M874 Armored Troop Transport

The M874 Armored Troop Transport (ATT), nicknamed Pangolin, is a variant of the standard which is suited for operations in areas of heavy combat. As its name suggests, the Pangolin features armored gullwing doors over the driver and passenger sides of the vehicle and split armored doors on the passenger module in the back, which has also been enlarged to make up for space lost in enclosing it. Being used in combat heavy environments it also features a M43 Remote Weapon Station (RWS) mounted ahead of the troop module and behind the crew compartment.
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==Origins==
The M874 Pangolin was born during the rise of the in the early 2500s as a measure to better protect UNSC Army troops engaged with Insurrectionist forces. As the Insurrection spread, more urbanized and developed worlds soon found themselves fiercely contested by the existing UNSC garrisons and rising Insurrectionist groups. The standard UNSC vehicle, the , and its troop transport derivative, the M831 TroopHog, both served as the main transports for forces on these colonies. 
However as time went on, it became clear that the Warthogs highly mobile and nimble design was becoming a liability. Insurrectionist forces had begun employing various weapons such as machine guns mounted on window washing platforms and makeshift incendiary weapons like Molotov's to take advantage of the unprotected design of the Warthogs. In response to the quickly mounting casualties, the tasked with creating an Urban Warfare and Survival Kit for existing Warthogs and TroopHogs.
==Development History==
The original plans for the Hog Urban Survival Kit (HUSK) were drawn up in 2502, under a team of designers led by Daren Wladislaw. The main focus of the plan was to offer greatly improved survivability while also affecting the original roles of the vehicles as little as possible. Such parameters resulted in fairly lightweight but still very sturdy gullwing doors made of armor with Kevlar spall liners, reinforced bulletproof glass and add-on plates to the frame of the vehicle. The FAV variant would also receive a similarly armored screen around the rear gunner as well the gun itself receiving a larger gunshield. The variant meanwhile was enclosed on the sides of its troop module and had two doors to the rear through which troops could enter and exit.
While Wladislaw had pushed for further enclosing of the vehicles and further improvements to the armor, his requests were rebutted as they violated the weight restrictions and could not maintain the mobility requirement without his proposed engine rebuild. However the addition of the latter would have made the ease of distribution far more limited. 
Testing with the initial models worked well against general small arms fire thanks to the improved armor and the addition of doors on both the FAV and TroopHog. However, the former saw an increased likelihood of the turret being targeted due to its now increased size profile. Furthermore, the large and exposed position of the gunner still proved to be a weakspot due to the amount of space it occupied. While the TroopHog did not have this issue, it faced a noticeable decrease in performance due to its greater usage of armor in general, hampering its top speed, acceleration and agility. When initially submitted to the Army for further testing, neither vehicle would pass as both were woefully under prepared for massed chemical weapon attacks from incendiary and corrosive weapons such as molotov's and acid bombs. As a result of this, all test subjects were deemed failures and were sent back to AMG to be redesigned.
Despite months of reworks and increasing pressure from the UNSC Army for results, Wladislaw and his team at AMG were caught in a rut. It had proven to be remarkably difficult to make a standardized kit for both the M12 FAVs and the M831 TroopHogs while also maintaining their respective functions and keeping the costs within allotted parameters. The armor could not easily be made better without increasing the weight and violating the weight limits. It could have been made stronger and lighter through usage of much more expensive materials, but this would nearly double project costs. This was further made difficult by the refusal of the Army to accept an engine overhaul, as the deployment of the kit would be greatly slowed by its addition. By March 2503, Wladislaw and AMG launched a formal appeal to the UNSC Army. 
Rather than the expected cancellation of the contract, the Board instead set forth a counter proposal.
The counter proposal had amended restrictions which allowed for the inclusion of engine modification, but also gave a greater weight limit, making it much easier to create sufficiently protected vehicle. These new limitations saw new composite doors, combining Titanium, ceramics, gel layers and spall liners, which created heavy armored doors which could resist sustained damage from chemical and ballistic weapons. Their weight and subsequent impact on speed was even diminished by overhauling the engine with new parts, a twincharging system and an overhauled drivetrain. The kit even managed to retain some modularity, with the M12s capable of mounting the gullwing doors but without an armored enclosure for the gunner. 
The absence of the M12 from the project also freed up funding to launch an inquiry into the installation of a remote weapons station on top of the M831. This could drastically improve the vehicles survivability in urban areas and perhaps even allow them some degree of autonomy, as they would not need an escort. This eventually took the form of an M43 Remote Weapons Station (RWS) which would be mounted on the brace between the, now reinforced, troop module and crew cabin. 
The final products were delivered to the UNSC Army for tests on August 29th, 2503, these were the M831 HUSK and, despite having been excluded, the M12 HUSK. While the M12s inclusion was met with skepticism, its performance was adequate, though not enough to have any significant interest from the Army. The M831 however, performed well within what the requirements stated, passing the ballistic and chemical weapons tests with flying colours. Despite the upgrades though, it still faced difficulties regarding its stability and agility when it came to the mobility testing, however it was still within the acceptable parameters. By the end of testing in October, 2503, a final decision was made to adopt the HUSK kit for the existing M831s, albeit without the drivetrain upgrades and RWS, while the full vehicle with the kit would be adopted as the M874 Armored Troop Transport, nicknamed the 'Pangolin'.
