Tyrandis
09-03-2008, 04:08
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TF-71 "KAGETAKA" (Shadowhawk) Advanced Tactical Fighter
Seventh Generation Tactical Aircraft of the Militaristic Federation
[Abstract]
Origins of the TF-71 (Tactical Fighter, Generation 7, Model 1) Advanced Tactical Fighter may be traced to a modernization effort of Imperial Aerospace Corporation regarding its older ACI-73D Aquilas. The adoption of the TF-70, termed ACI-77 Atratus in Doomani service, essentially obsoleted its predecessor in the air superiority role for which it was designed. Although burdened with literally thousands of airframes, IAC relegated its ACI-73 fleet into secondary roles to devastating effect, as evidenced in the performance of the fighter during the third invasion of Kahanistan. Tyrandis Precision Machine Import/Export Corporation’s assessment of the remarkable performance exhibited by the ACI-73s during the conflict came down to the versatile and highly adaptable nature of the airframe’s design. TPMI/EC proceeded to file inquiries with IAC regarding the ACI-73 Aquila’s technical data, for use in development of new-build successors to the TF-62 Sparrow in the multirole function. IAC responses to TPMI/EC were guarded, though corporate negotiations ultimately agreed to a joint fighter program. Unfortunately, conflicting design philosophies led to an extremely protracted period of development, with numerous prototypes being fielded and rejected.
The central dispute between TPMI/EC and IAC regarding Project HIEROPHANT/KAKUMEI, as the TF-71 program codename was called, lay with sharp disagreements relating to the new aircraft’s core attributes. TPMI/EC and by proxy the Tyrandis Federal Air Service as a whole was put under enormous political pressure for the unequivocal commercial and doctrinal failures of the TF-70 “Shukusei” Advanced Air Superiority Fighter. Spiraling costs incurred by the untested and unproven technologies pioneered in the venture, compounded by malfunctions caused by poor quality control, led to a fly-off cost of over two hundred million dollars per unit. This exorbitant price tag was justified by the TFAS establishment with the apparent success of the aircraft in Doomani and Pwnage service – the so-called “13,000:0” kill-loss ratio of the TF-70. Detractors, however, all pointed to the less-than effective resistance of the air forces the aircraft opposed. The ultimate test of veracity arrived at the Thunder Dawn warfare exercises hosted by the Remarkably Sane Dominion of Juumanistra, where the purported “best fighter in the world” was matched against its direct competitor, the Na-24G Mako. The results were less than satisfying – a record of twelve defeats to one controversial victory (that resulted in the death of Juuman pilot 1st Lt. Keiko “Edge” Davenport) in a variety of scenarios led to a complete re-evaluation of TFAS doctrine and equipment. The conclusions drawn by an investigative committee into the failures of Thunder Dawn were stark: the TF-70 and its ever-more complex avionics and materials technologies did not justify the attendant costs in maintenance and fabrication problems. Even more critical was its evaluation of TFAS thinking as far too systems-intensive and ignorant of the realities of pilot experience.
As a result of the inquiry, TPMI/EC prioritized reliability and ease of production over Imperial Aerospace Corporation’s objections. The latter had only the experience of its ACI-77 Atrati squadrons in lopsided operations against the Kahanistani Republican Air Force – hence, it preferred to acquire a new type which would emphasize the same characteristics that made the ACI-77 triumph over its enemies. Ultimately, the issue was settled when the IAC team behind the original ACI-73 Aquila program threw its support behind the TPMI/EC position.
Project HIEROPHANT/KAKUMEI from its conception thus emphasized several attributes: agility, low-observability, and cost-efficacy. These choices were inspired by the original ACI-73. As an evolutionary development of the proven Aquila platform, the TF-71 “Kagetaka” (Shadowhawk) Advanced Tactical Fighter retains a significant physical resemblance to its precursor. As a completely new design however, TF-71 introduces unmatched capabilities in air warfare for a modest premium. TF-71 is frequently referred to as an “omni-role” aircraft by the Tyrandis Federal Air Service, with superb air-to-air and air-to-ground performance. Overhauled avionics, “supermanueverability”, and a rugged airframe contribute to a highly versatile and lethal fighter. The only limitation of the TF-71 is its pilot – the aircraft is widely regarded as extremely demanding, both mentally and physically due to its unique aerodynamic design. Kagetaka will supplant the older TF-62 fighters that currently fill the Federal Air Service’s multirole function over a period of twenty-five years. Low-Rate Initial Production is currently under way, although it is estimated by TPMI/EC that full-scale production lines will open within the decade to produce approximately twenty thousand units for the Federal Air Service alone.
[Specifications]
Type: Multi-role Fighter Aircraft
Contractor(s): Tyrandis Precision Machine Import/Export Corporation, Imperial Aerospace Corporation, GEM Aerospace
Personnel: 1 (Pilot)
Length: 16.2m
Wingspan: 12.2m
Height: 4.2m
Empty Weight: 10,200 kg
Loaded Weight: 16,800 kg
MTOW: 23,820 kg
Speed:
Cruising Speed: Mach 0.8
Max Supercruise: Mach 1.4
Max Speed: ~Mach 2.3
G Limits: +10.5/-4 G
Wing Configuration: Trapezoidal diamond in combination with ruddervators canted at 45 degrees, forward horizontal canards + one downward-pointing vertical canard beneath the forward fuselage. Airfoils are supercritical and mission-adaptive.
Ranges:
Ferry Range: 3,550 km
Combat Radius: 1,210 km
Service Ceiling: 19,820 m
Engines: 2x Imperial Aerospace D/VPCBT-2A Variable Post Compression Bypass Turbofan, providing 108kN thrust ea.
Cannon: D/ACU.230A 23x135mm CTA Gast Gun
Payload: 6,800kg max
[Airframe]
The TF-71 Advanced Tactical Fighter’s construction and aerodynamic design is an evolution of the ACI-73D Aquila, much like the overall development program. Requirements surveys conducted for Project HIEROPHANT/KAKUMEI essentially called for the preservation of the basic concepts behind the predecessor design – that of stealth and agility – and accentuating these characteristics through the introduction of newer materials processing and fabrication technologies. Although superficially similar to the older aircraft, the TF-71 represents a dramatic increase in mission capability with its incorporation of the latest advancements in aeronautical science. However, Kagetaka remains loyal to the original objectives of ACI-73 – a smaller, compact fighter designed to “rely on pure stealth and maneuverability to allow for it to sneak up on enemy formations and deliver difficult-to-evade close range ordinance.” The unparalleled flight performance of the TF-71 “Kagetaka” is a direct result of this design philosophy.
The differences in aerodynamic layout between the TF-71 “Kagetaka” and the ACI-73 are subtle, but contribute to a marked superiority of the former aircraft as regards aircraft agility. Like most modern fighter aircraft, the TF-71 is designed with negative static stability to promote pilot responsiveness. The main lifting surfaces – the wings – are of the same diamond wing configuration as the ACI-73, which imparts excellent structural characteristics. This shape concentrates the load force onto the strongest point of the airframe, where fuselage meets wing. The wing design also exhibits very little drag at transonic and supersonic speeds as it adheres to the Whitcomb area rule closely, with the widest point of the fighter aligned directly with the midsection. A supercritical airfoil is mated to this wing which provides significantly improved transonic performance, higher lift, and superior overall aerodynamic characteristics as compared to the ACI-73D. The diamond wing exhibits a very high degree of blending with the fuselage, which allows for increased usable lift and an extended range as the larger wing volume may accommodate more fuel for the aircraft’s powerplant. This extra wing area also contributes to the aircraft’s agility by reducing wing-loading, although pilots of experimental versions frequently complained of poor low-altitude performance due to airflow buffeting. The problem was largely solved with the introduction of Direct Force Control capability in the fighter’s control systems. DFC allows for the digital electronic control system to adjust the motion of the fighter without having to change the attitude of its fuselage, greatly enhancing performance in air combat maneuvering. The primary enabler of DFC in the TF-71 Advanced Tactical Fighter is a forward vertical canard, mounted beneath the fuselage. This surface extends during low-speed flight, and affords the TF-71 pilot superior agility in the horizontal attitude to virtually every other fighter available on the export market. The canard plane acts somewhat similar to a rudder as it slews left and right for sideslip control though the effect is magnified due to its position. As an example of this functionality, a pilot may keep his nose perfectly on target when following a bogey through high-G manuevers at all times. This canard retracts to lie flat against the TF-71’s airframe at high speeds to reduce drag. Two other conventional canard foreplanes are located near the nose of the fighter to reduce the impact of stall and spin by stabilizing airflow over the main wings and delaying airflow separation. These canards have a 15 degree anhedral to reduce aerodynamic stability.
