AEJ 36 Seraph
General Characteristics:Performance:
- Role: Air Superiority Fighter
- Crew: 1
- Length: 21.0 m
- Wingspan: 15.0 m
- Height: 3.8 m
- Wing area: 95 m2
- Empty weight: 16,800 kg
- Loaded weight: 29,100 kg
- Fuel weight: 10,800 kg
- Max takeoff weight: 38,700 kg
- Powerplant: 2x SDI RM220 adaptive cycle afterburning turbofans, 205 kN each
Armament:
- Maximum speed:
- High altitude: Mach 2.9
- Supercruise: Mach 2.2
- Combat radius:
1,200 km (Mach 2.2 @ 20,000 meters)
2,000 km (Mach 0.85 @ 12,000 meters)- Ferry range: 5,600 km
- Service ceiling: 22,700 m
- Rate of climb: 470 m/s
- Wing loading: 285 kg/m2
- Thrust/weight: 1.44
- Maximum g-loading: +9.0/-3.0 g
Avionics:
- Air-to-Air loadout:
- Air-to-Ground loadout:
- Hardpoints: 4x underwing pylons, 2500 kg each
- SDI FMG 396 "Fenrir" X band AESA radar
- SDI EOS 600 Advanced Infrared Search & Track System
- SDI EOS 800 Multispectral Distributed Aperture System
- SDI FMS 266 "Hammerhead" Electronic Warfare system
- SDI FG 292 CNI system
Overview:
The AEJ 36 Seraph is an advanced, sixth generation, single seat, twin engine, all weather, stealth tactical fighter aircraft designed as a long ranged air-to-air combat aircraft with added versatility as a reconnaissance, electronic warfare, and strike platform.
Airframe & Construction:Designed to both minimize radar cross section while maximizing supersonic aerodynamics and maneuverability the design of the Seraph is fairly unconventional with large, diamond shaped wings, highly angled all moving V-tail, and a highly area ruled fuselage designed to minimize transonic drag rise. The Seraph is intended to be highly maneuverable at both subsonic and supersonic speeds with an extremely high thrust to weight ratio, low wing loading, a high maximum angle-of-attack, high instantaneous turn rate, and an inherently designed relaxed static stability. Both the wing and V-tail of the Seraph use supercritical airfoils designed to have favorable lift, stall, and pitching moment characteristics at high mach numbers. The clipped diamond wings have an aspect ratio of 2.0, the similarly clipped diamond V-tail an aspect ratio of 2.5, with both having a leading and trailing edges having a sweep of 45 degrees. The aggressively chined forward fuselage section, in addition to having various radar very-low-observability benefits, generates large amounts of vortex lift at supersonic speeds which offsets the rearward shift of the aerodynamic center as the aircraft goes supersonic. The aircraft's relatively high L/D ratio at both subsonic and supersonic speeds due to its unconventional blended wing-body shape also allows for efficient cruise performance at both subsonic speeds and in supercruise. The aircraft's structure uses a semi-monocoque design constructed almost entirely of composites including a combination of forged and machined titanium metal matrix composites (MMCs) which make up approximately 50% of the structural weight and graphite-polyiamide and graphite-epoxy polymer composites (PMCs) formed using vacuum assisted resin transfer molding which represent 25% of the aircraft's weight. The use of significant amount of composites in the airframe reduces weight, improves airframe heat resistance for sustained supersonic flight, and reduces the aircraft's radar and infrared signature while also enabling the Seraph to be less maintenance intensive than previous generations of aircraft. Traditional aircraft materials such as aluminum make up only approximately 15% of the aircraft's weight while the remaining 10% consists of other miscellaneous materials.
The internal structure of the Seraph is constructed primarily from SCS-8 silicon carbide fiber reinforced Ti-5Al-5Mo-5V-3Cr (Ti-5-5-5-3) titanium metal matrix composite (MMC) structures. Compared to conventional titanium alloys the titanium metal matrix composite exhibits superior specific strength, specific stiffness, fracture toughness, wear resistance, creep and oxidation resistance which results in reduced airframe weight, superior resistance to ballistic damage, increased airframe durability and heat tolerance, and reduced maintenance requirements. The fuselage is constructed from eight titanium metal matrix longerons, five running on top of the wings and three along the bottom, which run from the front of the cockpit where they sweep either upward or downward and thicken at the intake and then run back all the way to the middle of the ruddervators. The fuselage is then divided longitudinally by nine titanium metal matrix bulkheads made from monolithic forgings which are directly connected to the longerons to better distribute structural loads. The bulkheads located in the middle of the fuselage are also joined to the titanium MMC spars in the wings. The monolithic forgings used for the fuselage and wing titanium MMC structures are additionally subject to Hot Isostatic Pressing (HIP) in order to eliminate any voids or gas pockets caused by the forging process before the components are joined together to create the airframe. The titanium MMC wing torsion-box spars are constructed from sinusoidal wave spars creating using super plastic forming and diffusion bonding (SPF/DB) which are connected to additional titanium MMC wing box frames. The titanium-MMC longerons, bulkheads, and wing spars are joined by a mixture of robotic laser welding using a pulsed Nd:YAG (neodymium-doped yttrium aluminium garnet) fiber-optic laser and robotic friction-stir welding under an inert argon atmosphere.
The skin panels, inlet ducts, landing gear and weapons bay doors, forward fuselage longerons, outer wing spars, and V-tail structure of the Seraph are constructed from laser aligned honeycomb sandwich panels several millimeters thick made from a polymer matrix composite consisting of a 3D weave of multi-walled carbon nanotubes (MWCNT) reinforced carbon fibers embedded into a high temperature polymer matrix. The matrix material used is a radar transparent polyimide resin which has a service temperature in excess of 400° C. The Seraph's weapons bay doors, empennage ribs and spars, and rear wing ribs and spars are constructed out of the same style composite but with an epoxy matrix replacing the polyimide for applications where the high service temperature of the polyimide matrix are unnecessary.
