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Exhaust headers for a Merlin-powered Spitfire. 1:6 scale
The exhaust end is a "fishtail" ejector, as typically fitted to Spitfires (not Mustangs, Mosquitos, or Lancasters). The "engine" side is designed to go into a 5mm deep slot on the side of a 1:6 model fuselage. As such, all of the engine head is invisible, and just the ends of the headers are visible, extending out of the slot. The inner face of the slot should be vertical to put the headers in the correct orientation.
For strength, the walls of the model are 2mm thick at 1:6 scale. The thickness of the walls is disguised by using a chamfer and fillet on the exhaust mouth. Scaling down further may make the walls unacceptably thin, particularly the mouth.
If you're scaling it down much, or you want more of the engine detail, I suggest reworking the design (see "How I designed This" for a link to the design at OnShape.com).
This is a left-hand header set. For a right-hand set, take a mirror image.
