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PAF s' Specials
The Mirage III/5/50 Family

by Air Cdre (Retd) Kaiser Tufail

“Like a desert vision, so that enemy pilots should see it but never catch up with it.” Thus, Marcel Dassault lyrically interpreted the French Air Staff Requirement (ASR) of 1953 for ‘a lightweight all-weather interceptor, capable of climbing to 18 kilometres in six minutes, with level flight speed of Mach 1.3’. Sud-Ouest’s Trident, Sud-Est’s Durandal and Avions Marcel Dassault’s MD-550 were the three contenders bidding for the contract. The single-seat, tailless delta-winged MD-550 flew for the first time on 25 June 1955, powered by two non-afterburning Armstrong Siddeley Viper turbojets. After some redesign including installation of afterburners and a rocket motor and, reduction of tailfin size, Dassault figured that the aircraft was evocative of his ‘desert vision’ and aptly renamed it Mirage I. While it went Mach 1.3 in level flight with the assistance of a booster rocket motor, it did not have the endurance and, was too small to carry an effective payload. Dassault decided to substantially redesign the aircraft while retaining the tailless delta on an area-ruled (‘wasp-waisted’) fuselage and, enlarging the latter to house a single afterburning SNECMA Atar 101-G turbojet [1]. The prototype Mirage III made its maiden flight on 17 November 1956 with the test pilot Roland Glavany at the controls. The prototype also featured moving inlet shock cones which later helped attain speeds up to Mach 1.8.

When some NATO air forces and Luftwaffe selected the F-104G as the replacement for the F-86 Sabre, it became clear that versatility was the name of the game. The French government accordingly asked Dassault to proceed with a multi-role aircraft. The prototype of this version, the Mirage IIIA, flew on 12 May 1958. On 14 October 1958 it exceeded Mach 2 in level flight at 41,000ft, making it Europe’s first bisonic fighter and, prompting a pre-series production order of 10 aircraft by the French Air Force. These featured a bigger wing and were powered with SNECMA Atar 9B turbojet engine of 13,230-lbs static thrust with a variable (‘eyelids’ type) exhaust; the last six of them were also equipped with the production standard Cyrano I bis airborne intercept (AI) radar.

Mirage IIIC (Chasse – Interceptor)

The first production model of the Mirage series, the Mirage IIIC interceptor first flew in October 1960. It was largely similar to the IIIA, though 18 inches longer and brought up to full operational fit. It was powered by the SNECMA Atar 9B turbojet engine.

The Mirage IIIC was armed with twin 30mm DEFA-552 revolver-type cannon, fitted in the belly with the gun ports under the air intakes. Early production Mirage IIIC had three stores pylons, one under the fuselage and one under each wing, but a second outboard pylon was added to each wing, for a total of five. The outboard pylon was intended to carry a heat-seeking air-to-air missile.

Although provision for the rocket motor was retained, by this time the threat of the Soviet high-altitude bomber seemed to be over, and the booster rocket was rarely fitted in practice. The space for the rocket motor could be used for additional fuel.

Mirage IIICs were procured by the French Air Force, with initial deliveries in July 1961. The type was also exported to Israel and South Africa with one example going to Switzerland as a sample for licensed production.

The Israelis put their Mirage IIIC fighters to particularly good use in the 1967 Arab-Israeli War. This advertisement, and the low cost of the relatively simple and flexible Mirage fighter, helped make it a major French export.

Mirage IIIB (Biplace) was the two-seat version of the Mirage IIIA as well as the IIIC. It was without radar but was suitable for ground attack missions, in addition to training.

Mirage IIIE (Électronique)

While the Mirage IIIC was being put into production, Dassault was also considering an ‘electronically advanced’ all-weather fighter-bomber variant which eventually materialized as the Mirage IIIE. Its prototype flew in April 1961, followed by the first delivery to French Air Force in January 1964.

The Mirage IIIE differed from the IIIC in having a 12-inch forward fuselage extension to increase the size of the avionics bay behind the cockpit. The stretch also helped increase fuel capacity slightly. The Mirage IIIE is powered by an afterburning SNECMA Atar 9C turbojet having a variable (‘flower petals’ type) exhaust with a thrust rating of 13,670-lbs; it retains the rocket motor option.

