Jinmu ZF-33 Black Eagle

The Jinmu ZF-33 Black Eagle (Zhenian: ZF-33 검독수리) is a line of Zhenian, twin-engine, , aircraft built primarily by Jinmu Heavy Industries. Built primarily as a medium-sized multirole fighter complementing the ZF-21 Dragon that was set for introduction in the Republic of Zhenia Air Force and Republic of Zhenia Navy, the ZF-33 is more streamlined towards carrying out strike missions as a multirole fighter from the beginning compared to the ZF-21. The family is divided primarily into two variants - the ZF-33A and the  ZF-33B; all later variants have been developed directly from one of the two base variants for each branch.

The ZF-33 has entered service in both of its launch customers, the Republic of Zhenia Air Force and the Republic of Zhenia Navy, in 1604 AC, while it has been exported to a handful of its allies. With an estimated total of almost 1,700 units planned by 1620, the aircraft it set to replace various combat aircraft of previous generations and form the numerical bulk of the services' manned combat aircraft well into the mid-17th century. It is expected to see service within Zhenia until at least 1650, with speculations that the aircraft might make it to 1700 AC in some air forces.

Program origins and concept demonstration
What would eventually become the ZF-33 Black Eagle was developed from the Perspective Strike Fighter program that began in the early 1580s AC, a program dedicated to procure multirole fighters for the Republic of Zhenia Air Force to supersede the single-engine ZF-8 Phoenix multirole fighters and eventually complement what would become the ZF-21 Dragon. At the same time, the Republic of Zhenia Navy also issued demands to replace the aging ZF-11 Typhoons and several ground attack aircraft in service aboard its aircraft carriers and land-based naval air bases. Following several evaluations and reviews from the Ministry of Defense amid budgetary concerns and the advent of new security threats in the 1580s, a number of separate aircraft development programs were merged into the Next-Generation Air Combatant (NGAC) program in March 1583, with the primary objective to replace a large number of multirole and strike fighters within RZAF and RZN service.

Contracts to design and build a number of concept demonstrators were awarded to Jinmu Heavy Industries and the Paragon Group the same day. Each of the firms awarded the contract were to build a total of four concept demonstrators - two meeting Air Force standards, and two meeting Navy standards - fulfilling the requirements of the program. The two main contractors came up with fundamentally different designs, with Jinmu Heavy Industries pursuing a traditional wing-and-tail design, as opposed to the Paragon Group's design proposal featuring a delta-canard configuration similar to the one found on the ZF-8 Phoenix. While single-engine variants, set to use an improved derivative of the engines that were to power the ZF-21, were considered by both bidders, they were rejected under the insistence of twin-engine aircraft from the Navy. With the first proving models, the ZX-33 and the ZX-34, making their first flights in 1589 and undergoing rigorous testing across all speed and altitude spectrums by the Zhenian Ministry of Defense. The ZX-33 in particular, underwent both subsonic and supersonic testing, as well as proof-of-concept tests for its internal weapons bays, prior to its modification into the ZX-33B, after which it performed catapult-assisted takeoff and landing aboard aircraft carriers.

On January 16, 1591, the ZX-33 was chosen over the ZX-34 as the primary concept demonstrator that would receive the go forward to the NGAC program, while Jinmu Heavy Industries was selected as the primary contractor for the program's development and production. A consortium of several other contractors were also awarded auxiliary contracts to develop components of what would become the ZF-33. The outcome of the NGAC program received the designation 'ZF-33' from the Zhenian Ministry of Defense three days after the contract was awarded to Jinmu Heavy Industries.

Design and production


While many of the key components were already completed with the ZX-33, a handful of modifications were made from the concept demonstrator to what would become the ZF-33's production variant. Externally, significant changes were made to the vertical fin stabilizers and the divertless supersonic inlets, while the internal weapons bay was expanded in exchange of removing the smaller side weapons bay, thus resulting in an increase of armament diversity as well as a slight bump in armament capacity. Other modifications to its components, including its sensors and combat systems, were made over the course of its development, often done in tandem with the ZF-21's for exchanging of technical data. Major updates to its combat software, particularly regarding sensor fusion, had been made over the course of development. Other improvements, mainly towards its combat system software as well as sensor fusion and new technologies in manufacturing and maintaining the airframe, were drawn out over its course of development, although many emerged after the flight of the first production prototypes.

