war.

References

External links

* [http://afvdb.50megs.com/usa/m18hellcat.html 76mm Gun Motor Carriage M18 (with photos) - AFV Database]
* [http://afvdb.50megs.com/usa/auvm39.html Armored Utility Vehicle M39 - AFV Database]
* [http://www.wwiivehicles.com/usa/tank-destroyers/m18.asp M18 Tank Destroyer, Hellcat - WWII Vehicles (photos and video)]
* [http://www.heraldextra.com/content/view/272309/17/ "WWII tank to join in parade" - "Daily Herald" (Utah), 3 July 2008]