I was always feeling uncomfortable with the standard solution on the RV-4: NACA vents below the cowl cheek extensions and SCAT ducting to the eyeball vents. From the given location, space and geometry of the NACA vents, the ducting seems to interfere with the pilots legs or feet (at least with mine
). As I had a pair of custom made NACA vents with a rectangular cross section to be connected, I had the idea to fabricate a curved glass fiber duct. This gives me much more room for my feet on the pedals.
Sideview of prototype tube
View from above
The fabrication of the ducts and some related issues are documented under this thread: