Earth Mountain almost there, page-466

"... Still, a patent costs a lot of time and money - and you can only patent something that can be accurately described. Things that are patented have either very high potential commercial value, or a high likelihood of working, otherwise they are a waste of money to the patentholder. ..."

Hence the careful terminology used in a patent application and granted patent. I doubt if anybody would go through the process of lodging an application for a patent for a device that they were not confident actually worked. Like, how would you describe it and what it did without having shown it to do that thing? It may be possible to write a patent application and lodge it and have it examined, but would it be granted if it did not work?

In this particular case we know that there is a whole legacy of designs that have been built - and patents applied for by AP - that while they are protected they were not the final design that will be eventually manufactured - and patented of course. They did what they said, but had a few unexpected side consequences and limitations in their ways of working that were not helpful. As far as we know, the latest design, as being manufactured right now by EM, is the one covered by these patent documents.

Of course only time will tell.