1:48 Bristol Perseus Engine Mk.II - conversion for the Airfix Westland Lysander Mk.I/Mk.III (3D-Printed)

A radial with sleeve valves

The Bristol Perseus was the first series-produced aircraft engine in the world with sleeve valves. The nine-cylinder radial did without the poppet valves that Roy Fedden considered the weak point of more powerful engines, and instead worked with sliding sleeves in the cylinders. The result was smoother running, better charging and a power output of around nine hundred horsepower. It was exactly this engine that the Westland Lysander Mk.II version carried, used by the army cooperation squadrons before the outbreak of the Second World War and in its first months.

A conversion to the second series

The set is conceived as a conversion: it supplies the engine together with the matching cowling, so that a machine with this powerplant can be built from a commonly available kit. The whole block is printed as a single part, so the cylinders, pushrods and the fittings on the front face hold their relative spacing exactly and you do not have to put the radial together from individual segments.

Before you start gluing, compare the diameter of the cowling with the fuselage of the kit and fine-tune any difference by sanding the seating surface. The engine is best painted on its own, while it has not yet disappeared behind the cowling: a dark base, metallic shades on the cylinder heads and a thin oil glaze into the hollows will give the radial the depth you will then see through the propeller spinner at first glance.

Finally, a small note on the collecting side of things. Engines with this type of valve gear represent a separate line of development in British aviation, and a model that shows one of them exposed works as a rewarding display piece on a shelf and on a competition table alike.