==Operational History==
===Peacekeeping on Tellion===
The baptism by fire of the first Pangolins took place in October 2503, on the Outer Colony of Tellion. The first platoons of vehicles was issued to 'C' Company of the 217th Mechanized Battalion of the UNSC Army which was charged with peacekeeping in light of repeated insurrectionist attacks on military installations. First contact was made on 29th October, with a platoon coming under, sustained, heavy fire from various positions in buildings. Despite the angle, the small arms fire did little to phase the Pangolins, who soon responded with their own barrage of machine gun fire and missiles. The platoon was able to hold their positions and establish a perimeter which was soon reinforced with more troops.
As night fell, a second attack rung across the perimeter, this time being far larger and using several explosives which blew apart fortifications. As a result, the Pangolins were used as impromptu fortifications, their RWSs exchanging fire with enemies in buildings while the troops in the module returned fire through the rifle ports. The assault continued for over an hour, until the insurrectionists were overwhelmed and forced into a retreat. Reinforcements soon arrived to bolster the UNSC position, with more Pangolins being deployed to take the lead in advances. The aftermath of the assault revealed the Pangolins to be riddled with numerous marks of gun fire and shrapnel, though none of the fire managed to successfully penetrate their armor. 
The unexpected ferocity of the assault, as well as the Pangolin's performance during it, saw a greatly increased interest by Army units in the vehicle. Large numbers of Pangolins were acquired by the 217th Mechanized Battalion, replacing all their and supplanting their . This also paved the way for adoption by several other peacekeeping forces and military garrisons on planets with known insurrectionist activity.
===Battle of New Jasic===
Another major event involving the Pagolin took place in February, 2505, on the of Denthar. Denethar had been an Insurrectionist hotspot for the last three years, primarily due to the vehemently pro-UNSC position of the Governor. These policies had resulted in a heavily policed colony and growing resentment in the mining focused population, which further grew into an insurrectionist cell. This reached a boiling point on 11th February, as mass bombings and shootings took place against police forces and government installations in the capital city of New Jasic. The scale of the attack and crippling of effective response of the police saw an emergency state being declared, allowing elements of the 231st Infantry Battalion to deploy to the city.
The two companies of the 231st Battalion, equipped with M874 Pangolins and , were deployed to the secure a 4 street perimeter around the Headquarter. As the vehicles and troops dispersed throughout the streets, they were met with numerous ambushes and attacks by improvised weapons, resulting in the start of a protracted guerilla war throughout the city. The next two months would see repeated patrols and incursions throughout the city, majority of which were spearheaded by Pangolins. The vehicles performed well, however the prevalence of IEDs and subsequent fatalities saw the retrofitting of local area jamming modules within the troop module. A notable occurrence was on April 2nd, 2505, where a Pangolin was crippled by an IED and its crew turned the vehicle into an impromptu roadblock, preventing insurrectionists from gaining access to a key crossroad.
The turning point in the conflict came during Operation: CHECKMATE, an operation launched by elements of . Two platoons of special forces trooper would launch a rapid assault against the recently discovered headquarters of the rebellion. On April 29th, the operation was launched with the platoons raiding the ghetto, utilizing M874 Pangolins to ram straight through reinforced roadblocks. Prior to the operation, they were also used to rapidly set up a perimeter to prevent any of the innies from escaping. The operation proved to be a relative success, the ghetto which was being used as a headquarters had been dismantled a number of leaders and weapon stores had been captured or destroyed. Furthermore, the priority of the mission and subsequent collapse of organized rebellion in New Jasic greatly bolstered the reputation of the Pangolin.
===Expansion of Operators & Deployments===
The several early successes of the Pangolin in its first three years had a seen a notable rise in its popularity on heavily urbanized colonies, both with military and paramilitary groups. Most notably, it saw limited adoption by the , specifically for urban operations. It also saw further adoption by units of the , as well as base security forces of several branches. Though this was again limited to colonies with more active activity. The most surprising adoption came to be from several colonial militias as well as units of the UEG Bodyguard Corps and several SWAT units. However, due to the ever worsening situation of the Insurrection, many of these were issued without RWSs and with thinner door armor, barring those issued to the Bodyguard Corps. 
As a result, the Pangolin saw much wider use and far more deployments over the next six years. Several noteworthy operations involving the Pangolin took place in 2509, primarily as a result of several rival Insurrectionist groups rising across the Weatherby System. This was the single largest usage of Pangolins in a single campaign to date, with upwards of three Regiments employing the vehicle for operations in built up areas. A notable engagement occurred on the colony of Uthea I in March, 2511, which saw Pangolins being used alongside Scorpion tanks to hold off against repeated assaults by abnormally well armored and organized insurrectionists. While the attack came under much investigation, the role played by the Pangolin once again solidified its reputation and usefulness as an urban combatant.
===Operation: TREBUCHET===
The M874 Pangolins most widespread use came in 2513 at the onset of Insurrectionist rebellions across the . The ensuing counterattack by the UNSC, , saw mass deployment of UNSC forces across the system to quash the uprisings. Several Army and Marine Corps battalions, equipped with Pangolins, were deployed against the insurrectionists, the vehicle being used heavily to facilitate transport and breakthrough missions in the cities. Unlike previous instances however, the insurrectionists were both better organized and better equipped, seeing several vehicles getting destroyed by heavy weaponry. In particular, became a gauntlet for the Pangolin and other UNSC vehicles as they were pitted against remarkably heavily defended insurrectionists positions. The following years saw the spread of organized and well equipped cells across the , many of them descending into emergency states and seeing several UNSC deployments.
