A Matter of Scale
Before I get onto a brief reflection about scale, the photo below shows 2 cannon barrels.
The big one was what impelled me to converting a manual lathe into a CNC lathe. That time consuming, costly, and ultimately very satisfying project, started because the CNC lathe which I used to turn the big barrel could only handle the job by doing it in two stages…. doing the breech first then the muzzle. That was due to the big barrel being too long for the lathe, at 300mm (12″).
The small barrel was a test for the CNC converted lathe just finished, being the first complicated shape which I have made. To save on material, I made it at exactly half the scale of the big one, ie 150mm long (6″).
Comparing the two barrels reminded me, that if an object is twice as big as another, in all 3 dimensions (height, width, depth), it is 8 times as heavy. And any projectile, and weight of black powder, would also be 8 times the weight. But the wall thickness of the explosion chamber is only TWICE as thick.
My point is, that if scale is maintained, the smaller the cannon, steam engine, boiler, whatever….. the less likely it is to explode.
Not that these cannons will ever be fired. Just hypothetically.
If the scale is double the volume goes up 8 times. What no-one ever points out is that for the model to look realistic the detail required can also go up by a considerable amount. On my 3 1/4 Jenny Lind the rail round the footplate on just one side is just 1 piece of metal. On my 7 1/4 Jenny Lind one rail consists of
7 trims for the plates
4 special screws
4 standard screws
Dont let this discourage you.
Hypotheses must be tested! When do you plan to fire those beautiful little buggers? I may have to take a trip down under!
I would end up in jail if I fired them. Very strict gun laws (which I support!)
BTW loved those pics of the cannons and specs you posted from vacation.
Thank you for the feedback!