Traditionally, fighter aircraft have been limited to maneuver at angles of attack below 25 degrees due to the danger of airflow separation from the wing. In the design of the TF-71 "Kagetaka" Advanced Tactical Fighter, however, these limitations have been completely overcome with the implementation of mission-adaptive control surfaces combined with orthodox techniques such as vortex generation and vectored thrust. The adaptive wings of the TF-71 Advanced Tactical Fighter have no conventional ailerons, flaps, slats, or spoilers but rather utilize aeroelastic leading and trailing edges able to bend into a required position without leaving gaps. These are able to move from four degrees up to twenty five degrees down as enabled by its variable wing camber mechanism. Because the airfoil is able to adjust to a shifting flow, the TF-71 Kagetaka is the world's first production fighter capable of exploiting the phenomenon of "dynamic lift overshoot" at all airspeeds. The airfoil oscillates as the fighter's angle of attack increases which forces the airflow to stick to the wing and enables maneuvers previously unheard of. The wingtips are also aeroelastic to enhance roll rate, albeit this comes at the expense of optional wingtip hardpoints. Other physical features of the TF-71 supplement the adaptive airfoil in reducing wing stall. The fuselage chine and canards generate air vortices much like leading edge extensions on the F/A-18. At high angles of attack, the boundary layer flow becomes sluggish, which creates the danger of envelope departure and hence loss of control - the vortices serve to re-energize the flow and keep it moving over the wing surfaces, improving directional stability and lift. The sum of these varied efforts culminates in the TF-71 Advanced Tactical Fighter's remarkable "supermaneuverability", officially defined as the capability of full sideslip control at angles of attack exceeding maximum lift. Post-stall maneuvers have been tested and executed in production models at up to 70 degree angles of attack without stall. A pilot may snap his fighter 60 degrees off boresight in a split-second by manipulating the revolutionary control systems introduced by Kagetaka. In sum, the pilot of the TF-71 Advanced Tactical Fighter will have a decisive advantage in the modern close-range dogfight because of the extreme performance gap between his aircraft and those of his potential enemies.
The aerodynamic stresses of the TF-71's flight envelope demands an airframe able to sustain such challenges. However, TPMI/EC learned firsthand the penalties of seeking pure performance from the TF-70 Shukusei project, which led to the development of a different set of priorities for the TF-71 airframe. The morale and logistical problems created by an extremely maintenance-intensive aircraft like the TF-70 soon became a massive headache for the TFAS's service personnel (cults dedicated to the worship of ancient and malevolent deities from beyond the cosmos have found great popularity among disillusioned mechanical crews, who have lost faith in a benevolent god). Like its predecessor design, the TF-71 Kagetaka is a fully-modern, monocoque fighter aircraft. The frames and longerons of the fuselage are manufactured from high-strength 7475 zinc-aluminum alloy in order to reduce costs and weight as compared to titanium alloys. These components are superplastic-forming, which promotes fracture toughness and thermal creep resistance, and electron-beam welded to improve structural stability. The extensive use of electron-beam welding in the airframe also reduces airframe weight as this allows for the use of heavy fasteners to be kept at a minimum. Bulkheads and the superstructure as a whole feature resin transfer molded composites (primarily graphite-epoxy with polybenzothiazole in areas of higher thermal stress) of a high-strength/weight ratio, greatly easing fabrication processes. The wing structure, however, makes fewer compromises - the load-bearing spars are formed from Ti-1100, a very strong near-alpha titanium-aluminum alloy. The longerons are, however, 7475 zinc-aluminum as additional structural strength is unnecessary for these components. The fittings of the wings are hot isostatic pressing cast Ti-1100. The load-bearing skin of the aircraft is comprised of composites and titanium alloys near the front of the aircraft, with aluminum-lithium towards the empennage, and electron-beam welded to the longerons. Skin surface panels are formed from titanium on the leading edges of the aircraft and carbon-fiber reinforced para-polybenzothiazole resin. Use of these composites in place of a standard metal skin reduces machining costs and weight. The canards and ruddervators are the most expensive component of the airframe, as they are manufactured from Ti-1100 metal matrix composite, reinforced by monofilament silicon carbide. The aft fuselage features a very high amount of titanium due to the high thermal stress from the TF-71's powerplant, although this is reduced somewhat by the use of carbon-carbon foam in a cavity surrounding the nacelles.
[Avionics]
The considerations of the TF-71 Kagetaka's electronics development were borne from hard lessons learned from previous TPMI/EC development programs, and the intended mission goals of the aircraft. Budgetary analysis by the Defense Advanced Research Projects Agency indicated that in order to replace the older TF-62s on a 1:1 basis, the fly-off price could not exceed one hundred and twenty million dollars per unit. As avionics and associated flight systems constitute a majority of modern aircraft costs, TPMI/EC economized wherever possible without sacrificing the key capabilities necessary to combat operations. The wide variety of roles that the TF-71 will be called to fill, from ground-attack to maritime strike to fighter sweep, requires an electronics package just as versatile as the basic airframe. TF-71 is the first Tyrandisan aircraft to features extensive use of Commercial Off-The-Shelf components, as previous experiences with all in-house design led to extremely maintenance intensive systems with little if any practical value. All individual electronic elements are unified under the Mark 3b Integrated Modular Architecture centralized processing network, to maximize pilot SA (situational awareness) and improve mission readiness rates of the TF-71. A derivative of the more advanced Mark 3 IMA implemented in the TF-70, the Mark 3b coordinates and controls mission-sensitive information on a tightly integrated software and hardware platform. Mark 3b relies on common processing modules and protocols between systems to reduce avionics costs and weight. Communications between individual elements are conducted over a rugged 2GB/s fiber optic backbone, which provides sufficient bandwidth while maximizing reliability. In addition, the use of this non-proprietary point-to-point bus allows for integration of foreign avionics into the Mark 3b to be simplified. The heart of the Mark 3b is the Central Integrated Processor [CIP], a computer hosting every individual element of the mission systems software. Two CIPs are found in avionics racks located to the front of the aircraft, with one operating as a backup. The CIP consolidates functions previously managed by separate mission and weapons computers, and dedicated signal processors to achieve maximum electronics integration. Twenty two processing modules handling general purpose, signals processing, image processing, switching, and power management operations are installed in the baseline TF-71. The CIP was designed with "pluggable growth" in mind, and eight additional slots for processing modules hosted on a card interface are available for expansion. This will enable the TF-71 to remain operationally effective even as newer aircraft types are introduced by foreign competitors, reducing long-term costs by a considerable margin.
As a whole, the Mark 3b Integrated Modular Avionics package is comprised of three main subsystems dedicated to mission management, sensor management, and vehicle management. All elements of the Mark 3b are modularly installed. Cooling for the entire suite is provided via a PAO (polyalphaolefin) liquid solution. The Mark 3b also includes fully functional diagnostic software which enables support personnel to quickly identify and solve problems with the TF-71's electronics systems.
The Mission Management Suite subsystem of the Mark 3b is composed of the terrain/navigation suite, fire-control, munitions management and Electronic Warfare equipment. CIP resources are allocated to each function as necessary.
Navigation is provided by the CDI-1 system. Where previous avionics systems treated the myriad location-determining sensors of an aircraft as a discrete source of information, CDI-1 manages the data gathered by each individual system and presents it to the pilot in a coherent way. CDI-1 includes two primary sources of navigational information – an Inertial Reference System and a Terrain Reference System calibrated against each other to provide for unmatched accuracy in location.The Terrain Reference System relies on careful measurement of the terrain profile passing beneath the aircraft with a RADAR altimeter and comparison with digitally-stored geographic data. The primary advantage to using a TR system is that a standard TF (terrain-following) navigation scheme will alert enemy Electronic Surveillance Measures far sooner, due to the RADAR beam's direction. On the other hand, a TRN altimeter has an extremely narrow beam width whose energy is directed downwards, rendering virtually all ESM measures impotent. The Inertial Reference System component is comprised of two ring laser gyroscopes and an accelerometer located in the forward fuselage, coupled with GPS uplinks compatible with most standard satellite interfaces. Only one of the gyroscopes is necessary for normal operation; data from the second is fed to the TF-71’s fire control systems to automatically adjust gun position for drift.
Fire control is governed by the Stores Management System, which monitors all phases of weapons release. Data from the Sensor Management Suite is linked to this component, which constantly updates the pilot’s interface on target disposition and type. It draws on CIP resources to rapidly calculate suitable firing solutions. The Stores Management System also functions to inform the pilot of the condition of payload, control weapons launch sequences, as well as door controls and emergency weapons jettison.
The TF-71 Kagetaka features an all-new Integrated Electronic Warfare System, comprised of various subsystems installed in modular apertures around the aircraft. In practical terms, the system determines the location and nature of all potential threats, thereby warning aircrew when they are being tracked, targeted, or engaged. A superheterodyne RADAR Warning Receiver provides all-aspect radar warning capability, supporting analysis, identification, tracking, mode determination and angle of arrival (AOA) of mainbeam emissions, plus automatic direction finding for correlation with other sensors, threat avoidance and targeting information. The radar warning system is active all of the time, providing both air and surface coverage. It also provides defensive threat awareness and offensive targeting support–acquisition and tracking of main beam and side lobe emissions, beyond-visual-range emitter location and ranging, emitter ID and signal parameter measurement. Packaged in two electronics racks, it includes cards for radar warning, direction finding and ESM. The antennas for the RADAR Warning Receivers are embedded in the external skin. Laser Warning Receivers are also present, which detects laser radiation and determines its bearing. In order to quickly track missile launches the Integrated Electronic Warfare System incorporates a set of Missile Warning Receivers, with their antennas built into the ruddervators. To increase the effectiveness of the system the MAW is also directly linked to the countermeasures systems allowing an instantaneous response to a local launch. The MAWs include a set of Rayleigh scattering processing modules, which serves to greatly improve resolution and accuracy regarding threat disposition.
