DAS-15 Tiger
| |
| Profile (n/a) | |
| DAS-15 Tiger | |
|---|---|
| Design details | |
| Type | Interceptor |
| Manufacturer | Detmerian Aerospace |
| Design No. | DAS-15 |
| Unit cost | $134 million |
| Service dates | 2005-present |
| General characteristics | |
| Crew | 2 |
| Length | 25.36 m |
| Wingspan | 16.12 m |
| Height | 6.08 m |
| Empty weight | 21380 kg |
| Payload | |
| MTOW | 46800 kg |
| Flight characteristics | |
| Engines | 2 × IMW ATG-15F |
| Speed | Mach 3.32 |
| Manoeuvrability | +7/-3 g |
| Thrust loadings | 0.57-1.064 |
| Fuel fraction | 0.39 |
| Range | 1720 km |
| Ceiling | 24500 m |
| Rate of climb | |
| Armament | |
| Internal | 15.75 m3 weapons bay |
| External | See Characteristics |
| Operators | |
| Sarzonia, UKIN, USNSEA | |
Development
Origins
The DAS-15 emerged from a request for proposals (RFP) by the Royal Isselmere-Nieland Air Force (RINAF) for a high speed, high altitude interceptor to counter the burgeoning number of Mach 3+ strike aircraft as well as the repercussions of Sarzonia’s inquiry into the failings of its armed forces during the Inkanan Civil War. Though the fall of the Unionist coalition saved the United Kingdom of Isselmere-Nieland Defence Forces (UKINDF) from a public airing of all of their flaws, such as the loss of much of the Navy’s Rapid Reaction Force’s air power to an onslaught of Doomingslandi and Inkanan Republican Dat’ Pizdy F-78 Sokols, a number of high ranking officers found themselves cashiered and the king personally castigated all three services and the Defence Procurement Agency (DPA) for failing to keep pace with training and technological developments.
Faced with His Majesty’s wrath as well as a generous contribution from the Royal Purse, the DPA’s Directorate-General for Aviation (DPA-DGA) issued General Operational Requirement, Number 78 (GOR-78). The specifications were far beyond any ever considered by domestic manufacturers. The aircraft had to have a combat speed of greater than Mach 3 at altitude and at least Mach 1.2 at sea level (ASL), an initial rate of climb of greater than 30.5 m/s (60,000 ft/min), a service ceiling greater than 24.2 km (80,000 feet), and an intercept radius of at least 1000 nm (1852 km) at a median operational speed of at least Mach 1.7 without aerial refuelling. The interceptor would have to carry at least four extended range air-to-air missiles (ERAAM) as well as two long range air-to-air missiles (LRAAM) and two beyond visual range air-to-air missiles (BVRAAM), be able to bear two 2000-litre fuel tanks for trans-oceanic deployments. It would have to be able to track at least forty targets at all altitudes and have secure locks on at least twelve of those, to engage targets with very small radar cross-sections (RCS) at sufficient stand-off ranges, and to serve as a discreet mini-airborne warning and control system (AWACS) when on station. Worse still, the new fighter would have to be able to make positive 3g manoeuvres at speed and altitude, have a landing speed of no more than 145 knots (268.54 km/h), and be able to perform at least three sorties a day with minimal maintenance.
Several designs fit most of the GOR-78 specifications, most notably Dat’ Pizdy’s F-78A Sokol and succeeding variants. Since neither the RINAF nor the DPA considered it likely that the Armed Republic of Soviet Bloc would grant an order from the UKIN, the DPA-DGA dropped the Sokol from the shortlist. The F-78 would, however, serve as the guideline by which all other designs would be measured.
Closer to home, diplomatically speaking, were designs from Sarzonia’s Avalon Aerospace Corporation, Praetonia, and the Omzian Democratic Republic and Adejaani’s OMASC. Praetonia’s L-82 Hussar strike fighter deigned to counter the Sokol’s air dominance by penetrating enemy airspace at high speed with its pulse detonation engines (PDE). Avalon Aerospace produced two aircraft in response to the terrible damage inflicted upon them by the Doomingslandi Air Force (DAF), the SZ-19 Predator and the SZ-20 Valkyrie. All three aircraft used PDE to produce the enormous thrust necessary to travel at speeds greater than Mach 3.
