Trevithick Dredger Engine. Gas or Coal?

Despite my best efforts, and good advice from experienced modellers, I have not been successful with using propane as fuel.  The engine runs, but I cannot get the boiler pressure over 20-22 psi, and that is not adequate.  Partly the problem is that the Trevithick boiler is the FIRST high pressure boiler ever, and is rather simple and primitive.  I do have alternative propane solutions, but they involve redesigning and remaking the burner.  I might end up doing just that, but meanwhile I am going to try coal.

I use coal to fire my 3″ scale traction engine.  It is messy, dirty, and a bit of a pain to get fired up.   But once going it is HOT.  And smells good.  But needs constant attention, observation, and skill.  Not just a matter of adjusting a gas knob.

But, the original Trevithick dredger engines used coal.  Or wood.  Or dried alpaca dung.

So I intend to build a coal grate.  The firebox is only 65mm diameter, so the coal lumps will need to be small, about 1cm diameter I guess.  I will make some sort of crusher to reduce the size of the traction engine coal.

I have made a start on the grate.    Again, it is all experimental.  And I will need a blower of some sort.  Maybe a small computer fan on the chimney.   All fun.   Wait and see.

No book review today!   And Antarctica and moon not mentioned!  I do have  a review in the wings about the Roman emperors who were monsters.  But another day for that one.