The first production prototype ZF-33A, nicknamed "Yellow Eagle" due to its lack of paint schemes at the time it was revealed to the public, rolled out and made its first flight from Changan Bukbu Air Base on May 16, 1596, while the aircraft line was also given the name "Black Eagle" by the Ministry of Defense the same day. Two more production prototypes were revealed over the next two years, each with slightly different design characteristics; the third production aircraft in particular, rolled out in December 1597, had its removed, indicating the end of data collection regarding the aircraft's aerodynamic characteristics. A handful of prototypes were additionally revealed to the public over its final courses of development, testing out many of the intended characteristics of the aircraft in various circumstances. Many of the prototypes differed slightly from one another, indicating refinements made to the aircraft's configuration over the course of its testing phase. Towards the end of such tests, the ZF-33 entered in 1603, when almost all testing, including live-fire of munitions and demonstration of sensor fusion, were completed. Full production was given the go-ahead in 1604, shortly before the first ZF-33As introduced to the Republic of Zhenia Air Force's 31st Fighter Combat Wing achieved (IOC); in comparison, the first ZF-33B units delivered to the Republic of Zhenia Navy, achieved IOC status in August 1605.

The Zhenian Ministry of Defense initially intended to procure over 3,500 aircraft over a 20-year period, with plans for the aircraft to form the numerical bulk of the nation's air power. Such plans were revised with revised doctrines geared more towards long-range strike and standoff warfare presuming the Hanmaric Ocean as the future battlegrounds of the RZDF; more resources were prioritized towards funding more ZF-21 units and keeping its modernized long-range ZF-7 Vanguard aircraft in service. Coupled with stalls in defense budget increases, procurement plans for the ZF-33 shrunk from over 3,500 aircraft across the defense forces to around 2,200 aircraft in the same range, as announced and finalized in 1605; the Ministry of Defense, however, opened possibilities to spring back procurement orders for the ZF-33 in the late 1610s, when the replacement of newer ZF-8 Phoenix aircraft within RZAF and RZN service are expected to become an issue.

Overview
The ZF-33 is a line of twin-engine, supersonic, all-weather stealth multirole fighter. As the second fully to be built and introduced to Zhenia, it combines low-observability, high maneuverability, sensor fusion and versatility into a single weapon platform, geared somewhat more towards being a strike fighter than the ZF-21 Dragon it is intended to complement.

The ZF-33 is primarily built around a wing-tail configuration with trapezoid-like clipped delta wings and two canted vertical stabilizers near its engines. Its flight control surfaces include ailerons, leading edge flaps, all-moving horizontal tail stabilizers and rudders on the vertical stabilizers. The aircraft is powered by two PF350-R improved afterburner turbofan engines, developed by Jinmu Engineering specifically for the aircraft type. It is capable of providing 75 kN of power each without afterburner, and 120 kN each with afterburner; while it has not been confirmed, there are rumors that the ZF-33, like the ZF-21, is capable of supercruise, although at a speed of around Mach 1.2, lower than that of the ZF-21. Because its diameter is smaller compared to the engines on the ZF-21, the PF350-R engines allow for a larger internal weapons bay to be fitted within the airframe without excessively widening the height of the aircraft.

Armament


The ZF-33 is equipped with one large internal weapons bay with a total of six weapons stations at the center of the airframe. The four innermost stations can carry ordnance up to 2,500 lb (1,100 kg), while the outer two weapons stations can carry up to 1,500 lb (680 kg) of ordnance as long as it fits the bay, although these bays normally carry air-to-air missiles. Given the capacity of its internal weapon bay, the ZF-33 normally carries an air-to-air payload of six missiles, all of which are stored within the internal bay to minimize its radar signature, while its typical air-to-ground payload configuration consists of two air-to-air missiles and two 2,000-lb guided bombs. Two compartments behind the weapons bays contain flares, chaff, and towed decoys, further increasing the survivability of the aircraft.

