Ammunition Reload Requirements of LAV Primary Weapon System Options

Ammunition Reload Requirements of LAV Primary Weapon System Options Geoff Pond, Ph.D., P.Eng. Land Capability Development OR Team Defence Research and Recherche et développement Development Canada pour la défense Canada Canada 1 Outline • Introduction – Current Medium-Weight Vehicle Capability – Weapon System Alternatives • Reload Requirements – Binomial Statistics – Monte Carlo Simulation – Wargaming • Conclusions Defence R&D Canada – CORA • R & D pour la défense Canada – CARO 2 Light Armoured Vehicle (LAV) – III with Delco Turret Entered in Service : 1998 Crew : 3 Dismounts : 7 Weapons : 25mm Dual Feed Cannon 7.62 Coaxial Machine-Gun 7.62 Pintle Mounted Machine-Gun Defence R&D Canada – CORA • R & D pour la défense Canada – CARO The third generation light armoured vehicle (LAV III) is the cornerstone of Canadian Army mounted operations. The LAV III is a wheeled infantry fighting vehicle as shown on this slide. This vehicle is crewed by three soldiers: a driver, gunner, and vehicle commander. In addition, seven soldiers occupy the rear passenger compartment. These soldiers may be dismounted to deliver more firepower on an opposition force, if required. 3 LAV III Inventory 310 Infantry Section Carrier (ISC) Variant + 180 Command Post Variant + 50 Forward Observation Officer Variant 540 LAV IIIs with Delco Turrets 33 LAV Less Kits (LKs) being converted to ISC w/ Nanuk Remote Weapon Stations Defence R&D Canada – CORA • R & D pour la défense Canada – CARO Currently, approximately 540 LAV III vehicles exist in the army inventory. The majority of these vehicles entered into service in 1998. To date, they have endured ten years of intense use, both during training and military operations. To extend its life and upgrade the vehicle to perpetuate its battlefield significance, a mid-life refit is currently being planned. As part of this refit, consideration is being given to replacing the vehicle’s turret. The Delco turret which is mounted on the vehicle houses a 25mm cannon, a coaxial 7.62mm machine gun, a pintle-mounted 7.62 machine gun, and two clusters of four 76mm smoke grenade launchers. The vehicle’s primary weapon system is the 25mm cannon which can shoot either in single-shot, or burst modes. Various 25mm ammunition types are fired by this weapon system but only two varieties are commonly employed on operations. To defeat lightly armoured or hardened targets, an armour-piercing fin stabilised discarding-sabot (APFSDS) round is employed. The alternative is a High Explosive Incendiary (HEI) round where the fuze detonates on impact and distributes an incendiary compound which burns flammable materials within a 5m radius. Use of both rounds can be accommodated by a primary and secondary ammo bin which feed the cannon. For example, the primary bin may be loaded with HEI and the secondary bin loaded with APFSDS rounds. Depending on the target, the gunner chooses the type of round that is most appropriate, by the flick of a switch. The primary bin contains 150 ready-rounds and the secondary bin contains 60 ready- rounds. When all ammunition has been expended, the ammo bins are restocked by the turret crew from inside the vehicle. 4 LAV III – Nanuk RWS Nanuk RWS LAV III - Nanuk • 33 LAV LK’s ISC • mounts a .50 cal machine-gun • first unit delivered, full delivery expected fall 2009 • to be deployed on Taskforce 1-10 as the Force Protection unit for the Provincial Reconstruction Team Defence R&D Canada – CORA • R & D pour la défense Canada – CARO Recently, a limited number of Canadian LAV IIIs have been fitted with a remote weapon system named the Nanuk. An image of this system mounted on the vehicle is shown on this slide. A remote weapon station such as the Nanuk is controlled remotely by crew from under the protection of the vehicle armour. The major disadvantage of this type of system is that reloading the system is done from outside the vehicle, exposing the crew. 5 Study Question Given the ammunition usage and reload characteristics of each vehicle type, how many vehicles within a platoon will be available to engage opposition forces at any given time? Defence R&D Canada – CORA • R & D pour la défense Canada – CARO 6 Op Medusa Strength 2,000 1,200 Casualties 12 512 Captured 0 136 Longest Threat Period 4 hrs Largest Ammo Expenditure 600 rounds Defence R&D Canada – CORA • R & D pour la défense Canada – CARO A threat period of 4 hours with 600 rounds expended per vehicle was selected in order to replicate the worst case scenario as described by returns from an inquiry made in theatre through the Army Lessons Learned Centre (ALLC). For this engagement, friendly and opposition force strength and casualties are detailed in this slide’s table. 