Active countermeasures equipment is also installed in the TF-71 Advanced Tactical Fighter, and their effectiveness is supported by highly sensitive passive receivers. The Imperial Aerospace Corporation-made Electronic Defense Automatic Response System (EDARS) provides a full spectrum of automated countermeasures to defeat tracking systems in contemporary use. The key component of EDARS is the D/EJS-3A Electronic Countermeasures Suite. This system is an active RADAR jammer, designed to be used in circumstances when stealth is not nessessary (i.e., when a missile already has a lock). TPMI/EC software upgrades have enabled the D/EJS-3A to engage in DRFM (digital radio frequency memory) jamming including standard barrage or noise modes. In the DRFM mode, the TF-71 manipulates received radar energy and retransmits it to change the return the hostile RADAR sees. This technique serves to provide conflicting and confusing information for enemy interpretation. For example, the jammer may change the range the transmitter detects through alterations in the delay in pulse transmission or the velocity the radar detects by changing the Doppler shift of the transmitted signal. An XC-100 countermeasures dispenser is internally mounted, which is programmed to deploy multi-spectral chaff and flares only in the direction of a threat as determined by the passive sensors. The flares are treated with chemical additives that spoof the IR sensors of most IR guided missiles. Additionally, data from the radar warning equipment is linked to the chaff cutting mechanism – the XC-100 is sophisticated enough to interpret the RWR’s information and cut the aluminum strips to increase reflectivity to the RF band being deceived.
The Sensor Management Suite subsystem of the Mark 3 package combines the TF-71 Kagetaka's RADAR, IRST, integrated signal processing, encrypted data, communications, and the Joint Tactical Information Distribution System interface, allocating CIP processor power to the sensor subsystems as required by the mission. With the advanced, centralized architecture employed by the Mark 3b IMA, the SMS implements sensor fusion for the pilot to enhance situational awareness and reduce pilot workload. By automating the task of interpreting sensor data, the TF-71 removes the possibility of conflicting data gathered by the various sensors and eliminates the need for manual cross-referencing.
The primary detection tool of the TF-71's pilot is a DPARS-92 Active Electronically Scanned Array RADAR, housed in the nose of the fighter. Designed to reduce weight, cost, and reliability issues as compared to the older AN/PSI-7 system used in the TF-70, the DPARS-92 is installed as a planar tile-array in nose-mounted radome. The DPARS-92's transmitter and receiver functions are composed of 4,000 individual transmit/receive (T/R) modules that each scan a small fixed area, negating the need for a moving antenna, which further decreases ESM detection probabilities as well as aircraft volume issues. DPARS-92 relies on "quad-pack" transmit-receive modules, developed originally by Livermore Electric (a subcontractor of GEM Aerospace, which TPMI/EC contacted as a partner in the fighter program). These dies consolidate four arrays (each consisting of four MMIC chips - a drive amplifier, digital phase shifter, and low-noise amplifier, and a RF power amplifier) onto one chip, which greatly reduces weight, volume, and materials costs. The chips are manufactured on gallium-arsenide wafers due to the higher electron mobility and reduced noise GaAs affords than conventional silicon. To protect the antenna from detection by hostile ESM systems, it is mounted in a bandpass radome, transparent only to the band of frequencies utilized by the radar. When it is not in use, suitable electrical impulses turn the bandpass characteristic off, making it totally opaque. The RADAR's elimination of hydraulics for antenna movements and distribution of transmission functions into the T/R modules alleviates logistical concerns. The DPARS-92 is a Low Probability of Interception [LPI] system, meaning that the waveforms of the RADAR have a much longer pulse and lower amplitude, as well as a narrower beam and virtually no sidelobe radiation. The result of this waveform modification is that the transmitted signals are virtually undetectable by enemy ESM receivers, as the RF energy emitted is spread over a wide range of frequencies, hiding among the noise of benign signals that clutter the microwave region. A tertiary data channel screens hostile ECM measures. In air-to-surface operations the radar will support functions such as synthetic aperture radar (SAR) ground mapping.
An AN/RSI-1 Inverse Synthetic Aperture RADAR processes the Doppler shift resulting from target motion as a means of improving RADAR resolution. Thanks to shared components with the AN/PSI-7, the AN/RSI-1 is highly compact, and adds less than 30 lbs to the aircraft's weight. By measuring the much larger Doppler shifts created by the TF-71's own motion and the target's changes in attitudes, the AN/RSI-1 is able to extract the Doppler effects due to pitch, yaw, and roll of the different parts of the target aircraft, processing these to obtain a clear physical profile. This information is cross-referenced against a database of known aircraft types and presented to the pilot.
Passive detection equipment will see frequent use during TF-71 operations (as these betray no warning of the fighter's approach). The aircraft includes an Integrated Electro-optical Sensor System, providing high-resolution imagery, automatic tracking, infrared-search-and-track capability, and laser designation and rangefinding. The IESS utilizes a fixed imaging infrared-array to reduce maintenance costs, and is mounted internally behind a bandpass window to reduce drag and aircraft RCS. The assembly is also shared by an optical laser system, and is housed in the forward fuselage with a 140 degree field of view. The DIRST-6G infrared search and tracking system from the ACI-73D provides additional detection options . This system is comprised of several infrared scanners which passively scan the surrounding air for heat signatures, picking out differing infrared levels and mapping them out for the central processor, which in turn interpretes the data, picking out aircraft and displaying them for the pilot via the Mission Management Suite. Each individual sensor scans across red-scale wavelengths from 2.4-13 microns to enable all-aspect detection capabilities. The sensor is cryogenically cooled via Freon gas, which allows for the system to interpret finer temperature gradients across longer distances. Estimated range for each sensor is quoted at approximately 100km under optimal conditions. All data gathered by the system is post-processed by the Sensor Management Suite to enhance resolution.
The Mark 3b includes a comprehensive Integrated Communication Navigation Identification Avionics suite, which combines the functions of current communications equipment, such as HF SSB (High Frequency-Single Side Band), VHF/UHF, SINCGARS, Have Quick, EJS, JTIDS, various navigational aids and transponder/interrogator facilities compatible with NATO-standard IFF systems. Based on common digital and RF processing modules , the system allows for all these functions to be seamlessly built into just one package. It also takes up half the volume and weight of the aforementioned equipment. The ICNIA provides functions such as beyond-visual-range identification friend-or-foe; secure, multichannel, multiband voice communications; and intraflight data link exchanges, synchronizing the displays of multiple aircraft. The Central Integrated Processors filter much of the information being passed to the pilot, presenting him with only data necessary for the phase for the mission currently being flown, to prevent information overload.
The Vehicle Management Suite is responsible for cockpit controls and displays, flight and maneuver control, and engine/power control. It is independent of the CIP, with separate processing provided by three Vehicle Management Computers. Each computer contains a processor card, I/O card and power supply card. All three VMCs process data simultaneously, calibrating results across each other to assure data integrity. In the case of divergent data, two processors can discard the output of the other processor. Interfacing to the VMCs are remote I/O computers installed across the aircraft, which receive flight control and other inputs from hundreds of digital, analog and discrete sensors. These provide data to the VMCs via the fiber optic network control. The VMCs also govern a Utilities Control System, which manages and automates the various mechanical utilities found aboard the fighter. Examples of these include primary and backup electrical systems, hydraulics (for aircraft control actuators, brakes, nose wheel steering, intakes, et al.), fuel stores and climate controls in the cockpit.
The TF-71 is controlled by a centralized fly by light fiber optic system that takes both control input from the pilot and feedback from the various sensors and control surfaces around the airplane. Due to the critical role aircraft response times play in tactical aviation, a FBL control scheme was chosen for the TF-71 Kagetaka. More importantly however, fly-by-light offers an attractive alternative to interference prone fly-by-wire systems. The popularity of EMI-based air defense weapons was not lost on TPMI/EC designers; thus, the control system is nearly immune to such errorneous behavior caused by outside sources. Additionally, the flight envelope characteristics of the aircraft are programmed into the system, which prevents the pilot from engaging in maneuvers which would induce a total loss of control. A manual override is available, in case of deep stall (which remains a theoretical possibility although no instances have yet occurred). Should the aircraft depart its flight envelope for any reason, however, a failsafe switch in the cockpit may be engaged that will cause the Vehicle Management Suite to automatically return the aircraft to level flight. Finally, the system is adaptable to irregularities in instructions due to malfunction by reconfiguring itself and biasing the pilot’s controls to compensate. All motors utilized in the transmission are brushless, which improves efficiency, reliability, and reduces generated EMI levels.
Some variants of the TF-71 Kagetaka include a "computerized associate", essentially a primitive artificial intelligence that serves as a combination of copilot and backseater. Designated the Advanced Mission-supporting Intelligent Assistant or AMIA, the AI is believed to improve the situational awareness and survivability of the fighter through a number of autonomous functions. The pilot is according to accounts from defectors, hooked up to health sensors which monitor blood pressure, pulse rate, breathing patterns, and electrical activity in the brain. Should the system determine that the pilot is incapacitated, due to red/blackout or other reasons, AMIA will automatically seize control and attempt to fly a safe, evasive route back to its pre-programmed base location. AMIA is also able to execute simple oral commands given by the pilot, such as display switching, stores management, or changing radio frequencies. Most interesting of all are AMIA's electronic warfare and countermeasures support functions, however. It is capable of intelligently analyzing strength, frequency, and location of hostile sensor sites through a data highway connection with the Sensor Management Suite. AMIA will render a display of these locations, estimate range of detection relative to the TF-71 Kagetaka's location, and advise navigational course for the pilot so as to evade detection. Also, AMIA is capable of limited assistance during mission operations. For example, if the Missile Alert Warner systems detect a launch, AMIA will automatically cycle the RF jammer to the frequency band tracking the fighter and advise the pilot to activate said equipment. Also, AMIA's connection to the Sensor Management Suite allows for it to provide tactically useful guidance to the pilot. Sensors and data links will acquire data, which are centrally processed by CIP resources, and activate tactical decision aids–or "planners." Search, attack, avoidance and denial planner modules would work simultaneously on the fused data, producing action plans for the pilot. The search planner is intended to help pilots locate targets. This software application would look, for example, at all the possible places where a column of tanks could be, based on factors such as the last siting, the road network, terrain and the speed of the vehicles. After the tanks have been located, the attack planner could plan the ingress route, assess the vulnerability of the tanks, and indicate where the wingmen should be. While these tasks are proceeding, a "fast track" process would send any high-priority threat information directly to the pilot, who would determine, with the help of an "avoid planner," the evasion route. These processes are executed by AMIA in fractions of a second, permitting pilots in a multiship formation to counter or avoid multiple threats and at the same time attack multiple targets. Unfortunately, the technology behind AMIA remains immature and prone to software errors, and only limited numbers of these systems will be deployed operationally.