Group Captain Lawrence Elstridge, the head of RINAF’s evaluation team, voiced concerns regarding the serviceability of PDE-powered aircraft. Without a notable increase in funding and personnel resources, the Air Force was leery of purchasing an aircraft that would require considerable down-time between missions and an expanded maintenance retinue. Neither Demers Turbines nor Isselmere Motor Works (IMW), the UKIN’s foremost aero-engine companies, had succeeded in manufacturing an operational PDE (see Propulsion below), a fact that both exacerbated the RINAF’s worries about falling behind and emphasised the troublesome nature of the new technology.
G/C Elstridge and DPA-DGA’s Director-General, Sarah Oldham, similarly agreed on the electro-thermal chemical (ETC) autocannons fitted to the L-82 and SZ-20. Though the 35mm and 32mm cannons produced much greater velocity and range than Royal Isselmere-Nieland Ordnance’s (RINO) conventional 30 × 173 mm ACA.41, both demanded volume that would be better filled with fuel since much of the GOR-78’s usual operational envelope would be at speeds at which guns would become deadweight.
Thus, though the L-82 and SZ-20 were both astonishing aircraft, especially in terms of speed, the DPA-DGA’s GOR-78 Committee shortlisted only the more conservative SZ-19 Predator, even though the SZ-19’s range without refuelling, 1600 nm (2964 km), was the subject of some concern within the RINAF.
OMASC’s F-125 Rapier filled most of the GOR-78 specifications precisely. Though its range without refuelling was less than that desired (3800 km), it possessed an impressive array of electronics, the right performance characteristics (speed, service ceiling, payload), and like the SZ-19 was a proven in-service design. The F-125 had superb radars, the forward array capable of search ranges of up to 450 km and the rear set of ranges up to 200 km. The forward radar was able to track forty targets as well and could detect and track aircraft with small RCS such as the Lockheed Martin F/A-22 Raptor and the Northrup Grumman B-2 Spirit at an acceptable range. The Rapier’s use of turbofans instead of PDEs was its greatest advantage over the Sarzonian design, catapulting it to the top of the GOR-78 shortlist.
Faced with the GOR-78 Committee’s surprising ambivalence to Avalon Aerospace’s SZ-20 and OMASC’s F-125, Detmerian Aerospace Dynamics (DAS) recovered from the fear that it would suffer its first loss of a domestic contract. Immediately, DAS set to work on completing and revising studies for high speed warplanes begun after the successful completion of the DAS-6 Scimitar. Three offered the best prospects: Indigenous Design Prototype, Number 53 (IDP-53), IDP-57, and IDP-58. Of those three draughts, IDP-58 evinced the most promise and proceeded towards full development.
In the meantime, DAS contacted the UKIN’s two main aero-engine manufacturers, Demers Turbines and IMW, to design an engine capable of at least 18000 kgf (176.52 kN or about 39,683.21 lbs. of static thrust) and capable of sustaining a combat speed of Mach 3+ at altitude and at least Mach 1.2 at sea level. As noted above, both Demers Turbines and IMW had conducted research into PDE finally culminating in the LPDE-3 (T84D-LA) by their joint holding company, Lethe Aero-engines Corporation (LAC), producing 5120 kgf (50.21 kN or 11,287.67 lb. st.). Unfortunately, larger and more powerful PDE befuddled the engineers of both firms. IMW’s PDE, the ATG-20D (T71D-IM) was prone to emitting shattered, superheated turbine blades during consecutive testing, requiring the checking of turbine discs after each test. In the Demers Turbines engine (TMD-1 or T72D-DT), the combustion/detonation module was shaken apart in two separate tests. Inquiries into those incidents revealed that the moulds for casting ATG-20D blade-discs (blisks) transferred impurities to the powdered nickel alloy, whilst the TMD-1’s combustion/detonation module was too light and its active cooling mechanism, using bypass air as well as argon gas that would be taken from the aircraft’s atmosphere recovery kit (ARK), failed to operate properly and was inadequate to the task. Weight and size issues have continued to thwart the development of PDE in the UKIN as operational engines.
Luckily for DAS, Demers Turbines work on missile motors and IMW’s research into developing more conventional gas turbines for high speed flight led to a pair of turbofans capable of sustained Mach 3 flight, the T73F-DT and its larger cousin the T78F-IM (see Propulsion below). Having found a powerplant that could reliably power a Mach 3 aircraft, DAS engineers only had to devise an airframe that could take advantage of the tremendous power the engines provided.
Test and evaluation
Work on turning the IDP-58 into a genuine prototype advanced quickly. Within four months of receiving the request for proposal DAS advanced its submission for GOR-78. Computer and wind tunnel testing revealed the basic soundness of the design. Demers Turbines and Lyme and Martens Industries (LMI) collaborated to build the Goblin DFP.1 one-eighth scale uninhabited prototype that confirmed that optimistic initial assessment.
The Goblin DFP.1 uncrewed aerial vehicle (UAV) prototype equipped with two Demers Turbines T73F-DT augmented turbofans flew two months later. Though the test vehicle was just able to attain Mach 3 flight due to lift-induced drag and supersonic stability issues around the target speed, the Goblin enabled DAS engineers to make several airframe – including improved air intakes for sustained high angles of attack (AOA) – and software corrections. After ten months of evaluating the UAV prototype, the first IDP-58 development aircraft (DA1) took flight powered by two IMW ATG-11F (T71F-IM) augmented turbofans similar to those used in the DAS-6 Scimitar.
Patrick Mutahi, DAS’s chief test pilot, stated that the much smaller engines ‘rattled about’ and made the aircraft decidedly underpowered. In spite of these flaws, the third IDP-47 prototype achieved Mach 2 on its sixth flight with a decent power reserve. The flight test engineers resolved a number of problems, including a problem with an over-inflating full-pressure suit and another with the aircrew ejection mechanism, before the second batch of development aircraft (DA5 and DA6) equipped with T78F-IM augmented turbofans entered testing and evaluation. DA5 attained Mach 3 on its fourth flight both it and DA6 fulfilled most of the RINAF’s GOR-78 with the exception of operational intercept radius (928.73 nm or 1720 km rather than the desired 1000 nm), which the engineers remedied with two stations above the wing root for Mach 3+ capable 1500-litre conformal fuel tanks.
Acceptance
DAS presented the first DAS-15 production aircraft, now nicknamed the Tiger after Sarzonia’s national animal, to the 206th Interceptor Squadron (Operational Conversion Unit or OCU) of RINAF’s Central Experimental Test Establishment (CETE) eighteen months after the first flight of the IDP-58. Testing aircrew, composed of pilots with at least three hundred flight hours in the Scimitar and at least one thousand flight hours in fighters and weapons systems operators with a minimum of five hundred flight hours in either the Spectre FGR.4 or Swordfish S.2. Aircrew readily took to the aircraft, praising its tremendous acceleration even when fully loaded, its stable handling, and its good weapons load, and the Tiger enjoyed quick acceptance into Air Defence Command’s operational squadrons.
Structure
Construction
On paper, the DAS-15 Tiger is a relatively conservative high speed design. Sporting a shoulder-mounted delta wing, twin vertical fins, a pair of ramped variable geometry intakes, and petal nozzles, the Tiger would seem to be a product from the 1950s or 1960s instead of the twenty-first century. Closer inspection reveals a much less hidebound and far more adventurous fighter.
Unlike most DAS aircraft, only 4.6% per cent of the Tiger’s empty weight comes from composites. The majority of the weight comes from metal alloys that are more capable of withstanding the high temperatures of sustained Mach 3+ flight such as titanium and nickel alloys (70.5% and 8.6% by weight respectively) and steel (8.2%), with most of the remainder coming from advanced ceramics (6.1%).
Reduced signature
Ordinarily, the large quantity of nickel alloys and steel with their high electromagnetic (EM) signatures would act as a beacon for radar. The Royal Shipyards of Isselmere-Nieland (RSIN) and the Isselmere-Nieland Nuclear Energy Commission (INNEC) both assisted DAS and IMW with their extensive experience working with high-strength, low EM-signature alloys able to bear the incredible stresses the DAS-15 airframe must endure. Pritchard Chemicals and Fabrics, plc (PCF), the UKIN’s foremost dye and paint manufacturers, devised a radar absorbent paint capable of reducing the skin’s radar reflectivity even further. PCF, DAS, and the RINAF tested the paint in several low visibility schemes, managing to craft a coating that can withstand the intense friction and a pattern that minimises the Tiger’s visibility to optical sensors at operational altitudes.
The DAS-15 is a large aircraft and its enormous engines and leading edges produce a noticeable infra-red (IR) signature at high speeds. As the Tiger is intended as a long-range interceptor rather than as a dogfighter where IR missiles and sighting systems pose the greatest threat, the RINAF found the DAS-15’s large potential thermal presence to be an acceptable trade-off for high speed. Even so, DAS and IMW engineers developed systems that would further reduce the aircraft’s visibility to enemy sensors.