The Mirage IIIE avionics featured a Thompson-CSF Cyrano II dual-mode (air, ground) radar in the nose and a Marconi Doppler navigation radar under the forward fuselage, the two components being central to the ‘all-weather’ capability. The Cyrano II radar was compatible with the Matra 530 semi-active radar homing missile, one of which could be carried under the fuselage.

A sizeable number of Mirage IIIEs were built for export, being purchased in small quantities by Argentina, Brazil, Lebanon, Pakistan, South Africa, Spain, and Venezuela. Each had its own sub-type and country designation, with minor variations in equipment fit.

Two versions of the Mirage IIIE that were manufactured outside France, under license, were the Australian Mirage IIIO and Swiss Mirage IIIS (both dispensed with the ‘E’ sub-type label and only used the country codes). The Australian version had two further variants, attack and fighter, essentially differing in avionics. The Swiss version had a Hughes TARAN-18 fire control radar compatible with the Hughes Falcon semi-active radar-guided missile.

The equivalent two-seat trainer for the French Air Force was designated as Mirage IIIBE while for the rest of the export customers it came to be known as Mirage IIID (Dual).

Mirage IIIR (Reconnaissance)

The Mirage IIIR reconnaissance variant first flew in November 1961. It retained the twin DEFA 30mm cannon and external stores capability of the Mirage IIIE but instead of the AI radar, it housed five OMERA optical cameras in the nose. Later models (known as Mirage IIIRD in France) had the Doppler navigation system under the forward fuselage similar to the IIIE; these also had the provision for carrying the Cyclope infra-red package.

Mirage 5

The next major variant, the Mirage 5, grew out of a 1966 Israeli Air Force requirement for deletion of avionics (normally stored in a bay behind the cockpit) from the standard Mirage IIIE and replacing it with more fuel storage for the ground attack mission. As a consequence, fuel capacity was increased by 500 litres. When introduced, the Mirage 5 did not feature the Cyrano II AI radar; instead, it had a small Aida II ranging radar in a long, slender nose. Like its predecessors, the Mirage 5 carries twin 30mm DEFA-552 cannon, and can lift a payload of four tonnes (8,800 pounds). It features two more stores pylons, fitted at the rear junctions of the fuselage and wings, for a total of seven stations.

The Israelis had placed an order for 50 Mirage 5 aircraft, the first of which flew in May 1967. Rising tensions in the Mid-East led French President Charles De Gaulle to embargo the Israeli Mirages on the eve of the 1967 War. The aircraft continued to roll off the production line, even though they were embargoed. By 1968, the batch was complete and the Israelis had made final payments but, unable to get the impounded aircraft, they reluctantly accepted a refund. The 50 aircraft eventually found their way into the French Air Force as Mirage 5Fs.

Like the Mirage IIIE, the Mirage 5 was popular with export customers, with different variants sporting a wide range of different avionics. While the Mirage 5 had been originally devised for the clear-weather ground attack role, it was reoriented for the multi-role mission with some avionic fits. As electronic systems became more compact and powerful, it was possible to squeeze the avionics in the nose alongwith the Cyrano II AI radar and Doppler navigation equipment. This variant combined the best of range, payload and electronics and, aptly came to be known as Mirage 5E (Électronique). A Mirage 5 version equipped with the Agave radar, optimised for use with the Exocet AM-39 anti-shipping missile, was also produced.

Reconnaissance and two-seat versions of the Mirage 5 were sold under the designation Mirage 5R, and Mirage 5D respectively. There was no clear dividing line between the configuration of a Mirage III reconnaissance or trainer version and that of a Mirage 5 equivalent, and in fact they were one and the same in many cases. A study of the differences shows that these designations were simply a clever marketing ploy to complete the particular Mirage sub-type package.

