A Bill Sweetman article about the Rafale. Obviously a bit old but some parts are still very interesting and it was never posted here, so ...
http://direct.bl.uk/bld/PlaceOrder.d...m=searchenginePragmatic Rafale: A study in French philosophy
Bill Sweetman - Jane's Information Group - 2005
Dassault's Rafale fighter was formally declared operational with its first user, Flotille 12F of the French Navy's Aeronaval, one year ago (2004). The second and larger customer for the fighter, the French Air Force, has taken delivery of five operational-standard aircraft at Mont-de-Marsan and will receive nine more this year, as the final assembly line at Merignac, near Bordeaux, gradually speeds up. The Armee de l'Air (AdlA) should start forming its first squadron - Escadrille de Chasse 1/7, around the end of the year, at St Dizier. A French government order for 59 Rafales, announced in December 2004, brings
total orders to 120 aircraft, for delivery by the end of 2011: 82 for the AdlA and 38 for the navy. The Rafale team has been under contract since February 2004 to develop the definitive operational version of the fighter, known as Standard F3, which is due to be operational in 2008. (The navy-only F1 is in service and aircraft are now being delivered to the F2 standard.)
At Dassault's flight test centre at Istres, four Rafales are completing the last F2 tests and are transitioning to support for the F3 programme. The French government's official intention is still to acquire 294 Rafales, replacing literally every fixed-wing combat aircraft in the AdlA and Aeronaval.
Dassault people were as surprised as everyone else when Singapore dropped the Typhoon from its short list of new fighters, leaving the contest as a titanic grudge match between the Rafale and the Boeing F-15T Eagle: a grudge match, because Dassault is still bitterly convinced that it was nothing except US political pressure, overt and covert, that threw the South Korean contest to Boeing. The motive for the decision to eliminate Typhoon is still unknown (although reports suggest that Eurofighter was unable to guarantee a multi-role configuration in time), and Dassault is respecting Singapore's request that contractors refrain from commenting on the contest.
The company says that the current 294-aircraft programme can be carried out profitably without export orders, within the planned EUR31 billion (US$40 billion) budget. Dassault's chief executive officer and chairman Charles Edelstenne has stated that the 294 Rafales will cost less than Germany's 184 Typhoons, developed through Tranche 2. What makes this claim believable is that the Rafale team is a visibly lean organisation. An unusual feature, that appears to work well, is that Dassault and Thales are effectively co-prime contractors, with Thales responsible for the large and critical avionics sector.
There is one final assembly facility, its overheads shared with Dassault's business jet business. Dassault itself is a low-overhead company that does not build ships or airliners. Flight testing is centralised at Dassault's Istres base, which is co-located with the French defence ministry's flight test organisation, the Centre d'Essais en Vol (CEV). Unlike Eurofighter the left and right wings will be built in the same place.
To reduce development costs, the programme adopts two key philosophies. One of these is 'do it well and do it first-shot'. The idea is to invest in ground testing and computer simulation so that an expensive flight test does not have to be repeated. The other is 'know where to stop'. There are service representatives at every level of testing, and the team constantly reviews results and decides - for example - when 90 or 95 per cent of a specification is adequate for the user's needs. "The last few per cent can cost a huge amount of money," comments Pierre-Cyril Delanglade, Rafale director at Dassault's flight test centre.
As an exchange student in France, the writer rode in both a Citroen DS19 and a 2CV and visited Le Mans' cathedral. French engineers, it was apparent, don't solve problems in quite the same way as a German or a British engineer would. Rafale is no exception, with important and unique features that are not always acknowledged.
For example: Rafale is not a large aircraft - it is smaller and less powerful than the Typhoon or the Super Hornet - but it is designed to carry an enormous external payload. Rafale has an operating empty weight of around 10 t, and has a maximum take-off weight 24.5 t. Without fuel or weapons, a Rafale weighs only 1.5 t more than an F-16C, but it can take off 4.5 t heavier. This allows Rafale to carry as much as 9.5 t of external stores in addition to 4.1 t of internal fuel.
Three 2,000 litre fuel tanks, two MBDA SCALP stand-off missiles and six MBDA MICA (Missile d'Interception et Combat Aerien) air-to-air missiles (AAMs) are a standard load-out, tested and qualified to 5.5 g and 600 kt. The Rafale cockpit uses touchscreens and the so-called head-level display (HLD), neither of which is found on any non-French aircraft. It is also apparent that the Rafale reflects an integrated approach to electronic warfare (EW) and low-observable (LO) technology that likewise has no exact parallel anywhere else.
Analysing Rafale's uniqueness starts with the aerodynamic and structural configuration. It is a compact aircraft, designed to have a small spot factor on an aircraft carrier without the complexity of folding wings: in fact, the carrier-imposed limit on weight was a factor in France's decision to sponsor its own fighter programme in the mid-1980s, rather than join Eurofighter.
Another difference of opinion concerned the canard layout. With a foreplane directly in front of the wing - a configuration which evolved from the Mirage 2000 via the experimental Mirage 4000 - the Rafale is less naturally unstable than the Typhoon. Although the Rafale's cleared flight envelope has a lower limit of 150 kt, the fighter has been tested down to zero airspeed and can recover except in extreme load conditions (such as with a heavy asymmetric load), so unlike Typhoon it does not need a system that prevents the pilot from getting into such a situation. Rafale may not be quite as agile at supersonic speeds as Typhoon, but the development of the flight control system has been less traumatic.
Another important feature, relative to Typhoon, is the main landing gear, which resembles that of the F/A-18, in that it has a complex articulation but retracts into a small space under the wing-body junction. This leaves the centreline and inboard wings free for heavy stores. Dassault's expertise in computer-aided design (CAD) is a matter of record: the Catia series of design tools, developed by subsidiary Dassault Systemes, is a world standard and is used by Boeing and Lockheed Martin. These tools were refined and deployed in the process of designing the shipboard and land-based versions of the Rafale.
The navy's Rafale M is rugged enough (the nose landing gear alone is of adolescent-oak-tree proportions) to survive botched landings that cause the airframe to deflect like a skyscraper in an earthquake; the land-based version, though, carries virtually no weight penalty as a result, while the differences are concentrated in the smallest possible number of parts. In fact, the concept of cousin parts used on the Joint Strike Fighter (JSF) -parts which carry different loads but which are produced on the same tools and assembled in the same way - was originated on Rafale.
Rafale's Low Observable (LO) design is unique. Compared with the normal US approach to LO, Dassault starts at the opposite end of the process, beginning with details and working towards the whole. The most important tool is not the outdoor radar cross-section (RCS) range or a large far-field indoor range, which gathers a global RCS picture, but a relatively small anechoic chamber that builds up the RCS from detailed measurements of each part of the aircraft. The result is that the dominant signature in any given frequency band or aspect can be treated until the desired performance is obtained. "We know what is important and which component is contributing to the RCS," says Delanglade. "Is it the missile, or is it the fin? We know which antenna has to be treated."
Visible LO-related features include appliqué coatings, with saw-toothed edges, along the trailing edges of the wing and canard, and on the landing gear doors. The oblique pylon that carries the fixed in-flight refuelling probe bears a close and non-coincidental resemblance to the pylon of an RCS range. The muzzle of the 30 mm GIAT Industries 30M791 revolver cannon is concealed by a frangible cover.
Rafale is not JSF - the all-aspect RCS is clearly higher than that of a JSF in clean configuration - but it uses LO in conjunction with both conventional and novel EW techniques, together with terrain masking and passive detection systems, to accomplish what Dassault refers to as 'discretion'. There is also room for improvement if required: early in the programme, work was carried out on a Rafale D (discret) version adding further RCS-reduction features such as shrouded weapons, and development work continues on other features such as a plasma screen to conceal the radar antenna.