Vehicle Management System & Flight Control Surfaces:Vehicle Management System (VMS): The Seraph's vehicle management system (VMS) is a quadruple redundant fully digital fly-by-wire control system responsible for controlling the aircraft in flight. The core of the VMS system are four vehicle management computers (VMCs) which interface using fiber-optic cables to the aircraft's control actuators, engines, cockpit controls, air data system, fuel system, and inertial navigation systems. The sensor subsystem of the VMS includes four air data computers (ADCs) and a low observable pneumatic air data system (LOPADS) which consists of four flush mounted pitot tubes located above the radome in front of the cockpit and four flush mounted static ports, two on each side of the fuselage, located aft of the radome above and below the forward fuselage chine and provides Mach, altitude, airspeed, angle-of-attack, and sideslip data to the VMS. The VMS system also includes a fuel-control system which can pump fuel from forward fuel tanks to aft ones and vice versa to allow the aircraft to change its CG and stability margin in flight.
Control surfaces: The control surfaces of the Seraph include twin all-moving V-tails, inboard and outboard variable camber flaperons (combined flaps and ailerons), and variable-camber leading edge flaps. The variable camber flaps and ailerons can be continuously deflected in flight to provide near-ideal wing camber for any flight condition and are smoothly blended into the wing to reduce both parasitic drag and the radar return of the control surfaces. The aircraft's control surfaces are controlled using a decoupled flight control architecture which the aircraft to maneuver in one plane without maneuvering in the other (such as turning without banking) and allows any of the aircraft's major control surfaces to provide any control surface function (roll, pitch, or yaw). Under normal flight conditions pitch is provided by deflecting the V-tails in opposite directions, yaw is provided by deflecting the V-tails in the same direction, and roll is provided by deflecting the wing ailerons in opposite directions. Yaw control can also be provided by differential thrust of the engines. The aircraft also features a virtual speedbrake capability achieved by deflecting the outboard flaperons up and deflecting the inboard flaperon and leading edge flaps down. The control surfaces of the Seraph are actuated using a series of self-contained electrohydrostatic actuators powered by the aircraft's electrical system and connected to the aircraft's vehicle management computers through fiber-optic cabling and replace the hydraulic actuators and pumps of a traditional fly-by-wire control system with self-contained actuators that convert the electrical power into localized hydraulic power for flight control purposes. Each control surface of the Seraph including left and right V-tails, inboard and outboard trailing edge flaperons, and leading edge flaps is independently actuated using a series of EHA-VPVM (electro-hydrostatic actuator with variable pump displacement and variable motor speed) actuators which employ variable speed brushless DC permanent magnet motors to drive a variable displacement servopump which is connected to the two chambers of a hydraulic cylinder that is used to actuate the aircraft's control surfaces.
Self-Repairing Flight Control System (SRFCS): A Self-Repairing Flight Control System (SRFCS) is integrated into the aircraft's Vehicle Management System is designed to detect damage or failure in the V-tails, flaperons, and leading edge flaps. When the system detects damage or loss of a flight control surface or actuator the system then compensates by reconfiguring the remaining flight control surfaces and changing the control laws of the flight control software so that aircraft remains controllable and can be landed safely by the pilot. The SRFCS displays all damage to flight control actuators and surfaces to the pilot through the multifunction display in the cockpit which indicates to the pilot the extent of the damage and any flight speed or maneuverability limitations imposed by the damage. The SRFCS combined with the Seraph's decoupled flight control system and lifting body fuselage allow the aircraft to potentially lose an entire wing or one of its V-tails and still maintain controlled flight. In the event all the aircraft's control surfaces are destroyed or disabled the Seraph's Vehicle Management System can command increasing or decreasing engine thrust to pitch up or down (respectively) and differential engine thrust to turn, proving enough control to steer the aircraft to an airfield and perform a safe landing.
Propulsion:The Seraph is powered by a pair of SDI RM220 afterburning turbofans which each deliver up to 205 kN of thrust will full afterburner. The RM220 engine employs adaptive cycle engine (ACE) technology which allows the engine to change its overall bypass ratio and fan pressure ratio through the use of adaptive geometry devices in flight. The core of the RM220 is a two-spool turbofan with a low pressure spool consisting of two stage fan and single stage low pressure turbine and a high pressure spool consisting of five stage high pressure compressor with core driven fan stage (CDFS) and a single stage high pressure turbine. The two stage fan employs a blisk construction with rotor and highly swept wide-chord blades constructed from carbon fiber reinforced polyamide with Ti-6Al-4V titanium alloy reinforcement along the leading edges. The five stage high pressure compressor employs integrally bladed rotors (IBTs) is constructed from Ti-48Al-2Cr-Nb gamma titanium-aluminide (TiAL) alloy which provides comparable or better temperature and creep performance compared to conventional nickel super alloys while having half the density. The first stage of the high pressure compressor is a core driven fan stage (CDFS) and employs extended blade tips that act the third stage of the two stage fan and supercharges the flow entering the engine's bypass flow streams. The combustor of the engine is a double-dome annular combustor with two toroidal primary combustion zones and employs a combustion liner constructed from 3D woven SiC/SiC ceramic matrix composite (CMC) consisting of silicon carbide (SiC) fibers woven into a chemical vapor infiltrated (CVI) SiC matrix and a rare earth monosilicate environmental barrier coating (EBC) for increased oxidation resistance at higher temperatures. The high pressure turbine employs a rotor and blades constructed from 3D woven SiC/SiC with environmental barrier coating with internal blade cooling channels through which high pressure bleed from the compressor flows through after first being cooled by a heat exchanger located in the engine's triple-bypass FLADE duct. The internal cooling channels are combined with additional film cooling on the surface of he high pressure turbine blades to keep the Sic/Sic composite within it normal operating temperature limits. The counter-rotating low pressure turbine also employs 3D woven SiC/SiC construction but unlike the high pressure stage is not cooled.
