Door Air Deflectors for the STOL CH 750

Getting ready for summer (and the hot muggy weather that we've come to expect in central Missouri), we decided to remove the doors of our STOL CH 750 once again.

We decided to add air deflectors along the front of the cabin / door frame to maximize comfort with the doors off.  Air (or wind) deflectors are common on European cars - where many folks drive around with their windows open (many cars there are not equipped with air conditioning).  Automotive window air deflectors are typically made of formed acrylic and marketed for improving aerodynamics and aesthetics, reducing wind noise and drag, and sold as "wind deflectors," rain guards, visors, etc.

It's definitely windier flying with the doors off, but that's the point of taking them off.  Like a convertible or a motorcycle, it's about the "wind-in-your-hair" joy ride... (and slowing down into the sixties makes it quieter and more enjoyable).

Video Clip: Flying the STOL CH 750 Without the Doors (with air deflectors):

Air Deflectors with the Doors On

By adding air deflectors in front of the door (and attached to the cabin frame) we also "spoil" some of the airflow that "lifts" (pulls out) the domed bubble doors.  The bubble doors are fantastic for the extra cabin width and awesome visibility, but they also have a tendency to want to open if not securely fastened due to their "high lift" shape.

Here's a video clip showing our tests:

As you can see in the above video, the air deflector "spoils" the airflow on the front portion of the domed bubble door, decreasing lift (pull) on the door (and also noticeably decreasing wind drafts between the door and the cabin frame).  In our limited testing we didn't see any performance or handling differences with the air deflectors in place.

As you can see in the video clip, this prototype deflector is just a piece of bent Lexan (t=0.080):  We sheared a strip approx. 80 mm. wide by 700 mm. long, and formed it on the bending brake (we had to heat it with the heat gun to get it to bend enough).  It's attached to the cabin frame using the existing windshield screws.

A couple of years ago we posted this video clip showing how easy and quick the doors are to remove, and how you can stow them in the baggage area behind the seats:



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Comment by Bob McDonald on May 30, 2012 at 5:26pm

Are there any plans in place at Zenith to make these "air deflectors" available from the factory?

Comment by Jonathan Porter on May 17, 2012 at 2:23pm

Flying doors off is amazing - we do it a LOT.... but not on mission flights.  However, when you fly lots of local kids it is great for quick changeovers and it reduces the heat in the cabin... The idea of creating a change in the airflow over the bubble doors is interesting... It may even improve aerodynamics - as it does on some of the cars in Europe... Great to see that you fiddle in the factory too!

Comment by Brian Unruh on May 16, 2012 at 7:31pm

I had alot of fun flying with the doors off this past summer and fall. The wind was not too bad though in the cockpit of my 701 but this is a very good idea. I took up 7 people with the doors off and they all loved the experience!

Comment by Bob McDonald on May 16, 2012 at 11:53am

Air deflectors might even make flying with the doors removed just "a little less breezy" experience. Good stuff :>)

Comment by Paul Sanders on May 16, 2012 at 11:22am

Cool idea, and probably something that would work well for me in our 110+ summer heat (though at least it's a dry heat :) ). Not sure my wife would get in with no doors on, though.

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