At the risk of being accused of self-promotion*, simplification of the “powerhead” was one of the main objectives Roger Gregory and I were after in trying to update Goddard’s patents to an ultracentrifugal engine. My original motive for approaching Roger with this strategy was a combination of Walker’s strategy of “a rocket a day” (which required very cheap manufacture) and Gary Hudson’s Roton. We had some rotational stability tests run at Texas A&M. Also we had a few prototypes fabricated in an automotive machine shop by a guy who designed and fabricated custom equipment for silicon fabs. But I can’t attest to the feasibility of this design since I had limited computational modeling capability (pretty much everything getting done with TK!Solver) and we didn’t complete testing before money ran out (as it was coming out of my pocket and I had to pay lawyers for international applications).
As I recall, we were at the hairy edge of melt-down because the chamber pressure hence temperature was very high and propane’s cooling properties were limiting, even though we were running both propane and LOX as coolants. I haven’t thought much about revising the design to possibly take advantage of additive fabrication for more sophisticated topologies that might permit LOX to pick up some of the slack since LOX was a lot better coolant and we had a lot more of it flowing. I had this idea, at the time (1996) that the way to get access to space was to motivate the NASCAR culture to start doing vertical drag races (which is a phrase some others picked up on but applied in a different manner than I intended). When I was working as VP for E’Prime Aerospace in Titusville, one of the investors was heavily into the drag racing circuit, which is why I thought it might have been a relatively easy sports market to penetrate.
Roger passed on to me an idea that Gary came up with to increase the thrust to mass ratio: Surround the engines with stationary magnetic containment that served to provide image currents hence maglev forces to reinforce the walls of the engine. Since the containment isn’t under rotation (let alone supersonic rotation) it can be lighter than similar containment mass added to the rotating engine.
One of the nice things about the design is that the rotational bearing rings were of small diameter so the tangential speed-induced stresses on the internal balls were correspondingly small.
*Of course, that patent is no longer in effect so my only conflict of interest in mentioning it is non-financial.