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105-mm fire support vehicle


Also referred to as the LAV-AG, the LAV-105 was to be the primary fire support vehicle for the LAV I series, but the design ultimately proved unworkable

Country of origin Canada (hull) and USA (turret)
Entered service Cancelled
Crew 3 men
Dimensions and weight
Weight 16 t
Length (gun forward) 8.25 m
Hull length 6.9 m
Width 2.65 m
Height 2.68 m
Main gun 105-mm rifled
Barrel length 52 calibers
Machine guns 2 x 7.62-mm
Projectile weight ?
Maximum firing range ?
Maximum rate of fire ?
Elevation range - 8 to + 15 degrees
Traverse range 360 degrees
Ammunition load
Main gun 30 rounds
Machine guns 1 000 rounds
Engine diesel
Engine power 350 hp
Maximum road speed 100 km/h
Amphibious speed on water ~ 5 km/h
Range 650 km
Gradient 60%
Side slope 30%
Vertical step 0.5 m
Trench 2 m
Fording Amphibious


   Intended to form the fire support component of the US Marine Corps (USMC), the LAV-105 was to use a 105-mm gun to engage a wide range of targets that for which the weapons on the other LAVs were unsuitable, which as structures, troop concentrations, and hostile armor at close range.

   The USMC's interest in such a vehicle was as old as the LAV program itself, but it wasn't solidified into an official requirement until 1988, as the "LAV-AG" (Light Armored Vehicle, Assault Gun). While the chassis was to be the same General Motors (now General Dynamics Land Systems) LAV I and the gun to be used was the XM35, the USMC accepted competing bids for the turret. Cadillac Gage was declared the winner of the competition, effectively finalizing the design of the LAV-105. A 40-month full-scale engineering development contract with that company was signed, and the first 3 vehicles were to be delivered for USMC operational testing by May of 1992. However, it was not accepted into service, for reasons elaborated upon below.

   The LAV I hull of the LAV-105 is essentially identical to that of the LAV-25, with the only notable change being the addition of a couple of small pontoons to the sides, to compensate for the weight of the turret. The Cadillac Gage turret is a reduced-size version of that used on that company's Commando Stingray light tank and V-600 fire support vehicle. The proportions of the turret were significantly reduced to allow LAV-105 to conform to the USMC's size requirements for the LAV I family, and also had the additional benefit of reducing the vehicle's overall weight (relative to a standard Stingray turret). Both the gunner and vehicle commander have their own hatch, along with the driver, allowing all three crewmen to immediately enter or exit the vehicle simultaneously.

   The turret traverses 360 degrees in 6 seconds, with gun elevation from -8 to +15. The main gun and coaxial gun are stabilized in 2 planes, allowing the LAV-105 to fire on the move with great accuracy. Both the turret motors and gun trunnion motors were electric, which not only eliminated the need for hydraulic fluid and the potential for troublesome hydraulic leaks, but also greatly increased the crew and vehicle's survivability and safety margins (most armored fighting vehicle crew casualties have historically been the result of fires, and most of these fires in turn were fueled by burning hydraulic fluid).

   The main gun is a Waverliet XM35, the same 105-mm/L52 gun used on the M8 Buford light tank. The XM35 is a low-recoil force gun, as opposed to a low-pressure gun; meaning, instead of requiring reduced-charge ammunition, its recoil absorption mechanisms allow it to fire full-power NATO 105-mm tank ammunition with a sharply-reduced recoil. The weapon is fed by an autoloader developed by Fairey Hydraulics Limited (FHL), with a reload delay of 7.5 seconds. Spent casings are ejected horizontally through an ejection port in the turret bustle, as on the M8. It is also possible for the commander or gunner to manually override the autoloader and cycle ammunition manually in the event of a malfunction, though this takes considerably longer. The weight of the entire autoloader system is only 145 kg. Included with the main gun was a 7.62-mm M240C coaxial machine gun, fed by 200-round belts. Provisions were also included for a 12.7-mm H2HB on the turret roof, and stowage for its 12.7-mm ammunition, but it does not appear that this weapon was ultimately integrated into the prototypes. Two quadruple-tube M257 smoke mortars were installed on the turret glacis plate.

   The total ammunition loadout was 30 105-mm shells and 1 000 7.62mm rounds. The autoloader has a ready ammunition capacity of 8 shells, while the other 22 shells are stowed inside the replenisher. 400 7.62mm rounds are carried as ready ammunition, with the remaining 600 being stowed.

   The fire control system included a digital ballistics computer, an eye-safe laser rangefinder, and a day/night range sight system with both conventional optics, a HIRE 240-line passive thermal imaging system, an LSSP (Line of Sight Stabilization Platform) sight stabilization system, and a Commander's Independent Thermal Viewer (CITV). The CITV can also be used as gunnery sights, which gives the LAV-105 a "hunter-killer" capability when combined with the vehicle commander's override. Interestingly, all of the components of this fire control system were Raytheon products.

   Protection for the LAV-105 is essentially the same as that of the LAV-25. The hull armor is made of the same Bisalloy 500 steel, providing protection from 7.62-mm armor-piercing rounds, shell splinters, shrapnel, and debris, while the turret is protected by Cadillac Gage's patented Cadloy steel, at a great enough thickness to defeat 12.7-mm ball ammunition. Twaron spall liners are included as well, eliminating or at least reducing any back-spalling in the interior.

