Medium Armored Vehicle

Annex C

Self-Propelled Howitzer

1. General Description of Operational Capability.

a. Mission Area.

b. Operational and Organizational Concept. The IBCT is enabled by a fire support system that is optimized for timely, lethal, and accurate pro-active counterfire.

The center of gravity for this capability is the Fires and Effects Coordination Cell (FECC) that employs internetted sensors and C4ISR capabilities to deliver non-lethal and lethal effects throughout the distributed battlespace. The FECC will proactively focus joint and internetted effects against counterfire targets (enemy mortar, artillery, rockets, C4ISR, logistics nodes, ADA, and maneuver formations). Additionally, the FECC will be able to direct close support effects.

Within the IBCT, the Self Propelled (SP) Howitzer Battalion will provide lethal proactive counterfire essential for the survivability of the dismounted infantry of the IBCT and other close support fires as required.

2. Threat.

3. Shortcomings of Existing Systems.

4. Capabilities Required.

a. System Performance. Key Performance Parameters (KPPs); Asterisk (*) indicates a KPP.

*(1) The SP Howitzer will integrate athe Light Weight 155mm (M777)cannon system with capabilities equal to or greater than the Lightweight 155 (M777) on a common chassis within the IBCT and be capable of firing all currently fielded and developmental US and North Atlantic Treaty Organization (NATO) Standard 155mm munitions and propellants. In addition the system must be able to achieve a range of 30 kilometers (assisted) and be able toachieve a maximum rate of fire of not fewer than five rounds per minute for three minutes in low angle (less than 800 mils elevation) indirect fire.

Rationale: The essence of pro-active counterfire is enabled by the SP Howitzerís 30km range and maximum and sustained rates of fire. Additionally, the range of the howitzer coupled with the diversity of 155mm munitions (projectiles, fuzes, and propellants) and future precision munitions are necessary tools to ensure maximum effects when executing proactive counterfire. Rapid rate of fire will allow the weapon system to destroy target sets of 120mm, 130mm, and 152mm in small groups to battery size targets normally exposed for limited periods of time. Counterfire must be able to destroy these fleeting targets before they have the opportunity to take protective measures or interdict IBCT elements. Sustained rate of fire allows for protracted target engagement after initial target engagement has been delivered in order to achieve desired target effects.

(2) Range.

(a) Minimum range. The SP Howitzer shall have an indirect fire minimum range using high angle fire (elevations of 800 mils or more) of not more than 3.7 km.

Rationale: A direct support artillery weapon must be able to engage close in targets with high angle fire. Such targets in complex terrain may be protected from the effects of low angle fire. The 3.7km minimum range requirement will assure close fire support for the maneuver arms even for targets which lie in deep defilade.

(b) Continuity of Range. The SP Howitzer shall be capable of engaging targets throughout the entire range band of the weapon.

Rationale: Support of the maneuver arms demands that the field artillery direct support weapons provide the required support at all achievable ranges. Sufficient range overlap must be available between successive charges. This will assure that the fire mission can be completed without the necessity of changing charge, which would result in slowing mission response and affect subsequent corrections if engaging a moving target.

(3) Rate of Fire. The sustained rate of fire will be at least two rounds per minute for an indefinite period of time or as governed by a thermal warning device.

Rationale: Sustained rate of fire is essential for proactive counterfire lethal effects over a protracted period of time throughout the distributed battlespace.

(4) Accuracy.

(a) Bias Accuracy. SP Howitzer shall have bias circular error probable (CEP) not exceeding 200160 meters at 25 km. Accuracy is based upon applied meteorological corrections no more than two hours old, with a spatial separation between the MET station and the midpoint of the firing trajectory of not greater than 20km. This accuracy is also based upon firing a M549A1 projectile at low angle with maximum charge.

Rationale: The bias accuracy is required to provide accurate, close fires in support of maneuver operations in both the offense and the defense. The requirement is based upon analyses derived from sanctioned modeling and simulations to determine cost and operational effectiveness.

(b) Precision Accuracy. SP Howitzer will have a range precision probable error for low angle indirect fire not greater than 0.0030 (0.3 percent) of range for unassisted projectiles and 0.0035 (0.35 percent) of range for extended range projectiles. Deflection probable error shall not exceed one mil at any range in low angle fire for both unassisted and extended range projectiles.

