Military Review

Airborne "Scorpion"

During the Second World War, there was a steady tendency to increase the caliber of anti-tank artillery. So, the American army entered the war with the 37-mm guns, and ended it with the guns 76 and 90 mm. The increase in caliber inevitably entailed an increase in the mass of the gun. For infantry divisions, this was not critical (it was necessary only to introduce more powerful tractors), but the situation was different in the airborne units.

The lessons of the Arnhem operation, during which the British paratroopers had to fight with the German tankswere taken into account by the American command. Since 1945, the U.S. airborne divisions received the 90 mm T8 anti-tank gun, which is the barrel of the 90 mm M1 anti-aircraft gun, combined with anti-recoil devices of the 105 mm M2A1 howitzer and a lightweight gun mount. It turned out to be a 3540 kg gun, suitable for parachute landing from S-82 Pekit aircraft, but problems started on the ground: the crew could not move such a heavy system across the battlefield. A tractor was needed, which means that the number of military transport flights doubled aviationrequired for the transfer of an anti-tank battery (division).

The solution could be the creation of a compact self-propelled anti-tank guns. For the first time such an idea was expressed in October 1948 at the conference in Fort Monro, devoted to the prospects for the development of anti-tank weapons, and in April of the following year the customer introduced tactical and technical requirements. The main one was the mass, which should not exceed 16 000 pounds (7260 kg) - the load capacity of the Packet and the heavy landing glider developed at that time (but never accepted for service).

The development of an airborne tank destroyer was entrusted to Cadillac Motor Kar, which was part of the concern General Motors. The chassis design was based on solutions tested on the Otter M76 amphibious tracked carrier. Due to the limited dimensions of the cargo compartment of the aircraft, the self-propelled gun could not be supplied with a wheelhouse, not to mention the roof - I had to confine myself to a small gun shield. The latter was intended to protect the crew from the powder gases when fired, but not to protect against bullets or shrapnel.

The first prototype T101, top view.
Estes KW M50 Ontos and M56 Scorpion 1956-70. - Oxford: Osprey Publishing, 2016

The prototype, which received the T101 index, was ready in 1953 year. Two years later, the car successfully passed military tests in Fort Knox, and it was put into service under the designation M56 Gun Self-Propelled Anti-Tank - “MXXUMX self-propelled anti-tank gun”. The widely occurring name "Scorpion" was approved in 56, the less common was the unofficial name "Spat" (from the abbreviation SPAT - Self-Propelled Anti-Tank). Series production МХNUMX lasted from December 1957 to June 56, its volume amounted to 1957 units.


The M56 self-propelled gun is an unarmoured small-sized tracked combat vehicle adapted for parachuting from a C-123 Provider and C-119 Flying Boxcar (and, of course, from heavier military transport planes) and for transporting helicopters on an external hanger. The car body is aluminum welded, the crew consists of four people.

The crew M56 was placed openly.
Estes KW M50 Ontos and M56 Scorpion 1956-70. - Oxford: Osprey Publishing, 2016

Engine-transmission compartment with a six-cylinder opposite four-cycle carburetor engine of air cooling "Continental" AOI-402-5 with a capacity of 165 l. with. and the Allison manual gearbox CD-150-4 (two gears forward and one reverse) is located in the front of the M56 body. The rest of the space is occupied by the combat compartment, combined with the control compartment. In the center of it on the thumb knot of the M88 there is an 90-mm gun M54. To the left of the gun there is the driver’s workplace (for him, in the gun shield there is a glazed window with a windshield wiper- “janitor”), to the right is the gunner’s place. Behind the driver-mechanic is placed the commander, behind the gunner - loader. At the stern of the machine is an ammunition on 29 unitary shells. For the convenience of the loader behind the ammunition there is a folding step.

