The small duty cycle seemed to ramp into the medium duty cycle. The medium duty cycle was decent. The high duty cycle intermittently failed to operate the solenoid inside the 5 msec, making it very ragged. My current theory on the PWM is that there may only be a narrow range of off times that do not either have solenoid opening problems, or allow the chamber pressure to blow down to the point that the nozzle flow separates. We may not be able to deeply throttle smoothly, but we should be able to get high percentages by stretching the total cycle time instead of shrinking the off time more.
More experimentation is needed.
This started out the smoothest run, but got ragged at the end. This stayed ragged the entire time. Something may have happened to the pack at the end of run 5. We don t know. Test one of the new engines with a new pack compressed a half inch and no spreading plate.