[Canopy/Cockpit]
The TF-71 features a fully modern polycarbonate canopy, which provides excellent protection against birdstrike. In order to improve pilot visibility and reduce optical signature, the transparency is tinted and treated with a polarized laminate. This process eliminates glint. A plasma-deposited indium-tin oxide is applied externally in order to prevent hostile RF signals from entering the reflective cockpit area. A layer of neoprene insulation is also present to maintain the integrity of HUD displays.
The layout of the TF-71's cockpit systems were of paramount concern to the TPMI/EC and IAC design team, as a modernization of the older ACI-73. Intended to maximize situational awareness for the pilot, displays and flight symbology are fully automated by the Mark 3b Vehicle Management System, with processing power for sensor system integration drawn from CIP resources specifically assigned to this purpose. Use of the fiber-optic bus interface allows for the high level of system bandwidth required for this application. The TF-71 features a fully digital, all-glass cockpit that has eliminated the confusing switches and dials of previous cockpit designs - this improves the effectiveness of the pilot by allowing him to concentrate on his mission, rather than his equipment.
Unfortunately, ergonomics and pilot comfort were largely disregarded as priorities. In an effort to increase pilot tolerance to 10Gs before G-LOC (Gravity-induced Loss of Consciousness), the seat is reclined 65 degrees and the rudder pedals are elevated by 6 inches off the ground. By lowering the position of the pilot's head, blood circulation is improved - however, sitting in this position is remarkably uncomfortable. A Kampferian pilot of a prototype aircraft was killed in a crash after he accidentally lost his grip and spilled a cup of scalding hot coffee onto himself in level flight, because of the awkward seat. Moreover, internal TPMI/EC studies have shown an alarming discovery of higher rates of spinal injury for pilots of the TF-71 as compared to other fighter types. New production models will feature a reclining seat to address this issue.
The centerpiece of the fighter's cockpit avionics is a wide angle, 6 in. tall Heads-Up-Display. It is reinforced with vulcanized rubber and has minimal framing to preserve pilot visibility over the aircraft's nose. The system is capable of rendering a full range of flight and mission-critical information. TPMI/EC control software automates the displays and makes available to the pilot vital information useful to the phase of a sortie being flown at a time. The operator of the TF-71 may also queue up additional displays on the HUD or multifunction head-down displays through an intuitive touchscreen interface. All data outputs from the Mark 3 avionics subsystems are made available to the pilot through the Kagetaka cockpit's AMLCD screens. The integration of these disparate elements through the Mark 3b serves to greatly enhance a pilot's situational awareness and combat effectiveness. For example, the data extracted from the CDI-1 navigational system allows for an astonishingly accurate "God's-eye-view" of the terrain surrounding the TF-71 at any point in time. Integration of navigational equipment with the Sensor Management Suite enables targeting symbology to be directly overlaid onto this map, thus providing a pilot with an unprecedented level of control over the battlespace.
There are limitations to the HUD/MFD combination however; it forces a pilot to look straight ahead in order to receive information about his aircraft and its surroundings, which leaves him vulnerable to attack at points all around him. As a result, the TF-71 features a set of Helmet Mounted Displays in the pilot's flight helmet. The helmet itself is an advanced, self-contained unit comprising the HMD, night vision equipment, microphone and headphones, and oxygen mask. Thanks to advancements in engineering techniques pioneered by TPMI/EC, the system is 20% lighter than previous-generation helmets even with the addition of the integrated electronic equipment, and provides the same level of protection. The HMD projects critical information onto a semi-reflective transparent visor in front of the pilot, and shares the symbology library used in the the HUD and MFDs. Additionally, motion-tracking capabilities are built into the flight helmet with a full six-degrees of freedom. This is linked to the stores management component of the Mark 3b avionics package, and allows for a pilot to cue up a weapon and engage targets from very-high off-boresight angles.
During simulator studies of the TF-71, TPMI/EC engineers found that pilots were unable to access their touchscreens during high-G maneuvers. In order to rectify this issue, a direct voice input system was developed and implemented. The DVI system incorporates advanced voice recognition techniques that enable it to respond to commands with a latency of only 80ms with an accuracy rate of over 99.7%. Additionally, it is able to interpret the pilot's voice even when distorted by the stresses of air combat maneuvering or G-forces. The use of DVI enables a pilot to look down at his MFDs for a minimum of time, thereby improving his situational awareness through a significant reduction in pilot workload.
[Stealth]
The tradition of the ACI-73 Aquila's stealth attributes have been preserved and even enhanced in the design of its successor aircraft. In keeping with the objective of "first shot, first kill", the TF-71 is engineered to be even more difficult to detect than the already elusive ACI-73. The airframe layout was designed with computational RCS modeling techniques, to achieve "spike alignment" of reflected RF waves. The angles incorporated on all horizontal leading and trailing edges are kept as different as possible, thereby dumping the reflected RF energy to the fighter’s port and starboard sectors. This results in large, but narrow RADAR signature spikes that are extremely difficult to track effectively. Kagetaka exhibits a high degree of wing/body blending, which provides desirable aerodynamic characteristics such as improved lift, while also reducing RCS by allowing electrical surface currents to flow over the surfaces without interruption. The lack of discontinuities in the mission-adaptive wings prevents traveling waves from re-radiating too strongly (as they must pass along the surface with embedded RAM elements). Some composite panels in the aircraft's construction are RADAR Absorbent Structures (honeycombed Kevlar sections bonded to carbon-fiber skins), which are intended to absorb microwaves in higher-frequency regions. The primary RADAR Absorbent Material utilized in the TF-71 are Schiff base salts. Derived from research by Carnegie-Mellon University, the material, which is a fine black powder physically resembling graphite, consists of a long chain of carbon atoms with alternating double and single bonds and a nitrogen atom interrupting the string near one end. The chain carries a positive charge, associated largely with the nitrogen atom. A negatively charged 'counterion,' made up of varying composition depending on the specific salt, sits nearby, weakly connected to the chain. The counterion prefers to sit in one of two locations near the chain. A single photon easily dislodges the counterion from one location and forces it into the other. A short time later, the molecule relaxes, and the counterion returns to its original position. Notably, certain salts required a very small amount of energy to shift the counterion - they could be triggered by RADAR energy of certain frequencies. As a result, the Schiff base salts are able to absorb radio waves, and dissipate the energy as heat. This unique property is fully exploited in the fighter’s construction - a mixture of salts tuned to surveillance frequency bands most often employed by air to air RADAR systems (X, L, etc.) are dissolved in a binder chemical and used to treat the external resin panels. The SBS class of materials is additionally 90% lighter than previous-generation ferromagnetic absorbers, and extremely inexpensive to fabricate. Most importantly, Schiff base salts are durable enough to withstand maritime conditions without degrading RF absorptive qualities. Areas of higher reflectivity on the basic airframe have circuit analogue RAM applied. These are thin sheets of copper wire, arranged in complex geometries to scatter and diffuse RADAR signals. The leading edges of the ruddervators have embedded arrays of titanium-aluminum triangles that perform the same function, trapping RF energy inside like an echo chamber.
Exact RCS of the TF-71 Advanced Tactical Fighter is comparable to the larger TF-70, although this varies somewhat based on aspect of view.
In order to reduce electro-magnetic signature, the avionics bays built into the TF-71 are treated with Electric Wave Absorbing Material, developed by TPMI/EC. EWAM is a six-layer, non-woven cloth comprised of stainless steel and polyethyl fibers. The material is applied to the inner walls of the electronics housing in the Shukusei, and serves to eliminate electro-magnetic leakage from the on-board equipment. Under laboratory conditions, EWAM absorbs 99% of all emitted EM radiation, and reduces passive electromagnetic sensor detection vulnerability.
Infrared signature was addressed in a number of ways by TPMI/EC. The most prominent are the scalloped, flat nozzles located aft of the fighter. Although some horizontal attitude control is sacrificed, the use of these nozzles in place of the circular 3D nozzles found in ACI-73 is alleged to decrease infrared signature by an enormous factor as the exhaust plume forms a flat "beavertail" of wide lateral area that cools much faster than the high-intensity stream formed by round nozzles. These also contribute to aircraft agility by providing vectored thrust in the pitch axis over a range of 25 degrees up and down. Infrared signature is further suppressed with the use of extremely expensive carbon-carbon foam injected into cavities surrounding the engine nacelles. This material is exhibits superb thermal absorption qualities, and also contributes to RCS reduction by weakening RF return. Inorganic microparticles with absorptive qualities in the IR spectrum are also used on the empennage surface panels.
