But the whole act of building an engine rests on the work of engineers and physicists who developed the metallurgy and designed the components and production machinery to make the components.
I doubt there is a single physicist designing model engines. They are too busy figuring out how to make fusion reactors, or how quarks work. I even doubt any model engines have any body working directly with metallurgy. Instead their metals suppliers will let them know of new materials that will make their engines better. You don't know that an engineer doesn't do the same job they did 40 or even 20 years ago. It has become very high tech research stuff. Some are the underlings to physicists, the designers of the fusion reactors and atom smashers they demand. Not many designing model engines, except maybe as a hobby.