F-371 Halberd

The F-371 Halberd was an atmosphere and exoatmosphere capable, four engine, twin-seat, carrier-capable air/space superiority fighter used by the United Nations Space Command Navy. Based on the spaceframe of the small, carrier-capable F-419C Sabre short range interceptor, the Halberd was an air/space superiority starfighter, designed to maximise on speed, agility, range, armament and protection, without sacrificing any aspects of its performance. Being more capable against single ships than either the Sabre or the F/A-352B Longsword, the Halberd was more expensive and produced in fewer numbers than these craft. The Halberd's role was much like the F-419C Sabre's, but differed in that the Sabre focused on speed, agility and weaponry over endurance and range. The Halberd, however, aimed to outdo allied and enemy craft alike in all aspects of performance, making it more effective but more costly than other fighter craft. Unlike the Longsword strike starfighter, which focused primarily on ground attack but had secondary abilities in air combat, the Halberd was not intended for ground attack or anti-ship roles and possessed no dedicated air-to-ground or air-to-ship capabilities; however, could attempt these roles to a limited extent using its multi-role weaponry. The Halberd was introduced formally in 2554, too late for the Great War that spawned its development.
==History==
In the early 2550s the UNSC Navy began seeking a superiority starfighter to supplement its existing Sabre interceptor and Longsword strike fighter. A key requirement of the fighter was that it be carrier-capable and small enough to launch from frigate-class vessels; this meant attention was turned to the F-419C Sabre, a carrier-based spacecraft whose small size was almost revolutionary at the time of its introduction. The basic spaceframe of the Sabre remained unchanged, although its components, internal mechanics and external appearance were drastically altered, in order to boost the new design's performance. The design was completed in 2554 with the design being named the F-371 air/space superiority fighter. Although not deployed in numbers as great as the craft it derived from, the Halberd saw use throughout the UNSC Navy where it operated from all types of warships which were designed with fighter hangars, including the Remembrance-class frigate. The Halberd proved itself more than a match for Covenant fighters on a one-on-one basis, though like all UNSC fighter craft suffered considerably when faced with the vast numbers of fighters deployed from Covenant vessels. The Halberd was operated exclusively by the UNSC Navy during its long service life.
==Role==
As a superiority starfighter, the Halberd's only role was the destruction of enemy aircraft, whether they be fighters, bombers, dropships or ground attack craft. Unlike the Sabre, the Halberd possessed both spatial and atmospheric engines, allowing it to transition between planetary and spatial combat effortlessly, operating across these environments to pursue and destroy the enemy. Despite this atmospheric ability, it was only operated by the UNSC Navy, who used it as a carrier-based craft for defence of UNSC warships against fighter attack or boarding attempts, and support of Navy and deployed Marine forces in atmospheric and spatial operations. Due to its extreme speed and agility, on a par with the F-419C Sabre, it was adept at intercepting and destroying enemy single ships while avoiding their return fire, and striking more vulnerable air targets such as gunships and troop transports. The Halberd was also commonly tasked with escorting and protecting UNSC bombers in their assault on enemy capital ships, while also intercepting and destroying incoming fighters and bombers attempting the same. The Halberd possessed better shielding and armour than the Sabre, along with a larger weapons complement and far greater range, allowing it to perform more difficult and demanding tasks with greater autonomy from the carrier vessel. Featuring two cyclic internal hardpoint bays, the Sabre could be equipped with a mix of guided munitions to engage multiple target types, though almost always carried 'air-to-air' missiles such as the AIM-109 Medusa and BGM-14 Volley. While not intended for ground attack or antiship missions, the Halberd could if necessary be equipped with ordnance for the task, although this did not play to the craft's strengths of air/space superiority. Like the Sabre, the Halberd's small size meant it could be carried by some of the smallest UNSC warship classes, such as the Remembrance- and Daring-class frigates, which could house a full squadron of them for offensive and defensive support.
==Layout==
The F-371's layout bore a resemblance to the F-419C Sabre, from which the Halberd was developed. The fuselage was aerodynamically shaped and was designed to reduce RADAR cross-section, while the large elongated nose featured the main sensory equipment including the powerful forward-facing AESA RADAR, LADAR and gravimetric sensor array, as well as ultraviolet and passive infrared sensors. Behind this was the cockpit, which consisted of a front pilot and rear weapons operator position and featured a tandem layout. Further back the fuselage widened into the main body, the top of which featured the main atmospheric engines. These were two large hybrid turbofan/scramjet engines that took up most of the upper fuselage's internal space. Between these engines on the dorsal side of the fighter was a remote-operated turret, which mounted the two M477 railguns. Below this, in the leading edges of the Halberd's angular hull, were hatches through which the two M490 railguns were deployed for firing. Mounted either side of the Halberd's main body were two very large fusion rockets, which powered the craft in exoatmospheric flight. The sides of these surfaces mounted relatively small control surfaces, which provided a minimal amount of lift in atmospheric flight but enhanced agility considerably. RCS thrusters were numerous across the Halberd's body, which gave it extreme maneuverability in both atmosphere and space flight. The craft's underside contained two hatches which would open to expose the large cyclic hardpoint bays, larger than those on the Sabre, which would house the Halberd's missile armament. The underside of the F-371 mounted eight additional external hardpoints, which could be used for the addition of extra guided ordnance, fuel tanks, railgun ammunition or specialised electronics packages, all at the expense of endurance.
