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The Emergency Escape System of the L3 expeditionary complex
The Emergency Escape System, or SAS, of the N1-L3 system was designed to carry the crew capsule away from the rocket in case of a catastrophic emergency during the final pre-launch countdown and in the first few minutes of ascent to orbit.
The payload fairing of the L3 lunar expeditionary complex (right) with the attached Emergency Escape System, SAS. The SAS system for the L3 complex had a design and operational scenario similar to that of the Soyuz spacecraft and the L1 circumlunar vehicle. However within the L3 architecture, the escape rocket had to carry considerably more mass, resulting from the larger Orbital Module of the LOK crew vehicle and its DOK attitude-control module with propellant, which all had to be separated from the rocket along with the Descent Module carrying the crew. The much larger assembly, which would detach from the rocket and escape in emergency, had a length of 15.81 meters. The escape system included multiple solid-propellant motors, which were responsible for various aspects of the initial escape from the rocket, for the subsequent maneuvering into the descent trajectory and, ultimately, separating from the assembly, so the Descent Module could proceed with a parachute landing. At the very top of the SAS stack was the Separation Rocket Engine, RDR (from the Russian Raketny Dvigatel Razdeleniya), which was responsible for the separation of the escape system at the end of the escape sequence. Apparently, it had around 14 nozzles of two different calibers, with seven larger nozzles aligned around Plane III in the vehicle's coordinate system. Because the larger nozzles produced more thrust than their counterparts on the opposite side of the rocket, they would cause the SAS rocket to pitch at separation, once the escape system had completed its job and the 18 pyrotechnic devices attaching the SAS tower to the fairing of the L3 spacecraft had fired. Below the RDR motor was the main Central Rocket Engine, TsRD (from the Russian Tsentralny Raketny Dvigatel) which performed the main job of pulling the escape assembly, including the top section of the payload fairing, GO, with the Orbital Module, OO, and the Descent Module, SA, with the crew inside away from the failing N1 rocket. The eight main nozzles of the TsRD engine were arranged in a circle around the fairing connecting the SAS system to the main fairing of the L3 spacecraft below. Right above the main nozzles of the TsRD engine, there were four small sideway-facing nozzles connected to the same motor. They performed pitch and yaw control of the vehicle during the escape under the thrust of the main TsRD motor. In case of firing on the pad, they apparently helped to pitch the escaping vehicle away from the launch tower standing next to the rocket. Various SAS sub-systems, such as electric switches and two KIOO-14 gyroscopic instruments responsible for flight control of the escape assembly were housed in the fairing, known as GO (from the Russian Golovnoi Obtekatel). The fairing also contained the two batteries, which powered the escape system, as well as the PVU programming timer, which managed the escape sequence. The separation of the SAS fairing from the main fairing of the L3 system was performed with 18 pyrotechnic devices on their common interface. According to the 1965 preliminary design of the N1-L3 complex, if everything went well during the launch, the rocket tower of the escape system would separate from the ascending N1 rocket soon after the jettisoning of the first stage (Block A) and around 20 seconds into the operation of the second stage (Block B). The separation of the escape tower would probably be closely followed by the splitting and jettisoning of the main fairing protecting the L3 complex. From that point on in the ascent, the emergency escape would be performed by means of the LOK crew vehicle all the way until the Block V engine cutoff command at orbital insertion. Development history The technical assignment and basic specifications for the experimental testing of the SAS escape system of the L3 expeditionary complex was issued in 1966, or soon after the introduction of the first-generation escape system for the Soyuz 7K-OK spacecraft. Little else is known about the system, but it came handy during four N1 launch failures in 1969, 1971 and 1972, all of which took place during the operation of the first stage.
Components of the L3 escape system:
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Interface between the SAS fairing and the main fairing of the L3 expeditionary complex (right)
The launch escape system of the N1-L3 complex next to the access tower on the launch pad
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