===Siege of the Garrophon System===
One of the most brutal and longest operations that took place as part of Operation: TREBUCHET was the Siege of the Garrophon System in 2515. The nature of the system as a piracy hotspot saw both the UNSC and CMA Navies vying for overall control of all anti-piracy operations in the region. However as TREBUCHET launched, many CMA units came under UNSC control, this inadvertently caused a deep seated divide between the UNSC and CMA forces, resulting in several ships defecting and joining the Insurrection. The result of this situation was the deployment of the 236th and 510th Fleets to the Garrophon System, kicking off its prolonged siege. 
Initial battles were relegated to space combat where the UNSC fleets easily overcame and decimated their rebel counterparts, suffering little to no casualties. The true siege began as mass deployments were conducted across the two main worlds in the system, Garrophon I and Kliment. Both of these saw en masse deployments of UNSC Army and Marine Expeditionary Units, both of which were equipped with several detachments of M874 Pangolins and M650 Mastodons. These 'Buster' units were instrumental in taking ground during urban battles, the Pangolins acting as secure, rapid transportation while the Mastodons and Scorpions shattered defenses. However the Pangolin was not alone, in fact it operated alongside other M12 variants such as the M12R which were used as rapid fire support.
As the months dragged on through the siege of the system, the fighting began to ground into a halt as Insurrectionist forces inexplicably began employing UNSC vehicles, including Pangolins. In Insurrectionist hands, the Pangolin was often treated as a moving barricade and roadblock, usually being fitted with even more armor and manually operated turrets. The sight of such UNSC vehicles in Insurrectionist hands resulted in massive investigations into colonial militas and CMA units, revealing several Insurrectionist sympathizers. Due to this revelation, the UNSC invasion force doubled down, seizing equipment and stockpiles from compromised CMA units and authorizing the use of heavier weapons in 'Buster' units. This saw Pangolins equipped with .50 cal machine guns along with missile pods, the combination allowing for greater ease in defeating entrenched units but risking more civilian casualties. 
A notable engagement took place on Kliment, on 22nd, September 2515, involving a Pangolin equipped 'Buster' unit as they attacked an Insurrectionist held neighborhood. During the firefight, a trio of Pangolins were noted as laying down heavy fire through several fortified buildings, allowing infantry units to move in and clear them out from inside. This inadvertently resulted in the deaths of 50 civilians due to the usage of human shields by the Insurrectionists and the use of heavy weapons and explosives to overcome the fortified buildings. This was followed by questioning into the way the vehicles were used, with local news sources blaming UNSC forces for haphazard and excessive usage of heavy weapons against civilian targets. However, these were largely from known, pro-Insurrectionist stations and as a result were initially ignored. The vehicles continued their use on the frontlines, being a valuable asset in the transportation and support of troops in heavily contested frontal positions.
===Outbreak of the Human-Covenant War===
Operation: TREBUCHET would continue for nearly a decade after the Siege of Garrophon, the Pangolin seeing much further use over the course of the campaign. The Pangolin saw even further use as the intensified, saving the lives of hundreds on UNSC troops in ambushes. However the storied career of the Pangolin and its once sought after upsides came to an alarming and violent end in 2525. In September, 2525, the UNSC announced a general alert across the colonies as they came into conflict with the , an alien empire seeking the destruction of humanity. 
The first instance of Pangolin equipped units combating Covenant units came in December 2525, on the colony of New Richmond. A Covenant fleet had rapidly decimated the and had begun mass landings across the colony, clashing with CMA and UNSC Army forces. The overwhelming size and firepower of the invasion force had shattered initial attempts to break their lines with armored units, pushing UNSC forces onto the back foot. Pangolins being used to transport troops through the fighting were targets of favor, often being focused due to their greater size and lower agility. Furthermore, multiple impacts from plasma weapons on the doors had caused several troops to be trapped inside their vehicles, behind superheated armored doors and covered in molten metal.
 
A similar fate came of Pangolins acting in defensive positions, plasma weapons tearing through their armor and killing their crews or crippling the vehicles. As a result, many saw emergency measures being enacted and ejected their doors to make them more maneuverable. While this was initially regarded as an isolated incidence due to the overwhelming size of the enemy force, it would soon grow and become a major issue with the Pangolin as the War carried on. Even further engagements in the same system saw Pangolins becoming easy targets due to their inability to rapidly navigate or evade incoming plasma fire, lest they flip and crash.
==Role and Usage==
The primary role of the M874 Pangolin, from the moment it was proposed, was to serve as an uparmored and more capable alternative to the comparatively lightly armored M12 series and its variants such as the M831 TroopHog. To this end, it was equipped with numerous upgrades including its distinctive armored doors and Remote Weapons Station (RWS). It was because of this that the vehicle found heavy use by UNSC Army units stationed on more urbanized colonies which were noted to have high levels of Insurrectionist activity. In practice, the vehicle performed exceptionally well with its armored doors protecting the crew from the majority of weapons used by insurrectionists. Furthermore, its RWS allowed for much greater flexibility in operations in congested city streets. These were so advantageous that the vehicle saw further adoption as an escort vehicle for VIPs, a SWAT transport and a general transport for the UEG Bodyguard Corps. 
Despite these successes during the Insurrection, the Pangolin would all but disappear in the changing environment of the Human-Covenant War. In particular, its once very useful armored doors became its greatest weakness, as Covenant plasma weapons melted through the armor after only a couple of shots. Furthermore, the RWS also became a weakness as a short burst of plasma fire could cause a catastrophic cook-off of ammo, threatening the vehicle and troops around it. Though its most notable failing was its weight, all the additions had greatly reduced the agility of the vehicle despite maintaining the top speed and cross country performance. There were attempts to rectify this by substituting the carbon nanotube layer with thin layer of titanium carbide but this proved to be a minor improvement at best. It was because of this that the Pangolin saw very little use after the first five years of the War, many being relegated to reserve units or being used as armored transports. However, they did find limited use in the hand of special operations units, notably in the hands of Spartan and ODST teams being deployed behind enemy lines.
