RFM 1/35

The M109 is an American 155 mm turreted self-propelledhowitzer, first introduced in the early 1960s to replace the M44. It has been upgraded a number of times, most recently to the M109A7. The M109 family is the most common Westernindirect-fire
support weapon of maneuver brigades of armored and mechanized infantry
divisions. It has a crew of four: the section chief/commander, the
driver, the gunner, and the ammunition handler/loader.

The British Army replaced its M109s with the AS-90. Several European armed forces have or are currently replacing older M109s with the German PzH 2000. Upgrades to the M109 were introduced by the U.S. (see variants) and by Switzerland (KAWEST). With the cancellation of the U.S. Crusader, Non-Line-of-Sight Cannon and M1299
the M109A6 ("Paladin") will likely remain the principal self-propelled
howitzer for the U.S. until a replacement enters service. 

M109A7

The newest M109 version for U.S. service is the M109A7, formerly
known as the M109A6 Paladin Integrated Management (PIM). The M109A7
shares common chassis components with the Bradley Fighting Vehicle (BFV)
such as the engine, transmission, and tracks. This creates commonality
with other systems and maximizes cost savings in production, parts
inventory, and maintenance personnel. The M109A7's onboard power systems
harness technologies originally developed for the XM1203 Non-Line-of-Sight Cannon.

The electric drive is faster than the previous hydraulic system,
and the automatic rammer more consistently rams the round into the gun
for consistent velocities and better accuracy. It features a 600-volt
onboard power system to accommodate additional armor and future
networking technologies as they become ready. The M109A7 can sustain a
one-round per-minute rate of fire and a maximum rate of fire of four
rounds per minute. Weighing 78,000 lb (35,000 kg), the M109A7 is 10,000 lb (4,500 kg)
heavier than its predecessor, and it has the capacity to grow to
110,000 lb (50,000 kg). Even with the weight increase, the M109A7 can
travel faster than previous versions at 38 mph (61 km/h) and is more
maneuverable than a BFV.

Prototypes of the vehicle underwent government testing in preparation for a Low-Rate Initial Production (LRIP)
decision. The testing included RAM, mission and ballistic hull and
turret testing. The M109A7 was slated to begin LRIP by 2013. The U.S.
Army planned on procuring a fleet of 580 sets of M109A7 howitzers and M992A3 field artillery ammunition supply vehicles.

In October 2013, the Defense Acquisition Board
approved the decision to start M109A7 production. The FY 2014 budget
called for $340.8 million in Paladin funding, which would be two dozen
vehicle sets at $14.4 million per vehicle. The Army plans to buy 133
vehicles, in 66 one-half vehicle sets starting in 2014. One M109A7
howitzer and two supporting M992A3 ammunition carriers will be destroyed
during tests. A Full-Rate Production (FRP) decision was planned for
February 2017.