The second prototype T101, rear view. Well visible ammunition unitary shots to the gun.
Estes KW M50 Ontos and M56 Scorpion 1956-70. - Oxford: Osprey Publishing, 2016

Chassis self-propelled consists (with respect to one side) of the four large diameter rollers with a torsion bar, equipped with pneumatic tires. Tires have special tabs that allow, if they break through, drive to 24 km (15 miles) at speeds up to 24 km / h. Drive wheel - front location. Caterpillars are rubber-metal, 510 width mm. Each caterpillar consists of two bands made of rubberized fabric and reinforced with steel cables. The tapes are interconnected by steel forged crossbars with rubber pads. The ground pressure of the Scorpion is only 0,29 kg / cm2 (for comparison: for М47 and М48 tanks, this indicator is 1,03 and 0,79 kg / cm2, respectively), which ensures good machine maneuverability.

Installed on the "Scorpion" 90-mm gun M54 (barrel length - 50 caliber) was developed on the basis of the gun M36, used on tanks M47. Compared with the prototype, it is lightened by 95 kg. The range of pickup angles in the vertical plane is from −10 ° to + 15 °, in the horizontal one - by 30 ° to the right and left. The barrel of the gun is a monoblock with a screw breech and a single-section muzzle brake. The wedge gate, semi-automatic, vertical. On top of the breech of the gun are mounted two cylinders of hydraulic recoil devices. Guidance guns have hand drives, manual loading. The gun is equipped with a M186 telescopic sight with variable magnification (4-8-multiple).

The range of used ammunition is quite wide and includes all types of unitary shots for tank guns M36 and M41; It is also allowed to use 90-mm projectiles of anti-tank guns of the German company "Rheinmetall". To solve the main task - fighting tanks - can be used: M82 armor-piercing-tracer with an armor-piercing tip and a bursting charge; M318 (T33E7), M318A1 and M318A1C armor-piercing tracer without explosive charge; armored piercing tracer shells M304, М332 and М332А1; M348 (T108E40), M348A1 (T108E46) and M431 (T300E5) cumulative non-rotating (fired) shells. In addition, the ACS can fire the M71 high-explosive fragmentation projectile, the M91 fragmentation-tracer, the M336 framing, the M377 fragmentation (with swept striking elements) and the MNNXX smoke.

The machine is equipped with a VHF radio station AN / VRC-10, which is served by the commander. The means of night observation are represented only by a helmet-mounted night vision device of the driver.

Prototype of a self-propelled mortar on the M56 chassis.
Estes KW M50 Ontos and M56 Scorpion 1956-70. - Oxford: Osprey Publishing, 2016

On the basis of the M56, two experimental self-propelled guns were created. In 1958, an anti-tank ACS was tested at Fort Benning, where instead of 90-mm guns, they installed 106,7-mm no recoil М40 - with transportation of such weapons the usual jeep coped easily, so they did not accept it. Another self-propelled gun, also not included in the series, was armed with an 106,7-mm mortar M30. On paper, there are also options for reequipment of the M56 SS-10 and Entak anti-tank guided missiles.

Service and combat use

According to the original plans, each of the three US airborne divisions (11-i, 82-i and 101-i) was to receive a scorpion battalion (53 machines in each). But the adoption of the M56 into service coincided with the reorganization of the infantry and airborne divisions - transferring them from the usual "threefold" to the "pentom" structure. Now the division did not include three regiments, but five combat groups — essentially, reinforced infantry (airborne) battalions. As a result, the "Scorpions" entered service with anti-tank platoons that were part of the company’s headquarters of the airborne combat groups (VDBG). This platoon included control (platoon commander (lieutenant), his deputy (sergeant) and radio operator with a jeep equipped with AN / VRC-18 radio station) and 3 fire sections (in each 8 man and 2 self-propelled M56 self-propelled guns). Thus, the platoon consisted of 27 man of personnel, 6 "Scorpions" and 1 jeep.