- Name: SDI RM220
- Type: Adaptive Cycle Afterburning Turbofan
- Length: 5,080 mm
- Diameter: 1,170 mm
- Dry Weight: 1,800 kg
- Bypass Ratio: variable
- Compressor: Two stage fan, core driven fan stage (CDFS), five stage high pressure compressor
- Combustor: Pressure-gain combustor
- Turbine: single stage HPT, counter rotating single stage LPT
- Maximum Thrust: 159 kN (dry), 205 kN (with afterburner)
- Overall Pressure ratio: 26:1
- Turbine inlet temperature: 1,980 °C
- Specific fuel consumption: 20 g/Kn-s (dry), 40 g/Kn-s (afterburning)
- Thrust-to-Weight Ratio: 9.0:1 (dry), 11.6:1 (with afterburner)
The variable cycle features of the RM220 engine include the ability to alter fan pressure ratio through the use of a split variable-geometry fan with twin bypass streams and bypass ratio control altered through the use of a second airstream controlled using Variable Area Bypass Injectors (VABIs) that can either be used to provide additional air flow for higher fuel and propulsive efficiency or can be used to provide additional thrust by increasing core flow and and airflow for cooling the high temperature parts of the engine. The adaptive cycle RM220 adds an additional third bypass stream controlled by a row of variable inlet guide vanes and a single compression stage made by extending one row of main fan blades into the third bypass stream, a fan on blade or FLADE arrangement. Additionally the RM220 includes a core driven fan stage (driven by the high pressure turbine) which provides a boost in pressure to both the core stage and inner bypass flow streams, increasing the engine's overall pressure ratio. The split fan and Variable Area Bypass Injectors allow the RM220 to independently control both the high and low pressure rotor speeds to allow for higher airflow at subsonic speeds and higher specific thrust at supersonic speeds than would be possible with a conventional fixed-geometry mixed flow turbofan. To ensure efficient variable-cycle operation the RM220 also uses a variable-area low-pressure turbine nozzle (VATN) which allows the engine to operate with additional fan flow at low specific thrust settings to reduce engine noise during takeoff. The RM220 has three sets of VABIs. The first VABI is mounted aft of the frontal fan and allows the outer bypass duct to be open to operate in single or double bypass mode or closed to operate in zero-bypass mode. The second VABI is mounted aft of the rear split fan and permits fan operation in either single or double bypass modes. In single bypass mode the valve is closed so that the rear fan exhausts into the high-pressure compressor and into the inner bypass duct with the rear modulating VABI in the open position. When the second VABI valve is opened the engine operates in double-bypass mode where the rear fan air is discharged into both the inner and outer bypass ducts. The rear or exhaust VABI operates a a variable area bypass nozzle which injects the secondary bypass flow into the core stream behind the low pressure turbine into the afterburner or bypasses around the afterburner and inject the bypass into the variable-area low-pressure turbine nozzle (VATN) in either single or double bypass mode. The VABIs, which combined weigh only several kilograms, are individually actuated by lightweight Ti–Ni–Zr high-temperature shape memory alloy (HTSMA) actuators. The split-fan of the RM220 is additionally fitted with Variable Inlet Guide Vanes (VIGVs) which provide efficient thrust modulation across the engine's thrust envelope. For subsonic cruise the VIGV is used to reduce the flow entering the high pressure compressor with the rest bypassed to eliminate excessive spillage drag at low speeds and partial throttle settings. The VIGV are mounted in front of the high-pressure compressor and consists of stationary leading-edge vanes and variable trailing-edge flaps actuated with Ti–Ni–Zr high-temperature shape memory alloy (HTSMA) actuators that carry the mass flow rate of the engine as a function of engine cycle and freestream velocity. The RM220 has an additional set of Variable Inlet Guide Vanes which control the airflow into the third bypass stream (The FLADE duct) which bypasses boundary-layer flow around the core and injects it downwards of the turbine to cool the nozzle and reduce the infrared signature of the exhaust. The last ACE component, the variable-area low-pressure turbine nozzle (VATN), maintains engine efficiency at partial throttle settings by decreasing the nozzle area and thereby increasing the turbine inlet temperature to it's full-throttle state. Being able to operate in partial throttle settings is useful for low-speed loiter and for takeoff where the lower exhaust temperature due to the extra bypass air reduces the jet noise of the engine
The RM220 includes a fully digital FADEC (Full-Authority Digital Engine Control) system which includes a digital electronic control unit (DECU), ignition system, fuel control system, air flow control system (AFCS), adaptive cycle control system (ACCS), and various sensors. The FADEC system controls engine and afterburner fuel flow, variable inlet guide vane (VIGV) position, variable area bypass injector (VABI) position, variable-area turbine nozzle (VATN) position, and exhaust nozzle area as a function of throttle position and engine temperature and pressure sensor input in order to optimize the engine's thrust and fuel consumption over the aircraft's operating range while staying within the engines temperature and pressure limits. An integrated engine mode (IEM) in the FADEC also provides airspeed hold capability, providing a content acceleration or deceleration in response for a given forward or aft throttle displacement and an airspeed hold with the throttle placed into a center detent position. The core component of the FADEC system is the digital electronic control unit (DECU), a fuel-cooled computer system attached to the underside of the engine casing through vibration isolating mounts. The DECU contains two microprocessors independently connected through high speed serial links to the vehicle management system (VMS) and all engine actuators and sensors.
The Seraph uses a pair of of ASIs (Advanced Supersonic Inlets) on either side of the fuselage. The ASI is a divertless, three dimensional mixed compression inlets featuring a triangular shape designed to both maximize supersonic efficiency and minimize incident radar reflections. The ASI is similar in design to traditional divertless supersonic inlet (DSI) designs, with a contoured bump that diverts low-energy boundary layer air, but unlike the DSI which features external compression the ASI is a mixed-compression design with both external and internal supersonic compression. As mixed-compression inlets feature less drag and improved efficiency past supersonic mach numbers of 2.0 or higher the ASI, with a design mach number of approximately 2.5, allows for highly efficiency supersonic cruise at high mach numbers past the operating envelope of a simpler external compression diverterless inlet. In addition to the ASI's the aircraft has a a pair of auxiliary inlets located above the wing on either side of the fuselage. The inlet ducts are an S shaped and feature a spill door behind the engine face which vents above the wing. The exhausts are 2-D single expansion ramp nozzles (SERN) blended into the upper rear fuselage to reduce their radar signature and minimize the IR signature of the exhaust. The nozzle has a variable upper flap and a fixed lower half and is non-thrust vectoring. The nozzle troughs are made superplastic formed and diffusion bonded (SPF/DB) Ti-48Al-2Cr-Nb gamma titanium-aluminide (TiAL) alloy cooled using high pressure bypass air from the FLADE duct of each engine.
