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Self Propelled Howitzer (SPH)

M3 75mm
M109A6 Paladin
M109A7 Paladin
M2001 Crusader
M2002 RSV


Traditionally the main difference between a gun and a howitzer was both the arc of the round, and the length of the barrel relative to the bore of the barrel. A howitzer would have a barrel length 15 to 25 times the caliber of the gun, while a cannon would have a barrel more than 25 times the caliber of the gun. Howitzers were generally medium range, medium muzzle velocity, medium curved trajectory, between 20 and 30 calibers in barrel length. Napoleon III of France use the Gun-howitzer term in 1850 to describe shell amnunltion which was designed to fire at a high muzzle velocity to combine the best features of the gun and howitzer in one all-purpose weapon. Modern artillery has largely dispensed with these distinctions, as all have long barrels and fire rounds on lofted trajectories. The M777 Howitzer might be called a “gun-howitzer” because it has long barrel (like a cannon) and can be used in direct and indirect fire. Self-propelled guns (SPG) could be considered "gun-howitzers" because they are capable of direct fire (like a tank) and indirect fire (shooting at stuff beyond view range).

The self-propelled howitzer is mainly used to provide survivable and highly mobile fire support for armor and infantry troops. Self-propelled tube artillery are large howitzers mounted on tracked vehicles, less armored than tanks, but providing some crew protection. Modern vehicles provide 360 degree ballistic protection for the crew compartment, as well as overhead burst protection. They are supported by other tracked vehicles carrying additional ammunition. The latest versions provide more mechanization for moving and loading the heavy shells.

Field artillery batteries and sections may be stationary at "fire bases" in some low-intensity or static combat scenarios. But in "high-tech" combat, they must be highly mobile, whether to keep close behind the moving armor or to avoid the enemy's own counter-battery fire. Modern radars can locate the source of artillery fire quickly, perhaps even before the shells ("rounds") have landed. The addition of global positioning devices and on-board, interactive computers to the most modern howitzers or rocket launchers greatly increases their ability to "shoot and scoot" - to stop, fire rapidly at a mathematically determined location, and move elsewhere. Without this enhancement, emplacing the battery is a very deliberate and precise process.

Counterfire continues to be the greatest threat facing the artillery. Dispersion, hardening, and movement are techniques used to survive the counterfire threat; but those techniques should not be used in isolation. Dispersion is the least expensive method in terms of effort and time. Platoon installations, howitzers, fighting positions, and so forth should be no closer than 50 meters from each other, should not be on line, and should present a deceptively larger element. If the ground threat or the terrain makes wide dispersion of the battery or platoon elements impractical, hardening the position will greatly increase survivability. Fighting positions with adequate overhead cover for crew-served weapons and individual soldiers must be prepared and continuously improved. Gun pits for towed howitzers, and hull-defilade positions for self-propelled weapons substantially increase the ability of the unit to survive and continue the mission. Unplanned movement to an alternate position denies the maneuver force the amount of FA support it requires; it may increase the number of casualties.

Towed artillery crews might hesitate to fire their weapons and expose themselves to counter-battery fire. A self-propelled artillery system could fire a salvo, and then rapidly move to avoid counterbattery fire. The ability quickly move to another location increases the survivability against enemy counter-battery fire. Artillery fired scatterable mines are an effective way to prevent the displacement of enemy artillery once targeted for counter battery fire. Artillery and mortar batteries might establish two or three firing positions (located 600-800 meters apart) within each temporary firing position. After firing a mission, the battery would rapidly displace to avoid enemy counter-battery fire.

World War II witnessed artillery developments in response to the need to defend itself against armor and air attack. The result was the self-propelled artillery gun. These guns, often reaching 8-inch or 122 millimeter caliber, were mobile artillery mounted on tank chassis. Self-propelled artillery came in two forms: the assault gun and the light assault gun. The War spawned the development of the M-7 self-propelled artillery piece and the M-8 assault gun, both of which became potent forces in armored tactics.

The common field artillery weapon in Vietnam was the 105-mm, howitzer used in World War II and Korea; however, several carriages were used -- a low profile lightweight carriage for airborne units, the standard carriage used during World War II and Korea for infantry divisions, and the improved self-propelled carriage for mechanized units. Three batteries of self-propelled 155-mm howitzers and one battery of self-propelled 8-inch howitzers were assigned at division level and additional 155-mm and 8-inch howitzers and self-propelled 175-mm guns at corps level.

The M110A2 is a heavy self-propelled artillery piece designed to provide general artillery support to ground troops and close general support to armored columns, and was built in the early 1960's. It is highly mobile and maneuverable, and can be airlifted in large cargo aircraft. The gun is an 8" Howitzer traversing in it's own mount at the rear of the vehicle. The large spade at the rear is required for the massive recoil. It is hydraulically raised and lowered, and keeps the vehicle in place when the gun is fired. With a range of 20 miles, it has pinpoint accuracy. Being mounted on a tracked chassis allows it to support infantry or armor in nearly all terrain conditions. This diesel powered chassis is used for two other vehicles one of which is the M578. It uses a crew of five men, weighs 52,600 lbs, and had a top speed of 34 mph.

