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Snecma Atar
The Snecma Atar is a French axial-flow turbojet engine built by Snecma. It was derived from the German World War II BMW 018 design, and developed by ex-BMW engineers through a progression of more powerful models. The name is derived from its original design group, Atelier technique aéronautique de Rickenbach (Rickenbach Aeronautical Technical Workshop) near Lindau within the French Occupation Zone of Germany. The Atar powered many of the French post-war jet aircraft, including the Vautour, Étendard and Super Étendard, Super Mystère and several models of the Mirage.
Hermann Oestrich's team in charge of the development of the BMW 003 engine had moved to the town of Stassfurt, near Magdeburg, in February 1945. An underground production factory was being set up in a salt mine outside town by C.G. Rheinhardt in a desperate attempt to continue engine production in face of the now overwhelming Allied air campaign. This mine is well known historically as it was also being used for the storage of uranium compounds as part of the Nazi atomic bomb program.
The town of Stassfurt surrendered to US forces on 12 April 1945, and Oestrich hid much of the technical data in a local cemetery. The next day a ten-man team made up primarily of engineers from Pratt & Whitney arrived, and he handed the data over to them. Production restarted for US use while the war ground to a close, and the US forces cleared out the factory while they waited to turn the area over to the Soviets.
Oestrich had by this time moved to Munich for further interrogation, and from there to England at the request of British engine designer Roy Fedden. He had them work on the design of a turboprop engine for a proposed C-54 Skymaster-class four-engine transport. While working on this design, Oestrich was secretly approached by French DGER agents with an offer to take up further design of the 003 in France. The French forces had found a number of BMW 003 turbojet engines in their occupation zone after the war, and were interested in setting up a production line. These discussions had not progressed very far when Oestrich was allowed to return to Munich, only to be brought back to England in late August, then returned to Munich again where the US offered him and a hand-selected team jobs in the US, but without their families.
Oestrich instead accepted the French invitation, and by September had been set up at the former Dornier factories in Rickenbach in the French Zone, close to the northern border of Switzerland. Here they were soon joined by other former BMW engineers, as well as those from a number of other German firms, bringing the team to about 200 members. The group was named the Atelier Technique Aéronautique Rickenbach (Rickenbach Aeronautical Technical Workshop), or ATAR. They had re-engineered the 003 design as the ATAR 101 (model R.101) by October, and granted a production contract on the proviso that actual production would be carried out in France. In January a further five-year contract was offered to the entire team, including protected wages, provisions for their families, few travel restrictions, and the possibility of French citizenship. The contract was signed on 25 April 1946, and the drawings for the ATAR 101 were sent to SNECMA for production.
The first engine took some time to assemble. The first parts were available as early as May 1946, but a complete compressor or turbine was not ready until the middle of the next year. The first complete engine finally ran on 26 March 1948. By April 5 it had been brought up to 16,000 N (3,600 lbf) thrust and was continually improved until it reached 21,600 N (4,900 lbf) by October. During this time a new turbine made of solid high-temperature steels replaced the earlier air-cooled models, allowing for better aerodynamic shaping and an improved compression ratio. By January 1950 several additional engines had joined the program, bringing the total running time to over 1,000 hours, and a thrust of 26,490 N (5,960 lbf), making it among the most powerful engines of the era. The BMW 003 that it was developed from provided only 7,800 N (1,800 lbf), less than a third of the Atar.
The ATAR 101B introduced Nimonic turbine blades and more stator blades as well as a number of changes to fix minor problems seen in the earlier experimental models. The first B model passed a 150-hour endurance test in February 1951 at 23,500 N (5,300 lbf). A flight test followed on 5 December 1951 in the Dassault Ouragan, and starting on 27 March 1952, under the wings of a Gloster Meteor F.4. After delivering the initial production run of B models, the Atar 101C used an improved compressor and combustion chamber, raising the thrust to 27,400 N (6,200 lbf). The Atar 101D featured a slightly larger turbine with new high-temperature alloys that allowed the exit temperature to rise to 1,000 °C and the thrust to 29,420 N (6,610 lbf). The D model also included a new exhaust consisting of a long pipe ending in a nozzle with two "eyelid" shutters in place of the earlier fore/aft moving cone on the inside, a feature of the WW II Junkers Jumo 004 axial-flow turbojet, which was known as the Zwiebel (onion) from its shape. The Atar 101E added a "zeroth" compressor stage, raising the overall pressure ratio to 4.8:1 and the thrust to 36,300 N (8,200 lbf), surpassing the projected thrust of 34.3 kN (7,700 lbf) of the German BMW 018 turbojet still being developed in 1945. Various Atar 101 models were tested on a wide variety of aircraft.
An afterburner was incorporated into the D model to produce the Atar 101F of 37,300 N (8,400 lbf), while the same addition to the E model produced the 46,110 N (10,370 lbf) ATAR 101G. These were flight tested on the Dassault Mystère II in August 1954, but they did not see production on this aircraft. Their first success was on the Dassault Super Mystère which first flew under Rolls-Royce Avon power on 2 March 1955, followed by the 101G powered version on 15 May 1956. Production started in 1957 with a contract for 370 aircraft, but this was later cut back to 180 in light of the performance of the Dassault Mirage III which was then undergoing testing.