Power & Thermal Management:The Adaptive Power and Thermal Management System (APTMS) of the Seraph combines the functions of an auxiliary power unit (APU), emergency power unit (EPU), environmental control system (ECS), and thermal management system (TMS), and electrical power generation system (EPGS) in one integrated, adaptive system which actively manages the aircraft's electrical power generation and cooling needs in real time across various flight conditions. The thermal management system (TMS) component of the APTMS employs a vapor cycle system (VCS) which handles the majority of the waste heat from the aircraft' avionics and other systems. The VCS employs a series of cooled cooling air heat exchanger (CCHX) modules located in the FLADE duct of each RM220 engine which combined provide several megawatts of cooling capacity. Cooled air from both the the FLADE duct heat exchanger modules and from a fuel to air heat exchanger is incorporated into the vapor cycle system condenser and is used for cooling the working fluid in the refrigeration loop of the vapor cycle system with waste heat from the VCS transferred into the aircraft's internal fuel through a heat exchanger using polyalphaolefin (PAO) as the working fluid. Cooled working fluid from the VCS is used to cool the avionics and other electrical systems before being passed back into the VCS condenser, itself the heat-exchanger connected to the aircraft's fuel system. At subsonic speeds an interfuel tank recirculation loop is used to recirculate fuel between the colder wing tanks and the hotter internal fuel tanks which are used as aheat sink by the VCS system, the loop being closed off at supersonic speeds to allow the wing tanks to act as heat sink to absorb the heating loads on the wings during sustained supersonic flight.
Replacing both the APU and the ECS in the aircraft's adaptive power and thermal management system is an Integrated Power Turbomachine (IPTM), a miniature twin-spool turboshaft engine connected to a high-reactance permanent magnet machine (HRPMM) motor/generator unit which is initially used to start the IPTM and then used to generate power after the IPTM transitions to self-sustaining operation. Electrical power from the IPTM is then used to power the starter/generator units attached to each main engine in order to start both main engines. After starting both main engines the IPTMs transitions into cooling mode where the fuel flow to the IPTM is cut and the IPTM's compressor inlet is closed where thereafter electrical power from the main engine generators is used to power the IPTM's in closed-loop mode. Back EMF from the aircraft's hydroelectric control systems can also be used to drive the IPTM in order to temporarily offload the main engine generators. In closed loop mode air from the IPTM compressor is first passed through microchannel titanium heat exchangers located in the FLADE duct of each RM220 engine and then through an air-fuel heat exchanger before then being passed back into the IPTM where it is then further cooled and expanded in the IPTM's cooling turbine. Cool air from the IPTM is then used to pressurize the cockpit and to provide cooling for both the cabin air and for the aircraft's fuel tanks. In emergency power mode the IPTM functions as an APU, the compressor inlet is opened and air is compressed by the compressor, combustive, and then uses to drive the power turbine which produces electrical power for critical avionics and for re-starting the main engines. To increase the ruggedness and efficiency of the system the IPTM itself employs self-acting hydrodynamic foil bearings , eliminating the need for lubricated bearings and associated oil pumps and filters, and a Variable Area Turbine Nozzle (VATN) which when operated as a turbogenerator maximizes the specific fuel consumption of the IPTM across a broad variety of operating conditions.
Stealth:The Seraph is designed to have an extremely low radar cross section across multiple bands through the combination of airframe shaping and advanced radar absorbing materials. The Seraph is designed with broadband, all-aspect stealth in mind and features a combination of shaping features and radar absorbing structures and materials designed to counter 0.1-1 GHz long-range surveillance radars, 1.0–3 GHz AWACS radars, and 10 GHz fighter radars illuminating the aircraft simultaneously and from multiple directions. The aircraft is shaped using smoothly blended external geometry with a continuously varying curvature designed to minimize surface currents and scatter radar waves that hit the aircraft across its entire aspect. The leading and trailing surfaces of the wings, intakes and V-tail are all aligned parallel to each other at a 45 degree angle which concentrates specular radar returns into thin, narrow spikes on either side of the aircraft that minimize the chance an incident radar will get a strong return signal. The Seraph also lacks leading edge extensions and instead uses vortex lift generating chines blended into the fuselage which eliminates presenting corner reflections or vertical sides to radars while eliminating circular radar returns from the fuselage. The aircraft's large V-tails are positioned to eliminate corner reflections with the fuselage and sized to eliminate resonance or Raleigh scattering effects at lower UHF or VHF radar frequencies. Weapons bay doors, landing gear doors, and other access panels of the aircraft feature a saw-tooth shape designed to eliminate radar returns from traveling waves across the surface of the aircraft. Gaps between panels and joints on the aircraft are sealed using a combination of flexible conductive form-in-place (CFIP) sealant, conductive bulb seals, and conductive tape which is placed around ready access panels and used to seal the gaps between the the wing and the control surfaces. Reduction of the radar signature from the aircraft's inlets is achieved through the use of diverterless inlets blended into the leasing edge of the aircraft which eliminate the radar reflections caused by a traditional boundary layer diverter or other inlet structures. The diverterless inlets combined with S-duct serpentine intakes also serves to prevent line-of-sight view of the engine's turbine blades from any exterior view. Further reduction of the aircraft's radar signature comes from a hybrid dielectric/magnetic fiber-mat radar absorbing material which is cured into the aircraft's honeycomb composite skin. The RAM consists of randomly oriented carbon fibers infused with multiwall carbon nanotubes coated with a magnetic FeNi nanopowder which are aligned and then cured into an thermoset exposy resin to form a fiber-mat panel which is cured into the aircraft's composite skin. The RAM is made in two layers, the first designed to reduce reflected radar waves by having a thickness intended to optimize internal reflections and a second, more electrically conductive layer with a higher density of CNTs infused into the carbon fibers which dissipates the remaining radar energy as heat and electrical energy. The impedance of the fiber-mat RAM is matched to air at its outer surface and creates essentially a black body absorber from the VHF through W radar bands (0.1 - 60 MHz). Arrangement of the CNTs in multiple orientations allows the RAM to simultaneously absorb incident radar waves from multiple radar source impinging at different incidence angles. The 3D weave is cured into the aircraft's skin panels using a vaccum assisted resin transfer molding process to create each of the individual layers of the RAM (two in total) which are embedded with the composite skin of the aircraft and act as an additional structural member of the skin in addition to functioning as a radar absorbing structure. The RAM does not cover the entire aircraft and is placed in areas where the radar signature can not be reduced through shaping methods such as the wing and tail leading and trailing edges, inside the engine inlet ducts, and on the sides and underside of the fuselage. With the combination of stealth shaping and advanced RAM the Seraph has a radar cross section of around -45 dBSM across the frontal arc, -30 dBSM from the sides, and -35 dBSM from the rear.