==Armament==
The Halberd's primary armament was a pair of M490 30mm railguns, which it employed as a general purpose light armament against whatever targets it encountered. These large calibre railguns had a rate of fire of seven thousand rounds per minute and accelerated solid projectiles to fifteen thousand metres per second (15km/s); and were unsurprisingly effective against Covenant shielding and armour. These cannon were used in relatively close range combat to good effect against most targets including fighters and dropships; and could also be used to engage ground targets if necessary. The Halberd typically carried 3,000 rounds of ammunition for each of the railguns, limiting the amount the weapons could be operated; additional ammunition could be carried in containers on external hardpoints to remedy this somewhat. Unlike many UNSC spacecraft, the weapons did not possess dual feeding, meaning the guns could not be fired from a selection of two ammunition types; however, each cannon was commonly loaded with different munitions types to imitate this effect. The Halberd's railguns were located in the leading edges of its frame, and were concealed behind panels when not in use to reduce RADAR cross-section.
The Halberd was also armed with a single M6B W/AV G/GNR, mounted directly beneath the cockpit on the fighter's underside. The 'B' variant of the M6 W/AV was a scaled-up version of the M6A shoulder-fired, man portable antitank weapon. The M6B was developed for use as an anti-vehicle and anti-aircraft armament for UNSC fighter craft, which the Halberd used to great effect against single ships, destroying most fighter craft and dropships with a single hit. The weapon also had an antitank capability which allowed the Halberd to effectively engage armour if necessary, though its role as an air superiority fighter made this largely unused. The M6B W/AV was unlike the M490 railguns in that the Halberd had the capability for its extended use, with the ability to fire up to two hundred separate shots before needing to be re-armed. Unlike the M490, however, the M6B W/AV could not be used for sustained fire and instead emitted a coherent beam for less than a second, before needing to cool for up to four seconds.
The F-371's gun armament was rounded off by a dorsal turret which mounted two M477 15mm railguns. This turret provided all-round protection and deterrent against pursuing craft, and was capable of inflicting significant damage on unwary enemy fighters. This turret could be remotely operated by the Halberd's second crew member, though was more effectively operated by the fighter's computer systems, which made use of advanced targeting and IFF systems to efficiently attack targets. The M477 fired at 6000 rounds per minute and was fed by reserves of 8,000 rounds of ammunition.
==Shielding==
==Hull==
==Engines and Powerplant==
The F-371, given its dual atmospheric and exoatmospheric role, mounted two sets of engines to facilitate this. The Halberd's atmospheric engines consisted of two Chevron Aerospace F210 hybrid engines, which utilised a combination of turbofan and scramjet techniques to provide ideal performance at all speeds. While scramjets had excellent altitude and speed characteristics, they had no mechanical means of compression, meaning they unable to operate below supersonic speeds or start from a standstill. These drawbacks made it impractical and hazardous to fit an aircraft solely with scramjets. To compensate, the F210 engines operated as turbofans when on the tarmac, taking off and at subsonic and low supersonic velocities. To achieve this, they possessed a ducted fan and air compressor built into the engine's inlet body, to mechanically move air into the engine and compress it enough for combustion. This allowed the engines to generate thrust from a standstill and produce efficient, effective thrust up to Mach 3, allowing the Halberd to operate effectively at low velocities. At Mach 3 and above the fan and compressor folded back into the inlet body, opening up the engine for true scramjet mode, where the supersonic flow of air into the engine was self-compressed. In this mode the Halberd was capable of speeds up to Mach 26, which was sufficient to attain escape velocity, and an atmospheric flight ceiling of seventy five kilometres.
These hybrid engines, relying on combustion of fuel and oxygen in the air, were inoperable in spatial flight. Thrust in space was provided by two DF-710 fusion rockets. These rockets expelled material from the Halberd's single fusion engine, a Mark XXVIII TEMPEST Fusion Reactor, as propellant for forward thrust, providing extreme acceleration and a maximum speed of just under 230,000 kilometres per hour. The aneutronic fusion reactor minimised the amount of neutrons expelled along with the propellant, maximising thrust and reducing the chances of detection. As with all UNSC spaceborne fusion engines, hydrostatic systems cooled the the propellant to almost the temperature of surrounding space, preventing the craft from leaving a large thermal signature. The Halberd also featured magnetic field projectors and hydrogen 'ram scoops', allowing it to actively refuel its fusion reactor and rockets and boosting its endurance.
==Sensors and Electronics==
==Stealth and Countermeasures==