1:48 SAAB 21 resin exhaust manifold

Where the exhausts come out on an aircraft with the propeller at the back

On a piston aircraft the exhaust manifold is one of the places that immediately give away the quality of a build on a model. On the SAAB J 21 the situation is unusual too: the engine was housed behind the pilot and drove a pusher propeller between the tail booms, so the exhausts are not at the front along the sides of the cowling as on an ordinary fighter but at the rear of the fuselage nacelle. The shape and the spacing of the individual outlets are therefore visible in profile and from above, and the injection-molded part from the kit is usually only suggested in this place.

The resin replacement solves two things at once. For one thing it carries crisper edges and hollowed-out outlets, and for another it is cast in one piece, so there is no sanding of a parting seam exactly where that would be hardest to do. Once the casting gate is cut off, the finished part only has to be cleaned up, fitted dry and checked against the opening in the cowling.

Painting stands or falls on the heat discoloration of the metal. A dark base works well, then a thin coat of a burnt steel shade and finally dry application of a rusty and purplish pigment working back from the outlets. Inside the outlets we leave a deep black, because it is precisely the depth of the opening that creates the impression of real pipework.

The last step is seating it. The part is glued with cyanoacrylate glue and it is good to fit it only once the surrounding cowling is painted, otherwise the heat discoloration you worked so hard on gets covered over. Anyone building the model with the engine compartment open will appreciate that the manifold can be fitted with a visible run through to the cylinders, which on this machine is one of the few views inside.