Having decided the fan location, the next step was to make the ducting. I hot wire cut a pair of blanks from pink foam, and curved them to an “S” planform and an arched shape in elevation to clear the wing by means of saw-cuts, with parcel tape pulling the blanks into the required curve – Pic 1. My new ducts comprise an inner layer of 3oz glass cloth and an outer layer of 6oz twill weave glass, spiral wrapped with carbon tow at 20mm pitch.