The Mirage 5 was sold to Abu Dhabi, Belgium, Colombia, Egypt, Gabon, Libya, Pakistan, Peru, Venezuela, and Zaire, with the usual list of sub-type designations and variations in kit. (Abu Dhabi, Egypt and Libya ordered a mix of the no-frills Mirage 5 and the more capable Mirage 5E, while one of Pakistan's later orders included the Agave radar-equipped Mirage 5 with Exocet missile capability.) The Israelis eventually built their own copy of the Mirage 5 named ‘Nesher’, which was purportedly based on clandestinely obtained blueprints.

At the time of inception of Mirage 5, the experimental Mirage IIIV (three vee) was undergoing flight trials for vertical flight. To avoid confusion, Dassault decided to switch from Roman to the Arabic numeral notation for the new Mirage 5 variant. In the event, it also helped avoid confusion when Venezuela bought the Mirage 5V.

Mirage 50

A fully-equipped prototype rebuilt from a Mirage IIIR flew in May 1970, powered by the uprated SNECMA Atar 9K-50 engine, with 15,900-lbs afterburning thrust. Fit of this engine led to the next Mirage variant, the Mirage 50. The uprated engine gave the Mirage 50 better take-off, climb and acceleration characteristics and, better sustained turn rates than its predecessors.

While the Mirage 50 also incorporated newer avionics, it did not prove popular in export sales, as the first-generation Mirage series was becoming obsolescent and, the new swept-wing Mirage F1 offered better capabilities. Chile ordered a small quantity, receiving both the new Mirage 50 with Agave radar (later replaced by IAI’s Elta 2001 radar), as well as some ex-French Mirage 5s upgraded to Mirage 50 standard. Venezuela also ordered a few Mirage 50 fitted with the improved Cyrano IV radar and AM-39 Exocet missile, while survivors of the earlier Mirage IIIEs and 5s were upgraded to Mirage 50 standard. South Africa’s Atlas Aircraft produced a few Atar 9K-50 engines under license, which formed the basis of the uprated Mirage IIIDZ dual-seaters that came to be known as Cheetah D.

Canard Mirages

While the canard feature on Mirages did not constitute a new sub-type, the modification was sufficiently unique to warrant a separate mention. The canards concept started with the experimental Milan joint French-Swiss programme in 1968, which featured pop-out foreplanes (‘moustaches’) in the nose of a retrofitted Mirage IIIC. The nose foreplanes had been found to serve the purpose of improving take-off performance and low speed control, but also had the disadvantage of causing turbulence inside the air intakes, besides reducing pilots’ downward visibility to some extent.

Fixed canards mounted on the intakes were a feature of the Mirage 3NG (Nouvelle Génération), a variant that did not go into production but came to be a demonstrator of some of the newer technologies like fly-by-wire, when it was rolled out in 1982. These canards served the desired purposes and had none of the aerodynamic vices that had dogged the Milan project. Mirages of Brazil, Chile, Colombia, South Africa, Switzerland and Venezuela sported canards as part of their mid-life upgrade programs.

Production Run

Over 1,400 Mirage III, 5 & 50 were produced by Dassault or manufactured under license by Australia and Switzerland, till production ended in 1992. Besides reasonable price and easy availability, customisation was the key to export success of the first generation Mirage family. Dassault was glad to accommodate changes in equipment as per customer needs and budget requirements. Even whimsical country codes that played, for instance, on the Australian accent, Jewish religion, Libyan environment and Zaire’s egoistic leader were agreed to, if it satisfied the customer!

Country Codes

Argentina – A; Australia – O (‘Oztralia’); Belgium – B; Brazil – BR; Chile – C; Colombia – CO; Egypt – E, SD (cancelled Saudi order); France – F (Mirage-5 only); Gabon – G; Israel – J (‘Jewish’); Lebanon – L; Libya – D (‘Desert’); Pakistan – P (Mirage III), PA (Mirage-5); Peru – P (Mirage-5); South Africa – Z (Zuid Afrika); Spain – E (Espana); Switzerland – S; UAE – AD (Abu Dhabi); Venezuela – V; Zaire – M (‘Mobuto’)

