 It was expected to have a thrust-to-weight ratio of about 100—incredible compared to any "macroscale" engine but a logical consequence of scaling the technology down in size—and run at about 1.2 million RPM, making bearings a tricky issue.Since it could "spool up" in about a millisecond, it was envisioned as operating in a pulsed mode to conserve fuel and also provide a throttling scheme.A functioning gas turbine was never successfully implemented at this scale after years of development.