7 Simplifying Assumptions • No mechanical failures (stoppages, jams, etc) • No casualties • Reload requirements are randomly distributed throughout engagement • No ammunition management Defence R&D Canada – CORA • R & D pour la défense Canada – CARO The following slides detail a binomial probability model for the reload of the LAV III having either a Delco turret or a RWS. This basic model requires several simplifying assumptions. The most relevant of those assumptions are detailed on this slide. In addition to those, the following assumptions are also made: •The threat period is 4 hours •A LAV with RWS must withdraw 1km at a speed of 60km/hr prior to reloading •A LAV with RWS requires 10 minutes to reload •A turreted LAV reloads in place •A turreted LAV requires 2 minutes to reload •Each vehicle expends 600 rounds of ammunition during the engagement •The time for a withdrawn vehicle to regain situational awareness and reacquire a target when returning to the engagement is negligible •The ammo expenditure rate of each vehicle is independent of that of all other vehicles 8 Reload Time • RWS must have comparable calibre • RWS based on the ARX20 (Nexter) - 20mm - 100 round ammo box -Assumed to fire at same rate as 25mm Delco - Must withdraw 1km away from engagement in order to reload (to provide sufficient protection to gunner) Defence R&D Canada – CORA • R & D pour la défense Canada – CARO Some RWS include a 20mm or 25mm cannon, which is more similar to that currently part of the Delco turret. The ARX20 20mm RWS ammo bin fits 100 ready-rounds. Unlike the Delco turret, the weapon system is fed by a single ammo bin. This is typical of most RWS having a 20-to-25mm calibre cannon. Therefore, once 100 rounds have been fired, the system must be reloaded from outside the vehicle. To reload, the vehicle is expected to withdraw from an engagement to an area were the crew can safely exit the vehicle to access the RWS ammo bin. 9 Reload Probability 3( reloads )( 2min/ reload ) p = = 5.2 % turret 240 min 5( reloads )( 12 min/ reload ) p = = 25 % RWS 240 min Defence R&D Canada – CORA • R & D pour la défense Canada – CARO A threat period of 4 hours with 600 rounds expended per vehicle was selected in order to replicate the worst case scenario as described by returns from an inquiry made in theatre through the Army Lessons Learned Centre (ALLC). The 2 minute reload time for the turreted LAV is the standard reload time provided that a few rounds from the previous upload remain so that the new upload can be linked to it. Ten minutes to reload an RWS seemed appropriate provided by feedback from the ALLC and in consultation with staff who represent Army users in the development of future equipment acquisition. The probability of one of the vehicles reloading, p can be calculated as follows. For the Delco turret, 150 rounds can be uploaded to the primary bin. Assuming the vehicle's primary bin is full at the onset of the threat period, the vehicle requires three more uploads to reach the 600 round expenditure assumed to take place. The amount of time spent reloading is: 3 uploads × 2 minutes per upload = 6 minutes. Recall that the threat period is assumed to last four hours. The fraction of time spent reloading is therefore 6 minutes divided by 240 minutes = 0.025, i.e., 2.5%. This can be interpreted as “each LAV III having a Delco turret will spend 2.5% of the threat period reloading the ammo bins”. This process is repeated for the specifications of the RWS. 10 Calculations N x N −x P(x) = p 1( − p) x ( = ∪ = ) ( = ∪ = )− ( = ∩ = ) P RD 1 RR 1 P RD 1 RR 1 P RD 1 RR 1 Defence R&D Canada – CORA • R & D pour la défense Canada – CARO The binomial probability distribution may be used to model the expected number of vehicles available to engage targets. This model is based on a binary response indicating whether a vehicle is in the process of reloading, or not, where: N denotes the number of vehicles ( N = 4 for a platoon) x denotes the number of vehicles reloading p denotes the probability of one of the vehicles reloading Special caution must be taken when performing the calculations for a platoon having a mix of RWS vehicles and Delco Turret vehicles. In the Venn diagram on the left side, the union probability depicts the cases where either a) a vehicle with a Delco turret is reloading, b) a vehicle with an RWS is reloading, or c) both a vehicle with a Delco turret is reloading and a vehicle with an RWS is reloading. Since case c) corresponds to the scenario where two vehicles are reloading (not just one), we must remove this intersection area as depicted in the Venn Diagram on the right side.

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