Science Fair Project Encyclopedia
The XM29 Objective Individual Combat Weapon (OICW), also referred to as the Selectable Assault Battle Rifle, is a highly advanced new assault rifle / grenade launcher system slated to replace certain M-16 assault rifles with M203 underslung grenade launcher. It is scheduled to enter the service during the year 2008 in limited numbers.
Developed by Alliant Techsystems and Heckler und Koch, the OICW consists of a semiautomatic 20 mm smart-grenade launcher, an underslung assault carbine based on the HK G36 and XM8 firing a standard 5.56 x 45 mm NATO round, and a top-mounted computer-assisted sighting system with integrated laser rangefinder, thermal night vision capabilities, and up to 6x optical telescopic zoom.
The history of the one of the most ambitious projects in the history of small arms began late in 1986, when the United States Army Infantry School at Fort Benning published a military paper named "Small Arms System 2000" (SAS-2000). Despite the current trends towards caseless and flechette ammunition and compatible weapons, researched and developed under the ACR program (see HK G11 and Steyr ACR entries for some details), this paper stated that the conventional small arms had already reached their technological peak, and the only way to increase the hit probability in small arms is to introduce a weapon that combined the ability to fire explosive and fragmentation warheads with smart fusing and sighting/aiming technologies.
While most small arms research during the late 1980s in the USA was conducted under the ACR program, the idea first developed in SAS-2000 was supported by another US military paper, published in 1989 by the US Army TRADOC (Training & Doctrine) center. This paper, called "The Small Arms Master Plan" (SAMP), requested a new family of infantry "Objective" weapons, namely the Objective Individual Combat Weapon (OICW), Objective Personal Defense Weapon (OPDW), and the Objective Crew Served Weapon (OCSW). The SAMP stated that such weapons must utilize the latest developments in computers and visual technologies, as well as in small arms, and combine both high explosive warheads and traditional bullet firing capabilities in a single weapon that should be fielded circa 2000. Of course, the timelines and most of the weight and cost requirements set in this paper looked unrealistic from the start, but the development of the Objective weapons series began in the early 1990s.
During the early stages of research and development in the mid-1990s one out of the two teams was selected as a winner for further development contract. This team was lead by the US based Alliant Techsystems corporation (ATK), with Heckler und Koch (HK) from Germany, and the Brashear and the Omega companies (both of USA) as the other team members. ATK was responsible for system integration, and also developing the 20 mm Air Burst munitions; HK was responsible for both the 5.56 mm rifle and the 20 mm grenade launcher; Brashear worked on the sighting equipment and Omega provided the training means. The resulting weapon was type-classified by the US Army as the XM29 circa 2002. Present plans for fielding the XM29 are to issue four units per one infantry squad of 9 men.
The XM29 is a combination weapon, which has the 20 mm semi-automatic, magazine fed grenade launcher as its primary part, and the 5.56 mm compact assault rifle as its secondary part. Both parts are assembled into the single one-man portable unit, with the addition of the target acquisition / fire control system (TA/FCS), which is an essential part of the whole system. The XM29 will become an integral part of the future Land Warrior system, capable of communicating with the other parts of this system, including the tactical computers and helmet-mounted displays.
Early in 2002 the XM29 test weapons were successfully tested with the newest 20 mm HEAB (High Explosive Air Bursting) munitions, which will be a major "kill factor" for the XM29 weapon. The launcher is capable of firing in semi-automatic mode only, and is gas operated. It has a bullpup layout with the detachable box magazine located in the butt of the weapon. The rifled barrel is used to launch the 20 mm grenades up to 1000 meters with good accuracy. In the standard configuration most of the fire controls for the grenade launcher part are located on the rifle part, including the single trigger for both firing modules. It is quite possible, however, that the separate stock will be developed for the grenade launcher part, so it will be possible to use it without the rifle part attached.
The launcher has the provisions for the TA/FCS system to be mounted on its top, and the appropriate interfaces, so the data provided from the TA/FCS can be used to program the 20 mm grenade fuses. These fuses, used for the 20 mm HEAB ammunition, have multiple modes of detonation, including the direct impact mode and the air burst mode. In the latter mode the fuse is pre-programmed to explode the warhead at the preset range, which is calculated during the flight by counting the number of the grenade's rotations. This allows the round to defeat targets without direct impact, using the blast and fragmentation effect of the high explosive warhead. Shrapnel and other debris accelerated by the detonation of the airburst round then become more deadly to the enemy than direct fire. This is a major advantage over present small arms, which in most cases require a direct hit on the target to be effective, as it allows for greater aiming errors, and also makes possible to defeat targets in defilade, like trenches and so on. The high explosive warhead also has the advantage of not being dependent on its velocity to be effective, so unlike bullets, its effectiveness does not decrease with the increase of range.
The disadvantage of this system is the extreme complexity of the electronic fuses, which results in the high price of a single round of ammunition. The present plans stated that one HEAB round must cost about US $25, and it is still to be seen what will be the actual price when the system is fielded. It is interesting that the present design of the HEAB ammunition actually has two small HE warheads at the front and at the rear of the projectile, with the electronic fuse module located between them. While the HEAB is considered a primary round for the 20 mm grenade launcher, it is entirely possible to develop a low cost, direct hit only anti-armour 20 mm round with Shaped Charge warhead, which will be effective against lightly armored vehicles (APC, MICV and like) and various hardened targets.
Kinetic energy rifle
The rifle, or "kinetic energy" part of the XM29 system, on the other hand, is a fairly conventional, short-barrelled assault rifle, derived from the Heckler und Koch G36 assault rifle. The basic rifle part of the XM29 has no buttstock and no sights of its own, and thus can be used separately from the whole system only as emergency, personal defense weapon. While being mounted to the whole system, it can be used for close quarters work, both defensive or offensive (the 20 mm grenade launcher has a minimum range of fire of about 50–100 metres), or as an low-cost, low intensity medium range offensive weapon. Most of the XM29 system controls are built into the rifle part, around the trigger guard.
The target acquisition/fire control system (TA/FCS) is the most expensive and complicated unit of the whole system, since it must combine day and night vision capabilities, laser rangefinding unit, ballistic computer and various interfaces to the grenade launcher and external systems. It is used to find the targets in any light and weather conditions, determine the range to the target, calculate and display the aiming data, so the grenade or bullet could be fired to the desired point of impact, and then supply the data to the grenade launcher, so the range could be preset into the grenade fuse. In the case of damage to the TA/FCS the 20 mm grenade launcher still can be used in the direct impact mode, as well as the rifle part of the system.
The current research and testing showed that the XM29 can be up to 500% more effective than present small arms, but it is still to be seen if all the requirements will be met in the resulting system, especially regarding to the reliability of electronic components, weight (the XM29 currently weighs in at about five and a half kilograms when empty, and nearly seven when loaded) and, last but not at least, the unit price. Some experts have commented that the idea of the XM29 "...seems to make a soldier so expensive to field that he can't be risked in combat. Much like an aircraft carrier."
The contents of this article is licensed from www.wikipedia.org under the GNU Free Documentation License. Click here to see the transparent copy and copyright details