M17 Hedgehog

The M17 Hedgehog High Mobility Protected Utility Vehicle was a six-wheel, high mobility, off-road, lightly armoured support vehicle manufactured by CSG, and operated by the UNSC Army and UNSC Marine Corps. A rugged and capable vehicle, the Hedgehog was introduced in 2534 to fill a wide range of non-combat roles across the UNSC, though it could be fitted with appliqué armour and defensive weapons depending on the threat. The vehicle manufactured in two primary variants; an enclosed truck for general transport, utility and logistics roles, and a , which replaced the load compartment with the ability to tow specialised mission trailers. Equipped with appropriate trailers the Hedgehog was able to fill roles as diverse as troop transport and battlefield recovery. The Hedgehog was ubiquitous throughout the UEG's armed forces in the latter years of the Human-Covenant War.
==History==
The Hedgehog was first produced by CSG in 2531, in response to a UNSC requirement for a common chassis to replace the diverse and ageing vehicles operated by the Army and Marine Corps. A series of key performance requirements were given including minimum standards of protection, off-road performance, fuel efficiency and load capacity. Problems were initially encountered in reliability tests by the manufacturer, delaying acceptance by the UNSC, but these were sufficiently solved by November 2533, when an initial order for 170,000 M17 trucks and trailers was placed. The process of replacing legacy vehicles across all of the UNSC Army and Marine Corps' units was complex, and was completed gradually over a period of 17 years. By January 2551 an estimated 4.7 million Hedgehogs of both variants were in service across UEG world.
==Design==
The Hedgehog was a six-ton, six wheel vehicle, powered by an 18.0 litre 760Hp, 6 cylinder . With this powerplant the vehicle was capable of achieving speeds of 75 kilometres per hour on roads, with lesser speeds possible off-road. Rated for towing loads of up to 40 tons, in reality the Hedgehog could be placed under much greater burdens if necessary and continue to function. One armoured hydrogen storage tank was located on either side of the vehicle, between the front single and rear two axles. The Hedgehog carried its own , allowing it to convert any quality of water to hydrogen and thus source fuel without resupply. The hydrogen fuel was burned at very high temperature with the addition of a synthetic carbon/silicon catalyst, allowing a range of 950 kilometres on a single tank. Each of the six wheels had an independent drive-by-wire electric engine, with power transmitted directly from the engine. The independent wheel-drive system allowed variable torque to be transmitted to each wheel independently based on the terrain, determined by a forward-looking terrain sensor linked the the vehicle's computer system. This had the added benefit of allowing continued mobility even if one or more wheel was damaged. The truck's tyres were single-piece nanotube 'skeletons', which, rather than holding air under pressure in a single chamber, as with traditional tyres, distributed it through billions of microscopic cells. This rendered the tyres resistant to ballistic, plasma and blast damage that would otherwise have incapacitated the vehicle. The Hedgehog was also equipped with a self-leveling suspension system to negotiate rough terrain. All of the various trailers compatible with the Hedgehog shared these power and suspension features, making it a consistently well-performing off-road vehicle.
The wide cab was armoured with a thin layer of titanium-ceramic composite, which was sufficient to protect the occupants from Human and Covenant small arms fire. The Hedgehog featured a monocoque construction whereby this base armour made up part of the vehicle's chassis, reducing weight for the equivalent level of protection. Both the truck and manned trailers could be fitted with additional appliqué armor packs to protect the crew from ballistic and plasma damage, depending on the level of threat, while the underside of the hull made use of a V-shape, intended to deflect mine blasts sideways rather than into the hull itself. Such an explosion would instead blow off the vehicle's wheels, though the Hedgehog was capable of remaining mobile with up to two wheels on a single side, or three overall, being disabled. The ballistic and plasma resistant polycarbonate front windows were additionally protected by slat armour, designed to prematurely detonate or deflect projectiles and plasma bolts. The cab could accommodate three occupants, a driver, gunner and a third passenger. A manual unpowered hatch on the cab roof was located above the gunner's seat, on the right hand side, and could be accessed by standing on the seat. The Hedgehog could be equipped with either an M84 heavy machine gun or M73 general purpose machine gun for self defence. Optional roof-mounted weapons were fitted to the powered rotating turret, which could either be operated manually or be be remote-operated using the Embrasure Remote Weapon System, allowing the gunner to aim and fire the overhead weapon using a system integrated into the dashboard. Four- or eight-barrel smoke grenade dischargers could also be fitted to either side of the cab, should the situation call for it. The centre seat of the cab was equipped with a radio system mounted on the dashboard, and was typically the responsibility of the third crewmember, if there was one. In the event of three occupants being present, the centre one would also handle navigation, using a GPS system located between the driver and middle seat. 
