Scale Exhaust
The size of exhaust pipes on an FG-1D (Goodyear built F4U-1D) as measured by me (full scale is at local museum: the Kalamazoo Air Zoo) is 2 3/4" diameter. Dividing by 8, I arrived at a 1/8 scale size of 11/32" diameter (O.D.). I was able to find plastic tubes that exact size at my local hobby shop, however, I'm sure nobody would notice if you were not able to find that exact size and used 3/8" diameter instead.
So, beginning with the plastic tube, cut off 3 pieces about 3" long. This is longer than you will need, but the extra length makes it easier to work with in the mitre box.
Glue 2 of the pieces together, side by side (I used thin CA), then glue the 3rd piece directly on top of the other 2.
A 45 deg mitre box is needed for this next step: with 2 tubes held flat against one side of the mitre box, saw off one end as shown, so the the tube which is NOT against the mitre box side becomes the longest tube. NOTE: 2 tubes must be held against the side of the mitre box, NOT the bottom. Examine picture closely.
Now make 2 more cuts, about 1/2" to 3/4" ( length not critical)between the cuts, each cut being parallel to the the others. When you are done, you should have 2 pieces like the ones in the bottom picture.
Trim flashings away, then hold them one at a time against your Corsair, using the drawing as a guide. Note that the top exhaust on each side is slightly aft of the bottom one, and that they exit the fuselage about halfway between the cowl flaps and the wing leading edge. Also note that they are slightly below the wing. With an exhaust stack held in proper position against the fuselage, use a marker or scribe to mark the outline. Use an exacto knife to cut out a hole, making sure the cuts go forward at a 45 deg. angle. Use a file and/ or sandpaper to allow proper fit, then glue the exhaust stack into the hole. With the full scale, the stacks do not protrude very much, they are nearly flush with the fuselage. I however chose to leave them protruding about 1/8" for better effect, making them more noticeable.