For the first time on a DAS aircraft, ionisers are fitted to the wings’ leading edges that positively charge the air in front of the wings both to generate lift by minimising the effect of drag as well as to diffuse radar waves. The additional effects are to reduce the RCS and the IR signature created by the wings.[1] The ionisers, identified by the dielectric panels covering the majority of the leading edge, are most efficient from speeds of Mach 0.65 to Mach 2+, giving the DAS-15 extended range at cruising speeds. The ionisers are powered by the engines’ turbines.
The variable geometry titanium alloy intakes, cooled by argon taken as a by-product from the DAS-15’s atmospheric recovery kit (ARK) that produces oxygen from the air for the aircrew and nitrogen to fill the fuel tanks as they empty to reduce the risk of explosion and to ensure fuel flow in all flight regimes, not only slow the airflow to the engines to the subsonic speeds necessary for compressor operation, but have been designed to minimise radar reflections. The blunted lips on the intake ramps have the dual purpose of improving airflow to the engines whilst deflecting radar waves, lowering the chance of received returns. Baffles in the ceramic-lined engine ducts further reduce airflow speeds and shroud the compressor blades from radar detection.[2]
Intakes and airfoil
Unfortunately, in order for the Tiger to meet the GOR-78 specifications, the engineers had to make design decisions that undermined stealth. The intake and wing design are prime examples of engineers opting for performance over stealth. Considering the high flying nature of IDP-58’s missions, the stealthiest location for the intakes would be above the wing and behind the leading edge, shrouding the radar-reflective variable geometry ramps and fan blades from enemy emitters. Since the intakes would have to be large to admit the volume of air necessary to feed the engines, the wing would need to be mounted low, as on the Dassault Mirage IV bomber.
As an interceptor, the Tiger would have to climb quickly to its operational altitudes. Intakes mounted above a low-mounted wing would require substantial auxiliary intakes to ensure the airflow to the engines at high AOA, necessitating the intakes be placed ahead of the wing leading edge. Since the wing could not hide the intakes, the potential RCS of the IDP-58 rose.
GOR-78 specifications further required that each wing would have to be able to carry at least one large pylon-mounted supersonic 2000-litre external fuel tank. A low-mounted wing would require long landing gear to fit such stores. Since the wing had to be strengthened to cope with both Mach 3+ flight at altitude and supersonic speeds at low level, the main landing gear could not be fitted within the wing, but within the fuselage. Accordingly, the landing gear track for the IDP-58 would be comparatively narrow. To avoid the dangers associated with long narrow landing gear, a high-mounted wing seemed to be the answer.
Stability issues also supported the decision for a high-winged design. Shoulder-mounted wings afford greater stability, with a natural dihedral (raised wing) effect providing lift. Supersonic stability could be improved without having to resort to ventral fins by putting the wing at a slight anhedral (downward angle).
Finally, GOR-78’s recommendation that the aircraft be a mini-AWACS whilst on station pointed to two side-looking radar (SLAR) aerials, one on each intake. The aerials’ scans would be blocked by the large wing if the intakes were mounted above it, but would have an excellent view if the intakes were below. Faced with all of these reasons, DAS engineers equipped the IDP-58 with a shoulder-mounted wing.
The wing itself is peculiar. It outward appearance is an entirely conventional ‘cranked’ or compound delta, with a seventy-degree leading edge root extension (LERX) blending into a sixty-degree sweepback that diminishes to fifty-four degrees at the wingtips. The cranked delta wing prevents airflow separation over the wing thereby lessening drag caused by turbulence. Spanning the length of the leading edge are flaps that improve manoeuvrability by permitting air to circulate freely over the airfoil rather than separating. Two wingtip pods spoil the elegant effect somewhat, a sin mitigated by their importance to the DAS-15’s self-defence, as will be shown below.
As noted above, the Tiger is the first DAS design with ionising leading edges, with the ionisers fitted inside the leading edge flaps. The ionisers generate a negatively charged electrical field that creates a positively charged wavefront of air before the wing that counters drag caused by air friction and turbulence. Combined with the effect of the negatively charged engine exhaust and bypass air emerging from the nozzles, the positively charged air provides increased thrust as well. A slightly higher engine setting than normal is necessary to energise the ionisers, but the lift and thrust benefits outweigh the increased fuel flow, permitting the DAS-15 to fly further than otherwise possible.
