Self-propelled artillery
From Freepedia
Self-propelled artillery (also called mobile artilley or locomotive artillery) vehicles mount a large howitzer (or alternatively mortar or rockets) and are used for long-range indirect bombardment support. Though lightly armored, and sometimes equipped with machine guns, they are not designed for direct-fire combat. They usually count as armoured fighting vehicles if they possess some kind of shrapnel protection for the crews.
Self-propelled artillery have in the past included assault guns and assault howitzers. These are heavily armored vehicles which provide close fire-support for infantry.
Development of self-propelled artillery
The first type taken into production was the WWI Gun Carrier Mark I of 1917, based on the first tank, the Mark I. More effective self-propelled artillery became feasible after World War I with the development of rugged motor vehicles and the improvement of the tank.
At the outbreak of World War II virtually all artillery remained tractor-drawn (towed) or horse-drawn. While German Blitzkrieg doctrine called for rapid support of armoured units, during the invasion of Poland and France this was provided by the Luftwaffe and conventional towed howitzers.
Towed artillery has several disadvantages compared to self-propelled artillery. It is slower to go into action since the guns must be stopped, unlimbered, and set up before they can fire. If the battery is to shift positions, the guns must be limbered up before movement. Self-propelled artillery need only stop, confirm location, and begin firing. The response time is thus better from self-propelled artillery if a unit is moving quickly. Second, self-propelled artillery can carry light armor to protect the crews and weapons from counter-battery fire. On the flip side, towed artillery is vastly cheaper to build and maintain, and thus can be made available in greater numbers.
As the War progressed, all nations developed self-propelled artillery. Early models were often no more than an infantry field gun or anti-tank gun mounted on a truck. As the war progressed, tracked chassis and armoured superstructures became more common.
By the end of the war Germany and the USSR had developed heavily armoured assault guns which were designed to provide direct-fire support to infantry in the face of enemy anti-tank defences. The German StuG III and Soviet ISU-152 are good examples of this type of self-propelled artillery.
All main combatant nations also had lightly-armoured self-propelled artillery which was designed to provide an indirect support capability to fast-moving armoured formations. The US M7 Priest and German Wespe were typical examples. A somewhat different concept was the highly effective Soviet Katyusha self-propelled multiple rocket launchers. Effectively trucks with a rocket rack on the back, they were crushingly effective against German formations.
Finally, many combatants developed lightly-armored, open topped self-propelled antitank guns, such as the German Marder III and the Soviet SU-76.
After the Second World War, the assault gun concept became less widespread as the variety of armoured vehicles was streamlined into the main battle tank. Other SP artillery remained important.
Modern self-propelled artillery
SP artillery remains important in the equipment of many modern armies. It saw a significant role throughout World War II and in the first and second Gulf Wars.
Modern SP artillery is highly digitized with the ability to self survey firing positions using systems such as GPS and inertial navigation systems. This in conjunction with digital fire control/ballistic computers and digital communications allows individual guns to disperse over a wide area and still deliver rounds on target at the same time and same target as other guns in their battery.
These capabilities also increase survivability many fold as modern SP artillery can displace and avoid counterbattery fire much more quickly and effectively and if desired more frequently than previously possible.
In conjunction with modern logistic systems (where the SP gun's sytems can track and report on ammuniton consumption and levels) with similar navigation systems and palletised load dropping/lifting capabilities mean that the rapid displacement can occur without significant disruption to actually firing missions as it is possible for the ammunition to keep up with the guns.
A modern battery (6 guns) firing 43kg projectiles with a burst firing speed of 4 rounds per minute, can deliver over 1 metric tonne (1032 Kg) per minute, for up to 4 minutes. This is an immense weight of fire which can be delivered with very high accuracy.
