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Protrusion of control surface for energetic boundary layer and delayed separation

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aircraft

Well-Known Member
Joined
Jul 17, 2013
Messages
55
Location
Fremont, CA/USA
In "Flying On Your Own Wings", 2011, Zenith Aircraft designer Chris Heintz talked about the protrusion of a trailing aerodynamic surface to energize the boundary layer and delay the flow separation on the trailing aerodynamic surfaces (such as an elevator or an aileron). One way is increasing the thickness of the trailing surface as the following diagram from Mr. Heintz's book (a very good book, btw). thickerElevator.jpg

The other way is moving the hinge line (H.L.) of an elevator further aft to create a protrusion when the control surface has an deflection angle, also from Heintz's book.
aftHingeLine.jpg

According to him these two methods create a more energetic boundary layer and delays separation, which makes sense aerodynamically: when you have fresh stream in the boundary layer, it is more energetic, and a more energetic B.L. delays the separation. In the book he did not give any reference on this design approach.

It is my first time seeing this and very intriguing. I have some questions:
(1) Do these protrusions really have the benefits he claims?
(2) Have you seen these on his airplanes? planes designed by other people? I do not have access to an airport now.
(3) Any sources of publication (book, paper, report, anything!) that I can read more about this?
 
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