By Harvey Watkins
Back in the day when spirit went into your loco, rather than your binge drinking, and “the gas” was what you turned on before putting your head in the oven. I wanted a saddle tank loco as a contrast to all the side tanks and box tanks around. It would be a small prototype too, so I wanted to stay with external firing in order to maximise the boiler capacity and not get into pumped water systems and other complications I was not confident about.
“Ah well”, they said, “it won’t work, look at the Archangel Louisa”. Now having spent many happy hours on the lawn at Cock Lane, I knew about Louisa. She was a little one-off trial loco Stewart Browne had made by combining one of his standard, 7mm, Satan chassis and boiler items, with a saddle tank body – all to produce a free-lance quarry tank. Unfortunately the saddle tank and its boiler side shields were so effective at shielding, they choked the fire and the loco was a failure. So back in the box it went, as the saying goes. Louisa did reappear to run, but with large round ventilation holes punched in the saddle tank, rather spoiling the picture.
Well there are other ways to skin a pot-boiler, so, armed with an old Peckett catalogue and a couple of salient dimensions, I set out hoping to produce a bit of subtle fire shielding.
The loco follows an outside framed prototype with the valve gear between the wheels and the frames. This gives reasonably spaced frames allowing for a spirit tank between them, under the cab floor. From the tank the usual 3-wick burner runs forward under the boiler. Otherwise the chassis is a conventional twin cylinder item, with valve chests between the frames.
The saddle-tank and boiler, as seen, are all the firebox shell, and the real horizontal drum boiler is set high in the saddle-tank to give a reasonable height above the flames.
To ventilate the boiler, the saddle tank is set 3mm forward of the cab front, the toolbox is set on a little stand above the boiler top and beneath the stand is a vent, the dome is drilled all the way through, and the water manhole cover can be lifted away. This “hole and corner” venting has proved sufficient and even the removable water manhole is only used to boost the ventilation when steaming up.
As is usual with me, first lighting of the blue touch paper was accomplished with much trepidation, but she went! And apart for a time spent on the shelf, after leaping off a shelf on to a concrete path, she has continued to go. Thirty years on, and still in steam, I’m glad I didn’t listen to the nay-sayers. Don’t you listen to them either.