Vent Holes in Glare Shield

[Birdseyeview]

I'm installing the glare shield and have thought about the possibility of some vent holes along its forward edge to allow the heater fans to circulate some warm air by the wind shield during winter operation. The way my twin heater fans are wired they currently push air down through the heater core and into the cabin under the instrument panel. Can the polarity of these fans be switched to cause them to reverse direction? If so I could conceivably have a special switch to reverse the polarity to push air up to some vent holes in the glare shield when needed. I've scoured the forum for pictures and have seen a few glare shields with holes but most don't have any so I'm wondering if the holes work to keep the windshield from fogging up or if fogging simply isn't it an issue. Does normal airflow through the cabin with the heater running keep the windshield clear without any vent holes? The winters get cold here in Northern Illinois.

[Dave S]

Birdseye,

Exactly what you are talking about - I found very useful for winter flying.

I'd be reluctant to reverse the airflow through the heater core as that would put all the heat on the the instruments and panel and none on the feet/legs. I would estimate that the original design with downward flow was intended to balance off normal convection and get some air mixing in the cabin as well as direct the flow away from the electronics.

I don't have a lot of photos of this; however, the attached one shows where the vent for the pilots side is located - here is a second on the co-pilots side. The vent hole has a flange which a piece of SCAT tubing can slip over from below and the SCAT tubing is routed next to the heater core on each side with a tight U turn to capture the downward flow of the air from the heater & direct it up to the glare shield.

It does keep the frost off the windshield

I am guessing there are addittional solutions which other folks have used.

[Birdseyeview]

Looks like a nice simple solution. What diameter are your vents?

[HighWing]

I helped a guy finish a Series 5 several years ago. His intent was to take the Kitfox to Alaska and wanted some way to vent heated air to the windshield. We did essentially what Dave did. I made up some fiberglass scoops that would capture a portion of the downward flowing air and direct it up through scat tubing to the glare shield. I have photos of the lower parts, but none of the finished glare shield. I had made some slot shaped fiberglass outlets that the scat tube was attached to - something like a half inch by five inches. I checked and still have the tooling so if interested in some help with parts, send a private message.

[Dave S]

Birdseye - the SCAT tubing I used was 1 1/2"

I particularly like Lowell's fiberglass work. The fiberglass pickup Lowell designed would intrude about an inch less into the area below the heater core than my low tech U-turn bend of the SCAT tubing.