ENGINE INTERFACE PANEL
The engine interface panel, mounted above the turbopump LOX and fuel inlets, provides the vehicle connect location for electrical connectors between the engine and the vehicle. It also provides the attachment point for the vehicle flexible heat – resistant curtain. The panel is fabricated from heat – resistant stainless-steel casting made in three sections and assembled by rivets and bolts.
The electrical system consists of flexible armored wiring harnesses for actuation of engine controls and the flight instrumentation harnesses.
HYDRAULIC CONTROL SYSTEM
The hydraulic control system operates the engine propellant valves during the start and cutoff sequences. It consists of a hypergol manifold, a checkout valve, an engine control valve, and the related tubing and fittings.
The hypergol manifold directs hypergolic fluid to the separate igniter fuel system in the thrust chamber injector. It consists of a hypergol container, an ignition monitor valve, a position switch, and an igniter fuel valve. The hypergol container, position switch, and igniter fuel valve are internal parts of the hypergol manifold.
A spring-loaded, cam-lock mechanism incorporated in the hypergol manifold prevents actuation of the
ignition monitor valve until after the upstream hypergol cartridge diaphragm bursts. The same mechanism actuates a position switch that indicates when the hypergol cartridge is installed. The igniter fuel valve is a spring-loaded, cracking check valve that opens and allows fuel to flow into the hypergol container. The hypergol cartridge diaphragms are ruptured by the resultant pressure surge when the igniter fuel valve opens.
Ignition Monitor Valve
The ignition monitor valve is a pressure-actuated, three-way valve mounted on the hypergol manifold. It controls the opening of the fuel valves and permits them to open only after satisfactory combustion has been achieved in the thrust chamber.
When the hypergol cartridge is installed in the hypergol manifold, a cam-lock mechanism prevents the ignition monitor valve poppet from moving from the closed position. The ignition monitor valve has six ports: a control port, an inlet port, two outlet ports, a return port, and an atmospheric reference port. The control port receives pressure from the thrust chamber fuel manifold. The inlet port receives hydraulic fuel pressure for opening the fuel valves. When the ignition monitor valve poppet is in the deactuated position, hydraulic fuel from the inlet port is stopped at the poppet seat. When the hypergol cartridge diaphragm bursts, the spring- loaded cam-lock retracts to permit the ignition monitor valve poppet unrestricted motion. When thrust chamber pressure (directed to the control port from the thrust chamber fuel manifold I increases, the ignition monitor valve poppet moves to the open (actuated) position and hydraulic fuel is directed through the outlet ports to the fuel valves.