TF-71 "KAGETAKA" (Shadowhawk) Advanced Tactical Fighter
Seventh Generation Tactical Aircraft of the Militaristic Federation
[Abstract]
Origins of the TF-71 (Tactical Fighter, Generation 7, Model 1) Advanced Tactical Fighter may be traced to a modernization effort of Imperial Aerospace Corporation regarding its older ACI-73D Aquilas. The adoption of the TF-70, termed ACI-77 Atratus in Doomani service, essentially obsoleted its predecessor in the air superiority role for which it was designed. Although burdened with literally thousands of airframes, IAC relegated its ACI-73 fleet into secondary roles to devastating effect, as evidenced in the performance of the fighter during the third invasion of Kahanistan. Tyrandis Precision Machine Import/Export Corporation’s assessment of the remarkable performance exhibited by the ACI-73s during the conflict came down to the versatile and highly adaptable nature of the airframe’s design. TPMI/EC proceeded to file inquiries with IAC regarding the ACI-73 Aquila’s technical data, for use in development of new-build successors to the TF-62 Sparrow in the multirole function. IAC responses to TPMI/EC were guarded, though corporate negotiations ultimately agreed to a joint fighter program. Unfortunately, conflicting design philosophies led to an extremely protracted period of development, with numerous prototypes being fielded and rejected.
The central dispute between TPMI/EC and IAC regarding Project HIEROPHANT/KAKUMEI, as the TF-71 program codename was called, lay with sharp disagreements relating to the new aircraft’s core attributes. TPMI/EC and by proxy the Tyrandis Federal Air Service as a whole was put under enormous political pressure for the unequivocal commercial and doctrinal failures of the TF-70 “Shukusei” Advanced Air Superiority Fighter. Spiraling costs incurred by the untested and unproven technologies pioneered in the venture, compounded by malfunctions caused by poor quality control, led to a fly-off cost of over two hundred million dollars per unit. This exorbitant price tag was justified by the TFAS establishment with the apparent success of the aircraft in Doomani and Pwnage service – the so-called “13,000:0” kill-loss ratio of the TF-70. Detractors, however, all pointed to the less-than effective resistance of the air forces the aircraft opposed. The ultimate test of veracity arrived at the Thunder Dawn warfare exercises hosted by the Remarkably Sane Dominion of Juumanistra, where the purported “best fighter in the world” was matched against its direct competitor, the Na-24G Mako. The results were less than satisfying – a record of twelve defeats to one controversial victory (that resulted in the death of Juuman pilot 1st Lt. Keiko “Edge” Davenport) in a variety of scenarios led to a complete re-evaluation of TFAS doctrine and equipment. The conclusions drawn by an investigative committee into the failures of Thunder Dawn were stark: the TF-70 and its ever-more complex avionics and materials technologies did not justify the attendant costs in maintenance and fabrication problems. Even more critical was its evaluation of TFAS thinking as far too systems-intensive and ignorant of the realities of pilot experience.
As a result of the inquiry, TPMI/EC prioritized reliability and ease of production over Imperial Aerospace Corporation’s objections. The latter had only the experience of its ACI-77 Atrati squadrons in lopsided operations against the Kahanistani Republican Air Force – hence, it preferred to acquire a new type which would emphasize the same characteristics that made the ACI-77 triumph over its enemies. Ultimately, the issue was settled when the IAC team behind the original ACI-73 Aquila program threw its support behind the TPMI/EC position.
Project HIEROPHANT/KAKUMEI from its conception thus emphasized several attributes: agility, low-observability, and cost-efficacy. These choices were inspired by the original ACI-73. As an evolutionary development of the proven Aquila platform, the TF-71 “Kagetaka” (Shadowhawk) Advanced Tactical Fighter retains a significant physical resemblance to its precursor. As a completely new design however, TF-71 introduces unmatched capabilities in air warfare for a modest premium. TF-71 is frequently referred to as an “omni-role” aircraft by the Tyrandis Federal Air Service, with superb air-to-air and air-to-ground performance. Overhauled avionics, “supermanueverability”, and a rugged airframe contribute to a highly versatile and lethal fighter. The only limitation of the TF-71 is its pilot – the aircraft is widely regarded as extremely demanding, both mentally and physically due to its unique aerodynamic design. Kagetaka will supplant the older TF-62 fighters that currently fill the Federal Air Service’s multirole function over a period of twenty-five years. Low-Rate Initial Production is currently under way, although it is estimated by TPMI/EC that full-scale production lines will open within the decade to produce approximately twenty thousand units for the Federal Air Service alone.
[Specifications]
Type: Multi-role Fighter Aircraft
Contractor(s): Tyrandis Precision Machine Import/Export Corporation, Imperial Aerospace Corporation, GEM Aerospace
Personnel: 1 (Pilot)
Length: 16.2m
Wingspan: 12.2m
Height: 4.2m
Empty Weight: 10,200 kg
Loaded Weight: 16,800 kg
MTOW: 23,820 kg
Speed:
Cruising Speed: Mach 0.8
Max Supercruise: Mach 1.4
Max Speed: ~Mach 2.3
G Limits: +10.5/-4 G
Wing Configuration: Trapezoidal diamond in combination with ruddervators canted at 45 degrees, forward horizontal canards + one downward-pointing vertical canard beneath the forward fuselage. Airfoils are supercritical and mission-adaptive.
Ranges:
Ferry Range: 3,550 km
Combat Radius: 1,210 km
Service Ceiling: 19,820 m
Engines: 2x Imperial Aerospace D/VPCBT-2A Variable Post Compression Bypass Turbofan, providing 108kN thrust ea.
Cannon: D/ACU.230A 23x135mm CTA Gast Gun
Payload: 6,800kg max
[Airframe]
The TF-71 Advanced Tactical Fighter’s construction and aerodynamic design is an evolution of the ACI-73D Aquila, much like the overall development program. Requirements surveys conducted for Project HIEROPHANT/KAKUMEI essentially called for the preservation of the basic concepts behind the predecessor design – that of stealth and agility – and accentuating these characteristics through the introduction of newer materials processing and fabrication technologies. Although superficially similar to the older aircraft, the TF-71 represents a dramatic increase in mission capability with its incorporation of the latest advancements in aeronautical science. However, Kagetaka remains loyal to the original objectives of ACI-73 – a smaller, compact fighter designed to “rely on pure stealth and maneuverability to allow for it to sneak up on enemy formations and deliver difficult-to-evade close range ordinance.” The unparalleled flight performance of the TF-71 “Kagetaka” is a direct result of this design philosophy.
The differences in aerodynamic layout between the TF-71 “Kagetaka” and the ACI-73 are subtle, but contribute to a marked superiority of the former aircraft as regards aircraft agility. Like most modern fighter aircraft, the TF-71 is designed with negative static stability to promote pilot responsiveness. The main lifting surfaces – the wings – are of the same diamond wing configuration as the ACI-73, which imparts excellent structural characteristics. This shape concentrates the load force onto the strongest point of the airframe, where fuselage meets wing. The wing design also exhibits very little drag at transonic and supersonic speeds as it adheres to the Whitcomb area rule closely, with the widest point of the fighter aligned directly with the midsection. A supercritical airfoil is mated to this wing which provides significantly improved transonic performance, higher lift, and superior overall aerodynamic characteristics as compared to the ACI-73D. The diamond wing exhibits a very high degree of blending with the fuselage, which allows for increased usable lift and an extended range as the larger wing volume may accommodate more fuel for the aircraft’s powerplant. This extra wing area also contributes to the aircraft’s agility by reducing wing-loading, although pilots of experimental versions frequently complained of poor low-altitude performance due to airflow buffeting. The problem was largely solved with the introduction of Direct Force Control capability in the fighter’s control systems. DFC allows for the digital electronic control system to adjust the motion of the fighter without having to change the attitude of its fuselage, greatly enhancing performance in air combat maneuvering. The primary enabler of DFC in the TF-71 Advanced Tactical Fighter is a forward vertical canard, mounted beneath the fuselage. This surface extends during low-speed flight, and affords the TF-71 pilot superior agility in the horizontal attitude to virtually every other fighter available on the export market. The canard plane acts somewhat similar to a rudder as it slews left and right for sideslip control though the effect is magnified due to its position. As an example of this functionality, a pilot may keep his nose perfectly on target when following a bogey through high-G manuevers at all times. This canard retracts to lie flat against the TF-71’s airframe at high speeds to reduce drag. Two other conventional canard foreplanes are located near the nose of the fighter to reduce the impact of stall and spin by stabilizing airflow over the main wings and delaying airflow separation. These canards have a 15 degree anhedral to reduce aerodynamic stability.
