An engine for an F35 is designed to be stable, reliable, functionary in specific performance parameters over a designated operating range. The engine will operate with a myriad of secondary and subsidiary harmonics--unavoidable but managed.. Everyone involved damned well knows that the forces under constraint and management in such an engine are such that operations outside of design parameters will be catastrophic. Put a 600 hp engine in a 2,400 pound fiberglass car and hit the gas hard and see what happens. In addition, the engine is designed for a specific mating to a specific airframe. That is the beauty of it: matching the planned and realized operating specs (performance) across its sweet spot (which may indeed be narrow and quite specific with hell to pay for joy rides outside of the sweet spot) with the well-fitted matching component (the airframe). There are only few good matches in terms of airframes, and few good uses for the engine that drives the F35; and there are alternatively a large number of ways to misuse, mismatch, mismanage, poorly operate that engine. It is a good engine, I imagine, for its intended use, and a very poor if not contraindicated engine for 99.5% of all other possible uses. Never will you get perfection. The more you get to perfection over the specific operating range, the more trouble you may get outside that range. Technology shifts are like political revolutions, perhaps. You can imagine the near impossibility of shifting human energy systems from carbon based to alternatives for carbon. The built legacy for carbon conversion is overwhelming both in terms of on the ground plants and equipment but also for the knowledge base.