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[1] SNECMA - Société Nationale d'Étude et de Construction de Moteurs d'Aviation (National Company for the Design and Construction of Aviation Engines). ATAR - Atelier Technique Aéronautique Rickenbach (Rickenbach Aeronautics Technical Workshop)
[2] DEFA - Direction des Études et Fabrications d'Armement (Armament Research and Development Directorate)

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Appendix to 'THE MIRAGE III/5/50 FAMILY'

Delta Wing Aerodynamics


Sweep angle of the wing leading edge helps delay drag rise with increase in speed. In a swept wing, the velocity of the airflow normal to the leading edge is reduced by a factor of the cosine of the sweep angle, with a corresponding delay in drag rise. High sweep angles are, however, associated with the problem of wing-tip stalling which results due to the airflow drifting span-wise across the wing, causing the tips to stall before the rest of the wing. The result is usually a violent pitch up followed by a spin. Wing fences and notches are a stop-gap solution as they generate a vortex over the wing which virtually arrests the span-wise airflow.

On a swept wing, the torsional stresses during manoeuvring flight are enormous and indeed, dangerous at high Mach numbers. Greater structural strength can only be obtained by paying a greater weight penalty.

There is one way in which sharp sweep angles can be used without a lot of problems: delta wing. The shape is optimum for high speed flight. The extremely broad chord (average distance between leading and trailing edges) means that a low thickness-to-chord ratio needed for high speed flight can be achieved. The structure can be made rigid, has sufficient volume for fuel and, there are hardly any practical limits to the angle of sweep.

The low aspect ratio (square of the wingspan to wing area) of the delta wing gives excellent supersonic performance by presenting a smaller frontal area to the airflow. At lower speeds, however, the poor lift-drag ratio of the low aspect delta planform demands higher angles of incidence to generate the same amount of lift compared to a conventional wing. This causes greater induced drag resulting in speed bleed-off during manoeuvring flight; it also increases take-off and landing distances. It may be worth noting that the double-delta winged Draken, as well as the Mirage III/5/50, held the dubious distinction of having the lowest (actually worst) aspect ratio of any fighter to date (1.8 and 1.94 respectively), but this record has now been surpassed, surprisingly, by the very modern Tejas (1.75)!

By its very shape, a delta wing has a large area which tends to give a relatively low wing loading (aircraft weight per unit area of lifting surface ie, the wings). This helps offset its poor sustained turn performance and enables it to turn tightly at low speeds – often below its normal landing speed – especially in descending manoeuvres in which it can trade height for energy.

Woes of Tailless Deltas

To date, only a few tailless delta fighters have been produced besides the Mirage III/5/50. These include the F-102 Delta Dagger, F-106 Delta Dart, J-35 Draken, J-37 Viggen, Mirage 2000 and Tejas.

In a tailless delta, lift augmentation devices like trailing edge flaps cannot be installed for want of space (though in the Viggen, these are cleverly placed on the large fixed canards). Also, upgoing elevons diminish wing lift which needs to be compensated by higher take-off and landing speeds, worsening short-field performance. Many a pilot who ended up in the arrester barrier has ruefully wished for a longer runway when confronted with a take-off emergency.

Two modern tailless delta fighters, the Mirage 2000 and Tejas have unstable designs where the centre of gravity is aft of the centre of pressure. The inherent unstable nose-up moment reduces the pitch-up required for take-off or during manoeuvres; the harm done to wing lift by upgoing elevons is, thus, minimised to a considerable extent. Leading edge flaps/slats on these fighters also add to the total lift when they automatically activate at slow speed, thus allowing lower take-off and landing speeds.

Canards acting as control surfaces work essentially like tailed deltas, except that the ‘tails’ are located at the front. They obviate the need for elevons to change the pitch, hence saving precious main wing lift. Modern delta-winged fighters like Chengdu J-10, Eurofighter, Gripen and Rafale have fully active canard controls.

Some of the older Mirage III/5/50, Cheetah and Kfir found a partial remedy to their congenital woes through retrofit of small fixed canards, while the Viggen had fixed canards designed from the outset. These canards added to the overall lift in ways similar to the leading edge flaps/slats, except that they remained stuck out even when not needed in high speed flight!

 
 
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