Thanks for the link, Ghenghis the Engineer, and the narrative of page 16 completely rubbishes the Flight International correspondent's assertion (as quoted in post #1 by Centaurus) that "increasing the aileron deflection only (serves) to generate adverse yaw."
Am surprised to learn, however, 42 years after a short stint (500 hrs P2), of the issue of rudder lock. I'm sure it was not covered on my course or on the line at Morton's, and for that time we had some of the most experienced C-47/DC3 skippers in Europe, e.g., Jo Rechka and Bill Caldwell.
The same page of the NACA report also confirms that the heaviness of the aileron controls is slightly above normal limits at airspeeds over 140kts (presume that must be in a dive!). Even at approach speeds, it could be quite an effort to pick up a wing-drop on a gusty day. That, and the initial rudder loads in asymmetry (a frequent event...) may be why our petite lady pilot, Yvonne Pope, never sought to get a command on the Gooney Bird.
Chris