The trailing edge flaps are likewise important to the success of the Tiger. Despite the large size of the wing and its low thickness, the engineers decided that during take-offs and landing the IDP-58 would need air siphoned from the engines to blow over and around the trailing edge surface to improve lift. With the ‘blown’ flaps in operation, the DAS-15’s landing speed falls to 135 knots (250 km/h, 155.4 mph), providing the aircrew an additional safety margin.
Along with strong but light titanium alloy wingspars and ceramic supports, powerful ailerons and spoilers give the Tiger decent manoeuvrability in all flight regimes, permitting +7/-3 g instantaneous manoeuvres at supersonic speeds. The ailerons are used primarily for subsonic and low supersonic flight, whilst the spoilers are reserved for both low and high speed manoeuvres. A removable fence situated over the middle of the wing root ensures the minimum of tailfin buffeting and twisting. The conformal fuel tanks (CFT) that fit over the wing root possess a longer but shorter fence that performs the same function.
Like the main wing, the vertical tailfins are angled to stabilise the aircraft at supersonic speeds. The outward canting of the tailfins reduces the RCS by directing radar returns striking the surfaces away from the emitter/receiver.
Both the wing and the vertical tailfins serve as fuel tanks for the DAS-15, storing vast quantities of reserves (about 2800 litres and 200 litres each, respectively) that enable the aircraft to perform very long range intercepts.
Airframe
Aesthetics appear to have taken a distant backseat in the minds of DAS engineers in designing the Tiger, so much so that the DPA-DGA Nomenclature Directorate wondered whether they had chosen an appropriate official nickname. When one goes beyond the image and into the aircraft’s characteristics, however, one quickly sees that the DAS-15 truly conveys both the speed and the power of its flesh and blood cousin.
The long nose of the DAS-15 resembles that of an inverted shark, providing space for a large active electronically scanned array (AESA), the ARU.244 (see Electronics below) as well as part of the forward optronics array. The in-flight refuelling (IFR) probe is sited in the nose as well, positioned to the right of the pilot’s cockpit.
Located just aft of the WSO’s cockpit are the two gaping intakes for the ATG-23F turbofans announcing the beginning of the broad middle and aft sections of the fuselage. These sections contain the ventral weapons bay, the ARU.245 AESA mounted on the forward portion of the angled outside of each intake, and the vast majority of the fuel as well as the massive engines themselves. The angled sides of the aircraft disperse radar waves away from the emitter receiver, but at higher Mach numbers the larger frontal area leads to higher drag. Blending the various components – fuselage, intakes, wing roots, and wings – together lessens drag up to a point, as the Tiger demonstrates. The DAS engineers and the RINAF consider the reduced RCS and the improved scanning arcs for the SLAR arrays worth the increased drag, however.
DAS and the RINAF agreed on another key point, that high performance and maintainability need not be mutually exclusive. Developed from the outset as an operational aircraft rather than as a technology demonstrator, ease of access to the Tiger’s systems is very good. Engines can be quickly extracted and replaced in the field as can line replaceable units (LRU) and shop replaceable units (SRU).
Cockpits
Like most modern aircraft, the DAS-15 has glass cockpits filled with graphical displays rather than traditional steam-gauge analogue instrumentation. The polychromatic active matrix liquid crystal display (PAMLCD) multi-function head-down display (MFHDD) screens in both cockpits have been doped with an anti-glare solution and are also equipped with internal light meters to alter display brightness to suit prevailing conditions. A large AVQ.84 head-up display (HUD) encompasses the pilot’s view forward, whilst the large 48 cm × 44 cm DU-9909/AEQ.269 threat management display (TMD) dominates the WSO’s head-up view. The DU.9909 permits the WSO to co-ordinate air defence assets over a very broad area, with data on the horizontal positions of allied and other forces overlaid over a digital map display.
Aircrew commands operate through a voice command and hands-on-throttle-and-stick (VTAS) man-machine interface (MMI). Direct voice input (DVI) permits the pilot and WSO to choose between displays and sensor modes, facilitates communications between aircraft, as well as many other non-critical functions. The DVI’s present language library is housed in removable data-bricks for each of the aircrew for quick exchange and updating. The library may consist of up to five hundred commands developed in simulator flights and in the course of missions. Voice patterns currently on record in data-bricks for other DAS aircraft may be transferred over to those of the Tiger facilitating pilot and WSO conversion training.