   The mobility and performance of the LAV-105 is largely the same as the other LAV Is, due to having an identical chassis, powertrain, and suspension. The obvious difference is the extra weight, and the additional ground pressure it entails; tipping the scales at 16 t, the LAV-105 has the unenviable distinction of being the only LAV I variant for the US Marine Corps that's too heavy to be sling-loaded under a CH-47 Chinook or CH-53 Sea Stallion. Finally, while the LAV-105 was officially amphibious, no photos, videos, or other documentation indicates it ever swam through deep water, and the addition of pontoons to increase the vehicle's buoyancy have further increased the size and weight of the vehicle.

   However, while the LAV-105 was perhaps too heavy for the needs of the USMC, it was two other factors that were ultimately its undoing.

   The first was simply poor timing. The Cold War ended before the first vehicles could be delivered, and the resulting budget cuts forced the Marines to terminate the remaining funding cut from their budget. The Navy nonetheless relinquished US$33.8 million to the LAV-AG program in 1993, to acquire and test the first three vehicles.

   Of course, had timing and this been the sole problem, the LAV-105 might well have entered service at a much later date, but the second problem was much more serious. It wasn't discovered until the Marines finally began to fire live ammunition from the LAV-105 in the mid-1990s that the LAV I chassis and suspension could not withstand the recoil of a 105-mm gun --- not even a low recoil force gun. The recoil caused the vehicle to buck violently (reminiscent of the M551 Sheridan light tank of earlier years), overwhelmed and seriously damaged the suspension, and caused widespread stress cracking throughout the chassis', including its Bisalloy 500 steel armor.

   The USMC later in the 1990s attempted to resurrect the LAV-AG program later that decade, via the LAV-90. This vehicle was essentially an LAV I equipped with the Cockerill turret, armed with a smaller Mecar KEnerga 90-mm gun, but the test firings once again overwhelmed the chassis and suspension. After once again rejecting an LAV-AG candidate, the USMC and the industry quickly abandoned the entire concept, and have apparently never spoken of it again.




   LAV-90: A later USMC attempt at a "remedial" fire support vehicle, with a Cockerill turret sporting a KEnerga 90-mm gun. It was hoped that the LAV I could withstand the recoil of a smaller 90-mm gun, but this too overwhelmed the chassis. Did not enter production or service.


Related vehicles


   There are many other vehicles in the same design category as the LAV-105. Listed below are those most relevant to it.

   Stingray light tank: Has a variant of the same turret as the LAV-105, but a different L7A3 main gun. In service with Thailand.

   M8 Buford light tank: Has the same gun as the LAV-105, but a different turret, and also a different autoloader and replenisher. Did not enter production or service.

   VFM 5 light tank: Has the same gun as the LAV-105, but a different turret, and no autoloader. Did not enter production or service.

   V-600/LAV-600 Commando fire support vehicle: Essentially the arch rival of the LAV-105, the V-600 featured a V-300 chassis with a lowered roof, topped with the same turret and main gun as the Stingray light tank. Though it didn't have any of the recoil or structural issues of the LAV-105, the V-600 nonetheless never attracted any sales. Did not enter production or service.

   Piranha III fire support vehicle: This late 1990s vehicle was essentially the Belgian answer to the LAV-90, and consisted of a Piranha III chassis with the same 90-mm Cockerill turret. Unfortunately, it also had the same structural problems stemming from the recoil of the 90-mm gun, and the Belgian Army did not accept this vehicle into service. Did not enter production or service.

   Piranha III DF90 fire support vehicle: This later Belgian Piranha III fire support vehicle incorporated a new turret and recoil system, and was thus finally able to tame the recoil of a 90-mm gun. It was selected for operational service with the Belgian armed forces in 2006, and the first deliveries commenced in 2008.

   M1128 Stryker Mobile Gun System: A later and similar US Army vehicle combining a Stryker chassis with a General Dynamics Land Systems (formerly Teledyne) Low Profile Turret, armed with an M68E1 105-mm gun. This turret had already shown poor results on the Teledyne Expeditionary Tank and ASCOD, and unsurprisingly, it fared even worse on the Stryker --- especially in that the M68E1 was *not* a low recoil force or low-pressure gun, and the added "pepperpot" muzzle brake failed to tame its 30-ton recoil. The Stryker MGS nonetheless entered service with the US Army in small numbers, but its future is uncertain.

   LAV III Mobile Gun System: This vehicle was essentially an LAV III with a General Dynamics Land Systems Low Profile Turret, making functionally almost identical to the Stryker MGS. After waiting more than 5 years for GDLS to fix the Low Profile Turret and the M68E1 105-mm gun, and urgently needing new vehicles for fire support missions in Afghanistan, the Canadian Forces abandoned the LAV III MGS; the funding meant for it was diverted to an upgrade for their Leopard C2 main battle tanks, and an additional purchase of Leopard 2A6s. Did not enter production or service.

   AMX-10RC: This was one of the first wheeled reconnaissance vehicles to employ a 105-mm gun. Early models used a low-pressure gun, while later models employed a low recoil force weapon. It was also a major inspiration for the LAV-AG program. Even though it only had 6x6 configuration, the AMX-10RC was able to withstand a 105-mm gun's recoil, owing to the fact that it was a major design objective in the creation of both its chassis and suspension. Several nations have operated this vehicle, and it remains in active service.

   Zhalo-S: This Soviet 8x8 fire support vehicle was based on the BTR-70 chassis, and was essentially the direct counterpart of the LAV-105 in the Eastern Block. Unfortunately, its 85-mm gun also had too much recoil for its suspension to withstand, ultimately leading to the program's termination. Did not enter production or service.



   Article by BLACKTAIL

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