Stirlingengineforum.com

Hello All Stirlingites .
Thought I would have a bash at one of these engines as I have always been fascinated by them .I downloaded some plans from www. manfreds-hobbypage.de followed them to the letter and guess what ...Yes !! it didn't work .Decided that displacer was to small and tried design by FIZGIG again followed exactly and still no luck .

Details are Displacer Cyl Dia 25mm Displacer piston is 0.4 mm smaller than the internal diameter of the Pipe [Steel Cyl and hollow Al Piston ]

cylinder is 75mm long and piston is 50mm .Stroke is 24mm .
Power Cyl is Aluminium lapped and polished to a mirror finish and is 14mm diameter ,Piston is tufnol very low weight and friction .Stroke is 20mm
Flywheel is Al 50 x 10 mm with steel balance weights 20x20 mm at circumference .

They are 90 deg out of phase

When I try to spin the engine it rebounds the power piston back out as if its under compression ? Do you thinks its too well sealed .I was under the impression these engines were in a closed loop ??

I spent a fair bit of time on these and would really like to get one to run .

Anyone have any ideas !!

Thanks

Bob

Good ideas RS .Wife away all day tomorrow so will try your ideas on the flywheel .I have tried a gas torch on low to give a good heat difference and made a larger set of Al cooling fins .

Thanks again
Bob

Sounds like compression is a bit high. You should be able to have it spin over half a dozen or so cycles with the flick of the flywheel. I would shorten the power piston stroke or possibly try a heavier flywheel if changing the stroke isn't an option. Yes, it's a "closed loop"...but, I have read a very slight leakage isn't a bad thing as it allows the engine to find it's balance of atmosphere to internal pressure ratio as it's running. I'm not really sure what that means exactly and since one of my engines leaks a fair amount and the other is pretty tight and both run well... I'm on the fence with that one.

Just been refitting bathroom so haven't played with my workshop toys for last 10 days .Withdrawl symptoms AAGGHH!! Should find time to have a try next week .I will shorten the stroke as you suggest and get the compression down and you never know .

Regards
Bob

..............There is only 2 reasons these engines will not run. Air leaks and friction...............and maby your burner went out while you continued to spin it over for the next 8 minutes! ............Your power piston is too tight in the bore.