Modern jet engine turbines: each blade a single crystal (2015)

Veritasium https://youtu.be/QtxVdC7pBQM

I've always found the pigtail selector to be the coolest part of the process which just uses geometry to "select" a crystal that grows in the correct orientation for the turbine blade.

Efficiency was mentioned a few times, but without any hard numbers. What was the state of the art efficiency over time from a 1940s design to today? Have improvements plateaued or is there still a lot of theoretical gains on the table?

A good article on jet engines: https://www.construction-physics.com/p/why-its-so-hard-to-bu...

(2015)

"With recent decreases in the price of natural gas..."

Lots of trade secrets there. I wonder how many of them the BigAI companies have already collected.