The front of the vehicle accommodated a utility winch with 15 tonnes-force pull in a 1:1 configuration or 27 tonnes-force pull using an included pulley in a 2:1 configuration and anchor point on the vehicle. An array of visible and IR main headlights, as well as brake and warning lights, were positioned on the front and rear of the truck, with an infrared system in the cab allowing the driver to operate in total darkness. Both Hedgehog variants featured a ladder on either the back of the cabin or the load compartment, allowing the crew access to the cab roof without entering the cab itself, while various items of equipment such as spare tyres, jerry cans and spades were stowed externally. The Hedghog was capable of fording water as deep as 2.2 metres, though this figure varied between all of the compatible trailer units. The truck was air transportable in the and D-98 Osprey internally, and by the D-77 Pelican underslung.
===M17A1 Hedgehog GP Utility Vehicle===
The M17A1 GP (General Purpose) Hedgehog was utilised for general personnel and materiel transport by non-combat engineers, signals, intelligence and other non-combat support branches, but was used in largest numbers by the UNSC Army Logistics Corps. The enclosed load compartment of the truck could be fitted with benches to transport up to eight personnel, and was equipped with lashing points on the floor and walls to secure any type of load.
===M17A2 Hedgehog Tractor Unit===
The Hedgehog tractor unit replaced the enclosed load compartment of the GP truck for a turntable where the truck could mount any number of trailers, making it an extremely useful and flexible utility vehicle. The reinforced turntable moved through all axes, acting as a point of articulation and contributing to off-road performance. Indeed, the Hedgehog's design capitalised on this, using a hydraulic yaw steering system between truck and trailer in addition to standard wheel steering. When connected up, the trailer would draw power from the Hedgehog's engine automatically, powering its own onboard systems and also feeding power to the trailer's axles. The flat rear of the truck was also equipped with lashing points, enabling the truck to securely transport items even without a trailer.
==Trailers==
*M9 Troop Transport- The M9 Troop Transport trailer consisted of a long, lightly armoured enclosed cabin, with a downward-opening hatch at the rear for swift egress. This hatch was fitted with integral steps to allow fully equipped personnel to more easily climb the several feet into the trailer. Inside were two double rows of eight moulded bucket seats each, with two 'aisles' separating the seats, in total capable of carrying 32 personnel. The trailer had an in-built air conditioning system and a two-way radio allowing communication with the Hedgehog's cab. The trailer had two rear axles and matched the Hedgehog itself in off-road performance, and was rugged enough to withstand the wear of repeated troop boarding and debussing, though was universally noted by troops for its awful ride. The troop trailer was not designed for use in combat situations.
*M1 Flatbed- The M1 Flatbed trailer was a general purpose trailer designed to securely and swiftly transport all manner of materiel that could be transported in crates or secured with lashing points. The flatbed trailer was 6.1 metres in length, allowing it to carry ISO containers, and featured locking points to enable this. The M1 could hold three pump or tank modules, allowing it to be converted for specific tasks, and also had compatibility with some elements of the M12 Recovery System. When equipped with a tow bar, two M1s could be joined and towed by a single Hedgehog. The M1 Flatbed was most commonly used for logistical support of mechanised and armoured units and ammunition supply to self-propelled artillery.
*Water carrier-
*Fuel carrier-
*M12 Recovery System- The recovery trailer was a 6-wheel, 26-ton, all-wheel drive trailer for the recovery of damaged or incapacitated vehicles. The recovery mission equipment included a recovery winch, a crane and a flat recovery bed bolted to the trailer's chassis. The M12 was capable of lifting 15 tons at a distance of 2.7 meters or towing a 64 ton vehicle, and could recover most vehicles in two minutes once the crane was set up.