The M109 155mm self-propelled howitzer is the primary indirect fire support weapon of armored and mechanized infantry divisions. The M109A6 Paladin can move from road march to firing status in one minute giving it a true "shoot and scoot" capability. The M109A6 is the latest configuration of the venerable 155mm self-propelled howitzer. It boasts a ballistic computer for quick and accurate firing. Many of the Army's 975 M109A6 howitzers are serving in Iraq. The M992A2 FAASV is a companion vehicle that carries ammunition for the Paladin and uses essentially the same power pack.

Paladin's technology reduced the time soldiers are vulnerable to enemy fire. Every time a round is fired, the enemy can zero in on the position and fire back. If the battery takes too long to displace, they are probably going to get killed. In the past, it would take about 20 minutes to prepare a firing position and another 15 to 20 to displace. It was very manpower-intensive to emplace the battery before. A five-man crew served each of the six howitzers in the battery. Surveyers calculated the battery's location, and crew members ran communicaitons wire by hand. The gun sections each had a soldier who would run the wire to the fire-direction center, and when it was time to displace, he would have to go down to the fire-direction center, unhook the wire and roll it up. It didn't take soldiers long to figure out that that's not a good way to do business if you want to stay alive. New technology allowed Paladin to cut that wire link from the fire direction center, which limited how far the battery could disperse the howitzers on the battlefield.

From the move, the M109A6 Paladin can receive a fire mission, compute firing data, select and take up firing positions, automatically unlock and point its cannon, fire the first round in under 60 seconds and move - day or night. This "shoot and scoot" capability not only significantly improves responsiveness to calls for fire, it also protects the vehicle and crew from counter battery fire - significantly improving survivability.

By the late 1990s the Army faced a dilemma with regard to it's self-propelled howitzer fleet. On the one hand, it was in the process of upgrading its 155mm Paladin (M109 A6) howitzers, giving them on board capability to orient themselves, compute firing data, and fire rounds responsively. These improvements notwithstanding, the Paladin version of the self-propelled howitzer (SPH) did not overcome several shortcomings noted during the Persian Gulf War, most notably limited mobility and low rate of fire. Furthermore, foreign field artillery systems were gaining capabilities that significantly outstrip those of the Paladin, increasing the likelihood that U.S. forces might one day face opponents with more capable systems. Inherent limitations of the Paladin chassis tend to limit any further upgrades.

On the other hand, the Crusader system that the Army was considering as a replacement for the Paladin not only overcame the deficiencies but also holds out the promise of being able to carry out new fire support missions. But the Crusader is expensive, and it did not mesh well with the Army's far term vision of the future. Thus, the Army's dilemma was whether to retain the Paladin system and it's known deficiencies int the hope of perhaps developing a system that will both overcome these shortcomings and better fit the Army's vision of war fighting in the future or to continue to invest in Crusader, knowing it will be in the force well into the Army After Next era.

The Crusader system was the Army's next generation self-propelled howitzer (SPH) and artillery re-supply vehicle (RSV), designed to support Army XXI and the Army After Next. Crusader incorporated advanced technologies to increase rate-of-fire, accuracy, mobility and ammunition-handling, while reducing ownership costs and crew size. This system provided the firepower required to support the force commander's goals of dominating the maneuver battle, leveraging information dominance, and protecting the force. The Crusader system was to displace the M109A6, Paladin SPH, and the Field Artillery Ammunition Supply Vehicle (M992).

Like the Paladin, the Crusader would have fired different variants of 155 mm artillery rounds but have a higher rate of fire and increased survivability and mobility. Weighing about 20 tons less than the Paladin, two Crusaders could have been deployed via a C-5A or C-17 transport jet versus one Paladin. With the proposed use of robotics, a Crusader howitzer and ammunition resupply crew would be three people versus the current system's nine-man crew.

Planned as the replacement for the M109A6 Paladin Self-Propelled Howitzer, the Crusader program was officially terminated by the Department of Defense on 08 May 2002. Stating that it was a case of balancing the resourcing needs of fighting the current War on Terrorism with what is required for national military strategy in the future, Secretary of Defense Donald Rumsfeld made the announcement at a Pentagon press briefing. "This decision is about the reality of finite resources," Rumsfeld said. "It is necessary to make choices and those choices are not easy."

Deputy Secretary of Defense Paul Wolfowitz said there were basically two problems with the Crusader, Wolfowitz said. It still wasn't light enough nor precise enough in delivering indirect fires to support DoD's vision for a more deployable and lethal force. The cancellation of the Crusader had been the subject of several media speculative articles during late April and early May 2002. Also in early May, a legislative talking points document surfaced that was highly critical of any move to cancel the program. That document was reportedly from a Department of the Army source.

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Page last modified: 01-05-2022 16:51:12 ZULU