Rationale: The range and deflection precision is required to provide accurate, close fires in support of maneuver operations in both the offense and the defense. These accuracies are comparable to currently fielded weapons today, and are based on analyses derived from sanctioned modeling and simulations to determine cost and operational effectiveness. Precision accuracy relates to the proximity of the strike of successive projectiles fired at the same target. Precision accuracy is most influenced by improving the firing weapon system (platform) characteristics.

(5) Direct Fire. The SP Howitzer shall be capable of firing direct fire and must integrate an existing U.S. direct fire sight such as the M138 elbow telescope to provide this capability. It will be designed to accommodate an advanced sight capable of engaging a stationary, NATO standard sized direct fire target (2.5 meters square) at up to 1500 meters with a 30 percent probability of a first round target hit. This advanced sight will also include a simplified means to determine and set leads on moving targets, and will be fully functional and accurate when employed during night operations and in other periods of reduced visibility.

Rationale: Direct fire allows effective engagement of threatening enemy targets by providing the SP Howitzer the ability to fire at enemy threat in close proximity to the position and enable it to rapidly disengage. Direct fire is essential to the survivability of the SP Howitzer because of the dispersed emplacement of the weapons, which shall characterize its normal employment. The presence of night fighting capability will ensure that SP Howitzer can protect itself during night and in periods of reduced visibility.

(6) Elevation, and Traverse, and Recoil.

(a) The SP Howitzer shall require a power-assisted elevation device at fielding. In addition, a manual backup system is required.

Rationale: Powered elevation will considerably enhance the ability of the crew to achieve the firing rates specified above and provides a labor savings that will better support 24 hour operations. A manual means to elevate the weapon tube must be provided to assure that fire missions can be executed even during degraded mode operations.

(ba) Minimum Elevation. When the SP Howitzer is fully emplaced in a firing position on level terrain and ready to engage in firing missions, the cannon shall be capable of achieving a sufficiently low tube elevation to conduct direct fire.

Rationale: Depressing tube elevation to permit firing the SP Howitzer in a direct fire role will provide self-protection for the crew. Direct fire effects can be achieved through use of lower charge and firing higher quadrant using a variety of shell/fuze combinations.

(cb) Maximum Elevation. The SP Howitzer shall be capable of achieving a maximum tube elevation of not less than 1275 mils. This elevation control (handwheel and other device if there is one) shall be located on the gunnerís (left) side of the tube. A redundant control shall be located on the assistant-gunnerís (right) side.

Rationale: The elevation of 1275 mils assures that the SP Howitzer will meet its minimum range requirements in high angle fire in complex and urban terrain.

(dc) Traverse.

(1) The SP Howitzer shall require a power assisted traverse device at fielding. In addition, a manual back-up system is required.

Rationale: Powered traverse will considerably enhance the ability of the crew to achieve the firing rates specified above and provides a labor savings that will better support 24 hour operations. A manual means to traverse the weapon tube must be provided to assure that fire missions can be executed even during degraded mode operations.

(2) The SP Howitzer shall have an on-carriage traversing capability of 400 mils left and right of center. This traversing control (handwheel and other device, if there is one) shall be on the gunnerís (left) side of the tube.

Rationale: This traversing capability provides the ability for the weapon system to respond quickly to targets appearing in the anticipated sector within the range capability of the howitzer. It is essential that the firing weapon platform provide sufficient on-carriage traversing capability to engage targets of opportunity that are fleeting in nature without resorting to movement of the platform itself. If the platform must be moved to bring the weapon into the prescribed azimuth, then firing will be considerably slowed and responsiveness will suffer accordingly.

(e) Variable Recoil. The SP Howitzer requires a variable recoil system to allow firing at all elevation and charge combinations.

Rationale: Use of a variable recoil is required to preclude digging of recoil pits which detracts greatly from the responsiveness of the weapon system and creates considerable interference with other activities associated with the accomplishment of the fire support mission.

(7) Compensation for Cant. The SP Howitzer shall be operable at horizontal cant angles up to 178 mils without degradation to emplacement time or rate of fire.

Rationale: Compensation for cant angles up to 178 mils provides an adequate operational capability for most terrain conditions. For cant angles in excess of 178 mils, a time penalty will result in setting off of firing data, especially if the data must be set off manually. If terrain conditions result in cant angles in excess of 178 mils, repositioning of the weapon is the desired alternative.

(8) Boresighting. The crew of the SP Howitzer shall have an on-board means to quickly verify cannon tube and fire control alignment in the field environment as is provided by the M139 alignment device for the M198 Howitzer. If the alignment is found to be out by more than 0.5 mils, the crew shall be able to boresight the weapon tactically, without the need for an external reference point.

