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May 2004

Archangel C&M Princess

by Marc Horovitz

The Prototype
The Campbeltown & Machrihanish Light Railway carried coal and passengers between Campbeltown and Machrihanish, across the Kintyre Peninsula in western Scotland from 1906 to 1932. The railway owned just a few locomotives (click
here to see another of them). Princess was built by Kerr Stewart of Stoke-on-Trent in 1900 for the Campbeltown Coal Company. This was one of Kerr Stewart's “Skylark” class, basically a catalog engine that could be ordered at will and would be delivered in a short time -- seven weeks in this case. The engine was named after Queen Victoria’s daughter, Princess Louise, who had married the Duke of Argyll.

Princess had a very short wheelbase -- only three feet -- which gave a fairly rough ride. The engine was acquired by the C&M in 1906 and fitted with vacuum brakes for passenger service. It lasted a few year more, but was eventually set aside to languish. Its ultimate disposition is unknown.

The model
Archangel’s model is a fairly accurate representation of Princess (unlike some of the company’s other models, which tend more to be caricatures or free interpretations). It has a pot boiler, fired by a two-wick alcohol burner. The fuel tank is in the usual place under the cab. Slip-eccentrics control the valves and the boiler is fitted with a throttle, pressure gauge, and safety valve.

On the left side of the footplate is a standard displacement lubricator and on the right, a servo that is linked to the throttle. A NiCad battery pack is stuck to the underside of the roof to power the radio, while the receiver and on-off switch are carried messily in the coal bunker. No attempt was evidently made at concealment. I have a much smaller receiver somewhere, and so may try to swap them out and put a dummy coal load on top -- one more project for the future.

Two dummy sandboxes are perched atop the boiler. Under the forward one is a filler plug. The safety valve is inside the cab, exhausting through the roof. Blow-off pressure is 60 psi. The valve lifts with a distinct snap and closes just as sharply. I doesn’t make the characteristic Archangel razzberry sound, alas. The engine is painted black is lined with some rudimentary-but-neat red striping. It’s an attractive bundle that really captures the character of the prototype.

The run
April 30, 2004 -- temperature in the low 30s with snow off and on all day. This is a typical springtime day in the Rockies. (Temperatures in the 80s with bright sun would also be considered a typical springtime day.) Preparing Princess for steam is straightforward. Oil all around, drain and fill the lubricator, fill the boiler, fill the meths tank, and light up. I’d only run this engine a couple times before, but I had pleasant memories of a good, solid, controllable performance. I didn’t know how it would do in cold weather, though, being an externally fired locomotive. I needn’t have worried.

Pressure was up to 30 psi in five minutes or so. Another few minutes brought it up to blowoff. The safety let go with a pop, filling the cold, damp air with clouds of aromatic steam. Wonderful! I turned on the radio and opened the throttle (the only thing the radio controls -- reversing is manual). Princess lurched forward an inch or to, then stopped. I pushed the engine backward, reversing the valves, and tried again. Condensate in the cold cylinders again stopped the engine. I reversed it again and pushed it forward while simultaneously opening the throttle. The engine moved smoothly off, steam pouring from the stack.

The run lasted perhaps half an hour, with two or three brief stops for refueling. Princess is very controllable for such a small engine. Slow-speed running, even light, is no problem, and it can be brought smoothly to a stop in front of the station with ease. The cold and snow didn’t phase the engine and the atmospheric effects were all anyone could wish for. This was a great day for running a meths-fired engine. The run was followed up with a hot cup of cocoa, rounding out the afternoon nicely.


Builder Archangel (Great Britain)
Date built 1980
Gauge 32mm
Scale 16mm
Boiler Pot
Fittings Safety valve, pressure gauge, throttle
Fuel Alcohol
Blow-off pressure 60 psi
Cylinders Two, double-acting D-valve
Reversing gear Slip eccentrics
Lubricator Displacement
Dimensions Length, 9-1/2" over the end beams; width, 4-1/8"; height, 5-3/4"
Side elevations. The extremely short wheelbase of the drivers made for a lot of lateral motion on the prototype. Two sand domes helped with traction. Note the inclined cylinders.


Above: The radio gear is stuffed unceremoniously in the coal bunker. A smaller receiver would make the “installation” less obtrusive. Even though the antenna is all wound up, reception is still pretty good.

Right: Underneath, two wicks fire the simple pot boiler. Slip eccentrics on the rear driven axle control the valves. The fuel tank is at the bottom of the picture. A large chunk of lead between the frames at the top end, installed by a former owner, helps balance the engine.

Below right: The cab interior. A single servo controls the throttle. The receiver’s battery pack is stuck to the ceiling.

Below: The filler plug for the boiler is concealed beneath the forward sand dome.


Left: With 60 pounds on the clock, the safety valve lets go. Cold, damp air makes for wonderful steam effects.

Above: Princess happily trundles around the railway, despite the falling snow.



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