Traditionally, fighter aircraft have been limited to maneuver at angles of attack below 25 degrees due to the danger of airflow separation from the wing. In the design of the TF-71 "Kagetaka" Advanced Tactical Fighter, however, these limitations have been completely overcome with the implementation of mission-adaptive control surfaces combined with orthodox techniques such as vortex generation and vectored thrust. The adaptive wings of the TF-71 Advanced Tactical Fighter have no conventional ailerons, flaps, slats, or spoilers but rather utilize aeroelastic leading and trailing edges able to bend into a required position without leaving gaps. These are able to move from four degrees up to twenty five degrees down as enabled by its variable wing camber mechanism. Because the airfoil is able to adjust to a shifting flow, the TF-71 Kagetaka is the world's first production fighter capable of exploiting the phenomenon of "dynamic lift overshoot" at all airspeeds. The airfoil oscillates as the fighter's angle of attack increases which forces the airflow to stick to the wing and enables maneuvers previously unheard of. The wingtips are also aeroelastic to enhance roll rate, albeit this comes at the expense of optional wingtip hardpoints. Other physical features of the TF-71 supplement the adaptive airfoil in reducing wing stall. The fuselage chine and canards generate air vortices much like leading edge extensions on the F/A-18. At high angles of attack, the boundary layer flow becomes sluggish, which creates the danger of envelope departure and hence loss of control - the vortices serve to re-energize the flow and keep it moving over the wing surfaces, improving directional stability and lift. The sum of these varied efforts culminates in the TF-71 Advanced Tactical Fighter's remarkable "supermaneuverability", officially defined as the capability of full sideslip control at angles of attack exceeding maximum lift. Post-stall maneuvers have been tested and executed in production models at up to 70 degree angles of attack without stall. A pilot may snap his fighter 60 degrees off boresight in a split-second by manipulating the revolutionary control systems introduced by Kagetaka. In sum, the pilot of the TF-71 Advanced Tactical Fighter will have a decisive advantage in the modern close-range dogfight because of the extreme performance gap between his aircraft and those of his potential enemies.
The aerodynamic stresses of the TF-71's flight envelope demands an airframe able to sustain such challenges. However, TPMI/EC learned firsthand the penalties of seeking pure performance from the TF-70 Shukusei project, which led to the development of a different set of priorities for the TF-71 airframe. The morale and logistical problems created by an extremely maintenance-intensive aircraft like the TF-70 soon became a massive headache for the TFAS's service personnel (cults dedicated to the worship of ancient and malevolent deities from beyond the cosmos have found great popularity among disillusioned mechanical crews, who have lost faith in a benevolent god). Like its predecessor design, the TF-71 Kagetaka is a fully-modern, monocoque fighter aircraft. The frames and longerons of the fuselage are manufactured from high-strength 7475 zinc-aluminum alloy in order to reduce costs and weight as compared to titanium alloys. These components are superplastic-forming, which promotes fracture toughness and thermal creep resistance, and electron-beam welded to improve structural stability. The extensive use of electron-beam welding in the airframe also reduces airframe weight as this allows for the use of heavy fasteners to be kept at a minimum. Bulkheads and the superstructure as a whole feature resin transfer molded composites (primarily graphite-epoxy with polybenzothiazole in areas of higher thermal stress) of a high-strength/weight ratio, greatly easing fabrication processes. The wing structure, however, makes fewer compromises - the load-bearing spars are formed from Ti-1100, a very strong near-alpha titanium-aluminum alloy. The longerons are, however, 7475 zinc-aluminum as additional structural strength is unnecessary for these components. The fittings of the wings are hot isostatic pressing cast Ti-1100. The load-bearing skin of the aircraft is comprised of composites and titanium alloys near the front of the aircraft, with aluminum-lithium towards the empennage, and electron-beam welded to the longerons. Skin surface panels are formed from titanium on the leading edges of the aircraft and carbon-fiber reinforced para-polybenzothiazole resin. Use of these composites in place of a standard metal skin reduces machining costs and weight. The canards and ruddervators are the most expensive component of the airframe, as they are manufactured from Ti-1100 metal matrix composite, reinforced by monofilament silicon carbide. The aft fuselage features a very high amount of titanium due to the high thermal stress from the TF-71's powerplant, although this is reduced somewhat by the use of carbon-carbon foam in a cavity surrounding the nacelles.
[Avionics]
The considerations of the TF-71 Kagetaka's electronics development were borne from hard lessons learned from previous TPMI/EC development programs, and the intended mission goals of the aircraft. Budgetary analysis by the Defense Advanced Research Projects Agency indicated that in order to replace the older TF-62s on a 1:1 basis, the fly-off price could not exceed one hundred and twenty million dollars per unit. As avionics and associated flight systems constitute a majority of modern aircraft costs, TPMI/EC economized wherever possible without sacrificing the key capabilities necessary to combat operations. The wide variety of roles that the TF-71 will be called to fill, from ground-attack to maritime strike to fighter sweep, requires an electronics package just as versatile as the basic airframe. TF-71 is the first Tyrandisan aircraft to features extensive use of Commercial Off-The-Shelf components, as previous experiences with all in-house design led to extremely maintenance intensive systems with little if any practical value. All individual electronic elements are unified under the Mark 3b Integrated Modular Architecture centralized processing network, to maximize pilot SA (situational awareness) and improve mission readiness rates of the TF-71. A derivative of the more advanced Mark 3 IMA implemented in the TF-70, the Mark 3b coordinates and controls mission-sensitive information on a tightly integrated software and hardware platform. Mark 3b relies on common processing modules and protocols between systems to reduce avionics costs and weight. Communications between individual elements are conducted over a rugged 2GB/s fiber optic backbone, which provides sufficient bandwidth while maximizing reliability. In addition, the use of this non-proprietary point-to-point bus allows for integration of foreign avionics into the Mark 3b to be simplified. The heart of the Mark 3b is the Central Integrated Processor [CIP], a computer hosting every individual element of the mission systems software. Two CIPs are found in avionics racks located to the front of the aircraft, with one operating as a backup. The CIP consolidates functions previously managed by separate mission and weapons computers, and dedicated signal processors to achieve maximum electronics integration. Twenty two processing modules handling general purpose, signals processing, image processing, switching, and power management operations are installed in the baseline TF-71. The CIP was designed with "pluggable growth" in mind, and eight additional slots for processing modules hosted on a card interface are available for expansion. This will enable the TF-71 to remain operationally effective even as newer aircraft types are introduced by foreign competitors, reducing long-term costs by a considerable margin.
As a whole, the Mark 3b Integrated Modular Avionics package is comprised of three main subsystems dedicated to mission management, sensor management, and vehicle management. All elements of the Mark 3b are modularly installed. Cooling for the entire suite is provided via a PAO (polyalphaolefin) liquid solution. The Mark 3b also includes fully functional diagnostic software which enables support personnel to quickly identify and solve problems with the TF-71's electronics systems.
The Mission Management Suite subsystem of the Mark 3b is composed of the terrain/navigation suite, fire-control, munitions management and Electronic Warfare equipment. CIP resources are allocated to each function as necessary.
Navigation is provided by the CDI-1 system. Where previous avionics systems treated the myriad location-determining sensors of an aircraft as a discrete source of information, CDI-1 manages the data gathered by each individual system and presents it to the pilot in a coherent way. CDI-1 includes two primary sources of navigational information – an Inertial Reference System and a Terrain Reference System calibrated against each other to provide for unmatched accuracy in location.The Terrain Reference System relies on careful measurement of the terrain profile passing beneath the aircraft with a RADAR altimeter and comparison with digitally-stored geographic data. The primary advantage to using a TR system is that a standard TF (terrain-following) navigation scheme will alert enemy Electronic Surveillance Measures far sooner, due to the RADAR beam's direction. On the other hand, a TRN altimeter has an extremely narrow beam width whose energy is directed downwards, rendering virtually all ESM measures impotent. The Inertial Reference System component is comprised of two ring laser gyroscopes and an accelerometer located in the forward fuselage, coupled with GPS uplinks compatible with most standard satellite interfaces. Only one of the gyroscopes is necessary for normal operation; data from the second is fed to the TF-71’s fire control systems to automatically adjust gun position for drift.
Fire control is governed by the Stores Management System, which monitors all phases of weapons release. Data from the Sensor Management Suite is linked to this component, which constantly updates the pilot’s interface on target disposition and type. It draws on CIP resources to rapidly calculate suitable firing solutions. The Stores Management System also functions to inform the pilot of the condition of payload, control weapons launch sequences, as well as door controls and emergency weapons jettison.
The TF-71 Kagetaka features an all-new Integrated Electronic Warfare System, comprised of various subsystems installed in modular apertures around the aircraft. In practical terms, the system determines the location and nature of all potential threats, thereby warning aircrew when they are being tracked, targeted, or engaged. A superheterodyne RADAR Warning Receiver provides all-aspect radar warning capability, supporting analysis, identification, tracking, mode determination and angle of arrival (AOA) of mainbeam emissions, plus automatic direction finding for correlation with other sensors, threat avoidance and targeting information. The radar warning system is active all of the time, providing both air and surface coverage. It also provides defensive threat awareness and offensive targeting support–acquisition and tracking of main beam and side lobe emissions, beyond-visual-range emitter location and ranging, emitter ID and signal parameter measurement. Packaged in two electronics racks, it includes cards for radar warning, direction finding and ESM. The antennas for the RADAR Warning Receivers are embedded in the external skin. Laser Warning Receivers are also present, which detects laser radiation and determines its bearing. In order to quickly track missile launches the Integrated Electronic Warfare System incorporates a set of Missile Warning Receivers, with their antennas built into the ruddervators. To increase the effectiveness of the system the MAW is also directly linked to the countermeasures systems allowing an instantaneous response to a local launch. The MAWs include a set of Rayleigh scattering processing modules, which serves to greatly improve resolution and accuracy regarding threat disposition.