Rationale: Accurate alignment of the tube in the elevation and deflection arcs, with respect to the on board fire control equipment, is critically important to the overall system accuracy. The weapon can be out of boresight because of stresses on the weapon when traversing rugged terrain. The crew must always verify boresight when arriving in a new firing position. The ability to quickly verify alignment of the tube will give the crew confidence their howitzer will provide the required system accuracy.

(9) Propellant Ignition System. In the near term the current manually inserted primer type of ignition system is acceptable. However, it is highly desirable that a mechanical primer feed mechanism or other improved propellant ignition system be incorporated on the SP Howitzer to speed firing rates. The improved propellant ignition system shall be designed so that it will be inoperable unless the weapon breech is fully closed and locked. This improved ignition system shall be operable for 8 separate ignitions before it must be reloaded or replenished by a crewmember.

Rationale: The current manually inserted primer type of ignition system provides a reliable source of propellant ignition. However, a significant improvement in rates of fire can be achieved with a primer feed or other type of improved ignition system by elimination of the need to replenish the ignition source after each firing. A new improved ignition system also offers the opportunity to enhance safety features that will reduce the consequences of human error such as insuring that firing cannot occur unless the breechblock is properly secured.

 

(10) Breech Operation. The SP Howitzer breech will open automatically after firing. A manual back-up to the automatic operation is required.

Rationale: This characteristic will permit higher rates of fire needed to meet OPTEMPO requirements, and eliminate the necessity of the labor intensive step of opening the breech by hand after each round. Manual back-up is needed for continuity of operations in the event of mechanical failure.

(118) Emplacement. The SP Howitzer shall be emplaced and ready to fire in three minutes after the howitzer has stopped in the firing position. Ready to fire implies that the weapon is laid, a stable firing platform is established, and one round of ammunition is ready to be loaded, and communication is established. This will be accomplished by no more than five crewmen including the gunner.

Rationale: Initial emplacement of the SP Howitzer in three minutes will permit a responsive fire capability for the maneuver commander. This will meet requirements for target engagement when the howitzer is on the move and is consistent with howitzer capabilities today.

(129) Displacement. The SP Howitzer, shall be displaced from its firing position by no more than five crewmembers in two minutes.

Rationale: Rapid displacement will reduce the probability of adverse effects of threat counterfire, significantly enhancing crew survivability.

(130) Mission Response. The howitzer, when emplaced in a firing position with a fuzed projectile ready to load, shall be able to respond to an in-traverse low angle fire mission with the first round fired within 30 seconds (excluding copperhead). Response time for an in-traverse high-angle mission shall be within 45 seconds.

Rationale: These response times are needed in order for the SP Howitzer to provide increased rate of highly responsive fire support.

(141) Optical Fire Control. The SP Howitzer shall be capable of being layed by a U.S. positioning and direction determining system, for direct and indirect fire. A one-man one-sight system is acceptable. If a one-man one-sight system is selected the gunner shall set and/or read deflection and elevation by use of a readily visible display. An assistant gunner shall also be able to set and/or read elevation by a separate display mounted so as to be readily visible from the right side handwheel. It is permissible to select a U.S. standard automated fire control system as the primary means for fire control. If this is done, a back-up optical system is required to provide continuous operations.

Rationale: Conventional optical fire control provides an accurate means to lay the howitzer for direct and indirect fire. The secondary right side sight allows a second crewmember to assist in setting elevation, decreasing crew fatigue during prolonged firing. In certain firing situations especially in direct fire, it is highly desirable that a second crewman lay for elevation, because the howitzer gunner may have the added requirement to set leads to engage moving targets.

The use of GLPS allows the laying of the howitzer for position and directional control without the need to establish and transfer conventional survey.

(12) Elevation/Traverse. The MAV Howitzer shall require a power-assisted elevation/traverse device at fielding. In addition a manual back-up system is required.

Rationale: Powered elevation/traverse will considerably enhance the ability of the crew to achieve the increased firing rates specified above and provides a labor savings that will better support 24-hour operations. A manual means to elevate and traverse the weapon tube must be provided to assure that firing missions can be executed even during degraded-mode operations.

(153) SP Howitzerís equipped with optical fire control will have a U.S. Gun Display Unit (GDU) and Section Chief Assembly (SCA) mounted on the Howitzer.

