 Silicon was actually a good structural material at such scales, though increasing operating temperature would have dictated use of silicon carbide.A production device was envisioned as a centrifugal-flow engine about two centimeters across burning natural gas, with a single turbine disk for compression and a single disk for exhaust rotation.The design didn't look much like a conventional turbojet, resembling more a tiny flat cylindrical box with an inlet hole on one side and an exhaust hole on the other.