Avionics and weapons, however, are the focus of current development efforts - which is why Thales is Dassault's leading partner on the programme. (Snecma is the other principal member of the Rafale team, but plans for a more powerful M88-3 engine have been put on hold for budgetary reasons.) Rafale features a high level of sensor fusion, based on the fighter's central computers, and the fundamental difference between the F1 and F2 configurations is that the latter has the new Thales Modular Data Processing Unit (MDPU). Using commercial off-the-shelf (COTS) PowerPC chips, the MDPU replaces six line-replaceable units (LRUs) on the F1 version and is more powerful, supporting sensor fusion and providing a dramatic improvement in post-failure effectiveness.
Supporting avionics development are two flying test-beds - one for the Thales RBE2 radar and one for the Spectra EW system - anechoic chambers and austere hardware-in-the-loop test laboratories at Istres. The laboratories are designed so that each piece of actual aircraft hardware can be replaced by a PC-based computer simulation. For instance, a radar test may be more effective, and carried out more easily, if EW system inputs are simulated.
The Rafale is the first multi-role fighter to become operational with an electronically steered antenna (ESA). The Rafale ESA is passive: it has a single-chain exciter-receiver and travelling wave tube (TWT) amplifier, like a classic radar, but the beam is steered by two 'lenses', one working in elevation and the other in azimuth. The decision to use a passive ESA reflected a belief that an active ESA was a high-risk development and would not be ready in time, combined with the value of the ESA's instantaneous beam steering. Operationally, the principal advantage of the ESA over a classic radar is what the Rafale team calls 'track here while scan there'. With its agile beam, the radar can track airborne targets while searching for ground targets or supporting terrain-following. It is more robust against the classic split manoeuvre, in which the outer units of a four-ship group break left and right to escape from the fighter's search volume. The radar can continue to search for new targets while guiding four MICAs on to separate targets.
The F1 standard Rafale in service today has a full set of air-to-air modes, real-beam ground mapping and Doppler beam sharpening (DBS) mapping, together with an early terrain-following mode. F2 is similar, but adds full terrain-following and terrain avoidance, and sea search, while F3 brings on a high-resolution synthetic aperture radar (SAR) mode and sea target tracking. Rafale people like to joke that the competition between the Thales radar team and the same company's optronics division leads to higher performance from both. The frontal sector optronics (FSO) system becomes operational with F2. Principally dedicated to air-to-air combat and physically integrated with the radar, the FSO combines a turreted infrared (IR) search and track (IRST) unit with a video tracker and, under a greenhouse enclosure on the left side of the nose, a laser rangefinder. The range of the IRST is classified but is similar to that of the radar, according to Thales. It is also more precise and completely passive, and has a wider field of regard than the radar. If the target is within the rangefinder's envelope, the IRST can provide a three-dimensional track to the cockpit display and the fire-control system.
The video system provides target identification beyond the range of the unaided eye - extremely useful if rules of engagement demand positive identification - and target tracking within its range envelope. Videotape from the Rafale sensor, acquired in a NATO exercise, shows an F-16 turning, burning and dropping chaff in an attempt to shake the Rafale, with no effect whatever on the autotracker. One potential improvement is a switch to a day-night sensor. The laser improves gunnery accuracy: the standard burst from the cannon is only 21 rounds. Development of the Spectra EW system is also nearly complete, according to Philippe Ramstein, Rafale project director at Thales Airborne Systems. F2 includes almost all Spectra functions, except for a few that are still being tested. Spectra is a complete system that combines radar detection, analysis and jamming, laser warning, and automatic control of decoys. The radar detection function also provides targeting information to the weapon system, helping to detect and identify threats at long range.
The radio-frequency (RF) element of Spectra is both sophisticated and simple, says Ramstein, because it is all-digital. While analogue RF systems contain components that are physically sized to match their operating waveband, digital systems are inherently wideband. For example, while the F-15's ALQ-135 jamming system has separate low-band and high-band jammers, Spectra has one set of receiver and transmitter antennas covering all threats. It also has interferometric receiver antennas (the large flat plates located on the inlet ducts) which measure angle of arrival with 0.5º accuracy, and phased-array transmitters that generate correspondingly narrow (and therefore intense) jamming beams. Incoming signals are stored on digital RF memory (DRFM) chips, analysed and compared with an onboard library to determine the best jamming technique.
