Cockpit Ventilation ‘At Speed’

Most pilots I know like to have a little wind in their face for some reason. Cabin vents abound on most airplanes, and the RV line of aircraft traditionally use a NACA vent on the side of the fuselage to feed a 2-inch eyeball with 2-inch SCAT tubing. I have been flying my RV-8—a 170-knot airplane—for 20 years with just two 1-inch eyeball vents, and believe me—at those speeds, that is more than enough air! So when I got going on my F1 Rocket panel, I tossed the supplied 2-inch vents into the same box as the ones that came in my RV-8 kit and scrounged up some nice 1-inch eyeballs at the AirVenture FlyMart.

The Rocket build manual sort of leaves cockpit ventilation inlets up to the builder, but if you read between the lines, the designer shows a way to use three-quarter-inch PVC tubing in the wing root fairings to give you plenty of air without cutting NACA vents into the fuselage. Going that way, I realized the 1 1/4-inch SCAT tubing would fit perfectly over the fittings (and I happened to have a length of 1 1/4-inch SCAT … the stuff isn’t cheap!), so I put a chunk of aluminum in the lathe and made a reducer that took the 2-inch inlet on the back of the eyeball vent down to 1 1/4 inches. It’s a nice simple lathe project!

I then installed the necessary plumbing at the wing roots and routed the SCAT tubing up the sides of the footwell. All that was left was to keep the reducers in place—and a single #6 screw did that just fine after tapping a hole in the aluminum. We haven’t flown the airplane yet of course—but based on my use of the same size eyeballs for years in a slower airplane, I don’t think we’ll have a problem with getting enough air.

The bottom line is that if things are getting crowded behind your panel and the 2-inch SCAT is starting to get in the way, don’t forget that you can probably downsize considerably and still get all the ventilation you need—assuming you’re flying a relatively fast airplane. And why would you be flying a slow one?