ACS M56, prepared for parachute landing.
Estes KW M50 Ontos and M56 Scorpion 1956-70. - Oxford: Osprey Publishing, 2016

"Scorpion" could be transported on the external suspension of a heavy transport helicopter H-37 "Mojave".
Estes KW M50 Ontos and M56 Scorpion 1956-70. - Oxford: Osprey Publishing, 2016

In the first half of 1958, platoons of the Scorpions were formed in fifteen airborne combat groups, five in each division. However, already in July 1958, the 11 th WDD was disbanded - two of the WDBGs from its composition, together with the regular М56, were transferred to the 24 th Infantry Division, but in January 1959 were transferred to the 82 th subordinate. The latter transferred two of its VDBG to the 8 Infantry Division. Finally, in June 1960, one combat group from the 82-th Airborne Division was transferred to the 25-Infantry Division, and in order to complete the 82-th division, one of the VDBGs disbanded in 1958 was restored. A number of “Scorpions”, which turned out to be superfluous for the airborne combat groups, were sent to the infantry combat groups of the 1 Infantry Division in Germany, as well as the 1 Cavalry and 7 Infantry Divisions in the Republic of Korea.

SAU M56 from the 101-th Airborne Troops at the exercises. Under the breech of the gun one can see the sleeves of single shots. Fort Campbell, April 1960 of the year.
Estes KW M50 Ontos and M56 Scorpion 1956-70. - Oxford: Osprey Publishing, 2016

Airborne "Scorpion"

M56 self-propelled guns from the 1 Fighting Group of the 16 Infantry Regiment of the 1 Infantry Division during exercises in the Federal Republic of Germany. February 1961 of the year.
Estes KW M50 Ontos and M56 Scorpion 1956-70. - Oxford: Osprey Publishing, 201

In 1961, the “pentamic” structure was declared untenable and unsuitable for conducting combat operations in non-nuclear conflicts, and the US Army began another reorganization. In accordance with it, the airborne division consisted of three brigade headquarters and nine airborne battalions, as well as support units, including a tank battalion. It was assumed that he would receive new airborne tanks МХNUMX "Sheridan", but as a temporary measure (until the Sheridans were put into service) tank battalions 551 and 82 airborne troops in 101 were handed over 1964 "Scorpions" - machines, not not only tanks, but not having any reservations. They did not allocate funds for the maintenance of the crews of these vehicles, so until the receipt of the Sheridans these battalions remained “virtual”.

The only armored division that exploited the Scorpions and fought on them was the D 16 Tank Regiment Company (D-16), which was formed in 1963 as part of the 173-th Separate Airborne Brigade (VDBr) deployed on Okinawa Island. The company consisted of four platoons of four M56, a control section (four BTR MNNUMX) and a mortar section (three 113-mm M106,7 self-propelled mortars on the M106 chassis).

Self-propelled guns M56 company D-16 in Vietnam.
Estes KW M50 Ontos and M56 Scorpion 1956-70. - Oxford: Osprey Publishing, 2016

In May 1965, the 173 th WDBr was transferred to Vietnam. During the war, the strengths and weaknesses of the M56 were clearly manifested in the jungle. On the one hand, the good maneuverability of the self-propelled gun made it possible to move along “tank-inaccessible” terrain, on the other - for the 90-mm gun there were few suitable targets. The main task of the Scorpions was the direct support of the airborne battalions and companies operating on foot, and here the most serious shortcoming of the M56 - the complete lack of booking - was extremely acute. The events that took place on 4 March 1968 of the year became a drop that broke the patience of the paratroopers, when a company lost a 8 man in one battle. After that, the “tank crews” of the D-16 changed their M56 to more universal and much better protected M113 armored personnel carriers.

"Scorpions" of the Spanish marines at the parade in Madrid. 12 October 1967 of the year.
Estes KW M50 Ontos and M56 Scorpion 1956-70. - Oxford: Osprey Publishing, 2016

After the American army was decommissioned, part of the M56 self-propelled guns went to the warehouses, and some were transferred to the Allies. Spain received five vehicles in the 1965 year - until the 1970, they served in the anti-tank platoon of the marines. Neighboring Morocco in 1966-1967 was given 87 Scorpions. According to the Jaynes World Armiz reference book, in 2010, the Moroccan army had 28 M56 self-propelled guns in storage.

Moroccan "Scorpions" participated in the fighting in Western Sahara.

In 1960, two T101 prototypes, modified to the M56 serial standard, were handed over to the Federal Republic of Germany. The Germans were not seduced by an unarmored car and did not accept it. After a short test, both copies were converted into training machines for the training of driver-mechanics, removing the guns and installing glazed cabins.