Since 1997, when a Dassault engineer made an indiscreet reference to "stealthy jamming techniques that render the aircraft invisible", there has been speculation that Spectra incorporates active cancellation, a sophisticated EW technique in which the aircraft transmits a signal that exactly imitates the aircraft's radar return - but one half-wavelength out of phase, so that the radar sees nothing at all and there is no sign that it is being jammed. (It has been suggested that the B-2 was designed to incorporate active cancellation, but that the system was cancelled because it could not be made to work.) Ramstein's response: "I wouldn't know anything about that." But he points out that Spectra's primary features - speed and precision - would support such a technique if it was used. Active cancellation - like other jamming techniques - also takes less power on a reduced-RCS aircraft like Rafale.
Another element of discretion is terrain following and terrain avoidance (TF/TA), used on the logical grounds that the best radar can't detect Rafale if there is a million tons of rock in the way. The distinction between TF and TA is that the former is primarily two-dimensional, directing the aircraft up and down along a predetermined track, while TA defines a three- dimensional course that takes best advantage of ridges and contours to mask the aircraft.
Rafale uses two sources for TF/TA. The first is a combination of inertial and terrain-referenced navigation (TRN) data which provides metre-class accuracy over a global terrain database. The second, incorporated under F2, adds the RBE2, providing a wide-angle map of areas where the database may be unavailable, unreliable or outdated. "In Saudi Arabia, the terrain changes constantly," comments Dassault pilot advisor Jean Camus. Add TF/TA to the Rafale's agility with a heavy load and the result is impressive. "When we fly at 300 ft and 90º of bank at 550 kt and the pilot has his hands off the controls, we get some interesting reactions from foreign evaluation pilots," says Camus.
Using the radar in TF/TA is one example of sensor fusion, but the essence of sensor fusion is to combine the best information from each sensor in a single track file for each target. For instance, the radar may have the best range and velocity data, the IRST may have the most accurate angular measurement and Spectra may identify the target if it emits. The challenge is to do this without seeing one target as two or two targets as one. Sensor fusion comes on board with the F2 standard.
Fusion comes together in the cockpit, which - once again - does not look quite like any other fighter cockpit. It is cosy, in typical Dassault style, and the pilot's field-of-view (FOV) is dominated by a wide FOV head-up display and the unique HLD. The latter is a high-definition full-colour LCD screen, viewed through an optical chain that presents it collimated at infinity, with the same FOV as the HUD. The cockpit is laid out so that the coaming which separates the HUD from the HLD is on the pilot's eye-line,
while the HLD projects from the panel so that the viewing panel is close to the pilot's face.
Visually, the effect is of a very large, bright and clear display (it looks large because it is almost literally at the end of your nose) and the pilot can glance between the HLD and the HUD with an eye movement, without having to re-focus. The HLD can be used for a detailed tactical situation display, for a map or for video from the FSO.
The Rafale's 13 cm-square touch-screen displays, located on either side of the HLD, make more space for glass by eliminating the push-button around the bezel. Other designers have avoided touch-screens because they are seen as too hard to use in turbulence or manoeuvring flight. Dassault and Thales have developed their own screens that provide tactile feedback - the screen clicks and moves when pushed - and allow the pilot to brace his arm. Special silk-lined gloves include seamless fingertips and a chamois back to wipe any hand-prints off the screen. A similar touch-panel allows the pilot to interact with the HLD.
A helmet-mounted display (HMD) is due to arrive with F3. Earlier in the programme, this was supposed to be Thales' futuristic TopSight, but Sagem was selected as the supplier in late 2003. The Gerfaut HMD is a variant of the Denel Archer helmet family, using an optical tracking system. A digital voice input system has been developed, but not adopted by the customer.