There was once again a rise in use of the Pangolin after the end of the Human-Covenant War, primarily due to two factors. The first was the adaptation of the Pangolin to the M12B chassis which offered some more flexibility in its use. The other factor was the re-expansion of the UNSC into their damaged or abandoned colonies, many of which were now Insurrectionist hubs or sought to become fully independent. It was during these expansions that the Pangolin found relevancy again, being deployed as both peacekeepers and as part of mechanized incursion units to establish control on the colonies. This saw also saw further use of the Pangolin by private corporations as security vehicles, much like the M12 series had. This saw further variants of the Pangolin including an elongated 6x6 version for use as a frontier APC/armored transport.
==Design Specifications==
===Mobility=== 
====Chassis====
Despite the radical differences between the M831 and M874, they do retain a common chassis design, that of the M12 Warthog. The M874 Pangolin features a monocoque chassis which means that its chassis and body are a single unit which itself is composed of a titanium frame along with carbon nanotubes which surround the the titanium, providing further structural support and rigidity to the frame. The primary layer of ballistic protection comes from the usage of titanium armor and ballistic polycarbonates which make up the outer skin and immediate surface of the vehicle. This allows it to sustain shots from a variety of small arms and even some heavier weapons such as machine guns with exceptional ability. Behind this outer layer is a network of carbon nanotubes and titanium structural supports which further bolster the toughness of the vehicle. 
The carbon nanotube supported titanium frame continues throughout the vehicle, through the frame of the troop bay and crew area, all the way down into the engine bay. The engine bay and rear seating area in particular feature large amounts of extra cross-bracing to prevent the vehicles body getting warped in the event of a crash or other impacts such as falling. This also serves to encase the crew compartment in a well protected tub, which ensures their safety either in a roll, crash or fall. Both the crew compartment and seating area in the back, feature blast reducing seats which prevents or at least decreases the jarring done to the troops inside in the event of an explosion under the vehicle. 
The most striking difference of the Pangolin from its cousins, and its namesake no less, is the addition of eight armored doors to both the troop area and crew compartment. The doors in the crew compartment are of a single piece, gullwing design and open upwards, away from the vehicle. This design was chosen as split doors which opened left and right would block the view of the crew member dismounting the vehicle. As they are to protect the crew, the two doors of the troop bay are composed of several different layers, to achieve the most protection for the lowest amount of weight. 
*The primary and outermost layer of the doors is one of , which allows the vehicle to sustain ample amounts of damage from both plasma and ballistic weapons, the latter being further hampered by the angling of the door, making it more likely to ricochet rounds. 
*After an air pocket is the secondary layer of the armor which is a layer of . These carbon nanotubes are coated in a layer of ceramics which are specifically implemented to absorb heat. This gives the vehicle substantial protection, when paired with the titanium, against incendiary weapons and, inadvertently, making it tougher against plasma weapons. This would later be replaced with a thin layer of Titanium Carbide during the Human-Covenant War. 
*After another gap is the main Titanium frame upon which the armor is mounted which provides structural support for the door and armor
*Both beneath the frame, and even within some spaces in it, is a layer of Thermostable gel, which maintains the temperature on the inside of the vehicle and prevents the crew inside from becoming too hot or too cold. But under sufficient temperature shock there is a chance for the gel to fail. 
*In the event of Gel layer failure there is a final layer of Aluminum 7075 alloy armor between the potential ballistic or environmental hazard and the crew inside.
*The final piece of the armor is a simple Kevlar spall liner to prevent or reduce shrapneling in the event of a penetration by a weapon. 
All doors on the Pangolin are composed in this way to ensure the crew and mounted troops are as protected as they could be in a combat or in extreme heat or cold. The complement of 8 Troopers or 5 are to be seated in the rear bed of the Pangolin which, like the M831, features a large padded bench mounted in the center, capable of seating 3 Troops on each of the side benches and two at the end of the bench. Spartans can be seated in a similar manner, but with only 2 per side bench and one at the end due to their greater weight and size taking up more space. The troop bay is covered on all sides by three sets of split, vertical opening doors which open in two sections, one upwards and one downwards. The advantage of this layout is that it allows the embarked troops to open the upper half and fight from within the vehicle with ample cover for their bodies, and it provides an unobstructed view of the dismounting area when both are opened. 
The doors are opened by a simple two piece latch at the seam between the doors, one for the upper half and one for the lower. Conversely there is also a rapid opening method which requires pressing and holding down either the upper or lower latch as opposed to pressing them and letting go to disengage the locks. The opening and closing of the door is aided by compact and robust electric drives due to their great weight, these drives make the manipulation of all the doors remarkably easy, despite their mass. The final part of the rear doors is the viewports, two viewports on each side and the rear of the Pangolin. These are composed of Aluminium oxynitride which is mounted in a carbon nanotube supported frame, allowing it impressive bullet resistance. A similar glass and frame is present on the driver and passenger doors. The viewports facilitate the usage of two firing ports on each set of doors of the troop bay, these firing ports allow the usage of MA5/37 assault rifles, BR55/85 battle rifles and other small arms, allowing the crew to fight from the inside of the vehicle.
