Altitude Developmental Testing of the J-2S Rocket Engine in Rocket Development Test Cell (J-4) (Tests J4-1001-06, -07, -11, and -15)

Eleven firings of the Rocketdyne J-2S rocket engine were conducted. These firings were accomplished at pressure altitudes ranging from 80,000 to 108,000 ft at engine start signal. The major objectives for these tests were to verify stable idle-mode operation, confirm that oxidizer injection temperatures were not excessive during transition from main-stage to post-main-stage idle- mode operation, evaluate main-stage performance, and determine the rate at which thrust chamber temperature increased during pre-main-stage idle mode. A full- face oxidizer flow injector configuration was utilized during this series of tests for the distribution of oxidizer during idle-mode operation. Brief durations 20 sec of stable idle-mode operation chamber pressure oscillations or - psi were achieved. Oxidizer injection temperatures exhibited only insignificant increases 10F during transition to post-main-stage idle-mode operation. The maximum rate at which the thrust chamber temperature increased during idle-mode operation with high oxidizer 45-psia and low fuel 27-psia pump inlet conditions with 6Fsec. Three firings which simulated orbital restart conditions were prematurely terminated during transition to main stage by the vibration safety cutoff system. Liquid fuel was present at the injector at the dome prime when the excessive vibrations were first recorded.