Т101, converted into a machine for the training of drivers.
Omelyanyuk P. "Scorpion" - self-propelled gun for landing // Arsenal collection. - 2013. - №5

A number of retired М56 acquired the American fleet. The machines were converted into radio-controlled targets QM-56 and in 1966-1970 they used Fallon, Warren Grove and Cherry Point for combat training of attack aircraft pilots and fighter-bombers.

Overall rating

The M56 self-propelled gun had good mobility and powerful armament for its time. The cumulative shells of her 90-mm guns could surely hit any Soviet tanks of the first half of the 60-s. At the same time, the gun was too powerful for a seven-ton chassis, the front rollers of which, when fired, were taken off the ground. In addition, the absence of any reservation allowed the use of self-propelled guns against tanks only in defense (from ambushes), making the Scorpion unsuitable for supporting the assault in offensive operations.

Compared with the Soviet counterpart - the airborne self-propelled installation of the ACS-57 - М56 is more than twice as heavy (7,14 t against 3,35 t). In addition, the ACS-57 is smaller than its counterpart (its height is only 1,46 m versus 2 m) and, unlike the Scorpion, has a reservation at the front and sides, however, its thickness (4-6 mm) at a short distance did not even provide protection from conventional 7,62-mm bullets. As for weapons, the superiority of the M56 was overwhelming: the muzzle energy of its 90-mm M54 cannon was 4,57 MJ, and the 57-mm H-51 cannon mounted to ASU-57 was only 1,46 MJ. The parameters of mobility (speed and power reserve), both self-propelled guns were approximately equivalent.

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  1. andrewkor
    andrewkor 11 February 2018 06: 52
    It is strange that having developed airborne forces with rich combat experience and a powerful military-industrial complex, the Americans did not further develop the topic of increasing the mobility and firepower of a landing party. Were these questions really not raised by the military? In my opinion, everyone rested on the concept of using airborne forces: to capture and hold an object, a piece coast, mobility is not needed. On the other hand, this ACS is on the defensive in autumn even by the way!
    1. Cat
      Cat 11 February 2018 08: 48
      Why? Quite the opposite, the Sheridan tank, which was a "reaper, a swimmer and a pipe dude", was adopted for Scorpio! Especially on paper TTX: could swim, transported by air, even landing. In addition, he had a super-duper 152mm gun launcher. True, she buried him.
      1. andrewkor
        andrewkor 11 February 2018 11: 00
        And after the funeral, in general, a good device, the commemoration was delayed. The Americans developed a lot of light armored vehicles, so where is it, in particular in the airborne forces?
    2. tchoni
      tchoni 11 February 2018 11: 27
      Quote: andrewkor
      Really these questions were not raised by the military?

      They rose, I think) They only decided more pragmatically. Unlike our "Uncle Washi’s troops", parachuted and air raids on the rear of the rear by forces of the division, the Americans very early came to the conclusion that mass landings were impossible and unnecessary and, accordingly, reviewed the role and place of the Airborne Forces in real life. They left two divisions 101 and 82, sharpened for parachute operations (such as seizing airports and other bridgeheads for deployment), and the remaining tasks were assigned to light, air transport units equipped with conventional land equipment
      1. Chicot 1
        Chicot 1 11 February 2018 13: 53
        Quote: tchoni
        Unlike our "Uncle Vasya’s troops"

        Quote: tchoni
        decided more pragmatically

        However, quite recently, in the 82nd Airborne (if memory serves), the 25th Bench was testly thrown from the Globe. And it should be noted, in contrast to the notorious “Hammer,” they threw it quite successfully for themselves ... True, the cannon was removed from the “bench” before landing. After they set ...