Active countermeasures equipment is also installed in the TF-71 Advanced Tactical Fighter, and their effectiveness is supported by highly sensitive passive receivers. The Imperial Aerospace Corporation-made Electronic Defense Automatic Response System (EDARS) provides a full spectrum of automated countermeasures to defeat tracking systems in contemporary use. The key component of EDARS is the D/EJS-3A Electronic Countermeasures Suite. This system is an active RADAR jammer, designed to be used in circumstances when stealth is not nessessary (i.e., when a missile already has a lock). TPMI/EC software upgrades have enabled the D/EJS-3A to engage in DRFM (digital radio frequency memory) jamming including standard barrage or noise modes. In the DRFM mode, the TF-71 manipulates received radar energy and retransmits it to change the return the hostile RADAR sees. This technique serves to provide conflicting and confusing information for enemy interpretation. For example, the jammer may change the range the transmitter detects through alterations in the delay in pulse transmission or the velocity the radar detects by changing the Doppler shift of the transmitted signal. An XC-100 countermeasures dispenser is internally mounted, which is programmed to deploy multi-spectral chaff and flares only in the direction of a threat as determined by the passive sensors. The flares are treated with chemical additives that spoof the IR sensors of most IR guided missiles. Additionally, data from the radar warning equipment is linked to the chaff cutting mechanism – the XC-100 is sophisticated enough to interpret the RWR’s information and cut the aluminum strips to increase reflectivity to the RF band being deceived.
The Sensor Management Suite subsystem of the Mark 3 package combines the TF-71 Kagetaka's RADAR, IRST, integrated signal processing, encrypted data, communications, and the Joint Tactical Information Distribution System interface, allocating CIP processor power to the sensor subsystems as required by the mission. With the advanced, centralized architecture employed by the Mark 3b IMA, the SMS implements sensor fusion for the pilot to enhance situational awareness and reduce pilot workload. By automating the task of interpreting sensor data, the TF-71 removes the possibility of conflicting data gathered by the various sensors and eliminates the need for manual cross-referencing.
The primary detection tool of the TF-71's pilot is a DPARS-92 Active Electronically Scanned Array RADAR, housed in the nose of the fighter. Designed to reduce weight, cost, and reliability issues as compared to the older AN/PSI-7 system used in the TF-70, the DPARS-92 is installed as a planar tile-array in nose-mounted radome. The DPARS-92's transmitter and receiver functions are composed of 4,000 individual transmit/receive (T/R) modules that each scan a small fixed area, negating the need for a moving antenna, which further decreases ESM detection probabilities as well as aircraft volume issues. DPARS-92 relies on "quad-pack" transmit-receive modules, developed originally by Livermore Electric (a subcontractor of GEM Aerospace, which TPMI/EC contacted as a partner in the fighter program). These dies consolidate four arrays (each consisting of four MMIC chips - a drive amplifier, digital phase shifter, and low-noise amplifier, and a RF power amplifier) onto one chip, which greatly reduces weight, volume, and materials costs. The chips are manufactured on gallium-arsenide wafers due to the higher electron mobility and reduced noise GaAs affords than conventional silicon. To protect the antenna from detection by hostile ESM systems, it is mounted in a bandpass radome, transparent only to the band of frequencies utilized by the radar. When it is not in use, suitable electrical impulses turn the bandpass characteristic off, making it totally opaque. The RADAR's elimination of hydraulics for antenna movements and distribution of transmission functions into the T/R modules alleviates logistical concerns. The DPARS-92 is a Low Probability of Interception [LPI] system, meaning that the waveforms of the RADAR have a much longer pulse and lower amplitude, as well as a narrower beam and virtually no sidelobe radiation. The result of this waveform modification is that the transmitted signals are virtually undetectable by enemy ESM receivers, as the RF energy emitted is spread over a wide range of frequencies, hiding among the noise of benign signals that clutter the microwave region. A tertiary data channel screens hostile ECM measures. In air-to-surface operations the radar will support functions such as synthetic aperture radar (SAR) ground mapping.
An AN/RSI-1 Inverse Synthetic Aperture RADAR processes the Doppler shift resulting from target motion as a means of improving RADAR resolution. Thanks to shared components with the AN/PSI-7, the AN/RSI-1 is highly compact, and adds less than 30 lbs to the aircraft's weight. By measuring the much larger Doppler shifts created by the TF-71's own motion and the target's changes in attitudes, the AN/RSI-1 is able to extract the Doppler effects due to pitch, yaw, and roll of the different parts of the target aircraft, processing these to obtain a clear physical profile. This information is cross-referenced against a database of known aircraft types and presented to the pilot.
Passive detection equipment will see frequent use during TF-71 operations (as these betray no warning of the fighter's approach). The aircraft includes an Integrated Electro-optical Sensor System, providing high-resolution imagery, automatic tracking, infrared-search-and-track capability, and laser designation and rangefinding. The IESS utilizes a fixed imaging infrared-array to reduce maintenance costs, and is mounted internally behind a bandpass window to reduce drag and aircraft RCS. The assembly is also shared by an optical laser system, and is housed in the forward fuselage with a 140 degree field of view. The DIRST-6G infrared search and tracking system from the ACI-73D provides additional detection options . This system is comprised of several infrared scanners which passively scan the surrounding air for heat signatures, picking out differing infrared levels and mapping them out for the central processor, which in turn interpretes the data, picking out aircraft and displaying them for the pilot via the Mission Management Suite. Each individual sensor scans across red-scale wavelengths from 2.4-13 microns to enable all-aspect detection capabilities. The sensor is cryogenically cooled via Freon gas, which allows for the system to interpret finer temperature gradients across longer distances. Estimated range for each sensor is quoted at approximately 100km under optimal conditions. All data gathered by the system is post-processed by the Sensor Management Suite to enhance resolution.
The Mark 3b includes a comprehensive Integrated Communication Navigation Identification Avionics suite, which combines the functions of current communications equipment, such as HF SSB (High Frequency-Single Side Band), VHF/UHF, SINCGARS, Have Quick, EJS, JTIDS, various navigational aids and transponder/interrogator facilities compatible with NATO-standard IFF systems. Based on common digital and RF processing modules , the system allows for all these functions to be seamlessly built into just one package. It also takes up half the volume and weight of the aforementioned equipment. The ICNIA provides functions such as beyond-visual-range identification friend-or-foe; secure, multichannel, multiband voice communications; and intraflight data link exchanges, synchronizing the displays of multiple aircraft. The Central Integrated Processors filter much of the information being passed to the pilot, presenting him with only data necessary for the phase for the mission currently being flown, to prevent information overload.
The Vehicle Management Suite is responsible for cockpit controls and displays, flight and maneuver control, and engine/power control. It is independent of the CIP, with separate processing provided by three Vehicle Management Computers. Each computer contains a processor card, I/O card and power supply card. All three VMCs process data simultaneously, calibrating results across each other to assure data integrity. In the case of divergent data, two processors can discard the output of the other processor. Interfacing to the VMCs are remote I/O computers installed across the aircraft, which receive flight control and other inputs from hundreds of digital, analog and discrete sensors. These provide data to the VMCs via the fiber optic network control. The VMCs also govern a Utilities Control System, which manages and automates the various mechanical utilities found aboard the fighter. Examples of these include primary and backup electrical systems, hydraulics (for aircraft control actuators, brakes, nose wheel steering, intakes, et al.), fuel stores and climate controls in the cockpit.
The TF-71 is controlled by a centralized fly by light fiber optic system that takes both control input from the pilot and feedback from the various sensors and control surfaces around the airplane. Due to the critical role aircraft response times play in tactical aviation, a FBL control scheme was chosen for the TF-71 Kagetaka. More importantly however, fly-by-light offers an attractive alternative to interference prone fly-by-wire systems. The popularity of EMI-based air defense weapons was not lost on TPMI/EC designers; thus, the control system is nearly immune to such errorneous behavior caused by outside sources. Additionally, the flight envelope characteristics of the aircraft are programmed into the system, which prevents the pilot from engaging in maneuvers which would induce a total loss of control. A manual override is available, in case of deep stall (which remains a theoretical possibility although no instances have yet occurred). Should the aircraft depart its flight envelope for any reason, however, a failsafe switch in the cockpit may be engaged that will cause the Vehicle Management Suite to automatically return the aircraft to level flight. Finally, the system is adaptable to irregularities in instructions due to malfunction by reconfiguring itself and biasing the pilot’s controls to compensate. All motors utilized in the transmission are brushless, which improves efficiency, reliability, and reduces generated EMI levels.
Some variants of the TF-71 Kagetaka include a "computerized associate", essentially a primitive artificial intelligence that serves as a combination of copilot and backseater. Designated the Advanced Mission-supporting Intelligent Assistant or AMIA, the AI is believed to improve the situational awareness and survivability of the fighter through a number of autonomous functions. The pilot is according to accounts from defectors, hooked up to health sensors which monitor blood pressure, pulse rate, breathing patterns, and electrical activity in the brain. Should the system determine that the pilot is incapacitated, due to red/blackout or other reasons, AMIA will automatically seize control and attempt to fly a safe, evasive route back to its pre-programmed base location. AMIA is also able to execute simple oral commands given by the pilot, such as display switching, stores management, or changing radio frequencies. Most interesting of all are AMIA's electronic warfare and countermeasures support functions, however. It is capable of intelligently analyzing strength, frequency, and location of hostile sensor sites through a data highway connection with the Sensor Management Suite. AMIA will render a display of these locations, estimate range of detection relative to the TF-71 Kagetaka's location, and advise navigational course for the pilot so as to evade detection. Also, AMIA is capable of limited assistance during mission operations. For example, if the Missile Alert Warner systems detect a launch, AMIA will automatically cycle the RF jammer to the frequency band tracking the fighter and advise the pilot to activate said equipment. Also, AMIA's connection to the Sensor Management Suite allows for it to provide tactically useful guidance to the pilot. Sensors and data links will acquire data, which are centrally processed by CIP resources, and activate tactical decision aids–or "planners." Search, attack, avoidance and denial planner modules would work simultaneously on the fused data, producing action plans for the pilot. The search planner is intended to help pilots locate targets. This software application would look, for example, at all the possible places where a column of tanks could be, based on factors such as the last siting, the road network, terrain and the speed of the vehicles. After the tanks have been located, the attack planner could plan the ingress route, assess the vulnerability of the tanks, and indicate where the wingmen should be. While these tasks are proceeding, a "fast track" process would send any high-priority threat information directly to the pilot, who would determine, with the help of an "avoid planner," the evasion route. These processes are executed by AMIA in fractions of a second, permitting pilots in a multiship formation to counter or avoid multiple threats and at the same time attack multiple targets. Unfortunately, the technology behind AMIA remains immature and prone to software errors, and only limited numbers of these systems will be deployed operationally.