In addition to the internal weapons bay, the aircraft is also capable of using a total of six external weapons stations for armaments, at the expense of stealth. Each of the weapon stations are capable of mounting an array of ordnance, normally those too large to fit into the internal bays, specifically drop tanks and larger standoff air-to-surface missiles unable to be fit within the internal bays. Development of the 'Musso', an external rack that would allow for the ZF-33 to carry up to four air-to-surface guided bombs per external weapon station, has been underway with the introduction date set for 1614. Other external mounts, including electronic jammer pods, reconnaissance pods and buddy-to-buddy refueler pods, have been offered to the aircraft for installation in packages, many of which, with adequate accompanying software upgrades, allowed for easier conversion of aircraft in their roles. There have been proposals to allow for the aircraft to mount external weapons pods, each capable of carrying up to four air-to-air missiles, on four of the six weapons stations to increase its ordnance capacity while limiting increases in radar cross-section, although the idea has not gone beyond RZAF testing platforms.

Both the ZF-33A and ZF-33B are equipped with a 20 mm autocannon alongside 250 rounds, mounted near the right wing root of the air frame. It is intended as a last resort in air-to-air warfare when the aircraft is out of missiles, as well as providing last-minute fire support against ground targets by. As of 1610 AC, due to extensive integration efforts in the 1600s AC, the ZF-33 is capable of using almost all guided and unguided munitions and missiles within the RZAF and RZN's arsenal within its weight capacity. Proposals for future upgrades include the integration of hypersonic missiles as well as the installation of directed energy weapons including ; the former is rumored to be undergoing testing within RZAF facilities, while the latter has only been proposed and never brought to reality.

Cockpit




Like other modern fighter aircraft, the was implemented into the ZF-33 to increase the pilot's situational awareness. Like the ZF-21 Dragon, it uses a 20- by 8-inch (50 by 20 cm) panoramic touchscreen at the center of the cockpit, which replaces the older, less adaptable button screen system, to display flight instruments, weapons bays, combat information, warnings and caution. A short stand-by display beneath the panoramic touscreen augments the main display, often used to display information not highlighted on the main screen. Unlike the ZF-21, however, the ZF-33 lacks a in favor of a  (HMD) that provides higher coverage and situational awareness around the pilot and the aircraft. The bubble-shaped canopy has an internal frame for structural support, while it is connected to the seat ejection system to allow for safer escape in emergencies. The ejection seat is linked to an auxiliary oxygen bottle and onboard oxygen support systems to ensure high-altitude survival, while an independent onboard oxygen generator, linked to the aircraft's (APU), provides further life support in normal circumstances. Between the ejection seat and the main cockpit is a right-hand side stick and throttle hands-on throttle-and-stick system.

The helmet-mounted display as well as the accompanying control system on the ZF-33 is an improvement from the same helmet-mounted displays on the ZF-21, the helmet-mounted display on the ZF-33 is the pinnacle of its cockpit. Replacing the head-up display (HUD) found on most legacy fighters, the helmet-mounted display shows key flight and combat information, as well as targeting and other key functions, directly onto the helmet visor. Connected with sensors and cameras constituting the Cheongu Distributed Aperture System, the ZF-33 is capable of providing 360-degree views and coverage of threats and targets around the aircraft, thus eliminating almost all blind spots. Another key function of the HMD include a "look-and-shoot" function, which allows for the pilot to target and aim missiles by merely looking at the target, made possible by cuing missile seekers at high angles off-boresight. The helmet-mounted display also features built-in night vision cameras and customizable views according to the need of the pilot, while future updates are estimated to include augmented by onboard -based command systems into the helmet-mounted display, which will in turn be linked to the overall controls of the aircraft's systems.

