French jet-engine programme
Without doubt the most important French jet-engine programme, the SNECMA (Societe Nationale d'Etude et de Construction de Moteurs d'Aviation) Atar owes its origins to wartime German BMW axial-flow designs.
The SNECMA Atar 101 is a French axial-flow turbojet engine
Atar 101
Used in Dassault Super Mystère fighter-bomber
Atar o8
Two-stage turbine and improved compressor, non-afterburning, developed in 1954-1956.
An Atar 8K50 removed from a Super Etendard, NAS Landivisiau, France
Atar 08B
Used in Dassault Étendard IV
Atar o8K-50
Simplified non-afterburning version of Atar 9K-50 for Dassault Super Étendard
Atar 09
Integrated starter, improved compressor optimized for supersonic flight, afterburner.
Atar 09C
Used in Dassault Mirage III and 5 fighters
Atar09K-10
Improved combustion chamber, turbine blade cooling; used in Dassault Mirage IV bombers
Atar09K-50
improved Atar 9C with a redesigned turbine and upgraded compressor resulting in improved fuel consumption and thrust; used in Dassault Mirage F1 and Mirage 50.
Atar Plus
Joint development with ITP and Denel, new compressor, new turbine, new electronics.
From these SNECMA developed the much-improved Atar 9, with a redesigned compressor and new pattern of two-stage turbine. The Mirage IIIA was powered by the 9B which developed 13,225lb (5,999kg) in full afterburner, but this was replaced in the Mirage IIIC by the slightly more powerful 9B3 version rated at 13,320lb (6,042kg). For all subsequent versions of the Mirage III, Dassault used the Atar 9C rated at 13,670lb (6,200kg). This features a revised compressor with steel blades in the most thermally-stressed stages, a self-contained starter, and an improved overspeed which automatically engages at Mach 1.4 to boost the thrust at high supersonic speeds by up to eight per cent.
In addition to production by SNECMA, the Atar has been built under licence by Commonwealth Aircraft Corporation, Australia (for the Mirage IIIO), Fabrique Nationale, Belgium (for the Mirage 5), and by Sulzer Brothers, Switzerland (for the Mirage IIIs).
The Rolls-Royce Avon 67 turbojet was flight-tested in the Mirage back in February 1961, in the hope that the RAAF might specify this engine for its planned Mirage buy. Australia was already an Avon user, non-afterburning versions of the British engine having been installed in locally-built F-86 Sabres, and the engine offered significant performance. But when the RAAF finally signed for its new fighters, the Atar was specified, and this powerplant was to be used in one form or another for all delta-winged Mirage fighters until the late-1970s Mirage 2000.
Rolls-Royce Avon
It was inevitable that later and more powerful versions of the Atar would find their way into the Mirage III airframe. The Atar 9K-50 was developed for use in the Mirage Fl and 50 (see Mirage Fl entry for full details of this engine), but was also offered in the Mirage III.
The full story of uprated Mirage Ills is buried deep in classified Dassault and French government archives. The first production version of the delta Mirage to offer the Atar 9K-50 was a small batch of Mirage Ills delivered to what Dassault Breguet coyly describes as "a foreign operator already using Mirage III planes, and wishing a combat aircraft with a very high penetration speed".
The "foreign operator" in question was South Africa, which took delivery of these uprated Mirages between 1974 and 1975. Single-seat recce and two-seat trainer versions were designated IIIR2Z and IIID2Z respectively, and it would be surprising if the IIICZ fleet had not been reworked to accept the new engine. The Atar 9K-50 was also selected for the Mirage 50 (see Mirage 5/50 entry), but was to make a reappearance in the Mirage III series with the Mirage IIING flown in 1982.
IAI Kfir used the General Electric J79 instead
The SEPR 844 rocket motor is an optional unit, and replaces one of the internal fuel tanks. It burns red fuming nitric acid (RFNA) oxidiser contained in a tank within the rocket pack, plus aniline fuel carried in a special pack which replaced the DEFA cannon and their ammunition. These propellents are supplied to the engine by pumps driven by a shaft on the Atar, and the motor develops 3,300lb (1,500kg) of thrust.