About the Zero's elevator responsiveness and the cable stretch solutions: I noticed that this was mentioned earlier on in this thread and that someone was looking for a reference. There may of course be Allied reports saying the same thing, but the information can also be had from the horse's mouth so to speak
:
In his memoir book
Eagles of Mitsubishi, the Zero's Chief Designer Jiro Horikoshi actually dedicates a number of pages (pages 72 to 83) on this subject, and begins by stating that it was though that the Zero was actually TOO responsive in pitch at high speeds. That the roll response at high speed was poor is acknowledged in other parts of the book, but apparently the elevator was considered to be too responsive even at higher speeds. So while he confirms that stick forces in roll were too high, apparently they were not it pitch.
And those pages in the book also cover the solution, which was reducing the diameter of the elevator control cables from 4 to 3.5 and 3 mm in diameter. This introduced more flex in the elevator control circuit at high dynamic pressures, and it seems to have worked, because when they did flight trials, they concluded that not only did this fix the excessive responsiveness at higher speeds, but at the same time it did not mess with the low speed handling which still remained crisp.
Picture below from Jiro Horikoshi's book
Eagles of Mitsubishi
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