Stealth
Like the ZF-21, stealth has been a key factor in shaping the ZF-33's design, with the aircraft's overall design significantly shaped, if not dictated by efforts to minimize, infrared signatures and radio frequency signatures. The airframe shows extensive use of planform alignment on edges and (RAM) on the airframe, as well as sawtooth designs on access panels, nozzles and doors, serration of skin panels and direct masking of the engine and turbine via the usage of  (DSI) on either side of the fuselage before the engines. Its radar-absorbent fiber-mat skin with high percentages of radar-absorbent materials, covering the general airframe, further reduce its radar cross-section as well as provide more durable stealth coating than its predecessors. There have been attempts to reduce its infrared and radio frequency signatures, the former primarily done by redesigning of panels and internal systems to minimize external heat signatures and the latter mostly done by the usage of secure and the aircraft's dedicated electronic warfare system. Due to such extensive efforts to curb the signature of the airframe, the ZF-33 has been categorized as a 'very low observability aircraft' (VLO), the highest level of stealth from an aircraft, by the Zhenian Ministry of Defense; there have been estimates that the frontal radar cross-section of the ZF-33 is comparable to a from around 50 kilometers away.

Sensors, avionics and countermeasures
Perhaps one of the aircraft's most notable sensors include the Z/APG-90 (AESA) radar, which utilizes active electronic scanning for rapid beam agility and features numerous passive and active modes that correspond to the aircraft's role. With an estimated multiple target tracking range of almost 200 kilometers (108 nm), it is capable of tracking multiple targets simultaneously and is one of the key elements of the aircraft's sensor fusion and electronic warfare system. To augment the Z/APG-90 in providing situational awareness to the pilot, the ZF-33 is also equipped with the Cheongu Distributed Aperture System like the ZF-21, although the ZF-33 has one less multifunction camera along the length of the fuselage compared to the ZF-21 due to the existence of the EOTS. Providing all-aspect missile launch alerts, target tracking as well as 360-degree infrared and night-vision coverage linked to the pilot's helmet-mounted display, the implementation of the Distributed Aperture System significantly bolsters the pilot's situational awareness capabilities.



Consisting of several antennas for various radio frequencies and partly involving the Z/APG-90 AESA rdar, the ZF-33's AJS-301 'Leishen' electronic warfare suite carries out the functions of an all-aspect radar warning receiver (RWR) as well as, electronic anti-missile countermeasures and jamming against nearby threats. The (EOTS), mounted within a low-observable window under the nose of the aircraft, replaces the,  (IRST) sensors and partially  found on aircraft of previous generations, providing high-resolution imagery in various spectrums as well as targeting information for air-to-surface and air-to-air missions. The EOTS can double as a component of the Cheongu Distributed Aperture System, relaying target acquisition information to the combat management system using the Cheongu's network. The ZF-33 is the second Zhenian fighter aircraft after the ZF-21 to utilize the Z-Link multifunction datalink system, which allows for secure exchange of target acquisition and identification data without sacrificing the aircraft's low observability and thus increasing risk of detection.

Sensors and combat systems of the ZF-33 are managed by the onboard Dashan Combat Management System, which also hosts most of the software needed to operate the aircraft.

Variants
ZF-33A

The ZF-33A is the (CTOL) variant primarily aimed for service in the Republic of Zhenia Air Force and other air forces. It is considered the primary, standard variant of the ZF-33 family.

ZF-33B

A modification from the ZF-33A, the ZF-33B is a variant aimed for (CATOBAR) operations from. Differences from the ZF-33A include stronger landing gear and tailhooks to ease the landing process aboard aircraft carriers via carrier arrestor cables, foldable wings for storage within carrier hangars and larger wing and tail control surfaces for enhanced low-speed control in takeoff and landing.

Operators
 Katamur
 * Katamurian Air Force - 34 aircraft delivered out of a total of 120 ordered, as of July 1610; all aircraft are set for delivery by 1615.
 * Katamurian Navy - 15 aircraft delivered out of a total of 40 ordered, as of July 1610.

 Zhenia
 * Republic of Zhenia Air Force - 1,334 aircraft planned for complete delivery by 1620.
 * Republic of Zhenia Navy - 320 aircraft planned for complete delivery by 1617.