Yum yum:

model engines

This has got to be the most STW of all:

[video]http://www.youtube.com/watch?feature=player_embedded&v=ljC1rh-FGl4[/video]

Why aren’t Stirling engines used in real life applications?

There are!, Lots of space craft run with solar powered linear stirlings as power generators, and large scale industrial heat exchange and low level heat removal processes use them.

However, there are a lot of quite well tied up Patents surrounding the more practical embodiments of Stirling engines, that i suspect has prevented more wide spread take up. Currently, several versions are under development to provide domestic combined heat and power for private houses etc

I recall a tv program that mentioned stirling engined generators being used in WW2 due to being virtually silent, with a low heat signature and multifuel. Patents aren’t always a “good thing”.

Those are beautiful but I have to admit I think I prefer this one:

http://www.ebay.co.uk/itm/Stirling-Engine-Kit-Walking-Beam-Working-Model-Hot-Air-Stirling-Cycle-/290885680627?_trksid=p2054897.l4275

Size, weight and cost issues for larger scale use I think – it depends on what the tradeoff is between those and ultimate efficiency (though worth bearing in mind that practical applications don’t usually get anywhere near theoretical efficiencies). Clearly in the 21st century efficiency is seen as becoming more important for many applications, hence expect to see more of a revival.