====Suspension====
The suspension of the M874 Pangolin is left unchanged from its cousins and is an independent swing arm suspension, meaning it has four independent swing arms which are composed of the four axels. The advantage of this type of suspension is its nearly unmatched capability for navigating rough terrain, due to its independently powered and orientated axels. This allows for incredible degrees of wheel travel and impressive mitigation of shocks and bumps to the crew, as the suspension arms can move up and down freely. While this makes the Pangolin and other Warthogs incredibly capable off-roaders, it does have one major drawback which is the limitation of its speed. Due to the design of the suspension with its high ride, soft springs and heavy duty shock absorbers, it is incapable of reaching very high speeds. This results in a limitation of the speed of the Pangolin and other Warthog derivatives to 125 km/h. While this could technically be exceeded, the practical use and associated dangers of doing so have resulted in the vehicle being electronically limited to the 125km/h top speed.
The tires used on the M874, like other Warthog models and variants, are Single Unit Skeleton 614 tires. This is abbreviated as the SUS-614, designed by Michelin-Vance and AMG while it is produced by PUMA. The exact dimensions of the tires are 628/59 R24, this means that the tire have a track width of 628mm, while the 59 is the percentage of the width which is equal to the distance between the ground and the rim, this means a full tire height, excluding the rim, of 741.04mm. The final part is the R24, which is the size of the rim in inches, which, when taken along with the tire, gives a full tire height of 1350.64mm or 4.43 feet. However, while these are the exact technical figures for the size of the wheel, they are rounded to the nearest multiple of 5 for simpler organization, meaning the official designation for them are 630/60 R24.
The A&H SUS-614 has long since foregone the use of inert gases to provide buoyancy in the tires and instead utilizes a single frame skeleton composed of a network of carbon nanotubes, the result of such a frame means that the tires are all but indestructible, vulnerable only to large caliber anti-material rifles or explosive weapons. Another advantage of using such a single frame design is that the wheels are burst-proof, as there is no gas within the tire providing buoyancy, allowing it to sustain small arms fire for extended periods of time with little effect. Despite this, the ride comfort and stability of the tires is indistinguishable from normal gas-pocket tires. The tires utilize an all-terrain tread which allows the M874 and other Warthog derivatives to maintain an impressive and constant level of grip allowing operators to function without issue on shifting deployments on different worlds.
The steering provided on the M874, and all M12 variants, by an active four wheel steering system, meaning that all four wheels are capable of turning independent of one another. This is facilitated by the usage of both physical actuators as well as a computer controlled steering systems, the actuators being a redundant system in the event of the computers sustaining damage. These steering arms as they are called, extend down each of the four axles and connect to the electric motors at each wheel, the actuators and cables being protected by the armored axle covers. The reason such a system is used is to allow vehicles as large, heavy and powerful as the Warthog series to remain remarkably agile despite their bulk. In practice, the usage of the emergency brake or e-brake, in concert with this steering allows for making turns in a remarkably small circle. However this is not the case for the Pangolin, due to the addition of the heavy armored doors, RWS and the reinforced troop module. The addition of these upgrades has made the Pangolin very top heavy and therefore it runs the risk of rolling with ease when undertaking rapid changes in direction or e-brake turns. 
To facilitate the mobility of the M874 and its cousins and to ensure they don't crash regularly, is the four wheel braking system. The Pangolin makes use of large, carbon fiber reinforced, silicon carbide disc brakes, which are 26 inches in diameter. While this is technically larger than the externally visible rim of the vehicle, it is still useable since the interior of the rim, underneath the hubcap, is four inches larger than the exterior. This allows for a much larger brake to be fitted than the outside of the vehicle would suggest, however even this was considered small given the size and mass of the Warthog. As a result, the electric motors are capable of shifting into reverse and driving the wheels in the opposite direction by inverting the polarity of the motors. This, combined with the normal disc brakes, allow for the Warthog to stop with remarkable speed, enough to risk ejecting a passenger, though this is avoided in the Pangolin thanks to its doors.
====Powerpack====
The M874 Pangolin is powered by a Kristoff & Clifford 12.0 Liter Hydrogen Powered Engine-44627, abbreviated to K&C HPE-44627 or just HPE-44627. The HPE-44627 is a derivation of the standard Hydrogen ICE found in the normal M12 and M831 Warthogs but retains an 89% parts commonality. As the Pangolin was heavier than either the Warthog or Troop Hog, the powerplant also needed to be improved to allow the vehicle to maintain its battlefield mobility and off-road capability. The result of this was the HPE-44627 which features a greater power output and more torque while maintaining a favorable fuel efficiency even at high speed. The most noticeable improvements of the HPE-44627 are undoubtedly its Twin-charging, system which combines a centrifugal supercharger with a variable-geometry turbocharger to allow air to be forced into the engine and thereby increase its power and torque, the reason for the twin-charging is that the use of a supercharger and turbocharger means that air is being forced into the engine at all times. 
The supercharger used is a variant of the AMG Transport Dynamics TSSC-226 'Tusk' High Performance Supercharger which is an optional extra on the civilian 'Hog'. The difference between the standard 'Tusk' and that used on the Pangolin is the robustness and reliability of the supercharger, whereas the civilian variant is slated for maintenance every 27,000 miles, the model used on the Pangolin is able to go an extra 23,000 miles for a total of 50,000 miles through the use of more expensive and far more capable air filters. Further reliability is provided by the use of anti-corrosive coatings and a redesigned impeller which is capable of operating even with large amounts of pollutants on it. 