In addition to low radar observability the Seraph also features a variety of infrared signature management technologies. The carbon nanotube RAM coating on the aircraft also functions as a moderately effective infrared absorber due to the high infrared absorptivity of CNTs, reducing the aircraft's skin infrared signature in long-wave infrared wavelength (8–12 microns) by around half where the where the RAM is present. The 2D ejector nozzles of the aircraft also serve to reduce the infrared signature of the exhaust by promoting greater mixing of the hot exhaust with ambient air. The hot exhaust from the aircraft's engines is cooled using bypass air and additional secondary air inlets before exiting through exhaust trenches blended into the rear fuselage located between the twin V-tails. The exhaust trenches or tunnels are made of titanium-aluminum alloy coated with low-emissivity carbon/carbon (C/C) ceramic composite tiles and serve to shield direct view of the hot exhaust from the sides or from below the aircraft. To reduce the infrared signature of the airframe itself the fuel and bypass air streams are used as heatsinks for the avionics such as the radar and jamming system which by themselves generate a tremendous amount of heat when active. Further reduction of infrared signature is achieved by circulating fuel around the leading edges of the aircraft which also serves to reduce the heat buildup from sustained supersonic flight. The aircraft also features a series of deployable air scoops along the wings designed to provide cooling air to the engine and power and thermal management system and a set of air scoops located alongside the wing/fuselage junction to provide additional cooling air flow to the engine nacelles.
Avionics:The Seraph employs an Integrated Avionics System (IAS) architecture which uses sensor fusion from all the the aircraft's sensors and from and off-board data sources in order to achieve long range detection, high confidence BVR identification, and highly accurate target tracking for BVR weapons employment and/or threat avoidance before the Seraph is detected by enemy sensors. The system's air tactical situation model generates target track files of all air objects in the environment which are continually and automatically updated without pilot intervention. Detected air targets receive increasingly higher tracking accuracies as they penetrate a series of tactical engagement boundaries surrounding the aircraft which include the initial track and target ID, the engage/avoid decision, Rb 100 launch envelope, threat missile launch envelope, and threat missile lethal envelope/no escape zone. The boundaries are designed to provide the pilot with sufficient time to make decisions to engage or avoid targets without having to manually manage the aircraft's sensors. Data from the aircraft's sensors including radar, IRST, and EW data is automatically fused and correlated into a single integrated track file for each air and surface object with autonomous sensor tasking which selects the appropriate sensors and sensor modes to support the tracking accuracy requirements of each engagement boundary. The integrated track files for each air object including their kinematic and ID estimates and engagement boundaries are also displayed on the cockpit's multifunction display.
SDI FMG 396 Fenrir X band AESA Radar: The primary sensor of the Seraph is the FMG 396 Fenrir, a long range, low probability of intercept (LPI), fully digital multifunction X band (8-12 GHz) AESA radar which includes forward and side looking radar arrays mounted in the nose of the aircraft. Components of the FMG 396 radar include the chined frequency-selective surface (FSS) composite radome, main AESA, side AESAs, common beam steering computer, power supply, and radar support electronics enclosure. The radar system supports multiple simultaneous operation modes including long range search, long range cued search, all aspect medium range velocity range search, multiple target track, missile datalink capability, automatic target recognition, target cluster breakout/raid assessment, and weather detection. The radar also supports air-to-ground modes including high resolution synthetic aperture radar (SAR) mapping and ground and maritime moving target tracking (GMTI/MMTI) along with electronic warfare modes including electronics support measures (ESM) receiver and electronic-attack (EA) capability. The main array of the FMG 396 employs 2,400 full-duplex, multi-channel, dual-polarized transmit and receive (T/R) modules which each employ a gallium nitride (GaN) on diamond monolithic microwave integrated circuit (MMIC) front end with a silicon germanium (SiGe) Bipolar CMOS (BiCMOS) core chip. The side cheek arrays are smaller than the main array and each employ 600 of the same T/R modules as the main array with a conformal antenna blended into the side of the forward fuselage. The FMG 396 is fully digitized and includes a digital beam former (DBF) and digital receiver/exciter (DREX) module for every antenna element which contains a field-programmable gate array (FPGA), analog-to-digital converter (ADC), and digital-to-analog converter (DAC) which enable a variety of adaptive and dynamic beam-forming techniques to increase beam-scanning accuracy and increase electronic countermeasures resistance. The ECCM functionality of the FMG 396 include randomized burst-to-burst and pulse-to-pulse frequency-hopping, staggered multiple-PRF operation, randomized multiple-beam scan patterns designed to confuse hostile radar warning receivers, sidelobe blanking (SLB) and tapered illumination functions which reduces sidelobe emissions, adaptive null-steering and null-forming techniques for cancelling out directional jamming, and active jammer tracking on both elevation and azimuth. Low probability of interception/detection (LPD/LPI) operation is facilitated by frequency-modulated continuous wave (FMCW) operation which adaptively reduces radar power to the minimum necessary level to continue tracking targets. Automatic target recognition (ATR) techniques supported by the FMG 396 system include high range resolution profile (HRRP), inverse synthetic aperture radar imaging (ISAR), and jet engine modulation (JEM). Peak power output of the FMG 396 is 48 kW and maximum detection range is 400 km for a 1m2 target and 130 km for a 0.01 1m2 target in single-target track (STT) mode. High resolution SAR imagery with <0.3 meter spotlight and <1 meter stripmap mode resolution can be generated by the radar system out to 300 kilometers using enhanced real-beam ground map mode with optional doppler-beam sharpening for additional resolution improvement. The cooling system required to support the radar's high peak power output is a two-phase hydrofluoroether (HFE) based dielectric fluid based system using vapor chamber cold plates connected to the antenna modules which dumps the heat from the radar systems into the aircraft's vapor cycle system (VCS).
