This thread on the model engineers forum has been running for some time, there is a lot of frothing and posturing which I find it quite amusing. The OP is new to the hobby and seems determined to stir things up. Some here may appreciate my warped sense of humour. Dave
An interesting read but somewhat academic to ME boiler makers, having little practical application to improving the design. We are constrained by the physics of heating water to steam and modelling a prototype locomotive we would follow the outline of boiler to keep it as close to being phototypical. So the only scope for improvement would be in the innards of the boiler. But most MEs would follow the established design because changes may impact it getting approved by the BI and they would care little that their design changes could marginally improve the steaming rate and or reduce coal or water usage, But it did provide an understanding of how water is converted into steam by the formation of bubbles throughout the water space and how the size of these bubbles are affected by the internal construction of the boiler in their journey to the top of the water into the steaming space. The AMBSC Code Part 1 requires that the ligament distance ( ie the distance between tubes and flues) be a minimum of 3mm not because of efficiency but of safety because a too small a separation could cause an absence of water to occur and thereby generate a hot spot leading to a failure of the boiler at that point.
Built 3 1/2" Gauge LBSC's LMS Black 5 Doris and Martin Evans Rob Roy Building Don Young's Black 5