On the performance side the supercharger increases standard power output by 41% and low speed torque by 21 % which allows the Pangolin to both accelerate better and remain more mobile at low speeds such as those required in tight city streets. These performance figures are possible not solely due to the supercharger but also the crankshaft which has been reinforced and allows the engines to operate at a higher RPM, increasing the speed of the impeller in the supercharger.
The turbocharger used was developed specially for the Pangolin by AMG Transport Dynamics and is known as the VGTC-0276 'Claw' Variable Geometry Turbocharger. While the 'Tusk' supercharger was modified from a civilian to military requirement, the 'Claw' turbocharged was developed with military use at the forefront. this is evidenced by the intensive stress testing the turbos are put through, being made to run while being sprayed with water, mud, sand and other environment samples until they fail. As a result of this testing, and the decidedly less obstructive exhaust fumes when compared to fossil fuels, the 'Claw' is able to go between 43 and 51,000 miles without being cleaned out, depending on the terrain it is used on. Performance wise the 'Claw' turbocharger delivers a decent 22% power increase, this being an intentional design by AMG to allow the turbo to last far longer by operating at a lower boost pressure.
The combined use of the 'Tusk' supercharger and 'Claw' turbocharger allow the Pangolin to output an impressive 1197 horsepower (hp) for a power to weight ratio of 200.3 hp/tonne and torque of 3,591 N-m (2,648 ft-lbs) at 3,000rpm with a redline of 3,400rpm which allows it to reach an on-road top speed of 125 km/h (78mph) and an off-road top speed of 122 km/h (76mph). The latter being maintainable due to the impressive off-road ability of the M874 and by extension the M12 series. However, due to the large armored doors mounted on the tall troop bay and the installation of the remote weapons station in front of it, the top speed is rarely ever reached anywhere except open terrain or roads, with the vehicle often operating at lower speeds in practice to reduce the risk of rolling it.
In the event of damage to the engine, the Pangolin features a variety of safety systems to prevent a catastrophic detonation of the engine as well as diminishing incoming damage as best it can.
Engine maintenance is conducted by opening of the horseshoe shaped hood, which allows access to the air filters, cylinder heads, valves and main engine block. For in-field maintenance to the super or turbocharger, the vehicle needs to be lifted up which distends the wheels from the wheel arches and allows for access to the supercharger or turbo, a simpler method is the removal of the titanium fenders and inner wheel arch but this is not always possible in combat environments as it takes an extended amount of time to place them back. 
Refueling of the engine takes place from a filler port below the seating area for the passenger, the HPE-44627 is capable of taking all forms of water including mineral, brackish or even swamp water thanks to a Graf/Hauptman solar/saline actuator, which is capable of converting up to twelve liters of water into hydrogen on the fly. Detritus from the process is stored on board and disposed of by a flushing system which is activated from the center console in the crew compartment. This allows the Pangolin to travel 870 kilometers (540.6 miles) before it needs to be refueled, a range that can be easily extended by the addition of jerrycans or external fuel tanks to over 1000km.
====Drivetrain====
Reigning in the power of the K&C HPE-44627 is the MTR-3126LV Infinitely Variable Transmission (IVT), another development by AMG to allow the Pangolin to function at peak performance despite their substantial weight increase. The MTR-3126LV IVT is effectively the same transmission as the MTR-3116 used in the M12 Warthog but is rated for a higher tolerances and torque ranges which the Pangolin outputs. While the MTR-3116 could have, and in cases of desperation has, been used, the risk of the transmission suffering crippling damage or outright breaking due to the increased weight and torque was too great. 
 
An Infinitely Variable Transmission (IVT) is a specific kind of continuously variable transmission (CVT), in this case an epicyclic CVT. The transmission ratio includes a zero point that can be approached from either the positive or negative sides, also known as the input and output. In other words, a constant input, in this case coming from the engine, turning in the same direction, at the same speed, can be converted to an output. This output would be turning faster, slower, in the opposite direction, or not turning at all. This creates a “geared neutral” mode, you’d need infinite input revolutions to cause one output revolution. This manner of transmission allows the Pangolin, and by extension the entire Warthog family, to have a near infinite selection of forward and reverse gears and ratios. Allowing for extremely smooth transitions between 'gears' and a minimal loss in power. Furthermore, it allows for remarkably fast acceleration from idle or from low speeds, as well as deceleration of similar speed.
The power from the engine is transferred to the transmission through a lightweight, titanium and carbon nanotube forged driveshaft to its position beneath the crew cabin. The gearbox itself is mated to a pair of EPV-744M Electricity Generators, these are dedicated, military spec electric generators which are used to provide power to the wheels. The function of the IVT here is to simply regulate the power of the engine into the generator. The generator provides power to four, EM-590M Electric Motors, which are highly efficient and extremely durable electric motors made specifically for military vehicles. The power is provided to each motor via four sets of cables, all of which are encased in high strength, carbon fiber weaves. The reason for four of them is to provide redundancies in the event of the vehicle sustaining damage, as any one set is capable of transmitting the full power from the generator to each motor. The cables extend down each of the 4 axle arms along with the necessary steering arms in an enclosed titanium-carbon nanotube shell to protect the components inside from environmental and ballistic damage. 
The primary advantage of this system is an incredibly efficient propulsion system, allowing remarkably long ranges relative to the amount of fuel in the tanks. Another advantage of the system is its ability to function even when severe damage has been sustained, by having a specific motor for each wheel. This means that in the event of a wheel being blow off or crippled, the others are completely unaffected in the supply of power to their respective wheels. This is also why a second generator is mounted and why both are made of high strength and lightweight materials, so in the event of one being damaged, the others allow the vehicle to function without issue. As for repairs and reliability, the well protected underbelly and axle shells of the drivetrain can protect them from most environmental hazards and a large amount of ballistic damage.
