My new Loki Q motor on the left and an Atlas ICBM upper stage vernier motor on the right.
Graphite takes the heat of the solid AP propellant (left) which would melt the metal, whereas regenerative cooling keeps the Atlas nozzle from melting (right) – the liquid RP1 kerosene fuel flows around the nozzle capturing heat before being sprayed out into the combustion chamber, where it mixes with liquid oxygen.
The liquid fuel motor on the right, while small, is fundamentally the same as the larger versions that powered the Apollo and SpaceX rockets.
And some details from its predecessor:
“An LR101-NA Vernier rocket engine assemblage manufactured by ROCKETDYNE Corporation for installation onboard an Atlas SM-65 ICBM (Atlas “A”/XLR 89 NA-1). These engines were employed in various configurations to provide attitude (roll, pitch and yaw) control onboard the Mercury-Atlas, Atlas, Thor ICBM, Delta propulsion systems. A fixed-thrust, single-start, liquid bipropellant engine producing of maximum of 1000 pounds of thrust (nominal seal level), the engine design allows postoperative purging, regenerative cooling, thrust chamber gimbaling, and full-thrust runs of 325 seconds duration. It has a dry weight of 54 pounds and measures approx 28 x 27 ¼ x 20 inches (normal gimbaling arcs included). Designed propellant mixture is combination RP1 (highly refined liquid Kerosene) and LOX (liquid oxygen).
The engine consists of a thrust chamber assembly (a steel double-walled structure with a copper spiral regenerative cooling coils between the inner and outer walls), a pneumatically operated propellant valve with a valve position-indicating switch, an electrically fired igniter assembly, a pneumatically controlled oxidizer bleed valve, a fuel manifold pressure switch, a manifold gimbal assembly, propellant orifices, and pneumatic purge check valves. These components along with interconnecting electrical cabling and tubing assemblies are fixed in position on a welded tubular engine mount.
Gimbaling is facilitated via a pitch gimbal shaft, which provides for movement of the thrust chamber through a pitch-roll correct arc of 70 degrees on either side of the neutral position; and a yaw gimbal shaft which permits movement of the vernier thrust chamber through a yaw correction arc of 30 degrees (outboard) and 20 degrees (inboard) of the neutral position. In addition to performing the thrust direction gimbal function, the yaw shaft serves as a manifold for passage of fuel and oxidizer to the thrust chamber.”
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