The ‘Royal Scot’ chassis has lain in my workshop untouched for at least ten years. The lack of activity has been entirely due to either working on my larger gauge steam locomotives or restoring models for other people.
Recent retirement has meant that I have (a little) more time to pick up this project again. With the assistance of a young, enthusiastic apprentice with an aerospace company progress has come on in leaps and bounds over the past few weeks.
Refreshing my memory of Martin Evans’ drawings I discovered several shortcomings. Firstly, not all the dimensions were shown which meant measuring from the drawing and this revealed the second short coming. The drawings were stated as full size, but the copy was larger than full size……..
Oh, and to make matters even more complicated, the drawings of the loco are in inches whereas the drawing for the tender is in metric!
Fortunately, I could obtain through the Gauge ‘O’ Guild plans service some decent scale drawings of the unrebuilt ‘Scot’ and these helped me to fill in the blanks.
To get into the mood of the engine I started with the
Smokebox. A relatively straight forward piece of work with the added advantage it would locate the boiler.
Moving next to the boiler (some would say the heart of the engine) the design called for a Belpaire firebox with superheaters and fired by gas. It looked very tiny and fiddly to fit everything in, especially to plumb up the smokebox. In addition, the required diameter of boiler barrel tube was no longer available, the metric equivalent being either the same diameter as the smokebox or two sizes smaller. One of the distinctive features of the original ‘Royal Scots’ was the step down where the boiler was smaller than the smokebox.
Therefore, the barrel tube had to be smaller.
This meant there was going to be very limited room to install the regulator inside the barrel and to fit the superheater flues and if one did manage that there would be precious little water in the boiler. Given my experience with LBSC’s ‘BAT’ which was a similar design with a round top firebox I decided to modify the boiler and go for a straight barrel with a single fire tube and to dispense with the superheating. My experience with superheaters in this scale before has led me to believe they are pretty much useless anyway.
The regulator is fitted outside of the boiler with an extension running up through the cab roof ventilators to allow for adjustment of the fly. The main steam pipe will run externally to the cylinders beneath the cladding of the boiler which with the insulation will keep the steam as dry as the superheaters would have.
With an external regulator radio control could be fitted at a later stage.
The following photographs show progress to date.