M56 Scorpion

{{Infobox weapon

| name = M56 Scorpion

| image = M56 at AAF Tank Museum.JPG

| image_size = 300

| caption = M56 Scorpion preserved at the American Armored Foundation Tank Museum in Danville, Virginia.

| origin = United States

| type = Self-propelled gun

| is_vehicle = yes

| service =

| used_by = See Operators

| wars = Vietnam War
Western Sahara War

| designer =

| design_date =

| manufacturer = Cadillac Motor Car Division of General Motors

| unit_cost =

| production_date = 1953–1959

| number = 325

| variants =

| weight = {{convert|7.1|t|lb}}

| length = {{convert|4.55|m|ftin}} (excluding gun)
{{convert|5.84|m|ftin}} (overall)

| part_length =

| width = {{convert|2.57|m|ftin}}

| height = {{convert|2.05|m|ftin}} over gun shield

| diameter =

| crew = 4 (commander, gunner, loader and driver)

| armour = unarmored except for blast shield

| primary_armament = 90 mm M54 Gun
29 rounds

| secondary_armament =

| engine = Continental AOI-403-5 gasoline engine

| engine_power = {{convert|200|bhp|lk=in}}

| transmission = Allison CD-150-4, 2 ranges forward, 1 reverse

| payload_capacity =

| fuel_capacity = {{convert|210|L}}

| pw_ratio =

| suspension = Torsion tube over bar at wheels 1 and 4, torsion bar at wheels 2 and 3

| clearance = {{convert|0.32|m|abbr=on}}

| vehicle_range = {{convert|230|km}}

| speed = {{convert|45|km/h}}

| guidance =

}}

The M56 "Scorpion" self-propelled gun is an American unarmored, airmobile self-propelled tank destroyer, which was armed with a 90mm M54 gun with a simple blast shield, and an unprotected crew compartment.

History

The M56 was manufactured from 1953 to 1959 by the Cadillac Motor Car Division of General Motors for use by US airborne forces, though the vehicle was eventually used by the Spanish Navy Marines, Morocco and South Korea. With a crew of four (commander, gunner, loader and driver), the M56 weighed {{convert|6.4|t|lb}} empty and {{convert|7.7|t|lb}} combat-loaded. It had infrared driving lights but no NBC protection and was not amphibious.

The M56 was a fully tracked vehicle with rubber-tired run-flat road wheels and front drive sprocket wheels. It was powered by a Continental AOI-403-5 gasoline engine developing {{convert|200|bhp}} at 3,000 rpm, allowing a maximum road speed of {{convert|28|mph}} and a maximum range of {{convert|140|mi}}. Twenty-nine rounds of main gun ammunition were carried, and only the small 5 mm thick blast shield was armored.

In service

File:M56 SPAT during Operation Toledo 17 Jun 66.png firing at Viet Cong during Operation Toledo 17 June 1966]]

The M56 saw combat service with U.S. forces in the Vietnam War. It was deployed with the 173rd Airborne Brigade, which was the only Airborne Brigade deployed with the M56,{{cite book|url=https://books.google.com/books?id=TRLPt0ayfasC&q=173rd%20m56%20scorpion&pg=PA36|title=The US Army in the Vietnam War 1965-73|first1=Gordon L.|last1=Rottman|first2=Duncan|last2=Anderson|date=22 April 2008|publisher=Bloomsbury USA|via=Google Books|isbn=9781846032394}} where it was used mainly in a direct fire-support role. Its function as an air-mobile, self-propelled, anti-tank vehicle was eventually replaced in Vietnam by the troubled but effective M551 Sheridan which had a fully armored turret. The USMC used the M50 Ontos, which had an armored cabin and was armed with recoilless rifles, in a similar role (the running gear of the first Ontos prototype was the same as on the M56, but it was replaced for the production variant).

As for foreign operators, Morocco was the only export customer which used M56 Scorpions in actual combat. M56 Scorpions were deployed against Polisario rebels during the Western Sahara War. A number of examples were made available to South Korea but not used.{{citation needed|date=August 2018}}

Operators

=Former operators=

File:APC based on the M56 Scorpion.jpg

  • {{USA}}
  • {{ESP}}: 5 exported in 1965. Used by Tercio de Armada from 1966 to 1970{{sfn|Estes|2016|p=44}}
  • {{FRG}}: 1 for evaluation in 1960{{sfn|Estes|2016|p=46}}
  • {{MAR}}: 87 received in 1966-1967{{sfn|Estes|2016|p=44}}
  • {{ROK}}: 60 ex-American M56 were left as surplus but never used{{sfn|Estes|2016|p=44}}

{{-}}

Survivors

File:M56 Diorama of Destroyed M56 at AAF Tank Museum.jpg

File:M56 Culpeper.jpg

United States

South Korea

New Zealand

  • One example in M&M Military Vehicle Museum (Private Museum) under restoration.

See also

References

{{More citations needed|date=June 2017}}

;Notes

{{Reflist}}

;Bibliography

{{Refbegin}}

  • {{cite book|last=Foss|first=Christopher F.|title=Jane's Pocket Book of Tanks and Armored Fighting Vehicles|year=1974|orig-year=1972|publisher= Collier Books|id=LC Control No. 73-15286|page=153}}
  • {{cite book|last=Trewhitt|first= Philip|title= Armored Fighting Vehicles|year=1999|page=126 |publisher= Amber Books|location= New York, NY|isbn = 0-7607-1260-3}}
  • {{cite book|title=M50 Ontos and M56 Scorpion 1956–70: US Tank Destroyers of the Vietnam War|series= New Vanguard 240 |publisher=Osprey Publishing|first= Kenneth W |last=Estes|year=2016|isbn=9781472814739|url=https://archive.org/details/m50ontosm56scorp0000este|url-access=registration}}

{{Refend}}