SDI EOS 600 Advanced Infrared Search & Track System: Mounted in faceted low-RCS housing underneath the nose is an SDI EOS 60 Advanced Infrared Search & Track (AIRST) system, a step-stare infrared search and track system which consists of a two-axis stabilized mirror assembly, four-panel conformal optical window, and a high-magnification mercury cadmium telluride (HgCdTe) starring focal plane array (FPA) imaging infrared (IIR) sensor providing entirely passive long-ranged electro-optical search and track capability to supplement the active scan capability of the FMG 396 radar. The 1280 × 1024 pixel HgCdTe array used in the sensor operates in both the MWIR (3–5 µm) and LWIR (8–15 µm) wavelengths and uses a hybrid complementary metal-oxide semiconductor (CMOS) FPA architecture with telescope optics providing three step-wise field-of-views; 8°x 6.4° narrow field-of-view (NFOV), 16° x 12.8° medium field-of-view (MFOV), and 30° x 24° wide field-of-view (WFOV). The infrared sensor system is cooled to 180 degrees K using a six-stage thermoelectric peltier cooler and is mounted on a vibration isolated gimbal system which provides each sensor with +20°/- 45° degree elevation and +/- 75 azimuth scan coverage. The AIRST system supports both single and multiple-target tracking with track-while-scan (TWS) functions against up to 200 targets with < 0.25 mrad tracking accuracy and can also display infrared sensor feed at into the pilot's helmet mounted display or cockpit head-down display at a rate of up to 60 Hz to act as a FLIR for navigation or targeting purposes. Multi-Ship Infrared Search and Track (MSIRST) capability is also supported by the AIRST system which allows two or more Seraph aircraft to passively triangulate targets by sharing bearing and elevation data of target tracks from their AIRST systems using the aircraft's high speed tactical datalink enabling the generation of completely passive 3-D tracks of airborne targets. Maximum detection ranges for the AIRST are 130-200 kilometers depending on target type and aspect. Data from the AIRST can also be be sensor-fused in real time with radar data from the APG-96 to provide highly accurate and jam-resistant detection, tracking, and fire control capability to the Seraph's weapon suite.
SDI EOS 800 Multispectral Distributed Aperture System: the Seraph's EOS 80 Multispectral Distributed Aperture System (MDAS) consists of six 1280 × 1024 pixel mercury cadmium telluride (HgCdTe) starring focal plane array IR imagers similar to the ones used in the EOS 600 placed around the aircraft which provide 360 degree spherical situational awareness infrared search and track (SAIRST), missile approach warning (MAW), and 360 degree spherical day/night pilot vision. One sensor system is placed in the nose pointing forward, two in the nose pointing sideways, one aft of the cockpit pointing upwards, and two on the lower fuselage pointing downwards. The system allows for simultaneous 360 degree spherical tracking of air and surface targets, 360 degree spherical missile approach warning (MAW) capability, and 360 degree spherical pilot vision around the aircraft in all weather conditions. The MDAS is capable of simultaneously tracking enemy aircraft, surface and ground targets, surface to air, air to air, and ballistic missiles, can automatically cue appropriate missile countermeasures, and allows high off bore launching of missiles in any direction relative to the aircraft.
SDI FMS 260 "Hammerhead" Electronic Warfare System The FMS 266 "Hammerhead" electronic warfare system is a comprehensive offensive and defensive electronic warfare (EW) and electronic support measures (ESM) suite which combines passive radar warning receivers, countermeasures dispersal, and intelligent, adaptive phased array jamming functions. The combined radar warning receiver (RWR) and electronic support measures system (ESM) of the FMS 266 consists of 24 conformal load-bearing antenna structures (CLAS) blended into the carbon-fiber composite skin of the fuselage, wings, and tails of the aircraft. The antennas include 18 mid/high band antennas covering the 2-40 GHz frequency range and six low band antennas covering the 0.1–2 GHz frequency range which feed into a network of ultra-wide bandwidth digital receivers for signal processing of received radar signals and provides 360° spherical broadband, all aspect detection, identification, geolocation, and tracking of radar emissions in the 0.1-40 GHZ range with 40 GHz of instantaneous bandwidth combined with less than 1 degree RMS angle-of-arrival (AoA) precision through the use of dual-baseline interferometer and time-difference-of-arrival (TDOA) direction-finding techniques. The high cruise altitude of the aircraft allows the passive receiver system to detect and track line-of-sight RF emissions from ground and ship radars out to 600 kilometers (radar horizon limited) and RF emissions from airborne radars out to over 1,000 kilometers. The passive receiver system also supports bistatic over-the-horizon RF intercept capability allowing RF signals from ground based radars which reflect off aircraft, missiles, satellites, or other air or space borne objects to be detected and tracked by the system at ranges exceeding 2,000 kilometers. The EW subsystem employs resource sharing of common hardware components to perform the simultaneous search, detection, RF measurement, signal analysis, direction finding, identification, geolocation, and tracking of RF signals while simultaneously supporting active jamming of radar threats through the use of adaptive emitter tuning in ECM heavy environments. Functions supported by the FMS 266 passive radar receiver system include specific emitter identification and verification (SEI/SEV) and intentional modulation on pulse (IMOP) detection capability which provides signal detection and analysis and characterization of incident radar pulses in extremely heavy ECM environments. Precision location strike system (PLSS) capability is also supported by the system which allows up to three Seraph aircraft operating together to geolocate RF emissions in real time through the use of the aircraft's tactical data link. To precisely locate emitters PLSS functionality uses time-difference-of-arrival (TDOA) techniques to precisely geolocate threat emitters, direction-of-arrival (DOA) techniques to filter and identify specific threats, and distance measuring equipment (DME) techniques to precisely determine the aircraft's position with the respect to the emitters.