Rationale: Incorporation of currently fielded U. S. Gun Display Unit (GDU) and Section Chief Assembly (SCA) mounted on the SP Howitzer provide the Gunner and Section Chief the position corrected firing data faster than voice or analog system. This capability increases rate of fire and improves accuracy.

(164) Material Handling Equipment. The SP Howitzer shall require an on-carriage loading assist and power-ramming device, which will achieve a consistent ram at all elevations.

Rationale: A SP Howitzer, equipped with on-board equipment which permits the rapid loading of ammunition for increased rate of fire and precludes the necessity of crewmen lifting projectiles in order to load them, will allow improved rates of fire and support 24 hours operations.

(175) Automation and Fire Control. If a conventional U.S. fire control is used, the SP Howitzer shall be designed to accommodate the Towed Artillery Digitization (TAD) system, a state-of-the-art digital fire control system.

Rationale: TAD is a digital fire control system that will provide the necessary information to locate and lay the howitzer, provide on-board technical fire direction capability, and manage howitzer ammunition inventory. The SP Howitzer is expected to integrate TAD as the system is fielded and permanent secure mounting points for this system's attachment and use will ensure a stable, ergonomic arrangement.

(186) Crew Size. The SP Howitzer system will be fully operable and maintainable by a crew of six personnel for continuous operations.

Rationale: The SP Howitzer system supports the structure of a 288 man Battalion.

(19) C4I/Standardization, Interoperability, and Commonality. The SP Howitzer will be interoperable with all current Field Artillery Tactical Data Systems and US analog and digital fire direction, and command and control systems including: Initial Fire Support Automation System (IFSAS), Advanced Field Artillery Tactical Data System (AFATDS), Forward Observer System (FOS), and FBCB2.

RATIONALE: The SP Howitzer must interface with all current and developmental fire direction and command and control systems to provide a seamless interface with other fielded U.S. cannon, rocket and missile systems as well as required information interfaces.

b. Logistics and Readiness. A Reliability and Maintainability (R&M) Analysis will be developed from the MNS, this document, and the Operational Mode Summary/Mission Profile (OMS/MP)(TBP). Reliability, availability, maintainability, and durability characteristics will not be compromised. The weapon system will have the following characteristics:

Rationale: The SP Howitzer must have a high degree of reliability and availability, because it is an essential fire support asset in the IBCT and necessary to assure overarching fire support dominance. When a failure occurs, it will be quickly detected, isolated, and repaired to assure minimum downtime.

(1) Mean Rounds Between System Abort. The mean rounds between system abort shall be 800 rounds. Mission reliability will be based upon an 18 hour mission day.

Rationale: Reliability is based on the same 18 hour mission criteria used for the OMS/MP.

The mean rounds between system abort shall be 800 rounds. Mission reliability will be based upon a 18 hour mission day.

Rationale: Reliability is based on the same 18 hour mission criteria used for the OMS/MP.

(22) Durability. The cannon tube shall have a replacement life of at least 2,650 Equivalent Full Charge (EFC) rounds, based upon the M203A1 charge (1750 EFC based upon the M203 charge). The cannon tube fatigue life shall exceed the cannon wear life. The breech mechanism shall have a replacement life of at least 5300 EFC rounds based upon the M203A1 charge. The recoil mechanism and carriage and architecture will have a replacement life of not less than 15,900 EFC rounds based upon the M203A1 charge.

Rationale: It is essential that the cannon tube fatigue life exceed the wear life in order to avoid catastrophic failure and death or serious injury to the crew. The cannon tube replacement life of 2,650 EFC rounds is equivalent to current 155mm cannon tubes today. The breech mechanism generally is subject to less wear than the cannon tube and its life should be approximately twice that of the gun tube. The recoil mechanism, carriage, and supporting architecture are costly and essential parts of the weapon system. They serve to transfer the forces from the exiting projectiles to the platform and ground. As such they must be durable and resilient to the sudden and very high stresses from firing.

5. Program Support.

6. Force Structure. Projected Army initial requirement is 90. This will equip five brigade-size units with 18 systems each.

7. Schedule. First Unit Equipped (FUE) will be obtained when the SP Howitzer is fielded to a minimum of one brigade sized unit consisting of at least 18 howitzers. The IBCT will move from Initial Operational Capability (IOC) to Full Operational Capability (FOC) upon fielding of the Self Propelled Howitzer.

8. Program Affordability.