*M13 Bridge Layer- The Hedgehog's bridge-laying system was based on that of the recovery trailer, and was able to match the M808 Scorpion for off-road mobility even when fully loaded. The M13 was capable of carrying one 22-metre bridge or two 12-metre bridges, which could be launched in in two minutes or 90 seconds respectively. Both these bridges were able to withstand vehicles of size and weight up to and including the Scorpion. Using deployable trestles and wedges, the M13 could lay combination bridges at depths of 5 metres from the trailer itself. The M13 trailer was not capable of recovering its own bridges after deploying them, though this could be accomplished with the assistance of crane-equipped vehicles.
*towed artillery- The Hedgehog was employed extensively to transport the M114 105mm light gun and M118 155mm towed gun, as well as to run ammunition to gun positions.
*M15 Universal Weapon Base- The Hedgehog was employed alongside truck-mobile weapon systems, such as the , which could be towed and then deployed where necessary. Other deployable systems include the surface-to-air missile system, , and the AN/MPQ-37 Darkfire air/space RADAR, all of which used the same 'universal' base and compatible trailer.
*AN/MPQ-61 Transport Erector Launcher and RADAR- the AN/MPQ-61 TELAR was a towed launch and targeting unit, carrying six launch tubes for the MIM-16 Archer, and a fixed phased array RADAR. Where deployed the AN/MPQ-61 provided long range strategic and tactical air defence, and was used extensively during the insurrection to protect UNSC installations from potential suicide attacks by spacecraft. The TELAR was deployed in numbers to protect multiple vectors and relied on its own detection systems, but could also augmented by other UNSC air or space assets. The RADAR was a passive electronically scanned array radar equipped with a track-via-missile guidance (TVM) array. TVM was a missile guidance technique which combined both semi-active RADAR homing and radio command guidance from the ground, making detection by the target extremely unlikely. The RADAR's antenna array was made up of 256,000 individual receptors that refreshed the RADAR's beam up to three million times a second. This single RADAR was responsible for all functions, including search, identification, tracking, and engagement. It was also equipped with an IFF interrogator system to prevent accidental engagement of friendly or civilian targets. The AN/MPQ-61 also comprised a sidelobe canceller array, which consisted of three auxiliary antennas placed around the main antenna, and designed to detect and decrease interference that might affect the radar, such as enemy jamming attempts. The digitally directed beam created by the phased array RADAR was narrow and agile compared to a mechanically traversed dish, giving it the ability to detect targets like missiles or aircraft, and also highly resistant to electronic countermeasures. The Archer was a dual purpose anti-ship and anti-air missile, when launched from ground sites such as the AN/MPQ-61, though could with external targeting data be used in a surface-to-surface role, a fact that was exploited extensively by the UNSC Army against Covenant forces.
*AN/MSQ-67 Engagement Control Station- The AN/MSQ-67 ECS was deployed alongside a battery of AN/MPQ-61 Archer launchers as the command and control unit. The ECS consisted of a reinforced cabin from where the system could be monitored. The ECS was air conditioned, pressurised to resist chemical and biological attack, and shielded against electromagnetic pulse or other electromagnetic interference.
*AN/TPQ-39 air defence RADAR- The AN/TPQ-39 was a mobile, trailer-mounted, electronically scanned phased array RADAR designed to detect enemy fire in flight, such as projectile or plasma mortars, rockets, shells and missiles. The RADAR was a brigade level asset in service with the combat branches of the UNSC Army, with the exception of the Artillery Corps, who deployed it at the regimental level. The RADAR served two functions. Firstly, it would calculate the location of enemy units based on the trajectory of their fire, allowing brigades to factor known enemy locations into planning for further operations, and allowing artillery to effect counter-battery fire. The second function was to alert units potentially threatened by detected enemy fire, allowing them a limited period in which to take defensive measures. The AN/TPQ-39, when networked, would utilise the UNSC's inter-service battlespace management system to send an automated warning to threatened units, whether these be dismounted infantry or main battle tanks. If the former, infantry could seek hard cover with a few minutes' notice, while equipped vehicles could ready countermeasures if this was not already done. Units capable of intercepting enemy fire in flight, if they were in range, would be provided with the RADAR's targeting data and could attempt to intercept. The RADAR was capable of tracking up to 12,000 individual targets and had a maximum range of fifty kilometres.
Category:UNSC
Category:UNSC Vehicles