ELECTRICAL SEQUENCE CONTROLLER

The electrical sequence controller is a completely self-contained, solid-state system, requiring only DC power and start and stop command signals.

Pre-start status of all critical engine control func­tions is monitored in order to provide an “engine ready” signal. Upon obtaining “engine ready” and “start” signals, solenoid control valves are ener­gized in a precisely timed sequence as described in the “Engine Operation” section to bring the en­gine through ignition, transition, and into main – stage operation. After shutdown, the system auto­matically resets for a subsequent restart.

start Tank Assembly System

This system is made up of an integral helium and hydrogen start tank, which contains the hydrogen and helium gases for starting and operating the en­gine. The gaseous hydrogen imparts initial spin to the turbines and pumps prior to gas generator com­bustion, and the helium is used in the control system to sequence the engine valves.

HELIUM AND HYDROGEN TANKS

The spherical helium tank is positioned inside the hydrogen tank to minimize engine complexity. It holds 1,000 cubic inches of helium. The larger spher­ical hydrogen gas tank has a capacity of 7,257.6 cubic inches. Both tanks are filled from a ground source prior to launch and the gaseous hydrogen tank is refilled during engine operation from the thrust chamber fuel inlet manifold for subsequent restart in third stage application.

Flight Instrumentation System

The flight instrumentation system is composed of a primary instrumentation package and an auxiliary package.