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Snecma Atar
The Snecma Atar is a French axial-flow turbojet engine built by Snecma. It was derived from the German World War II BMW 018 design, and developed by ex-BMW engineers through a progression of more powerful models. The name is derived from its original design group, Atelier technique aéronautique de Rickenbach (Rickenbach Aeronautical Technical Workshop) near Lindau within the French Occupation Zone of Germany. The Atar powered many of the French post-war jet aircraft, including the Vautour, Étendard and Super Étendard, Super Mystère and several models of the Mirage.
Hermann Oestrich's team in charge of the development of the BMW 003 engine had moved to the town of Stassfurt, near Magdeburg, in February 1945. An underground production factory was being set up in a salt mine outside town by C.G. Rheinhardt in a desperate attempt to continue engine production in face of the now overwhelming Allied air campaign. This mine is well known historically as it was also being used for the storage of uranium compounds as part of the Nazi atomic bomb program.
The town of Stassfurt surrendered to US forces on 12 April 1945, and Oestrich hid much of the technical data in a local cemetery. The next day a ten-man team made up primarily of engineers from Pratt & Whitney arrived, and he handed the data over to them. Production restarted for US use while the war ground to a close, and the US forces cleared out the factory while they waited to turn the area over to the Soviets.
Oestrich had by this time moved to Munich for further interrogation, and from there to England at the request of British engine designer Roy Fedden. He had them work on the design of a turboprop engine for a proposed C-54 Skymaster-class four-engine transport. While working on this design, Oestrich was secretly approached by French DGER agents with an offer to take up further design of the 003 in France. The French forces had found a number of BMW 003 turbojet engines in their occupation zone after the war, and were interested in setting up a production line. These discussions had not progressed very far when Oestrich was allowed to return to Munich, only to be brought back to England in late August, then returned to Munich again where the US offered him and a hand-selected team jobs in the US, but without their families.
Oestrich instead accepted the French invitation, and by September had been set up at the former Dornier factories in Rickenbach in the French Zone, close to the northern border of Switzerland. Here they were soon joined by other former BMW engineers, as well as those from a number of other German firms, bringing the team to about 200 members. The group was named the Atelier Technique Aéronautique Rickenbach (Rickenbach Aeronautical Technical Workshop), or ATAR. They had re-engineered the 003 design as the ATAR 101 (model R.101) by October, and granted a production contract on the proviso that actual production would be carried out in France. In January a further five-year contract was offered to the entire team, including protected wages, provisions for their families, few travel restrictions, and the possibility of French citizenship. The contract was signed on 25 April 1946, and the drawings for the ATAR 101 were sent to SNECMA for production.
The first engine took some time to assemble. The first parts were available as early as May 1946, but a complete compressor or turbine was not ready until the middle of the next year. The first complete engine finally ran on 26 March 1948. By April 5 it had been brought up to 16,000 N (3,600 lbf) thrust and was continually improved until it reached 21,600 N (4,900 lbf) by October. During this time a new turbine made of solid high-temperature steels replaced the earlier air-cooled models, allowing for better aerodynamic shaping and an improved compression ratio. By January 1950 several additional engines had joined the program, bringing the total running time to over 1,000 hours, and a thrust of 26,490 N (5,960 lbf), making it among the most powerful engines of the era. The BMW 003 that it was developed from provided only 7,800 N (1,800 lbf), less than a third of the Atar.
The ATAR 101B introduced Nimonic turbine blades and more stator blades as well as a number of changes to fix minor problems seen in the earlier experimental models. The first B model passed a 150-hour endurance test in February 1951 at 23,500 N (5,300 lbf). A flight test followed on 5 December 1951 in the Dassault Ouragan, and starting on 27 March 1952, under the wings of a Gloster Meteor F.4. After delivering the initial production run of B models, the Atar 101C used an improved compressor and combustion chamber, raising the thrust to 27,400 N (6,200 lbf). The Atar 101D featured a slightly larger turbine with new high-temperature alloys that allowed the exit temperature to rise to 1,000 °C and the thrust to 29,420 N (6,610 lbf). The D model also included a new exhaust consisting of a long pipe ending in a nozzle with two "eyelid" shutters in place of the earlier fore/aft moving cone on the inside, a feature of the WW II Junkers Jumo 004 axial-flow turbojet, which was known as the Zwiebel (onion) from its shape. The Atar 101E added a "zeroth" compressor stage, raising the overall pressure ratio to 4.8:1 and the thrust to 36,300 N (8,200 lbf), surpassing the projected thrust of 34.3 kN (7,700 lbf) of the German BMW 018 turbojet still being developed in 1945. Various Atar 101 models were tested on a wide variety of aircraft.
An afterburner was incorporated into the D model to produce the Atar 101F of 37,300 N (8,400 lbf), while the same addition to the E model produced the 46,110 N (10,370 lbf) ATAR 101G. These were flight tested on the Dassault Mystère II in August 1954, but they did not see production on this aircraft. Their first success was on the Dassault Super Mystère which first flew under Rolls-Royce Avon power on 2 March 1955, followed by the 101G powered version on 15 May 1956. Production started in 1957 with a contract for 370 aircraft, but this was later cut back to 180 in light of the performance of the Dassault Mirage III which was then undergoing testing.