Weaponry is a major focus of current Rafale testing. F1, fielded as early as possible to replace the navy's vintage F-8E Crusaders, has an interim weapons fit comprising the RF version of MICA and the long-serving Magic short-range AAM. F2 adds three new weapons. One of these, SCALP, is essentially the twin to the MBDA Storm Shadow cruise missile, described in some detail in IDR 5/2005, pp45-51. SCALP testing has been completed and included a double firing and a 'global' end-to-end test in December 2004 (see IDR 03/05, p19 and IDR 01/05, p4).
The second air-to-surface weapon under F2 is Sagem's Armement Air-Sol Modulaire (AASM). With a maximum weight of 340 kg, AASM combines a standard bomb body with a tail kit that incorporates a small rocket booster and a nose section with steerable canard fins. The nose section incorporates either a GPS/inertial guidance system (the so-called decametric version) or a GPS/inertial system plus an imaging IR seeker, for metric-range accuracy. The IR seeker can be programmed before launch with a template of the target derived from reconnaissance imagery. This, according to Sagem, makes the AASM less susceptible to GPS jamming or outages than most weapons in its class. With rocket boost, the weapon has a maximum range of 50 km. Rafale carries a maximum load of six AASMs, on newly developed triple racks produced by Rafaut. The AASM carriage and release envelope has been cleared to Mach 0.9 and 680 kt. Nine weapons have been released and the first guided tests are due later this year, followed by service entry in 2006. The French government plans to acquire 3,000 AASMs.
Tests of the IR version of MICA from Rafale have also been completed, including a shot against a rapidly manoeuvring target that led to a direct hit and kill, even without a warhead. In a high-off-boresight mode, MICA works with the IRST to get the seeker locked on before launch, outside the radar's FOV. Under F3, Rafale is expected to exploit a unique feature of MICA IR - its combination of an imaging IR seeker with mid-course guidance, using inertial navigation coupled with a datalink - to hit targets beyond either visual or seeker range without any radar emissions.
Two specialised weapons in the basic Rafale programme, added under F3, are the AM39 Exocet anti-ship missile and the MBDA ASMP-A nuclear-tipped supersonic-cruise ramjet missile. These respectively allow the Rafale to replace the navy's veteran Super Etendards and the AdlA's nuclear-capable Mirage 2000N. The ASMP-A uses a new ramjet engine which increases the missile's range from 300 km to 500 km, and will be armed with a longer-life warhead that will also be fitted to new French sea-launched missiles. Airborne firings start this year, following the successful launch of an inert weapon late in 2004. Rounding out the F3 arsenal is the GBU-12 laser-guided bomb, which is accompanied by the Thales Damocles targeting pod. Already in service in the
Super Etendard and the United Arab Emirates' Mirage 2000-9, Damocles complements the FSO: it has larger, third-generation mid-IR optics and greater effective range, it incorporates a laser designator and its field of regard beneath the aircraft is unrestricted. One open decision is whether to incorporate a fixed navigation FLIR in the Damocles pod for Rafale, feeding imagery to the HUD.
Damocles is a candidate for active imaging technology, the subject of a Thales demonstration programme that should lead to a prototype test next year. This uses a laser to illuminate the ground rather than relying on ambient IR energy, and operates in the 1-micron band. It is expected to provide a substantial improvement in image quality.
The final F3 payload is the Thales Reco-NG (reconnaissance nouvelle generation) reconnaissance pod. Designed to cover the full spectrum of reconnaissance missions, from low to high altitude, the Reco-NG pod has an oblique optical chain in a rotating nose, for horizon-to-horizon coverage, and incorporates both a near-IR charge-coupled device (CCD) sensor and a mid-wave-IR focal plane array (FPA). The pod also carries an IR line-scanner for low-level reconnaissance, a high-capacity recorder and a datalink capable of real-time reconnaissance. It is being delivered with a ground-based management and exploitation system.