Even so, the cockpits of the DAS-15 are very different than those of current UKINDF fighters. Owing to the high altitude at which the Tiger operates, the aircrew wear full pressure suits developed by Isselmere-Nieland Space Agency (INSA) that protect them from cosmic and ultraviolet radiation and forces of acceleration (g) as well as regulate the aircrew’s temperature and provide an hour of air in event of cockpit depressurisation. The suits may also serve as flotation devices.
Since ejection at Mach 3 by conventional means would be fatal, the pilot and WSO sit within titanium alloy ejection capsules rather than ejection seats. Similar to standard ejections, once the process has begun, the aircrew’s legs and arms are restrained within the capsule’s confines to prevent loss of limb as the escape vehicle’s hood closes. Each capsule has three hours worth of air and is fitted with flotation devices capable of keeping the vehicle atop the waves in conditions up to sea state 5.
Visibility from the cockpit windows in comparison to other DAS fighters is poor. The pilot’s forward windscreen consists of three sturdy temperature-resistant pieces of glass contained within a titanium alloy frame. Both the pilot and WSO have single-piece titanium-framed canopies covering them, providing the pilot external visibility comparable to that in the F-4 Phantom II or MiG-31 Foxhound, further restricted by the escape capsule hoods that overhang the seats. The WSO’s vision is limited to two small side windows to reduce glare on the PAMLCD. To further reduce glare that might hinder reading the displays, both the pilot and the WSO may pull shades over the windows.
Situational awareness in the Tiger is not limited to what can be seen from the cockpit with one’s own eyes. The AVQ.108 helmet mounted display/sight (HMDS), which uses the same symbology as the AVQ.71 HMDS used in most UKINDF aircraft, is connected to the DAS-15’s various sensors permitting both the pilot and the WSO to identify, cue, and prosecute targets in conjunction with the VTAS interface.
Since the demands of high speed flight limit the aircrew’s vision from the cockpits, DAS and IMW co-operated once again to find a solution. The idea came from the L21 series of heavy armoured vehicles. Since sight is severely restricted when operating inside of a main battle tank, IMW engineers equipped that family of land vehicles with a series of vision blocks granting the tank commander and other tank crew members a 360-degree view of their environment. A similar scheme was adopted for the DAS-15, with five vision blocks placed on the aircraft: on the blended spine of the aircraft, on its belly aft of the ventral weapons bay, one in each of the two wingtip pods, and one in the tail pod above and between the engines. Either the pilot or the WSO may use the vision blocks, either conjointly or separately, by depressing a button on the throttles (pilot) or one of the sensor controllers (WSO) and may be displayed on the HMDS or one of the MFHDD. Vision block selection is determined by head position (if displayed on the AVQ.108 HMDS), the position of the depressed button, or by voice command. The transparency, positioning, and size of the display as it appears on the HMDS may be changed by voice command or on the vision block controls on the left-hand side instrument panel.
Performance
Powerplant
The ATG-23F aero-engine is a two-shaft low bypass ratio (LBR) augmented turbofan optimised for high speed, high altitude flight as well as ease of repair and maintenance. It is a modular design consisting of a three-stage fan or low pressure compressor (LPC) and a four-stage high pressure compressor (HPC), of which the first two stages may operate at variable rates. The LPC and HPC are each driven by a single-stage turbine (high pressure turbine (HPT) and low pressure turbine (LPT) respectively). To maximise fuel efficiency, the ATG-23F may vary its total compression ratio (TCR) from between 8-12:1. The low TCR in comparison with the ATG-8F or other modern fighter aero-engines is not as fuel efficient in low speed, low level fleet, but at altitude and speed the ATG-23F comes into its own due to the reduction in ram drag.
Two digital engine control and monitoring units (DECMU) regulate each engine’s LPC and HPC rates and those of the turbines, as well as the positioning of the variable intake guide vanes (VICG), engine temperatures at various points, and fuel burn rates for the engine’s pre-turbine combustor, the interstage turbine combustor (ITC), and reheat wicks. The DECMU ensure the safety of the aircraft and extend the lifetime of the engines markedly.
Future engines
The ATG-23F2 is the planned replacement for the current ATG-23F. The -F2 version offers two-dimensional thrust vectoring nozzles, ITC, and hybrid electric turbine engine (HETE) technology, all of which will drastically improve the DAS-15’s performance and place it among the top high speed fighters in existence today.
