RE: Building: Cosmic Wind - 1 / 2.6 scale
We had to fill the gap between the fuselage and the spinner. We used 10mm balsa, and sanded it down to the shape of the spinner / fuselage. It will only be 2 - 3 mm clearance between the spinner and fuselage.
The cylinder will be hidden beind the large air intake on the side. In the air intake on the other side, the muffler will probably be placed if possible.
We also need to cut out some more on the side to make free air flow to the engine. (Pic. 4) This will be behind the air-intake anyway, so they will be functionable.