The first cadre of AdlA Rafale pilots is working up at Mont-de-Marsan in southern France. In French practice, the first squadron leads an experimentation phase - which translates to 'gaining experience' - once the aircraft is fully service-qualified, which should happen for the F2 in early 2006. It will be a major exercise, since the Rafale is the first true multi-role fighter in the AdlA: Mirage 2000 units have been assigned to fighter, attack and nuclear missions, but with specially configured versions of the aircraft.
Dassault calls the Rafale a polyvalent or omnirole aircraft because it not only flies many different missions, but can fly them at the same time: it carries a full load of AAMs, even with SCALP or AASM on board. This complexity explains why 139 of the AdlA's 234 Rafales are expected to be two-seat B models. "Every mission is possible with one pilot," Air Force programme manager Commandant Cyrille Duvivier remarked at a conference in 2004, "but four hands and two heads are better." And crews will be trained with complementary skills. On the other hand, navy plans to acquire a two-seat Rafale BM version have been cancelled to save money. Offsetting the complexity of the mission, Dassault contends, is the ease of flying the basic aircraft, which extends from an automated two-click engine start, through fully automatic fuel management, to an in-development system that permits bad-weather landings, using GPS guidance, by aiming a velocity vector on the HUD at the end of the runway. "It's like driving your car," says Camus, noting that the navy has already been able to reduce the flying hours devoted to night carrier qualification. Of the complete system, he says: "It's a Game Boy." The AdlA's goal, in the near future, is to start converting pilots on to the Rafale straight out of their initial training. So far, there is only one firm plan for the Rafale beyond F3: the incorporation of the MBDA Meteor long-range AAM. A more powerful M88-3 engine has been designed, but is on hold, as is a gross weight increase and the use of conformal tanks. "We ask people whether they want thrust or performance," says Camus. "Unless you're flying in high mountains with heavy loads, you don't need it."
There are no specific plans for an F4 standard, rather, Thales believes that it has established a plug-and-play baseline that will accept faster processors and more acute sensors as they appear. This is how Rafale will acquire an active electronically scanned array (AESA) radar - if that happens, which for the moment appears to depend on the outcome in Singapore.
In fact, an AESA flew on Rafale in May 2003. According to Ramstein, a migration to AESA has been considered from the early days of the programme, and the RBE2 is designed so that an AESA front end can replace the current passive antenna and TWT. Power and cooling are adequate for the job. A programme called Demonstrateur de Radar a l'Antenne Active (DRAA) started in 2000, and the radar flew on a Falcon in late 2002 before flying in Rafale B301. "It was a difficult integration, taking two or three days," jokes Ramstein. The problem, however, is that DRAA relied on US-sourced high-power processing chips - which, after Korea and the Iraq war, no longer seemed like a good idea. A new AESA version of the RBE2, DRAAMA (DRAA modes avancées), using all-European technology, was launched in July 2004 and will be ready in 2007-08. "We have a firm commitment to AESA, which allows us to propose it for export," Ramstein says.
However, Dassault and Thales are not proposing to make the AESA the all-encompassing RF Cuisinart that Boeing (for example) envisages for the Super Hornet, with features such as passive detection, multi-beam operation and jamming. Nor does the team intend to exploit the AESA's wide bandwidth, which would mean a new radome. (This suggests that the current radome is a bandpass design, transparent at the RBE2 frequency but stealthily reflective at any other.) Rather, the approach is to minimise cost and risk by keeping the same modes as the RBE2, while harvesting what are seen as the most valuable advantages of the AESA. These include a 50 per cent-plus increase in detection range - a better match for Meteor - much better performance at the edges of the elevation and bearing envelope, better reliability through the elimination of single-point failures and lower through-life costs. With only 120 aircraft planned by 2012, the pace of the Rafale programme has been influenced more by budget considerations than by technology. Aside from Singapore, Greece and possibly Saudi Arabia, there are - for the moment - few potential export customers for the fighter, and nothing except some unexpected problems with JSF is likely to change that in the long term. But with its unique balance of high performance, heavy load and stealth, Rafale appears to be far ahead of most of the new generation in terms of maturity, and is positioned to take advantage of any new opportunities.