[Bazooka]

So, if the Stirling engine was invented in 1816, then why did it take 211 (!) years for somebody to realize the economic viability of the thing?

[Fester Chugabrew]

I think it's closer to 189 years. When it gets up to 200 we'll start realizing its viability.

[Wonder Warthog]

"So, if the Stirling engine was invented in 1816, then why did it take 211 (!) years for somebody to realize the economic viability of the thing?"

Because they are relatively complex and unreliable. The Stirling engine used in this application has been under development for at least 30 years (I have a book about it that I bought about ten years ago). The new design uses magnetic bearings and a whole lot of other high-tech stuff that just didn't previously exist. In the book, the working fluid was helium. I wonder wy they switched to hydrogen???

[Arkie2]

The stirling engine is being used very effectively in a new type of coastal patrol submarine that is so quiet and effective the US navy is very very concerned it may fall into the wrong hands, like Iran.

[Walkingfeather]

because the materials for the seals and such took that long to perfect. You could build small ones but larger ones were the challenge. I know dean kamen was working on perfecting it.