===Armaments===
Unlike the which it is derived from, the M874 Pangolin contains a mounting point for the M43 Remote Weapons Station (RWS). The M43 is a black sheep amongst vehicle mounted turrets in the UNSC as it is not crew serviced but rather is controlled by a screen which folds out from behind the passenger, along with this an arm with a control stick extend out from the dashboard. The turret is mounted above and behind the crew compartment, above the main vehicle spotlight and is capable of full 360-degree rotation and is capable of -20 to +50 degrees in depression and elevation respectively. The mount is fully gyro-stabilized and can mount weapons of up to 20mm on board. The sight package located on the left side of the turret contains a high definition day-night camera with a thermal camera mounted next to it and an eye-safe laser rangefinder. 
====Primary Weapons====
While most commonly fielded with the , the M43 is capable of attaching a variety of other weapons and launchers including:
* x 1 
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Both the M41 and M46 'Vulcan' Heavy Machine Guns are fairly common mounts as the increased stopping power of the 12.7mm rounds and the higher fire rate are far more effective against enemy infantry and low flying aircraft. However, to manage either of them, the weight of the turret is increased substantially, both due to the triple barrel design and the large, heavy ammo boxes which include 250-round box magazines, 400-round drum magazines or 500 round box-magazines. This results in the turret being heavier and having a slightly lower rotation speed which, combined with the longer barrels, make the weapons ability protect around the vehicle more difficult. Both are often fielded with the Compact Launch System (CLS) to allow the vehicle greater versatility in engaging targets.
The M43 is also capable of mounting the M460 40mm Automatic Grenade Launcher which is usually fielded with units operating in vehicle heavy environments or areas with dug in troops. The M460 utilizes a 40 round box magazine and includes several types of ammo including High Explosive (HE), Proximity Fuse (HE-VT), and High Explosive Dual Purpose (HEDP) which have a secondary EMP mode, the launcher is most often fielded with the latter. When the system is operating in a riot or non-lethal force situation, the aforementioned rounds are exchanged for smoke, tear gas and even rubber bullets to neutralize threats or pacify mobs.
The least used and most powerful of the M43's options is an M638 20mm Autocannon, derived from the one used on the Falcon. The M638 despite its power, accuracy and potency as a weapon seldom seen used on Pangolin's for several reasons. The weight of such a large gun, so high up on the vehicle makes the chances to rolling the vehicle far higher, the size of the gun also makes it even easier to hit and disable, the larger rounds making the potential ammo cook-off from the 100 or 200-round box magazine more damaging in the event it happens. The recoil of the gun also reduces the life of not just the stabilizers but also the turret itself as constant firing can weaken the mount or even warp the structure its mounted to. However the greatest reason is the abysmal rotation speed and sub-par depression which make the M638 a seldom used weapon, however there have been cases of Pangolins with 20mm guns being used as stationary pillboxes. 
====Secondary Weapons====
Aside from these there can also be accessory weapons alongside the main weapon, this in most configurations is the LAU-72 Compact Launch System (CLS) which contains four, 60mm ASGM-4 missiles. The ASGM-4 are high explosive missiles which travel at relatively high speed and are most often used to target emplacement or light vehicles such as Ghosts, Revenant's and even other Warthogs. The targeting software used in the missiles allow it to be a fire and forget missile and can attack on specific attack paths including ground skimming and top attack, the latter being exceptionally useful against Wraiths due to their large open gun mounts. While these missiles are non-reloadable in combat, they can be rearmed at a garage or base. The LAU-72 can be used alongside the aforementioned HMGs however caution is advised in using it alongside the M460 AGL due to the chance of the grenade launcher taking fire and possibly exploding which would cause a chain reaction and detonate the missiles or vice versa which would destroy the whole vehicle.
Conversely if a non-lethal response is needed or if the vehicle needs to disengage or cover its deployment, a cell of eight FHS375 smoke grenade tubes can be mounted. These would take the place of an accessory weapon but could also be loaded with tear gas to disperse crowds. Later iterations featured two dedicated clusters of four smoke grenade launchers on each side of the turret, capable of launcher the same smoke and tear gas rounds. Further non-lethal weapons such as M460 AGLs with rubber bullets or even high power hoses can be employed in the RWS when operating in riot operations.
====Sensors and Targeting Systems====
The sensor package of the M43 Remote Weapons Station (RWS) prior to the outbreak of the Human-Covenant War was decidedly smaller and more compact, so as to keep the profile of the turret low and the optics safe, close to the gun-shield. However, when the M43 was upgraded to respond to the Covenant threat, its sensors and optics saw a massive improvement to be able to respond to the new threat and style of combat. As the turret itself was up-gunned to be compatible with a wider variety of munitions, so too was the targeting software. The new EB292 'Owl' Fire Control System (FCS) allowed for acquisition of targets, ballistic correction and engagement out to ranges of 2 kilometers for weapons from 7.62mm to 20mm. Each weapons also has their own presets programmed into the FCS to ensure optimal performance and accuracy when engaging at long ranges. Furthermore, the firing solutions for the equipped weapon are updated as a target is being engaged, allowing the vehicle to combat moving targets while stationary or on the move itself. 
To improve the situational awareness of the gunner, the FCS is also fed data from six, wide angle sensors, three on each side of the turret, which are able to target and obtain solutions on targets which are not in the current line of sight.
