Fortran while historically important doesn't really seem like a good choice today.
I worked with a proprietary jet engine analysis software suite written in Fortran 77 and It felt very primitive, albeit fast.
Today I feel like C is a much better choice for speed and readability.
If you really need the fastest performance I dont think Fortran gives that much of an advantage writing assembly.
Aren't most people doing this kind of work these days engineers using matlab?
Fortran invented array-based programming, which arguably numpy advanced and now Julia finally perfected
With vector machines, Fortran yielded (much) faster code because (a) there was a whole lot of work on preprocessors for "dusty deck" code and (b) the lack of pointers and their overlap let the compilers do their stuff. C code needed a lot of #pragma's to let it know that some pointers didn't overlap and so could be optimized.
We found it best to to the front-end and I/O of the code in C and the compute in Fortran. Fastest calculations especially with those tailored libraries.