The offensive EW capability of the FMS 266 Hammerhead system includes 18 active ECM antennas, six low band transceiver antennas covering the 0.5–2 GHz frequency band, six mid-band transceiver antennas covering the 2–6 GHz frequency band, and six high-band transceiver antennas covering the 6–40 GHz frequency band located on the wingtips and leading and trailing edges of the aircraft's wings, and two receive-only broadband 8-arm spiral antennas located on the top and bottom of the fuselage covering the 0.5-40 GHZ frequency range. Each transceiver antenna employs GaN-on-diamond based active electronically scanned array (AESA) antenna technology with digital beam-forming and digital receiver/exciter units and provides 360 degree DRFM deception jamming of radar threats around the aircraft. Each antenna employs a frequency-selective surface (FSS) which consists of an organic honeycomb sandwich structure with embedded wideband end-fire phased arrays employing GaN-on-diamond T/R modules which are structurally integrated into the aircraft's skin panels, reducing drag and radar cross-section over conventional non-structurally embedded and external antenna. The FMS 266 is a fully cognitive and adaptive system; by using emissions data collected from the FMS 266s radar warning receiver the DRFM jammers can automatically adapt in real time to unknown waveform characteristics, dynamically synthesize countermeasures, and jam the waveform accordingly, allowing the system to effectively jam digitally programmable LPI frequency modulation continuous wave radars employing highly agile waveforms. The DRFM Jammers of the system also include false target generation capability which takes incoming radar signals and injects a variable delay line into the signal before transmitting it back to the receiver, allowing false targets to be generated and their range and speed varied to simulate a real aircraft. The false target generator system can generate up to 32 simultaneous false targets at ranges from less than 150 meters to over 675 kilometers from the aircraft with RCS of false targets varying from near-invisible stealth targets to large size blimps to spoof hostile radar systems. Jet engine modulation (JEM) and high resolution range profile (HRRP) returns for false targets can also be synthesized in order to confuse and spoof hostile radar automatic target recognition (ATR) techniques. To prevent the jammer output from blinding the aircraft's own communications system the FMS 266 includes an Interference Cancellation System (INCAS) located in the forward fuselage of the aircraft behind the radar which selectivity cancels out the jammer interference in the path of radiated signals. This is done by collecting a sample of the jammer interference signal and using it to create an anti-interference signal which it then mixes into the receive path for the protected transceiver to cancel out the interference from the jamming. For maximal modularity the INCAS system is built into self-contained LRUs and lacks the need for direct interface to either transmitter or receiver elements.
SDI FG 292 system: The Seraph's FG 292 CNI (Communications, Navigation, Identification) system is a multipurpose sensor suite which includes encrypted data links and communications systems, IFF system with combined interrogator/transponder, instrument landing system, GPS receiver, inertial navigation system, and radar altimeter system. The primary communications system of the CNI system is a software defined radio (SDR) proving multi-band, multi-mode capable, encrypted voice, data, and video communications between the aircraft and other platforms. The SDR supports up to 10 programmable 2 MHz - 2 GHz channels with 40 individual waveforms including UHF, EHF, and VHF demand assigned multiple access satellite communications (DAMA SATCOM), HF, UHF, and VHF line-of-sight airborne communications, enhanced position location reporting system (EPLRS), and tactical air navigation (TACAN) waveforms. The aircraft's IFF system consists of a combined interrogator/transponder unit with integrated cryptological computer supporting mode 5 elementary and enhanced surveillance (ELS and EHS) interrogation capability.
For communicating in defended airspace the CNI system includes an SDI penetrating tactical datalink (PTDL), an LPI/LPD fast switching ultra-high bandwidth directional communications system operating in the Ku through V bands (18-50 GHz). The PTDL allows flights of AEJ 39 and other PTDL equipped aircraft to exchange information in flight such as targeting information, weapons remaining, and fuel status. Six conformal 256-element phased array antenna assemblies with 1 GHz of instantaneous bandwidth are blended into the outer surface of the aircraft to provide complete 360° spherical transmit and receive coverage around the aircraft. The PTDL employs frequency agility, randomized burst, spread spectrum techniques, emissions control, and low-power directional transmissions to minimize detection probability by hostile ECM/ELINT receivers. To minimize transmission distance and thus transmission power required the the PTDL employs a "daisy chain" transmission system where the communicating aircraft sends the directional signal to a second, closest aircraft which then relays the signals to a third next-closest aircraft, who then relays the signal to a fourth aircraft, and so on.
Precise aircraft velocity and altitude above ground level (AGL) information is provided by a interferometric synthetic aperture radar altimeter (InSARA) system. Two C band (4.24 to 4.36 GHz) synethic aperture radar antenna blended into the lower surface of the aircraft's fuselage image the terrain underneath the aircraft; the two images then being correlated and the phase difference between the two images used to precisely determine the aircraft's elevation. The InSARA system also acts as an automatic ground-collision avoidance system (Auto-GCAS).
For navigation purposes the aircraft is equipped with a GPS spatial temporal anti-jam receiver (GSTAR) including controlled reception pattern antenna (CRPA), high dynamic range RF (radiofrequency) front-end, digital beamformer and digital receiver unit. The GSTAR system includes a formal antenna with +/- 12 MHz of instantaneous bandwidth and supports up to 16 simultaneous beams with digital beam steering and nulling and features a 36-channel (24 military and 12 civilian) digital receiver unit. The GSTAR system supports both Y-code and M-code GPS and is highly jam resistant with greater than 125 dB jam/signal ratio tracking performance. The GSTAR receiver also supports wide area differential GPS (WADGPS) functionality with 0.5-2 meter 3-dimensional position accuracy in flight for navigation and weapon targeting functions. The GSTAR receiver is coupled with two SDI designed TNS 300 IMU (Inertial Measurement Unit) systems each containing integrated 3-axis non-dithered laser-ring gyro (LRG) and 3-axis pendulous integrating gyroscopic accelerometer (PIGA which provide linear and angular acceleration, velocity, linear and angular position, and true heading outputs. The two IMU units are placed on the aircraft's centerline directly aft of the radar assembly and are additionally operated off two separate data buses to provide independent measurement data. The IMUs provide continuous measurement of the aircraft's acceleration and roll rate which is combined with airspeed and altitude data from the aircraft's air-data system and then input to the aircraft's flight control software. IMU data including magnetic and true heading is also input to the aircraft's navigation software where the IMU data is combined with GPS data to provide highly accurate navigational capability for the aircraft. The IMU system also provides motion compensation capability for the FMG 396 radar and EOS 600 AIRST system.
