What are the challenges for making an engine that does real work?

[cbstirling2]

If one used a magnetic clutch, one could completely enclose the stirling engine with the only seal being the Schrader valve.
The benefit here being good being no seals against a moving shaft, so that be very simple I would suspect.
Has anyone tried this?

Looks like someone patented the idea back in 1996:
https://www.google.com/patents/EP0918924A1?cl=en

[Aviator168]

Magnetic couplers are nice. But the designer has to make compromise between weight and torque.

[Ian S C]

I think Andy Ross mentioned a magnetic coupling he tried on one of his motors in "Making Stirling Engines".
Ian S C

[Aviator168]

Yes. He did with his 230w engine. Magnetic coupling can also transmit high power through a thick "semi" magnetic medium; but not the way he did it.