[Canopy/Cockpit]
The TF-71 features a fully modern polycarbonate canopy, which provides excellent protection against birdstrike. In order to improve pilot visibility and reduce optical signature, the transparency is tinted and treated with a polarized laminate. This process eliminates glint. A plasma-deposited indium-tin oxide is applied externally in order to prevent hostile RF signals from entering the reflective cockpit area. A layer of neoprene insulation is also present to maintain the integrity of HUD displays.
The layout of the TF-71's cockpit systems were of paramount concern to the TPMI/EC and IAC design team, as a modernization of the older ACI-73. Intended to maximize situational awareness for the pilot, displays and flight symbology are fully automated by the Mark 3b Vehicle Management System, with processing power for sensor system integration drawn from CIP resources specifically assigned to this purpose. Use of the fiber-optic bus interface allows for the high level of system bandwidth required for this application. The TF-71 features a fully digital, all-glass cockpit that has eliminated the confusing switches and dials of previous cockpit designs - this improves the effectiveness of the pilot by allowing him to concentrate on his mission, rather than his equipment.
Unfortunately, ergonomics and pilot comfort were largely disregarded as priorities. In an effort to increase pilot tolerance to 10Gs before G-LOC (Gravity-induced Loss of Consciousness), the seat is reclined 65 degrees and the rudder pedals are elevated by 6 inches off the ground. By lowering the position of the pilot's head, blood circulation is improved - however, sitting in this position is remarkably uncomfortable. A Kampferian pilot of a prototype aircraft was killed in a crash after he accidentally lost his grip and spilled a cup of scalding hot coffee onto himself in level flight, because of the awkward seat. Moreover, internal TPMI/EC studies have shown an alarming discovery of higher rates of spinal injury for pilots of the TF-71 as compared to other fighter types. New production models will feature a reclining seat to address this issue.
The centerpiece of the fighter's cockpit avionics is a wide angle, 6 in. tall Heads-Up-Display. It is reinforced with vulcanized rubber and has minimal framing to preserve pilot visibility over the aircraft's nose. The system is capable of rendering a full range of flight and mission-critical information. TPMI/EC control software automates the displays and makes available to the pilot vital information useful to the phase of a sortie being flown at a time. The operator of the TF-71 may also queue up additional displays on the HUD or multifunction head-down displays through an intuitive touchscreen interface. All data outputs from the Mark 3 avionics subsystems are made available to the pilot through the Kagetaka cockpit's AMLCD screens. The integration of these disparate elements through the Mark 3b serves to greatly enhance a pilot's situational awareness and combat effectiveness. For example, the data extracted from the CDI-1 navigational system allows for an astonishingly accurate "God's-eye-view" of the terrain surrounding the TF-71 at any point in time. Integration of navigational equipment with the Sensor Management Suite enables targeting symbology to be directly overlaid onto this map, thus providing a pilot with an unprecedented level of control over the battlespace.
There are limitations to the HUD/MFD combination however; it forces a pilot to look straight ahead in order to receive information about his aircraft and its surroundings, which leaves him vulnerable to attack at points all around him. As a result, the TF-71 features a set of Helmet Mounted Displays in the pilot's flight helmet. The helmet itself is an advanced, self-contained unit comprising the HMD, night vision equipment, microphone and headphones, and oxygen mask. Thanks to advancements in engineering techniques pioneered by TPMI/EC, the system is 20% lighter than previous-generation helmets even with the addition of the integrated electronic equipment, and provides the same level of protection. The HMD projects critical information onto a semi-reflective transparent visor in front of the pilot, and shares the symbology library used in the the HUD and MFDs. Additionally, motion-tracking capabilities are built into the flight helmet with a full six-degrees of freedom. This is linked to the stores management component of the Mark 3b avionics package, and allows for a pilot to cue up a weapon and engage targets from very-high off-boresight angles.
During simulator studies of the TF-71, TPMI/EC engineers found that pilots were unable to access their touchscreens during high-G maneuvers. In order to rectify this issue, a direct voice input system was developed and implemented. The DVI system incorporates advanced voice recognition techniques that enable it to respond to commands with a latency of only 80ms with an accuracy rate of over 99.7%. Additionally, it is able to interpret the pilot's voice even when distorted by the stresses of air combat maneuvering or G-forces. The use of DVI enables a pilot to look down at his MFDs for a minimum of time, thereby improving his situational awareness through a significant reduction in pilot workload.
[Stealth]
The tradition of the ACI-73 Aquila's stealth attributes have been preserved and even enhanced in the design of its successor aircraft. In keeping with the objective of "first shot, first kill", the TF-71 is engineered to be even more difficult to detect than the already elusive ACI-73. The airframe layout was designed with computational RCS modeling techniques, to achieve "spike alignment" of reflected RF waves. The angles incorporated on all horizontal leading and trailing edges are kept as different as possible, thereby dumping the reflected RF energy to the fighter’s port and starboard sectors. This results in large, but narrow RADAR signature spikes that are extremely difficult to track effectively. Kagetaka exhibits a high degree of wing/body blending, which provides desirable aerodynamic characteristics such as improved lift, while also reducing RCS by allowing electrical surface currents to flow over the surfaces without interruption. The lack of discontinuities in the mission-adaptive wings prevents traveling waves from re-radiating too strongly (as they must pass along the surface with embedded RAM elements). Some composite panels in the aircraft's construction are RADAR Absorbent Structures (honeycombed Kevlar sections bonded to carbon-fiber skins), which are intended to absorb microwaves in higher-frequency regions. The primary RADAR Absorbent Material utilized in the TF-71 are Schiff base salts. Derived from research by Carnegie-Mellon University, the material, which is a fine black powder physically resembling graphite, consists of a long chain of carbon atoms with alternating double and single bonds and a nitrogen atom interrupting the string near one end. The chain carries a positive charge, associated largely with the nitrogen atom. A negatively charged 'counterion,' made up of varying composition depending on the specific salt, sits nearby, weakly connected to the chain. The counterion prefers to sit in one of two locations near the chain. A single photon easily dislodges the counterion from one location and forces it into the other. A short time later, the molecule relaxes, and the counterion returns to its original position. Notably, certain salts required a very small amount of energy to shift the counterion - they could be triggered by RADAR energy of certain frequencies. As a result, the Schiff base salts are able to absorb radio waves, and dissipate the energy as heat. This unique property is fully exploited in the fighter’s construction - a mixture of salts tuned to surveillance frequency bands most often employed by air to air RADAR systems (X, L, etc.) are dissolved in a binder chemical and used to treat the external resin panels. The SBS class of materials is additionally 90% lighter than previous-generation ferromagnetic absorbers, and extremely inexpensive to fabricate. Most importantly, Schiff base salts are durable enough to withstand maritime conditions without degrading RF absorptive qualities. Areas of higher reflectivity on the basic airframe have circuit analogue RAM applied. These are thin sheets of copper wire, arranged in complex geometries to scatter and diffuse RADAR signals. The leading edges of the ruddervators have embedded arrays of titanium-aluminum triangles that perform the same function, trapping RF energy inside like an echo chamber.
Exact RCS of the TF-71 Advanced Tactical Fighter is comparable to the larger TF-70, although this varies somewhat based on aspect of view.
In order to reduce electro-magnetic signature, the avionics bays built into the TF-71 are treated with Electric Wave Absorbing Material, developed by TPMI/EC. EWAM is a six-layer, non-woven cloth comprised of stainless steel and polyethyl fibers. The material is applied to the inner walls of the electronics housing in the Shukusei, and serves to eliminate electro-magnetic leakage from the on-board equipment. Under laboratory conditions, EWAM absorbs 99% of all emitted EM radiation, and reduces passive electromagnetic sensor detection vulnerability.
Infrared signature was addressed in a number of ways by TPMI/EC. The most prominent are the scalloped, flat nozzles located aft of the fighter. Although some horizontal attitude control is sacrificed, the use of these nozzles in place of the circular 3D nozzles found in ACI-73 is alleged to decrease infrared signature by an enormous factor as the exhaust plume forms a flat "beavertail" of wide lateral area that cools much faster than the high-intensity stream formed by round nozzles. These also contribute to aircraft agility by providing vectored thrust in the pitch axis over a range of 25 degrees up and down. Infrared signature is further suppressed with the use of extremely expensive carbon-carbon foam injected into cavities surrounding the engine nacelles. This material is exhibits superb thermal absorption qualities, and also contributes to RCS reduction by weakening RF return. Inorganic microparticles with absorptive qualities in the IR spectrum are also used on the empennage surface panels.