Roger Penn’s


Roger Penn exhibited his version of a marine triple expansion engine at the 2013 Midlands Model Engineering Exhibition. Popularity of these model engines started with a design by O B Bolton which was fitted with a surface condenser and air pump. Later that design was completely revised by the late John Bertinat. Several other designs are available for compound engines, which make great models. A twin cylinder compound was described on these pages by Bob Middleton which can be built without castings. Roger’s model is to 1:16 scale.