        Why would this be? .. I'm not talking about a cannon, I'm talking about experiments that periodically occur on the endless expanses of the North American continent with parachuting technique ... Does pragmatism go away? .. Or do they also want to have Uncle Vasya’s troops as an adult ?. .
        1. tchoni
          tchoni 11 February 2018 14: 36
          And why don’t they throw shops at them? Judging by the film "The Man from the Capuchin Boulevard" - a job quite worthy for a cowboy))))) laughing
          They threw “sheridans” in due time, and with guns, howitzers, mortars, I am silent about hammers vashpe)))
          This is exactly the same programmatic approach: you need to be able to do everything, use only the useful.
          In our Airborne Forces, on the contrary, until recently, land equipment was absent as a class. What happened sideways during the establishment of constitutional order in Ichkeria. For the technique, adapted for parachute landing, suddenly turned out to be poorly adapted for urban combat (the luminous armor of the Hoyosho burns even from the Molotov cocktail, and it breaks through quite well), prolonged combat operations (all kinds of BMD och marches are contraindicated). Thank God now the situation has begun to change)))
          1. Chicot 1
            Chicot 1 11 February 2018 15: 28
            Quote: tchoni
            just the very programmatic approach: you need to be able to do everything, use only the useful

            I agree ...
            Quote: tchoni
            In our Airborne Forces, on the contrary, until recently, land equipment was absent as a class

            Still was present. But with its own specifics ...
            Quote: tchoni
            equipment adapted for parachute landing suddenly turned out to be poorly adapted for urban combat

            In fact, any armored vehicles are poorly adapted for military operations in a settlement. Which in the end has recently led to the creation of experimental "city tanks". The direction is certainly interesting, but whether it will give any real results is unknown ...
            Quote: tchoni
            hoyosho's luminous armor burns even from the Molotov cocktail, and it breaks through quite well

            It burns well with non-luminous armor from the “lighter”. And makes its way. For there is nothing absolutely invulnerable and the whole thing is the choice of means of destruction ...
            Quote: tchoni
            prolonged hostilities (all kinds of marches BMD Pts contraindicated

            And what else to expect from a car, essentially designed for 15-20 minutes of modern combat? ..

            I’ll say the hackneyed phrase, but all these are the consequences of the strategy of a big jerk to the English Channel ... However, it is worth saying that the designers coped with the task brilliantly. And I don’t think that someone would do better. And in principle, the Americans with their experiments proved it well ... Yes, and the Germans "Wiesel" is by no means a masterpiece ...

            Quote: tchoni
            now the situation has begun to change

            I would not say that something is changing dramatically. The BMD-4M and the Octopus, which are the continuation of the BMD-1/2 line, go to supply the troops ... And the plans for re-equipping the assault units with tanks look a bit odd, against the background of the presence of tank troops, as such ...
            Well, yes, however, they are much more visible at headquarters. Let them do what they wish, if only it would benefit ...

            Quote: tchoni
            And why don’t they throw shops at them? Judging by the film "The Man from the Capuchin Boulevard" - a job quite worthy for a cowboy)))))

            "Shop" in the studio! .. fellow True, without a gun ... lol
            1. would
              would 11 February 2018 16: 16
              In fact, any armored vehicles are poorly adapted for military operations in a settlement. Which in the end has recently led to the creation of experimental "city tanks"

              Which are nothing more than ordinary MBT, but with an additional reservation in which there is nothing supernatural. Well, except that a bulldozer knife is attached, but this is very controversial. At the same time during the Chechen wars, the city’s MBTs were absolutely not urban, but the protected DZ could easily keep more than one hit from the RPG that the militants had. A BMD will burn (or rather burned) from the first.

              So there may be “any armored vehicles are poorly adapted for military operations in a settlement”, but the BMD is not adapted for such a battle much stronger than existing MBTs at least, even significantly stronger than some modifications of the BMP and even the BTR-80 (meaning BTR- 80RE).
      2. andrewkor
        andrewkor 11 February 2018 15: 06
        So I'm talking about different concepts of the use of airborne forces in the United States and the USSR.
  2. kipage
    kipage 11 February 2018 07: 45
    Interesting article
    1. Cat
      Cat 11 February 2018 08: 55
      How to remove the language! Today is sincerely pleased with the selection and quality of articles and materials. For which I sincerely thank the authors, editors and moderators of VO.
      Sincerely, Kitty!