Snecma Atar

Snecma Atar
Company type	Product line
Industry	Aerospace
Founded	1946
Founder	Hermann Oestrich and former BMW engineers
Headquarters	France, France
Products	Axial-flow turbojet engines (Atar 101, Atar 08, Atar 09, Super Atar)
Parent	Snecma

Template:Infobox Aircraft Engine

The Snecma Atar is a French-designed axial-flow turbojet engine produced by Snecma, originating from the German World War II BMW 018 concept and further developed by engineers formerly with BMW. Its name derives from the Atelier technique aéronautique de Rickenbach (Rickenbach Aeronautical Technical Workshop) located in the French Occupation Zone of Germany. The Atar engine powered several important French post-war aircraft such as the Sud Aviation Vautour, Dassault Étendard IV, Dassault Super Étendard, Dassault Super Mystère, and multiple variants of the Dassault Mirage III.

Background

In early 1945, Hermann Oestrich’s team, initially responsible for the development of the BMW 003 engine, relocated to Stassfurt where production continued covertly despite ongoing Allied bombing campaigns. After the town fell to American forces in April 1945, Oestrich obtained technical documentation which he later transferred to representatives from Pratt & Whitney. Production briefly resumed under US oversight before the territory came under Soviet control.

Oestrich was subsequently moved between Munich and England for interrogation and engineering projects, including work on a turboprop engine for a four-engine transport aircraft. Simultaneously, French intelligence approached him with an offer to pursue further development of the BMW 003 engine in France, having identified BMW 003 units within their occupation zone and aiming to establish domestic manufacturing.

By September 1945, Oestrich accepted this proposal and led a group of roughly 200 former German engineers at the former Dornier facilities in Rickenbach near Switzerland. This team formed the Atelier Technique Aéronautique Rickenbach (ATAR). They reengineered the BMW 003 into what became the ATAR 101 by October and secured a production agreement contingent upon manufacturing taking place in France. In April 1946, a five-year contract was signed with SNECMA that included guaranteed wages and family benefits, with design schematics forwarded to SNECMA for serial production.

ATAR 101

The inaugural complete Atar 101 engine was successfully run on 26 March 1948, achieving thrust by early April and improving to by October. A new turbine constructed from solid high-temperature steel replaced previous air-cooled versions, resulting in enhanced aerodynamic performance and a higher compression ratio. By January 1950, cumulative operating time surpassed 1,000 hours with thrust reaching , making it one of the most powerful engines of its time—significantly exceeding the output of its BMW 003 predecessor, which delivered only .

The ATAR 101B variant introduced Nimonic turbine blades along with extra stator blades to resolve earlier minor issues. It completed a 150-hour endurance test at in February 1951. Flight trials commenced in December 1951 aboard the Dassault Ouragan and continued from March 1952 on a Gloster Meteor F.4. The Atar 101C featured improvements in compressor and combustion chamber design that raised thrust to . The Atar 101D incorporated a larger turbine using advanced high-temperature alloys, increasing exhaust temperature to 1,000 °C and thrust to . This model also introduced an innovative exhaust nozzle equipped with "eyelid" shutters replacing the previous movable cone design.

The Atar 101E added an initial "zeroth" compressor stage that increased overall pressure ratio to 4.8:1 and boosted thrust to , surpassing the anticipated performance of the WWII-era German BMW 018 turbojet. Multiple Atar 101 variants were evaluated across different aircraft platforms.

An afterburner was fitted to the D variant resulting in the Atar 101F with thrust; applying this technology to the E variant produced the ATAR 101G. Flight evaluations on the Dassault Mystère II took place in August 1954; however, these engines were not adopted for production in that model. The first successful production application was on the Dassault Super Mystère, initially flown with Rolls-Royce Avon engines in March 1955 before switching to Atar 101G-powered versions in May 1956. Production commenced in 1957 with an initial order for 370 aircraft, later reduced to 180 due to advancing performance capabilities of the Dassault Mirage III.

Atar 08 and 09

By 1954, as the Atar 101 reached the lower threshold of its power capabilities, SNECMA introduced the Atar 08 as a major enhancement. Although its size remained largely unchanged, it incorporated a nine-stage compressor replacing the earlier seven-stage design, driven by a more compact two-stage turbine. Notable advancements included a compressor rotor crafted from magnesium alloy. The Atar 08 B-3 delivered thrust and improved the overall pressure ratio to 5.5:1.

