Actually that rings a bell somewhere's. Might have been in "Stuka Pilot," or "War Planes of the Third Reich," but it does ring a bell.
Retractable gear cannot significantly correct the JU-87's faults without also altering the very things which made it the superior dive bomber. Think about this problem because what other plane is designed to create high lift? The JU-87 incorporates STOL qualities in to the design of the aircraft.
The JU-87 has the so-called Junkers Flaps, or sometimes called the Junkers Type, or Junkers Flying Flaps, or Junkers Double Flying Wing, because that's essentially what the control surfaces are; another small wing, and which is not the same as conventional control surfaces of other aircraft of it's time.
This a Junkers type control system on an Auster.
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Here are the pro's for the Junkers type control system.
Near zero lag in control input. Higher roll rate than plain ailerons. Shortened ground run when used as flaps (ailerons double as flaps). Favorable effect on main airfoil circulation. In the position of minimum drag the auxiliary wing can actually decrees the drag of the basic wing. No need to seal hinges. Remain effective when the main wing is stalled.
"Over the years Junkers flaps have shown up on many different light airplanes, (mostly home builts such as the Avid Aircraft), and with good reason. The phrase, "one of the most generally satisfactory high-lift devices investigated to date", keeps recurring throughout the NACA reports."
What's not so great is they have slightler higher drag and this of course increases exponentially with speed. They also have a higher pitching moment which is wonderful for a dive bomber and a STOL Aircraft, which an Avid is. The point is it's a high lift, slow speed control system. At high speed the Junkers system becomes dangerous because of flutter.