Though the Tiger is not intended as a dogfighter, thrust vectoring will confer a reduced RCS as well as improved take-off, climbing, and landing characteristics upon the DAS-15, greatly enhancing its capabilities. Weight savings gained from the substitution of heavier metal components by lighter ceramic equivalents with greater temperature tolerances will more than compensate for the weight penalty incurred by the new nozzles.
ITC – the addition of a supplementary annular combustor located between the HPT and LPT – offers fuel savings and higher thrust ratings especially at speeds greater than Mach 1.2. Combined with post-turbine reheat stages, ITC will give the –F2 engine maximum performance with improved fuel economy.
Even greater weight and resource savings will be made with the introduction of HETE technology. The use of electric joints and drives will reduce the number of parts within each engine as well as size of the reservoirs necessary for engine lubricants. Eventually, the RINAF plans to convert all of its aircraft to all-electric gas turbines, leading to greater efficiencies in resources, maintenance, and operational readiness.
Manoeuvrability
As a high-speed interceptor, the DAS-15 does not have the exceptional manoeuvrability of either the DAS-2 series or the DAS-6 Scimitar. Even so, the Tiger is able to handle instantaneous manoeuvres of up to +7/-3g and sustained manoeuvres of up to +6/-3g at supersonic speeds. At its maximum speed, drag created by air friction, the demands for steady airflow by the engines, and aircrew survivability tend to reduce manoeuvrability markedly to about half the aircraft’s maximum stated values, or about +3.5/-3g.
At lower speeds, the DAS-15 is slightly more spritely. Blown air flaps provide the aircrew with an additional safety margin during landings and other low speed manoeuvres, whilst the leading edge flap reduces airflow separation caused by rapid changes in AOA or quick manoeuvres. Purchasing air services must remember, however, that the DAS-15 is intended as a long-range interceptor, not a dogfighting air superiority fighter like the Scimitar.
Range
The operational range of the DAS-15 without either external tanks or aerial refuelling is an amazing 4200 km, conferring an operational intercept radius of 1720 km. With aerial refuelling, the Tiger’s range is limited only to that of the aircrew.[3]
The DAS-15’s radius of action may be extended with two 1500-litre conformal fuel tanks (CFT) fitted over the wing roots and engine intakes or two 2500-litre external wing tanks. The CFT can endure 9g manoeuvres as well as speeds greater than Mach 3, whilst the jettisonable wing tanks are stressed withstand sustained manoeuvres of up to 6g and speeds greater than Mach 2. Both the external wing tanks and the pylons to which they are connected may be jettisoned before entering combat to reduce RCS and permit increased manoeuvrability and speed.
Electronics
Flight control and operations
The DAS-15 has a quadruplex flight control system that maintains the stability of the aircraft throughout its flight envelope. In conjunction with the autopilot and the threat management system (TMS) that integrates the aircraft’s sensor data with that received through the CSZ.17 secure datalink, the Tiger can perform completely automated intercepts, including landing back at its home airbase after the mission.
This astonishing ability to perform computer-controlled intercepts was successfully proven during systems evaluation when DA5 destroyed a low flying Rook DRA.1 with a GWS.84A Peregrine missile. The RINAF has stated publicly, however, that fully automated intercepts are not within the service’s standard operating procedures (SOP).
Radar
The Tiger has four sets of radar eyes to scan the skies, ground, and waves for potential foes. The main or forward array, the ARU.244 AESA has 3600 transceiver modules able to search and track objects in a 120-degree arc ahead of the aircraft, and +50-degrees/-70-degrees in the vertical plane. The two ARU.245 AESA with 2000 transceiver modules each are located on the forward sides of the intakes perform a similar function with similar scanning arcs along the aircraft’s sides and in the vertical plane. As one might expect, both the ARU.244 and ARU.245 are optimised for look down, shoot down operations, but the aircraft also has a look-up, shoot-up capability as well.