The Atar 09 featured an upgraded afterburner, initially tested in January 1957 at , with thrust soon increased to . The 09C variant added an eighteen-flap nozzle along with a new Microturbo starter in December 1959. The Atar 9D was equipped with titanium components in its exhaust and afterburner sections, enabling continuous operation at Mach 2, compared to Mach 1.4 for the 09C. The Atar 9K reintroduced air cooling technology, enhancing both performance and fuel economy.

The Atar series 8 and 9 represented ten years of development that culminated in a widely produced engine powering numerous aircraft such as the Étendard and Super Étendard strike fighters, Mirage III, Mirage 5, Mirage F1 fighters, Mirage IV bomber, and several experimental platforms.

Super Atar

In response to French government initiatives aimed at achieving Mach 3 speeds during 1955, SNECMA explored an engine derived from the Atar 101 compressor but substituted steel for light alloys to withstand elevated operating temperatures. This change required an air-cooled turbine similar to those used in early prototypes. The resulting M.26 engine ran for the first time in May 1957, delivering 47 kN without afterburner; it was followed by the improved M.28 in September 1958 producing 52 kN.

These advancements paved the way for the Super Atar, which offered an afterburning thrust of 85 kN and incorporated variable stators—a feature that soon became standard across the industry. Despite this progress, the related test aircraft project (the Griffon III) was canceled, leading SNECMA to discontinue Super Atar development by 1960.

Other developments

The Atar design also served as the foundation for related engines such as the larger R.104 Vulcain and smaller R.105 Vesta, both developed in the early 1950s for distinct purposes—the Vulcain intended for the Mystère IV D fighter and the Vesta aimed at various roles. Neither engine reached production: the Mystère IV D program was canceled, and the Vesta lost out to the Turboméca Gabizo, which itself was eventually abandoned.

Description

The initial Atar 101 incorporated a seven-stage axial compressor featuring aluminum alloy blades mounted on an aluminum rotor. Its front bearing was supported by four vanes, one of which housed a power takeoff shaft. A unique characteristic was the separate Atar 5000 accessories section positioned at the front and driven via an extension shaft. The combustion chamber consisted of twenty steel flame cans arranged in a "canular" configuration feeding a single-stage turbine. Early versions measured 2.85 m in length with a diameter of 0.9 m and weighed approximately 850 kg; later C models extended to 3.68 m and weighed about 940 kg. Versions equipped with afterburners increased in length to 5.23 m, with weights ranging between 925 and 1,240 kg depending on the variant.

The Atar series 8 and 9 adopted a nine-stage compressor similar to that of the Atar 101 but introduced a steel first stage to improve resistance against foreign object damage. Their turbines featured two stages. The overall dimensions remained comparable to those of the Atar 101, while weight increased up to around 1,350 kg for the 9B model.

Variants

Atar 101B
Atar 101C
Atar 101D
Atar 101E
Atar 101F
Atar 101G

Equipped on the Dassault Super Mystère fighter-bomber

Atar 08: Two-stage turbine combined with an enhanced compressor, non-afterburning design, developed during 1954–1956.

Atar 08B: Installed in the Dassault Étendard IV
Atar 08C
Atar 08K-50: Streamlined non-afterburning variant of the Atar 9K-50, utilized by the Dassault Super Étendard
Atar 09: Features an integrated starter, compressor optimized for supersonic performance, and an afterburner.
Atar 09B
Atar 09B3
Atar 09C: Powerplant for Dassault Mirage III and Mirage 5 fighter aircraft
Atar 09C3
Atar 09C5
Atar09K-10: Enhanced combustion chamber and turbine blade cooling system; applied in Dassault Mirage IV bombers
Atar09K-50: An upgraded Atar 9C featuring a redesigned turbine and compressor improvements aimed at better fuel efficiency and thrust output; deployed in Dassault Mirage F1, Mirage 50, and Atlas Cheetah.
Atar Plus: South Africa’s adaptation of the Atar09K-50, incorporating updated compressor, turbine, and electronic systems.

Applications

Bibliography

External links

A site about some ATAR aircraft projects