Along with the FCS, the three main camera sights through which the gunner views the battlefield were also upgraded. The previous goals of compactness were abandoned during the upgrade and saw the replacement of the compact cameras with larger high definition cameras to allow for engagement at longer range. The first of these three camera sights is the primary viewing camera which is a M221 Day-Night FHD Camera System, otherwise nicknamed the 'Cyclops' due to how much larger it is than the previous cameras. The M221 features a wide FOV lens which along with the FCS can make engaging or responding to several targets easier, the lens can manage a a variety of zoom levels from a x1-x14 for use at long range. While in some cases the ability to make out targets at such ranges could be hampered, this does not occur in the M221 which utilizes a FHD 1440p x 1080p display, giving the gunner a clear sight during combat either in darkness or in daylight.
The second camera sight, which is smaller than the M221 but is still rather large, is the M711 Multi-Wavelength Gun Sight. This camera allows the gunner to engage targets in complete darkness or similar situations of visual obstruction such as heavy snow, rain or in dust storms. The camera itself is rater at 1440p x 1080p and is capable of covering a wide range of the electromagnetic spectrum, giving a wide range of view modes to better adapt to situations. As with the M221, the M711 also has a connection to the FCS and has its own presets, reticle and display parameters for firing the turret is adverse conditions. In regular combat the M711 behaves as a thermal sight capable of picking up enemy heat signatures and engaging them out to the same 2 kilometers thanks to the FCS.
The third sight is not especially large, has a fairly low field of view FOC and resolution of only 1080p x 720p, however, the M393 Back-up Gun Sight is nonetheless a vital part of the optical package of the M43 as its small size and capability to fight at night and day ensure that the vehicle is able to respond to fire even if its main optical systems are disabled. 
On the control and targeting aspect of the M43, viewing through the optics is provided by a 2560 x 1440p, 144hz screen which folds out from behind the passengers seat. The display is fed by the trio of cameras on the turret and is held in front of the passengers by a stabilized arm which allows its easy use, even over rough terrain. Furthermore the screen is linked to a trio of sensors on the right and left side of the turret which cover a cumulative 360 degrees which allows targets outside the line of sight to be tracked and identified to make engaging them easier. 
In the first series of models, actual movement, aiming and firing of the turret is managed via a fold out arm which is beneath the seat of the passenger and at its end, has a controller like device. This controller has two analog sticks, one for elevation and the other for rotation, and two triggers, one for firing the main gun and another for switching between zoom levels either by stages or gradient depending on the setting. When not in use, the arm which the controller is attached to collapses into a metal cover beneath the seat so as to reduce the risk of it injuring the passenger in a crash. During the Human-Covenant War, this controller design was reworked into a smaller design with only a single joystick which controlled both elevation and rotation, while the second joystick was replaced by a D-pad which allowed easier control of the optical settings. Furthermore, the triggers were moved into more receded positions and made stiffer to reduce the risk of accidental firings when the gunner or vehicle is jostled. 
====M48 Remote Weapons Station====
As the M43 was developed to fight the , it sported a relatively weak gun most of the time, when compared to those of the . This however had the aforementioned drawbacks as the extra weight decreased the rotation speed, hampering its effectiveness of the turret to support infantry. Furthermore the lack of an adequately sized gun shield to make space for the camera, sensors and missile pod, meant that the gun is also far less protected and prone to getting disabled, making it fall out of favor compared to better protected crew serviced guns.
As a result of these issues, and have been working on developing a new M48 Remote Weapons Station. The M48 is more robust than the older M43 and is made with stronger parts and features stabilization for weapons up to and including 14.5mm. It mounts a new gun shield which is 30mm thick and is made of Titanium-A3 derived armor to better handle impacts from plasma weapons, add on ceramic plates can also be fitted to further its protection. The development of more compact and higher resolution day-night optics also means that more space can be taken up by the gun shield and ammo boxes, meaning further protection and a greater amount of ammo carried. Despite the attempts to make the turret more survivable, there was an added option to 'eject' the turret should it be disabled or if the ammo risks cooking off and damaging the vehicle. In this situation, the mounting locks are disengaged and the mounting arm is extended outwards, pushing the turret up and out of its mounting so it may roll off the vehicle.
==Variants==
*M874: The standard version of the Pangolin which was first fielded in the Insurrection, equipped with composite armor doors and an M43 Remote Weapons Station, based on the .
*M874B: The Post-War version of the Pangolin which saw adoption by the UNSC Army in early 2553, equipped with composite armor doors, an M48 Remote Weapons Station and an alternate drivetrain due to it being based on the .
*M874B-UA: The M874B-UA, 'UA' meaning Up-Armored, is a modification of the M874B which features enhanced armor over the chassis and an improved composite armor make-up on its doors, allowing them to sustain repeated impacts from plasma weapons. Often fielded when operating alongside units or in areas with known threats.
*M874B-E: The M874B-E, 'E' meaning Extended, is a 6x6 version of the standard M874B which features a third axle at the rear as well as an extended rear bed, allowing for a larger troop module or to function as an armored transport.
*M874B-EUA: The M874B-EUA, 'E' meaning Extended and 'UA' meaning Up-Armored, is an uparmored version of the standard M874B-E. This variant features the enhanced UA armor package, including enhanced chassis armor and an improved composite make-up for the doors, allowing the vehicle to sustain multiple impacts from plasma weapons. Often fielded alongside the M874B-UA on joint operations with Swords of Sanghelios units or in areas with known Covenant threats. 
Category:UNSC Vehicles