Optronics
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Countermeasures
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Communications
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Displays
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Stores
Air-to-air
- Extended range air-to-air missiles: GWS.84A Peregrine
- Long range air-to-air missiles: GWS.75A Goshawk
- Beyond visual range air-to-air missiles: GWS.74A Kestrel
- Short range air-to-air missiles: GWS.65A Kite (atypical)
Air-to-surface
- Anti-radar missiles: ALARM, HARM, Pigeon, Ptarmigan
- Anti-ship missiles: Heron, Pelican, Petrel
- Bombs: GWS.47A Robin small diameter bombs; 227 kg and 454 kg iron bombs; 227 kg- and 454 kg-type GPS guided bombs; 270 kg and 500 kg laser guided bombs
Countermeasures
- 6 × 30-cell ALE.209 expendable improved countermeasures ejectors
- 2 × 3-cell ALE.212 Cuckoo towed decoys (maximum operational speed: Mach 1.6)
- GDS.94 Flamingo miniature air-launched decoy
- GDS.95 Firefly supersonic air-launched decoy
Characteristics
Type: Interceptor
Crew: 2; pilot and weapons systems operator
Wing geometry: Fixed, delta, at 4-degree anhedral
Inlet geometry: Variable
Dimensions:
Wing: span: 16.12 m; area: 104.41 m2
Fuselage: length: 25.36 m; height: 6.08 m
Weights
Empty: 21380 kg
Clean, equipped: 36091 kg
Operational: 38463.17 kg
Long range intercept: 46518.83 kg
Maximum take-off: 46800 kg
Propulsion: 2 × Isselmere Motor Works ATG-15F
Type: Twin-spool augmented turbofans
Thrust: Military: 13330 kgf (each); maximum reheat: 19200 kgf (each)
Bypass ratio: 0.34
Total compression ratio: 8.5-12
Fan/low pressure compressor (LPC) stages: 3
High pressure compressor (HPC) stages: 4 (first two stages may operate at variable rates)
Performance
Speed: Maximum, clean, at altitude (20 km): Mach 3.32; Maximum operational sustained (see Mission Payloads below), at altitude (20 km): Mach 3.15; Maximum, clean, at service ceiling (24.5 km): Mach 2.8; Maximum cruising speed (MCS), clean, at 20 km: Mach 2.4; Maximum operational cruising speed (MOCS) at 20 km: Mach 2.32; Maximum economical cruising speed (MECS), clean, at 11 km: Mach 1.6; Maximum operational economical cruising speed (MOECS) at 11 km: Mach 1.5; Maximum speed, clean, at sea level (ASL): Mach 1.28; Maximum operational speed ASL: Mach 1.14
Range: Ferry range (maximum fuel): 5120 km (2765 nm); Ferry range (with 2500-litre wing tanks): 4881 km (2636 nm); Ferry range (with 1500-litre conformal fuel tanks): 4665 km (2519 nm); Maximum cruise range (supercruise, internal fuel only): 4200 km (2268 nm); Intercept radius (supercruise with 10 min. combat): 1720 km; Intercept radius (supersonic cruise with 10 min. combat): 1092 km
Service ceilings: Clean: 24.5 km; operational: 24.4 km
Design g-loadings: Instantaneous, clean: +7/-3 g; Sustained, operational: +6/-3 g; High speed, high altitude: +2.25/-2 g
Expendable countermeasures
ALE.209 chaff and flare launchers: 6 × 30-cell ejectors
ALE.212 Cuckoo towed decoys (maximum operable speed: Mach 1.6): 2 × 3-cell launcher
Payload:
Ventral internal weapons bay (4.5 × 3.5 × 1 = 15.75 m3): 1750 kg (2 × GWS.75A Goshawk LRAAM + 2 × GWS.74A Kestrel BVRAAM)
Fuselage conformal/recessed stations (2; 6.1 × 0.34 × 0.16 = 0.332 m3): 800 kg each (GWS.84A Peregrine ERAAM)
Wing-root conformal stations (2): 2000 kg each (1500 litre conformal fuel tanks)
Wing stations: Inboard (2): 3000 kg/rated for 2500 kg stores; outboard (2): 1800 kg/rated for 1500 kg stores[4]
Fuel
Internal tanks: 18050 litres
Fuel fraction: 0.39
Weight: 14060.17 kg (JP4)
Thrust-to-weight ratios
Military: Clean: 0.739; fully loaded: 0.570
Reheat: Clean: 1.064; fully loaded: 0.821
Wing loadings (kg/m2)
Clean: 345.67
Operational: 368.39
Long range intercept: 445.54
Maximum take-off: 448.23
Cost: $125 million
Mission Payloads
Operational: Ventral bay: 2 × GWS.75A + 2 × GWS.74A; fuselage stations: 2 × GWS.84A (total)
Long range intercept: Ventral bay: 2 × GWS.75A + 2 × GWS.74A; fuselage stations: 2 × GWS.84A (total); Inboard wing stations: 2 × 2500 litre tanks (total); Outboard wing stations: 2 × GWS.84A + 2 × ADM.95 Firefly supersonic autonomous decoys[5]
Notes
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