I trust Brandon Sanderson to have done his research - in his book "The Rithmatist" he writes about coiled spring batteries that power a passenger train. I do wonder what could be achieved with a spring engine, in a world where the internal combustion engine hasn't been invented?
What would be required (tech and material wise - metalurgy, math etc.) to build a powerful engine, such that would power a full passenger train at practical-for-serious-transportation speeds, say 50 miles per hour? For how long would one battery last (Note that Sanderson wisely put in the ability to switch engines/batteries. A train/ship is allowed to stop for a couple o' minutes, then to keep going)?
How powerful can we get? Could we go 100 mph? more? Could we get ships and tanks and other power-hungry machines going on spring engines?
Think of how much gas can be saved, cost and green environment, etc...
EDIT: I found an article where something similair is discussed: why not a wind up car . ?In my question, however, I'm talking about a world where combustion/electric engines don't exist.