Cockpit:Canopy: The canopy of the Seraph is constructed from an organically modified sol-gel (ORMSOL) silica based nanocomposite which has excellent optical and thermal properties, high durability, high flexibility, and excellent ballistic performance at a substantially reduced weight compared to current glass/polycarbonate laminates. ORMSOL is made from a crosslink oriented nanocomposite made from a silica gel which has a higher optical transmission, higher tensile strength, higher heat tolerance, and less weight per unit of thickness compared to standard glass/polymer laminates. The canopy is specifically designed to be resistant to bird strikes and is rated to survive strikes from a 1.8kg object traveling at 230 meters per second. The canopy also features a thin layer of indium-tin-oxide nano particles designed to reflect radar emissions.
Cockpit displays and controls: The fully glass cockpit of the Seraph features a 50 x 20 centimeter Multifunction Colour Head Down Display (MCHDD) consisting of a panoramic 2560 x 1024 pixel active-matrix LCD (AMLCD) capacitive touch-screen display which can be configured to display relevant flight instrumentation, navigation, communication, and weapons system information and supports swipe and pinch-zoom capability with 5-point multi-touch capability allowing for the repositioning and enlarging or shrinking of the various display. The MCHDD also includes dual redundant LED backlights which support both daytime high-sunlight and nighttime NVG/NVIS compatible operation modes. Underneath the main MCHDD is an integrated control panel (ICP) which includes a keypad for entering entering communications, GPS, and autopilot data. The Seraph is also equipped with a direct voice input (DVI) system which allows the pilot to use voice commands to issue instructions to the flight control, navigation, communication, and/or weapon systems of the aircraft. The Seraph uses a right handed HOTAS (Hands on Throttle and Stick) layout with the control stick on the right and the throttle on the left of the cockpit.
Helmet mounted display: The pilot of the Seraph is equipped with the SDI Nemesis Advanced Helmet Mounted Display System (AHMDS), a fifth generation Helmet Mounted Display (HMD) which incorporates a curve wave guided holographic display (CWHD), built in night vision camera, high accuracy head and eye tracking system, laser eye protection, and a 3D-Audio/Active Noise Reduction system. The Nemesis features a shock absorbing liner made from a shear thickening non newtonian fluid and is constructed from a carbon nanotube reinforced carbon fiber composite which is custom molded to the head of each individual pilot. The panoramic, polarized visor of the nemesis is constructed from polycarbonate embedded with a nano-thin layer of tungsten oxide and tungsten bronze nanoparticles which provides both laser eye protection and anti-glare functions. The curve wave guided holographic display (CWHD) display of the Nemesis provides 80 x 40 degree field of view, 2560 x 1024 pixel resolution bi-occular imagery uses two LCOS (Liquid Crystal on Silicon) 1280 x 1024 pixel active-matrix liquid-crystal displays (AMLCDs) placed on either side of the helmet to display images onto a holographic optical waveguide built into the polycarbonate visor. For flying in low light conditions the Nemesis features a built in Electron Bombarded Active Pixel Sensor (EBAPS) based visible/near infrared (NIR) night vision camera with a 60 hertz refresh rate and a 1200 x 1600 pixel UXGA (Ultra Extended Graphics Array) resolution which incorporates advanced non-blooming, low halo technology with automatic gain control. The image from the night vision camera can be displayed directly onto the helmet’s visor, negating the need for the pilot to wear night vision goggles. The display also includes an LED backlight designed to increase the readability of the display in high-brightness conditions. A 9-axis internal measurement unit (IMU) and a substrate-guided wave (SGW) based eye tracking system built into the HMD provides precise tracking of pilot head and eye movementand allows both the X band radar and IRST to be slaved to the pilot's vision. Stitched, sensor fused output from the aircraft’s Multispectral Distributed Aperture System (MDAS) infrared cameras can also be displayed into the HMD to provide the pilot with 360 degree spherical day-and-night synthetic vision around the aircraft. The Nemesis also features a built in 3D-Audio/Active Noise Reduction (ANR) system with an additional built in binaural based threat warning system which reduces pilot fatigue and hearing loss, improves the clarity of radio transmissions, and alerts the pilot to threats around the aircraft.
Flight suit & life support: Seraph pilot wears a pneumatically controlled advanced anti-G-suit with partial-pressurization and assisted positive pressure breathing system that allows the pilot to briefly endure 9+ g turns without suffering g induced loss of consciousness as well as maintain breathing ability at altitudes exceeding 20,000 meters. The Seraph's life support system includes an on-board oxygen generation system (OBOGS) to generate oxygen for the pilot during flight. The OBOGS works by taking filtered engine bleed-air and passing it through a pressure-reducing valve to reduce the air to ambient pressure where the air is then passed over a zeolite-filled bed that absorbs the nitrogen molecules in the air which are purged from the bed and vented overboard . The 95% pure oxygen generated by the OBOGS is then fed into the pilot's breathing regulator. A back-up tank of liquid oxygen attached to the ejection seat is used to provide oxygen in case of an OBOGS or upon pilot ejection from the aircraft. Pilot ejection in the Seraph is via a SDI advanced rocket ejection seat) a rocket powered zero/zero capable ejection seat capable of ejection at any altitude from 0 to 30,000 meters and speed from 0 to mach 3.
Armament:The Seraph has three internal weapons bays, one located on the underside of the fuselage and two located on the sides of the air intakes. The ventral bay can accommodate up to six Rb 100 Wyvern missiles for air superiority missions or two Wyvern missiles and two 1,200 kg munitions for strike missions. The two side bays each contain a deployable trapeze launcher designed to carry a single Rb 80 missile.
